Commissioning Motor Variable Speed Drives (VSDs)

Engineering Encyclopedia Saudi Aramco DeskTop Standards

Commissioning Motor Variable Speed Drives (VSDs)

Note: The source of the technical material in this volume is the Professional Engineering Development Program (PEDP) of Engineering Services. Warning: The material contained in this document was developed for Saudi Aramco and is intended for the exclusive use of Saudi Aramco’s employees. Any material contained in this document which is not already in the public domain may not be copied, reproduced, sold, given, or disclosed to third parties, or otherwise otherwise used in whole, or in part, without the written written permission permission of the Vice President, Engineering Services, Saudi Aramco.

Chapter : Electrical File Reference: EEX30206

For additional information on this subject, contact W.A. Roussel on 874-6160

Engineering Encyclopedia

Electrical Commissioning Motor Variable Speed Drives (VSDs)

Content

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INTRODUCTION................................................................................................................ INTRODUCTION................................................................................................................ 1 SAUDI ARAMC ARAMCO O REQUIREME REQUIREMENTS................................................................................. NTS................................................................................. 2 EVALUATING EVALUATING MOTOR MOTOR VARIABLE VARIABLE SPEED DRIVES DRIVES UPON RECEIPT ......................... 6 Visual Visual Inspe Inspecti ction....................................................................................................... on....................................................................................................... 6 Verifi Verificat cation ion Agains Againstt Specifi Specificat cations ions ............................................................................ 6 Nameplate Nameplate Requirements Requirements ............. ....... ............ ............ ............ ............ ............ ............ ............ ............ ............ ............ ............ ...... 7 Design Design Require Requirement mentss ..................................................................................... 7 Instrume Instrumentat ntation ion and Control Control Requirement Requirementss .................................................... 8 EVALUATING MOTOR VARIABLE SPEED DRIVE INSTALLATION AND TESTING............................................................................................................................. 9 Visual Visual Inspe Inspecti ction....................................................................................................... on....................................................................................................... 9 Suitab Suitabil ility ity .....................................................................................................10 Physi Physical cal Damage...........................................................................................10 Damage...........................................................................................10 Solid Solid State State Devices Devices .......................................................................................10 Clean Cleanli lines ness....................................................................................................11 s....................................................................................................11 Mechanic Mechanical al Inspect Inspection ion ..............................................................................................11 Operat Operating ing Mechani Mechanism sm ...................................................................................11 Mounting Mounting Bolts.............................................................................................12 Bolts.............................................................................................12 Lubricat Lubrication ion ...................................................................................................12 Electrica Electricall Inspecti Inspection on and Test...................................................................................12 Point-t Point-to-Po o-Point int Wiring Wiring and Continui Continuity............................................................13 ty............................................................13 Contact Contact Resistanc Resistance........................................................................................13 e........................................................................................13 Insulat Insulation ion Resist Resistance.....................................................................................1 ance.....................................................................................14 4 Phase Sequence and Rotation........................................................................15 Rotation........................................................................15 High-Pot High-Pot Testing Testing ..........................................................................................15

Saudi Aramco DeskTop Standards



SYSTEM PRE-OPERATION PRE-OPERATIONAL AL CHECK-OUT CHECK-OUT PHASE ....................................................18 SYSTEM OPERATIONA OPERATIONAL L OBSERVANCE OBSERVANCE PHASE .........................................................20 WORK WORK AID AID 1: REFERENCES REFERENCES FOR EVALUATIN EVALUATING G MOTOR MOTOR VARIABLE VARIABLE SPEED DRIVES DRIVES UPON RECEIPT.......................................21 Work Aid 1A: Motor Variable Speed Drive Technical and Construction Require Requirement mentss ....................................................................................21 Work Aid 1B: Instrumentation and Controls.............................................................31 Work Work Aid 1C: Alarm and Indicatin Indicating g .........................................................................32 Work Aid 1D: Input and Output Interfaces...............................................................33 Interfaces...............................................................33 Work Aid 1E: VSD Microprocess Microprocessor.........................................................................34 or.........................................................................34 Work Aid 1F: Data Schedule....................................................................................34 Schedule....................................................................................34 WORK WORK AID AID 2: REFERENCES REFERENCES FOR EVALUATIN EVALUATING G MOTOR MOTOR VARIABLE SPEED DRIVE INSTALLATION AND TESTING..............36 Work Aid 2A: Testing Testing Requiremen Requirements ts........................................................................36 ........................................................................36 Work Aid 2B: Visual Inspectio Inspection n ...............................................................................37 Suitab Suitabil ility ity .....................................................................................................37 Physi Physical cal Damage...........................................................................................37 Damage...........................................................................................37 Solid Solid State State Devices Devices .......................................................................................37 Clean Cleanli lines ness....................................................................................................37 s....................................................................................................37 Work Aid Aid 2C: Mechanical Inspections, Inspections, Tests, Tests, and and Checks...... Checks ............ ............ ............ ............ ............ ..........38 ....38 Operat Operating ing Mechani Mechanism sm ...................................................................................38 Mounting Mounting Bolts.............................................................................................38 Bolts.............................................................................................38 Lubricat Lubrication ion ...................................................................................................38 Work Aid 2D: Electrical Electrical Tests and Checks ...............................................................38 Manufac Manufactur turing ing Facilit Facility y Checks Checks and Tests Tests ......................................................38 Point-t Point-to-Po o-Point int Wiring Wiring and Continui Continuity............................................................39 ty............................................................39 Contact Contact Resistanc Resistance........................................................................................40 e........................................................................................40 Insulat Insulation ion Resist Resistance.....................................................................................4 ance.....................................................................................40 0 Phase Sequence and Rotation........................................................................41 Rotation........................................................................41 High-Pot High-Pot Testing Testing ..........................................................................................41 Work Aid 2E: Operational Operational Checkouts and Tests Tests .......................................................42 Saudi Aramco DeskTop Standards



Power and Terminal Verification...................................................................43 Drive Operation Testing with the Motor Disconnected..................................43 Motor Rotation Rotation Check ..................................................................................44 Work Aid 2F: Excerpts Excerpts from from GI 2.710 .....................................................................45 GLOSSARY........................................................................................................................49

-----------------------------------------------------------------------------------------------------------------Table of Figures

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Figure 1: VSD With Self-Commutating Self-Commutating Inverter Inverter and Constant Current Control ........ ...... .. 4 Figure 2: Typical Results of High-Pot Tests............. Tests....... ............ ............ ............ ............ ............ ............ ............ ............ ......17 17 Figure 5: VSD Vendor Requirements and Equipment Site Conditions (from (from 17-SAMSS-517) 17-SAMSS-517) ...........................................................................21 Figure 6: General VSD Design Design Requirements Requirements (from 17-SAMSS-517)...... 17-SAMSS-517)............ ............ ..........22 ....22 Figure 7: VSD Construction Requirements (from 17-SAMSS-517) ............ ...... ............ ............ .......23 .23 Figure 7: VSD Construction Construction Requirements Requirements (from (from 17-SAMSS-517) 17-SAMSS-517) (Cont'd)......... ...24 Figure 7: VSD Construction Construction Requirements Requirements (from (from 17-SAMSS-517) 17-SAMSS-517) (Cont'd)......... ...25 Figure 8: VSD Component Component Design Design Requirements Requirements (from (from 17-SAMSS-517)....... 17-SAMSS-517)............. .........26 ...26 Figure 8: VSD Component Design Requirements Requirements (from (from 17-SAMSS-517) 17-SAMSS-517) (Cont'd)..27 (Cont'd). .27 Figure 8: VSD Component Design Requirements Requirements (from (from 17-SAMSS-517) 17-SAMSS-517) (Cont'd)..28 (Cont'd). .28 Figure 8: VSD Component Design Requirements Requirements (from (from 17-SAMSS-517) 17-SAMSS-517) (Cont'd)..29 (Cont'd). .29 Figure 8: VSD Component Design Requirements Requirements (from (from 17-SAMSS-517) 17-SAMSS-517) (Cont'd)..30 (Cont'd). .30 Figure 9: VSD Microprocessor Microprocessor Diagnostic Diagnostic and Event Recording System (from (from 17-SAMSS-517) 17-SAMSS-517) ...........................................................................34 Figure 10: Medium Voltage Induction Induction Motor Variable Variable Speed Drives Data Schedule Schedule (from (from 17-SAMSS17-SAMSS-517) 517).............................................................35 .............................................................35 Figure 11: Manufacturing Manufacturing Facility Facility Checks and Tests (from (from 17-SAMSS-517).......... 17-SAMSS-517)............39 ..39 Figure 12: Dielectric Absorption Ratio Chart........ Chart.. ............ ............ ............ ............ ............ ............ ............ ............ .........40 ...40 Figure 13: Example of DC Hi-Pot Hi-Pot Test (Good and Bad Cable Insulation) ............ ...... ..........42 ....42 Figure 14: GI 2.710 2.710 Excerpt....................................................................................46 Excerpt....................................................................................46 Figure 14: GI 2.710 2.710 Excerpt Excerpt (Cont'd) (Cont'd) ......................................................................47 Figure 14: GI 2.710 2.710 Excerpt Excerpt (Cont'd) (Cont'd) ......................................................................48




INTRODUCTION

When speed control of industrial motors is required for an installation, motor variable speed drives (VSDs) are used. Applications Applicatio ns for motor VSDs include pumps, blowers, fans, cranes, and compressors. Once a motor VSD for a given installation is chosen, the drive is ordered, shipped, and received. Once received, the VSD is receipt receipt inspected inspected and tested tested as part of the commissioning process. The commissioning process for motor VSDs that are installed in Saudi Aramco facilities ensures that a safe and cost-effective system is installed that performs to the specifications of the facility for the projected operating lifetime of the facility. Experience has shown that the time and effort that are expended up front to ensure safety, quality control, and adherence to Saudi Aramco and industry standards minimizes subsequent equipment failure. The motor VSD commissioning process involves evaluations, verifications, and checks that determine whether the proper equipment specifications and installation requirements are met. Tests are performed and the test results are evaluated to determine whether the motor VSD will operate properly and safely after it is placed in service. service. When a motor VSD is inspected and tested satisfactorily during the commissioning process, it should operate in accordance with manufacturer's specifications for its maximum useful life. Electrical Engineers must be able to direct the commissioning of new motor VSDs. This Module provides information information on the following following topics that are pertinent to the commissioning commissioning of motor VSDs for Saudi Aramco installations: •

Saudi Aramco Requirements

•

Evaluating Motor Variable Speed Drives Upon Receipt

•

Evaluating Motor Variable Speed Drive Installation and Testing

•

System Pre-Operational Pre-Operational Check-Out Phase

•

System Operational Observance Phase


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SAUDI ARAMCO REQUIREMENTS

Large process equipment and large process support equipment rely on motors for primary and ancillary functions throughout the manufacturing process (e.g., fans, circulation pumps, blowers). During the commissioning process, the Electrical Engineer will be required to be familiar with the design and construction requirements of motor VSDs. This section of the module will describe the Saudi Aramco requirements for motor VSDs. There are many different kinds of electronic ac drives that vary the speed of a motor. Electronic variable speed drives can be divided into the following three general categories: •

Static frequency changers

•

Variable voltage controllers

•

Rectifier/inverter systems

Static frequency converters convert the incoming line frequency directly into the desired load frequency. A typical example of a static frequency converter is the cycloconverter, which is used to drive both synchronous synchronous and squirrel-cag squirrel-cagee motors. Variable voltage voltage controllers controllers vary the incoming ac voltage, and they are commonly used in squirrel-cage and wound rotor induction motors. Variable voltage speed control is the least expensive, and it provides satisfactory speed control for small and medium voltage fans, centrifugal pumps, and hoists. Rectifier/inverter systems rectify the incoming ac and convert the resulting dc back to ac at the desired frequency. For Saudi Aramco squirrel-cage induction motor VSD installations, self-commutating inverters are used. Power thyristors thyristors are used to rectify rectify the ac, and they are arranged arranged in a conventional three-phase three-phase bridge circuit. Self-commutating Self-commutating inverters convert convert dc power to ac power. In addition to power po wer thyristors, auxiliary components (e.g., capacitors, diodes, coils, and other thyristors) are used to vary the commutation of the power thyristors to provide reactive power generation in the system. Figure 1 shows a simplified one-line diagram of a VSD that uses a self-commutating inverter with constant current control. The VSD consists of a thyristor-based thyristor-based rectifier rectifier bridge that that converts ac power to dc power, dc link smoothing reactors on the positive and negative legs, and a thyristor based current source inverter bridge that converts the dc power into variable voltage, variable frequency, current regulated ac waveforms.


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In Figure 1, the three-phase three-phase line line is applied applied to the the thyristors in the power converter. High power surge arrestors are used in the three-phase line to protect protect against voltage surges. The thyristors are mounted in modular groups that contain all of the associated surge suppression and gate isolation components. components. The thyristor gate control control signals are transmitted transmitted from the gate triggering triggering processor through fiber optic cables. The gate triggering processor regulator monitors voltages (e.g., E1 and E2) and individual thyristors to ensure that the gate signal is provided at the proper time. The gate signal signal causes causes each thyristor thyristor to conduct (or block) in response to control settings, limit settings, settings, and external inputs, such as motor speed or dc current. Because large power thyristors generate heat, a power converter cooling system is used on VSD systems for motors motors that are rated more than 746 kW (1,000 hp). The power converter cooling system provides optimum efficiency and increased reliability, and it minimizes the size of and dependence on air conditioning units. Dc link reactors (DCLRs) are used on the dc side of the power converters to control the current during normal operation operation and fault conditions. Two DCLRs are provided: one for the positive positive dc side and one for the negative dc side of the power converter. During normal and fault conditions, the DCLRs provide a constant current to the inverter and limit any dc ripple to a maximum of 10 percent. Figure 1 shows the direction of dc current (Idc) through the DCLRs (L1 and L2). From the DCLRs, the constant constant dc current is sent to to the self-commutated self-commutated inverter. At the inverter, the constant dc current is gated through a thyristor assembly that creates rectangular current pulses (Iac) that are 120 electrical degrees apart. The inverter creates creates the rectangular rectangular current pulses at a frequency and magnitude in response to thyristor gate control signals from the gate triggering processor. The frequency and magnitude of the rectangular current pulses will result in voltage drops (E) across each motor stator winding phase (A, B, and C) for proper squirrel-cage induction motor operation.


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Figure 1: VSD With Self-Commutating Inverter and Constant Current Control

To allow the retrofit of an existing motor without derating the system, the VSD output is filtered. The output filter provides a sinusoidal waveform that contains a maximum of five percent total harmonics to minimize motor heating. When required, a withdrawable output contactor conta ctor is also provided to disconnect and and isolate the drive and filter filter from the motor. motor. When required for the installation, a bypass is incorporated into the VSD design and construction. A bypass is used to bypass the VSD in case of a VSD failure or to operate the motor at full speed. A VSD bypass is accomplished through use of a withdrawable contactor or breaker (as shown on the engineering engineering drawings). Bypass protection protection must be in accordance accordance with 16-SAMSS-506 (for contactors) or 16-SAMSS-501 1 6-SAMSS-501 (for breakers). breakers). The bypass system system must provide a smooth, smooth, closedtransition synchronous transfer of the induction motor from the drive to the main ac line and from the main ac line back to the drive.


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Transition is accomplished without stopping or slowing the motor and without significant transients on the line. When an isolation transformer is installed in the VSD system, system, the isolation transformer must allow full voltage starting when a VSD bypass is specified in the Data Schedule. The minimum mandatory technical requirements for the procurement and installation of VSDs to control the speed of three-phase, 4 kV and 6.6 kV, squirrel-cage induction motors that are installed in Saudi Aramco industrial facilities are defined in 17-SAMSS-517. 17-SAMSS-517 covers specific references, design requirements, construction requirements, testing, and engineering studies that must be used in conjunction with the procurement and installation of VSDs. Excerpts from 17-SAMSS-517 are provided provided in Work Aid 1.


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EVALUATING MOTOR VARIABLE SPEED DRIVES UPON RECEIPT

The installation of motors in Saudi Aramco facilities is a process that occurs over a period of time. Variable speed motors drive specialized equipment that is critical to the manufacturing or refining process. Variable speed motor installations begin with an identified need for speed control of motors in a new facility. After the facility design is is approved, variable speed motors and their associated associated VSDs are ordered from the manufacturer. When the VSDs are received from the manufacturer, they they must be evaluated to ensure that they they are proper for the installation. installation. The purpose of the evaluation is to verify that the correct VSDs were received from the manufacturer and that the proper installation specifications and parameters were met. This section will describe how VSDs are evaluated upon receipt during the commissioning process. Visual Inspection

When VSDs are received from the manufacturer, a visual inspection should be performed. The purpose of the visual inspection inspection is to verify verify that the VSD that was received from the manufacturer manufacturer is in good physical condition and that the enclosures and cooling equipment (if present) have not been damaged during during shipment. During the initial initial visual visual inspection, inspection, the inspection inspection personnel look look for obvious equipment damage and determine whether all necessary equipment (e.g., contactors, alarm panels, and instrumentation) are present. A detailed inspection of the VSD equipment is also performed when it is completely installed at the site or facility. Verification Against Specifications

When a new facility or facility modification is at the equipment installation stage, the design of the installation has already been completed. The design and ratings of a motor VSD that is selected for a specific installation should be shown in the drawings, prints, or specifications for the installation. The purpose of verifying VSDs against the specifications specification s is to ensure that the VSD that is being installed meets Saudi Aramco and industry standards. Generally, the verification against specifications consists of a determination of whether the VSD that is to be installed matches the VSD that is specified for the installation. In most cases, this determination is accomplished by reading an electrical plan that identifies the motor size, the speed control parameters, and additional or optional items (e.g., bypass, isolation transformer, or cooling system). The Electrical Engineer inspects the manufacturer's nameplate data on the VSD, and he compares them to the requirements on the electrical plan to determine whether the VSD is correct for the installation. In other situations, the Electrical Engineer must rely on his knowledge of the correct application of motors and motor VSDs to determine whether the correct VSD is being used. The data schedule that was used to order the VSD from the manufacturer should also be consulted. consulted. The data schedule for medium voltage induction motor variable speed drives is provided in Work Aid 1. Any quality control, quality assurance, and test data that are provided with the motor VSD by the manufacturer should also be reviewed. Saudi Aramco DeskTop Standards

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Nameplate Requirements

Nameplates are required for all variable speed induction motor VSDs that are used in Saudi Aramco facilities. All devices that are located within a panel must be provided with suitable suitable nameplates to identify item and their function. The nameplate should contain manufacturer-type information. The information that describes the machine manufacturer's information should consist of the manufacturer's name, the serial or model number, and system parameters (e.g., voltage output and speed range). range). The system parameters on the nameplate nameplate should be in accordance accordanc e with system prints or electrical one-line diagrams. Nameplate physical construction requirements are provided in Work Aid 1. Design Requirements

Design requirements for variable speed motor VSDs should be in accordance with system prints or electrical one-line diagrams that are attached to the data schedule. Design requirements must include the following information: •

Input ac isolation transformer (when required)

•

Thyristor bridge cubicle

•

Control cubicle

•

Liquid cooling cubicle (when required)

•

DC link reactor cubicle

•

Contactor/switchgear cubicle

•

Output filter cubicle

•

Heat exchanger cubicle (for outdoor-liquid cooled systems only)

•

VSD bypass (when specified)

The cubicles are bolted together to form a continuous switchgear assembly, and the entire VSD system should be constructed for ease of maintenance in order to minimize downtime. Specific Saudi Aramco design requirements for VSD installations are provided in Work Aid 1. VSD indoor enclosure, wiring, and external connection requirements are also provided in Work Aid 1.


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Instrumentation and Control Requirements

The instrumentation and controls for VSDs must be designed for ease of operation and maintenance of the equipment. The minimum instrumentation and controls equipment that is required on VSDs for Saudi Aramco installations is provided in Work Aid 1. Indications must be provided (both local and remote) for VSD abnormal and alarm conditions. conditions. The minimum requirements for alarm and trip annunciators are provided in Work Aid 1. For overall control and indication, it is necessary for the VSD to interface with remote control and indicating equipment. For Saudi Aramco VSD installations, input and output interfaces are required. Minimum VSD input and output signal and contact requirements are provided in Work Aid 1. Because of the rapid speed of the converter/inverter process and because of the tight controls and tolerances that are required, VSDs use a microprocessor to control the process. VSD microprocessor diagnostic and event recording system requirements are provided in Work Aid 1.


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EVALUATING MOTOR VARIABLE SPEED DRIVE INSTALLATION AND TESTING

The process of determining whether motor VSDs should be commissioned is to verify that all of the electrical inspections and tests have been properly performed and to verify that the test results meet the specifications that are designated by the applicable Saudi Aramco and industry standards. Installation inspections are performed to verify that proper VSD installation materials are used, that installation specifications and parameters are met, and that proper installation procedures are followed. The installation inspection is conducted to ensure that VSDs will function properly once they are installed. Electrical tests are performed to check the ability of VSDs to function under all operating conditions and loads. Installation tests should detect shipping or installation damage, gross manufacturing defects, or errors in workmanship or installation. Although there is no Saudi Aramco Pre-Commissioning Form for induction motor VSD installations, accepted engineering practices should be used during the installation and testing phase of VSD commissioning. The proper evaluation of inspection and testing data during the commissioning process can maximize the operating time of VSD installations through a determination of trends towards failure. Failure prediction can drastically reduce equipment downtime. If a failure is predicted, operational changes can be made, maintenance can be performed, or equipment that is failing can be replaced in a controlled controlled manner. If a problem is corrected before it causes damage, operating costs will be lower because it can avoid a malfunction that can cause associated (or nearby) equipment damage and disruption of service that can make the activation of emergency repair crews necessary. A failure in any one of the many inspections, checks, or tests that are performed on VSDs during the installation and testing evaluation is sufficient to prevent the VSD from being commissioned. Visual Inspection

Visual inspections are used to assess the physical condition of VSDs during the commissioning process. process. A visual inspection inspection is a pass/fail pass/fail verification verification about a particular particular aspect of the physical physical condition or the operation of the the VSD. Because the criteria that are established to determine determine the acceptability of the visual inspections can be subjective, the visual inspections should be performed performed by an experienced experienced Electrical Electrical Engineer. Engineer. This section section will describe describe visual inspection inspection items for induction motor VSDs. Because of the different manufacturers, models, and configurations of VSDs, there may be several different courses of action for a visual inspection failure. The course of action depends on the part of the machine machine that failed the visual inspection. inspection. For example, example, a failure failure of cleanliness cleanliness visual inspection can generally be corrected through cleaning. A physical physical damage or suitability suitability inspection failure will probably require the replacement of the the damaged component. The following visual inspections are used to assess the condition of VSDs in Saudi Aramco systems:


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•

Suitability

•

Physical Damage

•

Solid State Devices

•

Cleanliness

Suitability

The purpose of the suitability visual inspection is to determine whether the motor VSD is appropriate for the application. Under normal circumstances, the suitability of the VSD should be determined before it is placed in the system; however, a visual inspection should be performed to ensure that the motor VSD is correct for the installation. installation. To determine the suitability suitability of a motor VSD, a visual inspection of the nameplate data should be performed, and the motor VSD should be compared compared to what is specified specified in the electri electrical cal system system single-lin single-linee diagram. diagram. Physical Damage

Physical damage to to a motor VSD VSD can lead to motor failure failure or improper improper operation. Because motors support fluid flow (e.g., lubricating or cooling oil), a motor VSD failure can lead to catastrophic equipment failure, fire, personal injury, or death. Any physical damage to a motor VSD or any missing parts that are noted during the physical damage visual inspection requires the immediate replacement of the damaged component. The most obvious and common forms of physical damage are cracks, dents, missing or broken pieces, and bent ventilation openings. The purpose of the physical damage inspection inspection is to identify identify whether corrective corrective maintenance maintenance or component componen t replacement is necessary. Motor VSDs that show any form of physical damage, no matter how small, should be determined to have failed the physical damage inspection. Solid State Devices

Solid state devices require a visual inspection prior to the VSD commissioning. Power thyristors generate a great deal of heat, and visual indications of overheating indicate damaged thyristors, improper cooling, or wiring problems. Printed circuit boards (PCBs) should be inspected to determine whether they are properly seated at the board board edge connectors. Board locking tabs should also be in place. When PCBs require cleaning, only manufacturer-approved cleaning solutions may be used. Solvents must must not be used on PCBs. PCBs.


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Cleanliness

The purpose of the cleanliness visual inspection is to ensure the proper operation of the VSD over its maximum operating life. Although a VSD is static (i.e., there are no rotating parts), the accumulation of dirt over a period of time can still impede the proper operation of the VSD by lowering the efficiency of the cooling system and by reducing the dielectric strength of the insulation. The accumulation of heavy amounts of dust and dirt should be cleaned away from from the VSD during maintenance cycles. Contacts that are used in isolation, supply, or bypass components, such as contactors or circuit breakers, should be checked for excessive wear and the accumulation accumulation of dirt. A slight discoloration or pitting at the contact's surface is normal and will not affect the proper operation of the contact. Mechanical Inspection

A mechanical inspection is used to assess the ability of the machine to physically perform what is necessary for proper operation. Because there are several mechanical inspection items that are associated with motor VSDs, there are a number of corrective actions for a mechanical inspection failure. The corrective corrective action action depends on the part of the VSD that failed failed the inspection. For example, a mounting bolt inspection failure can usually be corrected through adjustment of the bolts with a torque wrench. The general mechanical inspections and tests that are performed on motor VSDs that are installed in Saudi Aramco systems are as follows: •

Operating Mechanism

•

Mounting Bolts

•

Lubrication

Operating Mechanism

The operating mechanism for isolation, supply, or bypass components must be inspected during the commissioning process. During the mechanical inspection of the operating mechanism of VSDs, the Electrical Engineer should check for the proper operation of all moving parts. The operating mechanism's moving parts should exhibit freedom of movement with no evidence of sticking or binding. All operating mechanism fasteners and linkages should be checked for loose, broken, or badly deformed parts. parts. Improperly operating operating or damaged components must be replaced prior to commissio commissioning. ning.


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Mounting Bolts

The purpose of a mounting bolt inspection is to verify that the motor's mounting bolts are securely fastened. The bolts and frame mounts must be capable of preventing the VSD cabinets and internal equipment from coming loose during mechanical failure or electrical fault conditions. To perform the mounting bolt check, the manufacturer's technical manual is consulted for the proper bolt torque value. A torque wrench is then used to determine the amount of torque at the bolt. Improper torque values are immediately corrected. Lubrication

The lubrication system visual inspection should be performed in conjunction with the cleanliness visual inspection. The purpose of the lubrication visual inspection is to ensure that the moving parts of the VSD are provided with the proper lubrication. The items that are inspected in the performance performance of the lubrication lubrication system visual inspection inspection are dependent on the type of lubrication lubrication system with with which the VSD is equipped. equipped. Some magnetic magnetic starters starters and contactors are designed to operate without lubrication. lubrication. Lubrication of components that do not require require lubrication can cause improper operation. The manufacturer's technical manual should be consulted for lubrication requirements. Electrical Inspection and Test

During the commissioning process, electrical inspections and tests are performed to check the ability of induction motor VSDs to operate for a reasonable future period of time under all operating conditions and loads. Acceptance or installation tests will usually detect shipping or installation damage and gross defects or errors in workmanship in equipment construction. Once the installation and inspection data have been recorded and assembled, a methodical and consistent program of periodic data collection and evaluation should be established. As each new maintenance item, test, system addition, or system reconfiguration occurs, new inspections and data records will be required and should be added to the existing data on file. Because an electrical inspection or test failure can be caused by a design flaw, construction error, equipment age, or operational misuse, some type of troubleshooting or maintenance activity should be performed on the faulty faulty equipment. For example, an insulation resistance (megger) test failure can usually be rectified by cleaning the interior of the VSD to remove dirt or moisture. Some electrical inspection or test failures are not repairable, and they will require the replacement of the equipment before the VSD can be commissioned.


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The following electrical inspections, checks, and tests are performed on induction motor VSDs: •

Point-to-Point Wiring and Continuity

•

Contact Resistance

•

Insulation Resistance

•

Phase Sequence and Rotation

•

High-Pot Testing


Point-to-point wiring checks are performed to verify that VSDs comply with Saudi Aramco wiring diagrams and manufacturer's specifications. specifications. Terminations and terminal terminal blocks within within the VSD operations and controls cabinets are also checked for routing and labeling. During the point-to-point point-to-point wiring checks, control and metering equipment (e.g., transformers transformers and fuses) is checked for proper application and type. All VSD wiring is also checked for continuity and compared against the wiring diagrams that are provided. The VSD wiring continuity test is performed with a buzzer or bell-type continuity continuity tester. Written checklists checklists or drawings are used as reference material during the continuity tests. Contact Resistance

The purpose of the VSD contact resistance test is to identify contacts that are defective or detrimental to the operation of the contactor or the starter that is contained in the VSD. The contact resistance test may also identify loose connections in the contactor or starter. To conduct the contact resistance test, the equipment that is to be tested must be disconnected from the system, if possible. Generally, contactors contac tors or starters have removable cubicles cubic les or drawers to facilitate temporary removal for maintenance or testing. Once the equipment is removed, and with the contacts in the closed position, the leads of a digital, low-resistance ohmmeter are placed across the line and load sides of the contacts, and measurements are taken. A digital lowresistance ohmmeter can deliver enough power to the contacts to make accurate readings that have more validity than do those readings that can be obtained through the use of an ordinary multimeter. The contact resistance resistance is recorded on a test data sheet and retained retained in Saudi Aramco material history records. Increased contact resistance may be caused by contacts that do not make proper contact or by pitting on the surface of the contacts. The contact resistance values that are recorded should be consistent with the manufacturer's recommended values. Generally, values of contact resistance in excess of 200 microohms and deviations of more than +/- 20% should be investigated. Technical data to evaluate the results of the contact resistance test can be found in the equipment manufacturer's technical manual or in the Saudi Aramco Pre-Commissioning form, P-000, Testing Guide Lines. Saudi Aramco DeskTop Standards

13



Insulation Resistance

The purpose of the insulation resistance (megger) test is to directly measure the insulation resistance of the induction motor VSD components. An induction motor VSD takes ac power from the electrical distribution system, rectifies it, and then converts it to ac power at specified frequencies. frequencie s. The inverter/converter inverter/con verter section of VSDs consists of static semiconductor devices. Because the voltage potentials that are generated during the megger test can damage any connected semiconductor equipment, megger tests must not be performed on semiconductor equipment. Insulation Insulation resistance tests tests on induction motor motor VSDs are usually conducted on the ac input and the ac output sections of the VSD. Example VSD components that are megger tested are the input breaker or the contactor, the bypass (if used), and the ac output connections to the induction motor. In the insulation resistance test, the megger produces a voltage that causes leakage currents to flow in the insulation insulation between conductors. conductors. The amount of leakage current current flow that is detected detected through use of the megger results in a megger meter readout of insulation resistance in megohms. To conduct the insulation resistance megger test, each component that is to be meggered is electrically disconnected from the system. The megger is connected between each phase and from each phase and ground, and the megger is operated. Insulation resistance megger megger tests are be conducted for each phase combination. combination . The insulation resistance values are recorded on a commissioning test data sheet. During the commissioning process, the Electrical Engineer should evaluate the insulation resistance (megger) test values to ensure that the megger values that were recorded are greater than the manufacturer's minimum values. Information that is used to evaluate megger readings are provided in Work Aid 2. Any value of insulation resistance that is less than the minimum minimum specifications should be investigated by the Electrical Engineer who performs the test data evaluation. The ratio of two time-resistance readings (such as a 60-second reading that is divided by a 30second reading) is called a dielectric absorption ratio. The dielectric absorption ratio is useful in recording information about the insulation. If the ratio is a ten-minute reading that is divided by a one-minute reading, the value is called the polarization index. Because constant cranking is required for hand-cranked megger instruments, it is easier to run the test for only 60 seconds and take the first reading reading at 30 seconds. When a power-operated megger instrument is used, the results of running the test for a full ten minutes and taking readings at one minute and at ten minutes will give the polarization index. An explanation of the evaluation of the dielectric absorption ratio is provided in Work Aid 2.


14




In addition to the more familiar electrical tests, such as insulation resistance, Electrical Engineers who are commissioning VSDs should be familiar with the phase sequence and rotation tests that are performed. Phase sequence and rotation tests are performed to ensure that the power supply inputs to the VSD are at the proper voltage and in the proper phase sequence. Sequence and rotation testing testing are performed to ensure ensure that the motor (when connected) will rotate in the correct correct direction. If the motor that is being supplied by the VSD rotates in the wrong direction, damage can occur to the motor bearings and to the connected motor load. Phase rotation and phase phase sequence testing are usually final pre-energization requirements because they are performed through energization of a portion of the VSD. During the phase sequence and rotation tests, the ac power input leads are checked for proper markings to ensure that the sequence coincides with the incoming power system. A visual verification of the motor leads is also conducted to ensure that the motor leads are properly marked to coincide with with the VSD output leads. The motor lead markings and the VSD output lead markings must match so that the motor shaft will rotate in the correct direction. High-Pot Testing

When VSDs are installed for motors that are greater than 746 kW (1,000 HP), the power converters in the VSD must use a closed-loop liquid cooling system for optimum efficiency and increased reliability and to minimize the size of and dependence on air conditioning units. The closed-loop cooling systems have additional construction and testing requirements that are described in 17-SAMSS-517. 17-SAMSS-517. The closed-loop cooling system must be designed with a separate low voltage cubicle to allow coolant replacement or pump servicing with the drive completely operational. All cooling medium hoses must consist of flexible, high-dielectric material, and they must be high-pot tested to 50 kV. The dc high potential (high-pot) test is performed to provide positive proof that insulation has sufficient voltage voltage strength to to ride out overvoltage surges. surges. The dc high-pot test should be done prior to the initial energization of the motor VSD and after satisfactory satisfactory megohmmeter testing. The dc high-pot testing technique involves the measurement of increased dc voltage that is applied to the equipment under test. The value of the leakage current current is tracked as as the test voltage is increased through several steps, and this value becomes a criterion of the condition of the equipment insulation.


15



The Electrical Engineer should evaluate the dc high-pot test leakage current test data to ensure that the high-pot test test data meets the minimum minimum requirements requirements of a successful test. test. To conduct the dc high-pot test on cooling medium hoses, a test set is connected between the hose and ground. After the test set is connected, the initial test voltage of approximately 16.5 kV (33% of the maximum test voltage of 50 kV) is applied to the hose. The initial test voltage is held for ten minutes, and the leakage current, as read on the test set, is monitored. The value of leakage current is recorded at the end of each one-minute interval. The polarization index is calculated from this test data through division of the leakage current after one minute by the leakage current that is obtained after ten minutes. When the first ten minutes of the test are complete, the test voltage should be raised from the initial value to the maximum value in in ten equal steps. After each step increase in voltage, the voltage should be held at the new level for a period of one minute, and the leakage current should be recorded at the end of each minute. The results of a high-pot test are not compared to a specific value to determine whether the results are acceptable. Instead, the results of a high-pot high-pot test are analyzed for trends that indicate whether the insulation has sufficient strength to ride out overvoltage surges. A polarization index value of less than two, or dc high-pot test data curves that indicate a steady increase in leakage current over the duration of the test, should be investigated by the Electrical Engineer who performs the test data evaluation. Figure 2 shows a graphic display of the typical results of high-pot tests for both good and bad insulation. The graph that is shown in Figure 2A is for the first ten minutes of a high-pot test. The curve that represents good insulation shows a steep rise in leakage current over the first oneminute interval that is followed by a steady decrease in the value of leakage current over the remainder of the ten-minute interval. The curve that represents bad insulation shows a steady increase in in the value of leakage current current throughout the ten-minute ten-minute interval. interval. Such a curve indicates unsatisfactory insulation, and the high-pot test should be stopped. The graph that is shown in Figure 2B is for the last ten minutes of the high-pot test. The curve that represents good insulation shows a slow, steady increase in the value of leakage current as the test voltage is raised from the initial value to the maximum value. The curve that represents bad insulation shows a sharp upturn or knee when the test voltage is increased to the point at which the insulation starts to break down. A knee in the leakage current curve indicates unsatisfactory unsatisfactory insulation, and the high-pot test should be stopped.


16



Figure 2: 2: Typical Results of High-Pot Tests Saudi Aramco DeskTop Standards

17



SYSTEM PRE-OPERATIONAL CHECK-OUT PHASE

Although thorough checks and tests are performed at the manufacturing facility prior to shipment to identify any components that may be subject to premature failures, a pre-operational check-out phase of the commissioning commissioning process is conducted at the VSD installation installation site. Checks and tests that are performed at the manufacturing facility include thyristor testing, PCB burn-in (at 65oC), phase cell balance testing, testing, and a complete VSD burn-in at full load amps for 24 hours. Microprocessors, printed circuit boards, diagnostic boards, and similar devices (including software) are also tested at the manufacturing manufacturing facility for proper operation, sequencing, logic, and diagnostics. When load testing is specified in the data schedule, load testing at the manufacturing facility is performed and the manufacturer must determine determine the VSD efficiency. Data from all manufacturing facility checks and tests should be reviewed during the commissioning process. Once a VSD is installed, the system pre-operational check-out phase of the commissioning cycle for induction motor VSDs provides an opportunity for Saudi Aramco personnel to perform onsite wiring checks, subsystem subsystem component checkouts, checkouts, and VSD component interlock tests. tests. Before any testing that requires energization is conducted, however, all of the discrepancies that were identified during the prior portion of the commissioning process that could result in equipment damage or personnel injury must be corrected. During the pre-operational checkout phase, the VSD is still isolated and independent from the connected motor load. Subsystem testing testing before the VSD is connected to the motor load is critical to ensure the proper and safe operation of the VSD protection and control subsystems. Each VSD component is checked to ensure that it works individually and as a complete system. Subsystems are checked to ensure that electrical continuity exists for control and protective devices. The proper operation of all subsystems subsystems is tested tested through use of controlled controlled operation and checkout of the controls and protective devices. Although there are many different manufacturer's configurations of VSDs, most VSDs have similar subsystem subsystem and component operation operation and checkout test procedures. For a specific VSD's subsystem and component operation and checkout tests, the manufacturer's technical manuals should be consulted; however, a brief overview of testing is provided in the following paragraphs. VSD speed control operation and checkout testing is performed at both the local and remote control panels. Speed control operation operation and checkout testing testing consists of start, stop, ramp, reversing, jog, and frequency skip operations. The start, stop, and ramp operations are performed by starting starting and stopping the VSD and by observing different frequency outputs. VSDs can have coast, brake, and ramp stop features. The ramp and brake operations must be tested for proper operation. The time that it takes for for the VSD to accelerate to the required speed and the time that that it takes for the VSD to stop (for all stopping modes) must be within the manufacturer's specified time period. The controlled change of speed at a fixed fixed ramp rate for start, start, stop, and frequency change operations is tested, as well as the VSD minimum and maximum speeds.


18



The controlled operation and checkout of the VSD protective devices is performed to ensure that the various VSD VSD protective devices' devices' operational operational interlocks interlocks function properly. properly. Various VSD alarms, indications, trips, and interlocks that are provided with a VSD can vary with the size, the type, and the the manufacturer manufacturer of the the VSD. Generally, VSDs are provided provided with overvoltage, undervoltage, overspeed, and overcurrent overcurrent trips. If a VSD is equipped equipped with a bypass, a bypass bypass interlock is provided. Each control alarm, indication, trip, and interlock is tested during the controlled operation and checkout phase of the commissioning process.


19



SYSTEM OPERATIONAL OBSERVANCE PHASE

The system operational observance phase allows Saudi Aramco personnel an extended operational observance period to determine whether any abnormal conditions exist that were not uncovered during any previous tests or checks. Although an extended system operational observance phase would be an ideal way to determine the long-term operational capabilities of a newly installed system, it is not always practical. The added expense of conducting an extended operational observance of a newly installed system can sometimes outweigh the expense of simple system isolation and repairs in the event of a component or system failure. A careful study in each case should be conducted to determine whether a system operational observance phase is cost-effective for the given installation. The induction motor VSD operational observance phase of the commissioning cycle provides an opportunity for Saudi Aramco personnel to perform the following: •

VSD system and component temperature checks.

•

VSD operational inspections.

VSD system and component temperature checks are performed through the use of temperature monitoring equipment. During the VSD operational observance phase of the commissioning cycle, temperatures are monitored hourly on all operating VSD equipment. Any abnormal readings or conditions are investigated immediately before damage can occur. Noticeable abnormal conditions include any vibrations, noises, smells, or sounds that indicate damage or the potential for damage to the operating equipment. The system and component electrical parameters (e.g., voltage and current) are also monitored and recorded. The operational observance phase of the system and component operating conditions is complete after the operating conditions are normal and when no problem conditions exist.


20



WORK AID AID 1:

REFERE REFERENCE NCES S FOR EVALU EVALUATI ATING NG MOTOR MOTOR VARI VARIABL ABLE E SPEED SPEED DRIVES UPON RECEIPT

The minimum mandatory technical requirements for a VSD to control the speed of three-phase, 4 kV and 6.6 kV, squirrel-cage induction motors that are installed in Saudi Aramco industrial facilities are defined in 17-SAMSS-517, Medium Voltage Induction Motor Variable Speed Drives. 17-SAMSS-517 17-SAMSS-51 7 covers specific references, design requirements, construction requirements, testing, and engineering studies that must be used in conjunction with the procurement procurement and installation installation of VSDs. The information in this Work Aid contains combined excerpts from the following resources: •

17-SAMSS-517, Medium Voltage Induction Motor Variable Speed Drives

•

GI-2.710

•

Related Industry Standards

Work Work Aid 1A: 1A:

Motor Motor Variab Variable le Speed Speed Drive Drive Tech Technica nicall and Cons Constru tructio ction n Requir Requireme ements nts

Figure 5 contains information regarding VSD Vendor requirements and installation site conditions. Vendor Requirements

Site Conditions

The Vendor must supply a User's List that indicates the User company name, installation site, date of installation, and equipment characteristics that are similar to the equipment that is proposed. Vendor has total responsibility for design, procurement, production, quality control, testing, and documentation, as necessary to furnish a completed system conforming to the requirements of 17-SAMSS-517. The Vendor's system must be compatible with the main AC power system, with the electric motor, and with the driven equipment. The Vendor must be capable of providing any technical assistance that is necessary during the installation and start-up of the system. Equipment that is located indoors must be able to withstand temperatures that are below 35 deg C and a 50 percent relative humidity. Equipment that is located outdoors must be able to withstand exposure to: A desert area with high concentrations of windborne dust and sand. Major pollutants present such as H(2)S and hydrocarbons. A maximum ambient temperature of 50 deg C. Metallic surface temperatures as high as 75 deg C. A maximum relative humidity of 100 percent. • • • • •

Figure 5: 5: VSD Vendor Vendor Requirements and Equipment Site Conditions (from 17-SAMSS-517)


21



Figure 6 contains general VSD design requirements.

General Design Requirements

The VSD must consist of the following: A thyristor-based rectifier bridge to convert ac power to dc power. DC link-smoothing reactors on the positive and negative legs. A thyristor-based thyristor-based current source inverter bridge to convert conve rt dc power to a variable voltage, voltage, variable frequency, current-regul current-regulated ated waveform. The VSD must soft start the motor, limiting current so that no more than motor full load current is required to start and accelerate the load. The system must be in accordance with the attached electrical one-line diagram that is attached to the Data Schedule and must include the following: Input AC isolation transformer (when required) Thyristor bridge cubicle Control cubicle Liquid cooling cubicle (when required) DC link reactor cubicle Contactor/switchgear cubicle Output filter cubicle Heat exchanger cubicle (outdoor-liquid cooled systems only) VSD by-pass (when specified) The VSD system voltage must be either 4,160 V or 6,900 V as specified in the Data Schedule. The VSD must be electrically protected from damaging incoming line conditions of overvoltage, undervoltage, overcurrent, or phase failure. The motor that is being controlled must be protected from damaging VSD output conditions of overvoltage and overfrequency. The VSD must control the motor's speed proportional to a 4-20 mA automatic process signal. The VSD must be able to continuously operate the driven load over the speed range specified in the Data Schedule. • • •

• • • • • • • • •

Figure 6: General VSD Design Requirements (from 17-SAMSS-517)


22



Figure 7 shows VSD construction requirements.

General Construction Requirements

The drive must be constructed for ease of maintenance to minimize downtime. The components must be grouped by function and provide interchangeability between any assemblies that have the same function. The unit must be designed to permit ready access to thyristor modules, control modules and printed circuit boards. The placement of components, test points, and terminals must be such that they are accessible for circuit checking, adjustment, troubleshooting, and maintenance from the front of enclosure without removal of any adjacent module or assembly. The weight must be kept to a minimum to allow removal of assemblies by one person without the aid of lifting devices. The power bus must be tin-plated copper and conservatively rated for maximum current rating per NEMA standards. Short circuit bracing must be designed for available symmetrical fault current. A ground bus must be provided in the cabinets of the VSD and contactors, running the full length of all of the cabinets. The minimum size must be 6.4 mm by 50.8 mm (0.25 in by 2.0 in) and be rated for available short circuit current. The cubicles must be bolted together to form a continuous switchgear assembly. Power and control terminals must be easily accessible for cable entry in the cubicle top or bottom. Power terminations must be suitable for bolt-on lugs. Audible noise that is generated by the controller must not exceed a sound pressure pressure level of 75 dBA measured measured 1.5 M (5 ft) from from any surface of the enclosure.

Figure 7: VSD Construction Requirements (from 17-SAMSS-517)


23



Indoor Enclosures

Nameplates Nameplates

Enclosures must be either carbon steel or aluminum, designed in accordance with NEMA ICS-6. Power conversion equipment enclosures must be free-standing, dead-front, ventilated NEMA ICS-6 Type 1A and designed for front access only. Access panels (doors) must be double or full-length hinged. Doors must be lockable with identical lock and key combinations for each lineup. Handles, screws and hinges must be corrosion resistant as defined in NEMA ICS-6. A warning sign, written in both Arabic and English, must be installed on the front of each cabinet warning of interference that may be caused by portable communications transmitters. The enclosures must be cleaned, primed and painted with the Vendor's standard finish in accordance with standard practice for indoor enclosures. The color must be ANSI 61 light gray. All devices devices located located within within a panel must must be provided provided with suitable suitable nameplates to identify item and function. Device nameplates must be engraved laminated plastic with black 6.4 mm (0.25 in) characters on a white 64 mm by 25 mm (2.5 inch by 1 in) background background as a minimum minimum and must must be in the English English language. language. Warning nameplates must be engraved laminated plastic with white characters on a red background and must be written in both Arabic (Naskh script) and English. Exterior-mounted nameplates must be attached with stainless steel or brass screws. Nameplates within the compartment compartmentss may be attached with with permanent adhesives. Warning plates must be provided on each compartment door in which an external voltage source source is terminated, terminated, reading: "CAUTION - THIS UNIT CONTAINS AN EXTERNAL VOLTAGE SOURCE."

Figure 7: VSD Construction Requirements (from 17-SAMSS-517) (Cont'd)


24



Wiring

External Connections

The The con contr trol olle lerr inte intern rnal al wir wiring ing prac practtices ices,, mat mater eria ials ls,, and and codi coding ng must must be in accordance with the latest edition of the National Electric Code (NFPA 70) and other applicable standards. All internal wiring must be identified at each termination, junction box, and device. Identification must be made with permanently embossed wire markers of the heat-shrinkable, slip-on slip-on type. Adhesive type markers are prohibited. Wire markers must directly correspond to the schematic and wiring diagrams furnished with the unit. All control wiring must be stranded copper conductors, rated 90 deg C, abrasion resistant type. Insulated compression (crimped) ring tongue type terminals must be provided for for all wiring wiring terminati terminating ng of terminal terminal blocks. blocks. Soldered termina terminals ls are not acceptable for connection to terminal blocks. Terminal blocks must be provided for all externally-connected wiring. Terminal blocks must be one piece, phenolic, barrier type with pan head screws. A maximum of two wires per terminal point is permitted. All control wiring must be isolated from power wiring and all AC voltages must be isolated from all DC voltages. All line and load power connections must be compression bolted type lugs for reliability. reliability. The connections must include lock washers and anti-galvanic corrosion protection joint compound to assure long-term integrity. integrity.

Figure 7: VSD Construction Requirements (from 17-SAMSS-517) (Cont'd)


25



Figure 8 shows VSD component design requirements.

Isolation Transformer Design Requirements

Power Converter General Requirements

Isolation transformer, when required, must be in accordance with Buyer' Specification Specification 14-SAMSS-531, "Power Transformers" or o r 14-SAMSS-533, "Three-Phase Dry-Type Power Transformers". (Specifications may be amended to ensure suitability of the transformer for supplying the static power converter.) The transformer must limit the available fault current to a value which is safe for the converter thyristors. The transformer must allow full voltage starting when a VSD bypass is specified in the Data Schedule. The input to the power converters must be protected against voltage surges on the incoming line by the utilization of high power surge arrestors.

The thyristors must be mounted in modular groups. Each thyristor module must contain all associated suppression and gate isolation components and must be front accessible and front removable. Each module must contain a positive and negative leg of series connected thyristors. The thyristors must be standard, proven, readily available, converter grade. The system must be designed to continuously provide rated power in a 50 deg C ambient with a maximum thyristor junction temperature of 95 deg C without derating the system. All high voltage must be isolated at the module for operator safety in the regulator compartment. Gate pulses must be transmitted using fiber optic techniques. The regulator must monitor individual thyristors to ensure they receive their gate signal at the proper time and that each thyristor conducts and blocks at the proper times. Figure 8: VSD Component Design Requirements (from 17-SAMSS-517)


26



Power Converter General Requirements (Cont'd)

Should either the gate firing or thyristor conduction be improper, an alarm indication of the individual failed device must be provided. Each leg of the power bridge must contain series thyristors which have a minimum Peak Inverse Voltage (PIV) rating of 250 percent with all devices operating. The failure of one device, in any or all legs, must not cause a shutdown. With one device shorted, the PIV rating of the thyristors thyristors must be a minimum of 200 percent. All thyristors in the VSD must be tested to ensure they have similar characteristics so they will share the power reliably during turn-on, operation, and turn-off. Power converters must be air cooled.

Power Converters for Motors 746 kW (1,000 HP) or The cooling system must have redundant air ventilating fans so that one fan Less provides 100 percent converter enclosure enclosure cooling capacity at 100 percent of the motor nameplate load. Monitoring and alarm systems for cooling system failure must be provided. Power Power converters must use a closed loop liquid cooling system for optimum Converters efficiency, increased reliability, and to minimize the size of and dependence for Motors on air conditioning units. Greater than Converter cooling must be accomplished using a chemical mixture that has 746 kW an operating range from 0 deg C to 50 deg C. (1,00 (1,000 0 HP) The The cool coolin ing g syst system em mus mustt have have the the fol follo lowi wing ng maj major or com compo pone nent nts: s: Redundant 100 percent close coupled, centrifugal pumps with mechanical seals. A remote liquid to air heat exchanger A high temperature mixed bed resin filter. •

• •

Figure 8: VSD Component Design Requirements (from 17-SAMSS-517) (Cont'd)


27



Power Converters for Motors Greater than 746 kW (1,000 HP) (Cont'd)

DC Link Reactors (DCLRs)

Printed Circuit Boards

The cooling system must use NEMA frame motors in accordance with Saudi Aramco's Specification 17-SAMSS-503.

The cooling system must be designed with a separate low voltage cubicle to allow coolant replacement or pump servicing with the drive completely operational. All hoses must be comprised of flexible, high-dielectric material, rated to a minimum of 1724 kPa (250 psig) with an operating temperature range of -40 deg C to 121 deg C. All hoses must be Hi Pot tested to 50 kV. Two DCLRs must be provided. provided. One for the positive positive and one for the negative DC side of the power bridges to properly control current flow during normal operation and any fault condition. Each link reactor must limit the DC ripple to 10 percent. The reactor must be dry-type, air-core, convection-cooled, with Class F insulation not to exceed Class B temperature rise suitable for outdoor application in a maximum ambient temperature of 50 deg C. The reactor enclosure must be NEMA 1 indoor or NEMA 3R outdoor with screened or louvered openings. openings. The enclosure must must be provided with ground bus. All printed circuit board (PCB) components must be high quality, industrial grade type, designed to operate within modules using only internal natural-draft natural-draft air circulation, (no external fans), up to 50 degrees C., with a relative humidity of 95 percent. PCB components must be wave soldered to PCBs.



28



Printed Circuit Boards (Cont'd)

Output Output Filter Filter

Harmonic Filter

Component leads must not act as thru-board connection pins or be soldered on the component side of the board.

Each component on the board must be clearly identified by means of etching or high-temperature curing ink in accordance with Vendor's circuit schematics. Each PCB module must also be identified by type/revision number. All PCBs incorporating or supporting edge connectors must be provided with gold plated contacts. contacts. All edge connectors must incorporate incorporate a keying system to prevent improper board or module placement or orientation. LEDs which are installed on PCBs within modules must be mechanically protected by a transparent transparent cover, and be identified identified externally. externally. The VSD VSD output output must be filte filtered red to allow allow retro-f retro-fitti itting ng an existing existing motor without derating the system. The output filter must provide a sinusoidal waveform containing a maximum of 5 percent total harmonics to minimize motor heating. Filter capacitors must include resistors which will discharge the capacitors to a safe voltage within approximately one minute after removal of external power. Voltage rise in the converter filter must not exceed 5 percent of nominal bus voltage. The manufacturer must supply a withdrawable output contactor which will disconnect and isolate the drive and filter from the motor. When specified on the Data Schedule, the filter must also maintain a unity power factor under all normal normal operating conditions. conditions. The power factor must be automatically maintained with stepless control.



29



Harmonic When specified on the Data Schedule, the filter must also maintain a unity Filter (Cont'd) power factor under all normal normal operating conditions. conditions. The power factor must be automatically maintained with stepless control. Bypass When specif cified in the the Data Sch Schedu edule, the system must includ cludee a withdrawable withdrawable contactor or breaker (as shown on the engineering drawings) to bypass the drive in case of a VSD failure or to operate the motor at full speed. When specified in the Data Schedule, the bypass protection and control must be as shown on the engineering drawings. Bypass protection and control must be in accordance with 16-SAMSS-506 for contactors or 16-SAMSS-501 for breakers. The bypass system must be incorporated to provide a smooth, closed transition synchronous synchronous transfer of the induction motor from the drive to the main AC line and from the main AC line back to the drive. Transition must be accomplished without stopping or slowing the motor and without significant transients on the line. Figure 8: VSD Component Design Requirements (from 17-SAMSS-517) (Cont'd)


30



Work Work Aid Aid 1B: 1B:

Inst Instru rume ment ntat atio ion n and and Cont Contro rols ls

The instrumentation and controls for VSDs must include the following: •

Input ammeter with phase selector switch

•

Input voltmeter with phase selector switch

•

Output kW meter

•

Motor speed meter power factor meter

•

Output frequency meter

•

Output voltmeter with phase selector switch

•

Output ammeter with phase selector switch

•

Local speed potentiometer

•

Motor "start-stop" control

•

"Local"-"Off" "Local"-"Off"-"Remote" -"Remote" switch for motor "start-stop" control

•

Emergency shutdown push button

•

Cooling pump and blower control switch

•

Alarm status lamps

•

Logic power lamp

•

Red motor output contactor "closed" lamp (when required)

•

Green motor output contactor "open" lamp (when required)

•

Bypass contactor control (when required)

•

Red input contactor "closed" lamp (when required)

•

Green input contactor "open" lamp (when required)

Ammeters that are used must have scales that range from 0 to 150 percent of the maximum rated current. Voltmeters that are used must must have scales that range from 0 to 120 percent of rated voltage. All meters must have +/- 2 percent full-scale accuracy and must be designed in accordance with ANSI C39.1. Meter scales must must be 90 mm (3.5 in) or larger.


31



Work Work Aid Aid 1C 1C:

Alar Alarm m and and Indi Indica cati ting ng

An alarm annunciator must be provided and must include, at a minimum, the following indications: •

Motor stalled

•

Loss of speed command

•

Heat exchanger blower shutdown

•

Low cooling fluid level (liquid-cooled system)

•

Coolant purifier failure (liquid-cooled system)

•

High cooling fluid temperature (liquid-cooled system)

•

Output ground fault

•

One series thyristor failure (with indication of the actual device)

•

High ambient air temperature

•

Loss of any cooling water pump (liquid-cooled system)

•

Loss of any cooling fan (air-cooled system)

A trip annunciator must be provided and must include, at a minimum, the following indications: •

Incoming phase loss

•

Gate drive circuit failure

•

Inverter overvoltage

•

Inverter undervoltage

•

Output overfrequency overfrequency

•

Output overcurrent

•

Output overvoltage

•

Input overcurrent

•

Input overvoltage

•

Capacitor filter failure

•

Converter over temperature (air-cooled system)

•

Cooling fan failure (air-cooled system)


32



•

Cooling fluid over temperature (liquid-cooled system)

•

Cooling fluid low level (liquid-cooled system)

•

DC link reactor over temperature

•

Two series thyristor failures (with indication of the actual devices)

•

Manual emergency shutdown

•

Ground fault

•

Total cooling water pump failure (liquid-cooled system)

•

Loss of speed command

Work Work Aid Aid 1D: 1D:

Inpu Inputt and and Ou Outp tput ut Inte Interf rfac aces es

Each output must be an isolated form "C" contact that is rated 10 A at 600 Vac. The following following minimum outputs from the VSD must be provided: •

Alarm annunciator-summary

•

Trip annunciator-summary

•

Local control

•

Remote control

•

Output contactor open

•

Output contactor closed

•

Bypass contactor closed

•

Spare

The following 4-20 mA dc output signals must be provided: •

Output voltage

•

Output current

•

Output frequency


33



Input contacts must be rated 10 A at 600 Vac. The following following minimum minimum inputs inputs to the VSD must must be provided: •

Input signal (4-20 mA-frequency command)

•

Motor start

•

Motor stop

•

Input breaker open

•

User alarm

•

User trip

Work Work Aid 1E:

VSD VSD Mic Micro rop proce rocess ssor or

Figure 9 shows the requirements for the VSD microprocessor diagnostic diagnostic and event recording system. MicroProcessor Diagnostic System

The VSD must be provided with a diagnostic system with an event recorder and printer providing first out fault detection.

The control and regulation functions must be separate from the protection and annunciation functions to ensure that the integrity of one function is maintained in the event of a failure of the other. The microprocessor based diagnostic system must monitor all trip and alarm functions and display them on a front panel for analysis. The system must be capable of remotely transmitting alarm conditions, trip conditions, digital signals and analog signals. Conditions and signals must include the voltage and current waveforms of the induction motor, the input voltage and current to the drive, and regulator analog functions. Information must be able to be sent via a two wire RS232 port. The Vendor must provide normally open and normally closed fault contacts, pre-wired pre-wired to terminal blocks blocks for Buyer's Buyer's use, for all alarm alarm and shutdown shutdown conditions. Figure 9: VSD Microprocessor Diagnostic and Event Recording System (from 17-SAMSS-517)


34



Work Aid 1F:

Data Schedu dulle

Figure 10 shows the data schedule from 17-SAMSS-517 that is used to order medium voltage induction motor variable speed drives.

DATA SCHEDULE FOR 17-SAMSS-517 MEDIUM VOLTAGE INDUCTION MOTOR VARIABLE SPEED DRIVES _______________________________________________________________________ INFORMATION SUPPLIED BY BUYER 1. Buyer's Quotation Request/Purchase Order No.: _____________________ 2. Buyer's B.I./J.O. No.: ________________________ ____________________________________________ ____________________ 3. Buyer's Line Item No.: ____________________________________________ 4. Motor Rating: __________________________ ______________________________ ____ kW; ( ___________ HP) 5. Motor Voltage: ( ) 4,000 V; ( ) 6,600 V 6. Motor Full Load Amps: ____________ amps 7. Synchronous Speed: _______________ rpm 8. Driven Equipment wk (sq): _____________ Kg- m2 (________lb - ft2) 9. Supply bus voltage: ___________________ volts 10. Available Short Circuit Current: ______ rms rms symmetrical amps 11. Power factor correction required: ( ) yes ( ) no 12. The driven load load will will have a ( ) variable ( ) constant torque vs. speed profile over a speed range from _________ percent to ___________ percent speed. 13. Bypass Contactor/breaker required: ( ) yes ( ) no 14. Bypass synchronous synchrono us transfer required: ( ) yes ( ) no 15. VSD Efficiency test at 1/2 load, 3/4 load, and full load required: ( ) yes ( ) no 16. One-Line Diagram Attached: ( ) yes ( ) no ________________________________________________________________________ Approved: ______________ Date : ______________ Sheet

Dwg. No. NT- ___________ Revision No. ___________ 1 of 1

Figure 10: Medium Voltage Induction Motor Variable Speed Drives Data Schedule (from 17-SAMSS-517)


35



WORK AID AID 2:

REFERE REFERENCE NCES S FOR EVALU EVALUATI ATING NG MOTOR MOTOR VARI VARIABL ABLE E SPEED SPEED DRIVE INSTALLATION AND TESTING

The information in this Work Aid contains combined excerpts from the following resources: •

17-SAMSS-517, Medium Voltage Induction Motor Variable Speed Drives

•

GI-2.710

•

Related Industry Standards

Work Work Aid Aid 2A: 2A:

Test Te stin ing g Requ Requir irem emen ents ts

In addition to the manufacturing facility tests and checks, the following inspections, checks, and tests are performed on induction motor VSDs: Visual Inspection •

Suitability

•

Physical damage

•

Solid state devices

•

Cleanliness

Mechanical Inspections, Tests, and Checks •

Operating mechanism

•

Mounting bolts

•

Lubrication

Electrical Tests and Checks •

Manufacturing facility checks and tests

•

Point-to-point wiring and continuity

•

Contact resistance

•

Insulation resistance

•

Phase sequence and rotation

•

High-pot testing


36



Operational Checkouts and Tests •

Power and terminal verification

•

Drive operation testing with the motor disconnected

•

Motor rotation check

Work Work Aid 2B: 2B:

Visu Visual al Insp Inspec ecti tion on

Visual inspections are used to assess the physical condition of VSDs during the commissioning process. process. A visual inspecti inspection on is a pass/fail pass/fail verificat verification ion about a particular particular aspect aspect of the physical physical condition or the operation of the VSD. Because the criteria that are established established to determine the acceptability of the visual inspections can be subjective, the visual inspections should be performed performed by an experienced experienced Electrical Electrical Engineer. Engineer. Suitability

A visual inspection of the VSD to determine the suitability is performed prior to the VSD commissioning. To determine the suitability of a motor VSD, a visual inspection of the nameplate data is performed and compared to the electrical system single-line diagram. Physical Damage

A visual inspection of the VSD for physical damage is performed prior to the VSD commissioning. To determine whether there is any physical damage to the VSD, a visual inspection for cracks, dents, missing or broken pieces, and bent ventilation openings is performed. Solid State Devices

A visual inspection of the solid state devices is performed prior to the VSD commissioning. During the inspection of the solid state devices, the Electrical Engineer inspects the solid state devices for indication of overheating. Printed circuit boards (PCBs) are inspected to determine whether they are properly seated at the board edge connectors. PCBs are also inspected to determine whether board locking tabs are in place. Cleanliness

A visual inspection of the cleanliness of the VSD is performed prior to the VSD commissioning. The purpose of the cleanliness visual visual inspection is to ensure the proper operation of the VSD over its maximum operating life. life. During the VSD cleanliness inspection, the Electrical Engineer looks for the accumulation of dust and dirt, and he checks the contacts of circuit breakers or contactors for excessive wear and the accumulation of dirt. Saudi Aramco DeskTop Standards

37



Work Work Aid Aid 2C: 2C:

Mecha Mechanic nical al Ins Inspe pecti ctions ons,, Tests Tests,, and and Chec Checks ks

A mechanical inspection is used to assess the ability of the VSD to physically perform what is necessary for proper operation. Operating Mechanism

The operating mechanism for VSD isolation, supply, or bypass components must be inspected prior to the the VSD commissioni commissioning. ng. During the the mechanical inspecti inspection on of the operating operating mechanism mechanism of VSDs, the Electrical Engineer checks the operation of all moving parts for freedom of movement with no evidence of sticking or binding. All operating mechanism fasteners fasteners and linkages are checked for loose, broken, or badly deformed parts. Mounting Bolts

The VSD mounting bolts are inspected prior to the VSD commissioning. The mounting bolts are inspected to ensure that they are securely fastened and that the bolts and frame mounts are capable of preventing the VSD cabinets and internal equipment from coming loose during mechanical failure or electrical fault conditions. To perform the mounting bolt check, the manufacturer's technical manual is consulted for the proper bolt torque value. A torque wrench is then used to determine the amount of torque at each mounting bolt. Improper torque values are immediately corrected. Lubrication

The VSD lubrication system is inspected prior to the VSD commissioning. The lubrication visual inspection is performed in accordance with the VSD manufacturer's instructions. Work Work Aid Aid 2D: 2D:

Elec Electr tric ical al Tes Tests ts and and Chec Checks ks

Electrical inspections and tests are performed to check the ability of induction motor VSDs to operate for a reasonable future period of time under all operating conditions and loads. Acceptance or installation tests will usually detect shipping or installation damage and gross defects or errors in workmanship in equipment construction. Manufacturing Facility Checks and Tests

Figure 11 shows the major checks and tests that are performed on induction motor VSDs a t the manufacturing facility prior to shipment. Checks and tests are performed to identify any components that may be subject to premature failures.


38



PCB Testi Testing ng

Component Testing

All PCB's PCB's must must be be burnedburned-in in continu continuousl ously y for 168 hours hours at at 65 deg deg C. The PCB's must be tested after burn-in to insure they are functioning within specification. Thyristors must have the following critical parameters tested at rated current: gate pulse level turn-on turn-off high temperature forward blocking reverse blocking waveform characteristics All assembled phase cells must be tested for cell balance at rated voltage, maximum current, maximum dV/dT and maximum dI/dT. The complete drive must be burned-in at full load amps for continuous 24 hours. • • • • • • •

Operational and Control Testing

Control power must be applied to microprocessors, printed circuit boards, diagnostic boards and similar devices, (including software) to test for proper operation, sequencing, logic and diagnostics. diagnostics. When load testing is specified in the data schedule, the vendor must determine the VSD efficiency through use of the summation of segregated loss method at 1/2 load, 3/4 load, and full load. Figure 11: Manufacturing Facility Checks and Tests (from 17-SAMSS-517)


Point-to-point wiring checks are performed to verify that a VSD complies with Saudi Aramco wiring diagrams and manufacturer's specifications prior to the VSD commissioning. During the point-to-point wiring wiring checks, terminations terminations and terminal terminal blocks are are checked for routing routing and labeling, and control and metering equipment (e.g., transformers and fuses) is checked for proper application and type. All VSD wiring is also checked for continuity, and it is checked against the wiring diagrams that are provided. The VSD wiring continuity test is performed with a buzzer or bell-type bell-type continuity tester. tester. Written Written checklists or or drawings are are used as reference reference material during during the continuity tests.


39



Contact Resistance

Prior to the VSD commissioning, commissioning, contact resistance checks are performed to identify contacts that are defective or detrimental to the operation of the co ntactor or starter that is contained con tained in the VSD prior to the VSD commissioning. commissioning. To conduct the contact resistance test, test, the equipment that is to be tested is disconnected from the system. Once the equipment is removed and the contacts are in the closed position, the leads of a digital, low-resistance ohmmeter are placed across the line and load sides of the contacts, contacts, and measurements measurements are taken. The contact resistance resistance is recorded on a test data sheet and retained in Saudi Aramco material history history records. Values of contact resistance in excess of 200 microohms and deviations of more than +/-20% should be investigated. investigated. Technical data to evaluate the results results of the contact resistance resistance test can be found in the equipment manufacturer's technical manual or in the Saudi Aramco PreCommissioning form, P-000, Testing Guide Lines. Insulation Resistance

The results of all commissioning insulation resistance (megger) tests that are performed must be documented on the appropriate manufacturer or Saudi Aramco commissioning form. When the dielectric absorption ratio megger test is performed, the polarization index can be determined through use of the following equation: PI =

10 minute reading 1 minute reading

Figure 12 provides insulation conditions for 60/30 second ratio results and for 10/1 minute ratio results.

Insulat ulatiion Con Condi dittion

60/3 60/30 0 - Sec Secon ond d Rat Ratiio

10/1 - Minute Ratio (Polarization (Polarization Index)

Dangerous

- - --

Less than 1

Questionable

1.0 to 1..25

1.0 to 2

Go o d

1 . 4 t o 1. 6

2 to 4

Excellent

Above 1.6

Above 4

Figure 12: 12: Dielectric Absorption Ratio Chart


40




Phase sequence and rotation tests are performed to ensure that the power supply inputs to the VSD are at the proper voltage and in the proper proper phase sequence. Sequence testing and rotation testing are performed to ensure that the motor (when connected) will rotate in the correct direction. During the phase sequence sequence and rotation tests, tests, the ac power input leads are checked for proper markings markings to ensure that that the sequence coincides coincides with the the incoming power system. system. A visual verification of the motor leads is also conducted to ensure that the motor leads are properly marked to coincide with the VSD output leads. The motor lead markings markings and the VSD output lead markings must match so that the motor shaft will rotate in the correct direction. High-Pot Testing

For the commission commissioning ing of VSDs for motors that are 746 kW (1,000 HP) or larger, a high-pot test must be conducted on the cooling cooling medium hoses. The maximum test voltage voltage for the high-pot high-pot test is 50 kV. A polarization index (PI) test is performed by applying an initial voltage step of 16.5 kV (approximately one-third of the maximum voltage of 50 kV). The initial voltage step must be maintained at a constant level for ten minutes. The PI is calculated by dividing the one-minute leakage current by the ten-minute leakage current. A PI value of 2.0 or less must be investigated. After the initial ten-minute test, the dc test voltage is increased in approximately ten uniform steps. Each step should have a one-minute duration. The voltage is is increased until the maximum recommended dc value is reached. The following are the acceptable results of a high potential test: •

The microamperes leakage current should decrease in value during the initial ten minutes of the test at the initial voltage step. The microamperes leakage current should show a steady rise for the remainder of the test until the maximum test voltage is reached.

•

A steady-state or rising value during the initial ten minutes of the test indicates poor insulation and, as a result, the insulation should be rejected. A sharp or an exponential rise in leakage current that occurs during the step voltage changes or prior to the application of the maximum test voltage also indicates poor insulation.


41



The dc high-pot test should be secured if one of the following situation situation occurs: •

The duration of the test has expired.

•

A rapid rise in leakage current occurs.

•

The polarization index < 1.

The following are the characteristics of a satisfactory dc high-pot test: •

The leakage current gets smaller over time.

•

The polarization index > 1.

•

The leakage current increases on a straight line as voltage is increased. No "knee" is noticeable in the leakage current curve.

An example of dc high-pot test test data is shown in Figure Figure 13. Figure 13 shows both good and bad insulation test data.

Motor Insulation Class B F H

Maximum Allowable Insulation Temperature in °C 130 155 180

Figure 13: Example of DC Hi-Pot Test (Good and Bad Cable Insulation)

Work Work Aid Aid 2E: 2E:

Oper Op erat atio iona nall Chec Checko kout utss and and Test Testss

The proper operation of all VSD subsystems is tested through use of controlled operation and checkout of the controls and protective devices. Although there are many different manufacturer's manufacturer's configurations of VSDs, most VSDs have similar subsystem and component operation and checkout test procedures. For a specific VSD's subsystem component component operation and checkouts checkouts tests, the manufacturer's technical manuals should be consulted. For any testing, extreme care should be taken due of the presence of electric electric power and rotating rotating equipment. Failure to exercise exercise extreme caution when conducting operation and checkout testing can result in personnel injury or equipment damage. This section of the Work Aid contains a brief overview of generic VSD testing.


42



Power and Terminal Verification

Prior to a test of the VSD with the motor disconnected, a power and terminal verification is performed performed as follows: follows: 1.

Remo Remove ve powe powerr to to the the VSD VSD thr throu ough gh use use of of a disc discon onne nect ct devi device ce..

2.

With With all all pow power er to the the VSD VSD rem remov oved ed,, remo remove ve the the dri drive ve cov cover er and and ver verif ify y that that the the incoming ac power and motor connections are in accordance with manufacturer's manufacturer's specifications. The individual phase voltages (A-B, (A-B, B-C, and A-C) should be equal to the nameplate voltage rating ±10%.

3.

Verif Verify y that that all all cont contro roll and and logic logic inter intercon connec necti tions ons are made made in in acco accord rdanc ancee wit with h manufacturer's specifications.

4.

Verif Verify y that that the the ac line line power power at the the dis discon connec nectt devi device ce is withi within n the the rated rated value value of the drive.

5.

Disc Discon onne nect ct the the mot motor or lead leadss from from the the ter termi mina nals ls at the the dri drive ve..

Drive Operation Testing with the Motor Disconnected

1.

Repl Replac acee the the cove coverr of of the the VSD VSD and and assu assume me loca locall con contr trol ol of the the VSD VSD.. Set Set the the START/STOP switch to the STOP position and the speed setting to the fully CCW (stopped) position.

2.

Apply Apply input input power power to the VSD and verif verify y that that no abno abnorm rmal al condi conditi tions ons or fault faultss are are displayed on the control panel.

3.

Star Startt the the VSD. VSD. Veri Verify fy that that the the desir desired ed mini minimum mum and maxi maximum mum frequ frequenc encie iess are are obtained.

4.

Stop Stop the VSD. VSD. Veri Verify fy that that the the dri drive ve imme immedi diat atel ely y sto stops ps.. If the the VSD VSD has has a ramp ramp stop mode, verify that the drive ramps to a stop within the predetermined ramp time.

5.

Star Startt the the VSD VSD and and set set to the the max maxim imum um freq freque uenc ncy. y. Obse Observ rvee and and rec recor ord d the the acceleration time.

6.

Stop Stop the the VSD VSD and and obs obser erve ve and and rec recor ord d the the dece decele lera rati tion on tim timee for for each each sto stop p mod modee that is present (e.g., coast, brake, and ramp).


43



7.

If skip skip fre freque quenci ncies es have have been been progra programme mmed, d, star startt the the VSD and slow slowly ly incre increase ase the frequency. Verify that the VSD skips over the selected frequencies.

8.

If the the VSD VSD has has a reve revers rsee fea featu ture re,, tes testt the the rever reverse se oper operat atio ions ns of the the VSD VSD..

9.

If the the VSD VSD has has a jog jog feat featur ure, e, test test the the jog jog oper operat atio ions ns of the the VSD VSD..

10.

Remo Remove ve pow power er to to the the VSD VSD thro throug ugh h use use of the the disc discon onne nect ct dev devic ice. e.

11.

Remove Remove the VSD cover cover and and reco reconne nnect ct the the moto motorr lead leadss from from the termin terminals als at the the drive. Replace the VSD cover. cover.

Motor Rotation Check

1.

Verif Verify y that that the VSD is in the local local contr control ol mode mode and and that that the the loca locall cont control rolss have have the VSD stopped. If the VSD is equipped equipped with forward and and reverse modes, the VSD must be in the forward direction.

2.

Appl Apply y pow power er to the the VSD VSD thro throug ugh h use use of the the dis disco conn nnec ectt dev devic ice. e.

3.

Set Set the the freq freque uenc ncy y to to the the mini minimu mum, m, and and sta start rt the the VSD VSD.. Slow Slowly ly incr increa ease se the the frequency until the motor rotates. Observe that the motor rotates in the correct correct direction.

4.

If the the moto motorr does does not not rota rotate te in in the the corr correct ect dire direct ctio ion, n, sto stop p the the moto motor, r, remo remove ve the the power to the VSD, and consult the VSD technical manual. manual.


44



Work Work Aid 2F: 2F:

Exc Excerpt erptss fro from m GI GI 2.7 2.710 10

The following is an excerpt from GI 2.710, New Construction Check List Example, that illustrates the overall checklist and sign-off for major pieces of electrical equipment. 3. Electrical Equipment All substations, power cable, electrical equipment, Construction Construction Agency including lighting and wiring, to be checked for proper application, operation, and grounds. Distribution panels, switches properly identified, and all energization certificate requests signed.

Power Distribution Dept.

Project Inspection

Commissioning (Note 1) Figure 14 shows an excerpt from GI 2.710, General Instruction Manual, that illustrates the inspections and tests that should be performed on major pieces of electrical equipment prior to the turnover of a facility.


45



Figure 14: GI 2.710 Excerpt


46



Figure 14: GI 2.710 2.710 Excerpt (Cont'd)


47



Figure 14: GI 2.710 2.710 Excerpt (Cont'd)


48



GLOSSARY dielectric absorption ratio

The ratio of two timed insulation resistance readings (such as a 60-second reading that is divided by a 30-second reading).

insulation resistance

The amount of opposition to the flow of electric current that is offered by an insulation.

polarization index

The ratio of a ten-minute insulation resistance reading divided by a one-minute insulation resistance reading.

squirrel-cage

A motor in which the secondary circuit consists of a scroll-cage winding.


49

Commissioning Motor Variable Speed Drives (VSDs)

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