Best Practice SABP-P-005
28 October 2006
Transformer Factory Acceptance Tests Document Responsibility: Consulting Services Dept.
Saudi Aramco DeskTop Standards Table of Contents 1 2 3 4
Introduction.................................................... References.................................................... Definitions...................................................... Factory Acceptance Tests for Power Transformers.........................................
Table I – Transformer Name Plate Rating Information.................................................... Table II – Design Tests........................................ Table III – Transformer Routine Tests................. Table IV – Transformer Applied Test Voltages Levels............................................................
2 2 3 4
4 5 5 7
Appendix A........................................................... 8
Previous Issue: New Next Planned Update: 28 October 2011 Page 1 of Primary contact: Basel A. Ishwait on phone 966-3-8745133 Copyright©Saudi Aramco 2006. All rights reserved.
Document Responsibility: Consulting Services Dept. Issue Date: 28 October 2006 Next Planned Update: 28 October 2011
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SABP-P-005 Transformer Factory Acceptance Tests
Introduction 1.1
Purpose The purpose of this Practice is to establish guidelines in reviewing power transformers Factory Acceptance Test (FAT).
1.2
Scope This Best Practice gives general guidelines for reviewing the requirements of power transformers’ Factory Acceptance Tests i.e. routine tests and design tests.
1.3
Disclaimer This Best Practice is being provided for the general guidance and benefit of Saudi Aramco engineers reviewing Factory Acceptance Test (FAT). The use of this Best Practice during factory acceptance test, however, does not relieve the manufacturer from his responsibility or duty to confirm or to verify the accuracy of any information presented or from his contractual liability to perform an accurate FAT that conforms to Mandatory Saudi Aramco Engineering Requirements. The use of the information or material contained herein will not guarantee that the resulting product satisfies the applicable requirements of Saudi Aramco Standards. Saudi Aramco assumes no responsibility or liability whatsoever for any reliance on the information presented herein or for FAT performed by manufacturer in accordance with this Best Practice document. Moreover, this Best Practice is intended only to provide guidelines for Saudi Aramco engineers and shall not be considered as a replacement for the Mandatory Saudi Aramco Engineering Requirements. Saudi Aramco® is a registered trademark of the Saudi Arabian Oil Company. Copyright, Saudi Aramco, 2004.
1.4
Conflicts with Mandatory Standards In the event of a conflict between this Best Practice and other Mandatory Saudi Aramco Engineering Requirement, the Mandatory Saudi Aramco Engineering Requirement shall govern.
2
References This Best Practice is based on the below referenced standard: 2.1
Saudi Aramco References Saudi Aramco Engineering Standard SAES-P-121
Transformers and Reactors (31 July, 2004) Page 2 of 8
Document Responsibility: Consulting Services Dept. Issue Date: 28 October 2006 Next Planned Update: 28 October 2011
SABP-P-005 Transformer Factory Acceptance Tests
Saudi Aramco Materials System Specifications 14-SAMSS-531 2.2
Power Transformers (29 June 2005)
Industry Codes and Standards American National Standards Institute
3
ANSI C57.12.00
Standard General Requirements for LiquidImmersed Distribution, Power, and Regulating Transformers
ANSI C57.12.10
American National Standard for Transformers 230 kV and below 833/958 through 8333/10,417 kVA, Single-Phase, and 750/862 through 60,000/80,000/100,000 kVA, ThreePhase without load Tap Changing; and 3750/4687 through 60,000/80,000/100,000 kVA with Load Tap Changing - Safety Requirements
Definitions Factory Acceptance Test (FAT): A performance running test conducted at the factory to check the integrity of the equipment. Routine Test: A test to verify the quality control of the manufacturer and are performed on all equipment. They ensure the quality and uniformity of the workmanship and materials used. Routine tests are sometimes referred to as production tests. Design Test: A test made to determine the adequacy of the design of a particular type, style, or model of equipment and its component parts to meet its assigned ratings and to operate satisfactorily under normal service conditions or under special conditions if specified; and to demonstrate compliance with appropriate industry standards. Other Tests: Tests are specified by the user for specific applications. Class I Transformers: Transformers which have winding voltage less 115kV. Class II Transformers: Transformers which have winding voltage 115kV and greater. Basic Impulse Insulation Level (BIL): This is the reference insulation level expressed as an impulse crest (or peak) voltage with a standard wave not longer than a 1.2 x 50 microsecond wave. A 1.2 x 50 microsecond wave means that the impulse takes 1.2 microseconds to reach the peak and then decays to 50% of the peak in 50 microseconds.
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Document Responsibility: Consulting Services Dept. Issue Date: 28 October 2006 Next Planned Update: 28 October 2011
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SABP-P-005 Transformer Factory Acceptance Tests
Factory Acceptance Tests for Power Transformers Factory Acceptance Tests (FAT) are performed to ensure that the equipment has been assembled properly and will perform reliably in accordance with its nameplate rating. FAT consists of routine and/or design, and other tests as applicable in compliance with specified international standards as well as operational tests of all ancillary equipment and devices. Commentary Note 6 The majority of transformers used in Saudi Aramco facilities are what designated in the industry as fans-only auxiliary cooling with natural oil flow and defined in the standards as: •
ONAN/ONAF (oil natural, air natural/oil natural, air forced) and the old designation was OA/FA.
•
ONAN/ONAF/ONAF (oil natural, air natural/oil forced, air forced/oil forced, air forced) and the old designation was OA/FA/FA.
Table I - Transformer Name Plate Rating Information Manufacturer (Name/Plant location) Transformer Serial No. KVA rating at ONAN (minimum) and ONAF (maximum) ratings High voltage winding (kV) BIL of high voltage winding (kV) Low voltage winding (kV) BIL of low voltage winding (kV) Impedance at ONAN (minimum) rating (%)
4.1
Design Tests Data for the below tests should be witnessed and certified signed copies of the test data should be obtained documenting the test results.
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Document Responsibility: Consulting Services Dept. Issue Date: 28 October 2006 Next Planned Update: 28 October 2011
SABP-P-005 Transformer Factory Acceptance Tests
Table II - Design Tests
Test Description
Test completed (Yes/No) or Not Applicable
Comments
Temperature rise at ONAN and ONAF (minimum and maximum) ratings
Lightning impulse test of high and low voltage windings (Class I transformers)
Audible sound level at minimum and maximum ratings
Load test of tank moving and lifting devices
Pressure test of transformer tank
4.2
Routine Tests Generally, routine tests are performed on a basic transformer that is not completely assembled. The radiators, cooling fans, conservator tank, and protective devices such as the temperature, oil level, pressure vacuum gauges and pressure relief may not be installed. However, the basic transformer and components should be completely assembled, i.e. tap changer, current transformers, control cabinets etc. Data for the below tests should be witnessed and certified signed copies of the test data should be obtained documenting the test results. Table III - Transformer Routine Tests Test Description
Test Completed (Yes/No)
Comments
Resistance measurement of all windings Winding insulation resistance Core insulation resistance
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Document Responsibility: Consulting Services Dept. Issue Date: 28 October 2006 Next Planned Update: 28 October 2011
SABP-P-005 Transformer Factory Acceptance Tests
Ratio test of all windings on all voltage taps Verify polarity of windings Verify phase relation of windings Measure winding Insulation power factor Measure the no-load losses and excitation current at rated voltage and rated frequency on the rated voltage connection Measure no-load losses and excitation current at 110% of rated voltage and rated frequency on the rated voltage connection Impedance voltage and load loss at rated current and rated frequency on the rated voltage connection, and at the tap extremes (minimum and maximum voltage taps) Zero-phase sequence impedance voltage (applicable to transformers 5,000KVA and larger only) Lightning Impulse test (routine test for Class II transformers) Low frequency induced voltage Low frequency applied voltage Low frequency applied voltage on auxiliary devices and control circuits. (1500 VAC for one minute) Low frequency applied voltage on current transformer circuits. (2500 VAC for one minute) Insulating oil test/analysis Dissolved gas in oil analysis Leak check
Operational test of all devices Check operation of No Load Tap Changer through the complete tap range Check operation of Load Tap Changer through the complete tap range. Operate the tap changer mechanism manually as well as electrically Check Current transformer ratio and polarity Check operation of cooling fans. Verify correct rotation of fan blades, measure and record the running current and operating voltage Verify correct operation of circuits and devices in the control cabinets
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Document Responsibility: Consulting Services Dept. Issue Date: 28 October 2006 Next Planned Update: 28 October 2011
SABP-P-005 Transformer Factory Acceptance Tests
Verify operation of pressure relief device Verify operation of sudden pressure relay Verify correct operation of top oil and winding temperature gauges Verify operation of oil level gauge Check application of breather Check painting and positioning of parts Verify that transformer dimensions comply with project drawings and requirements Note: Impulse and partial discharge tests are considered to be routine tests for transformers with windings 115kV and higher.
Commentary Note 6: A special routine impulse test for distribution transformers is required for overhead-type, pad-mounted type, and underground-type liquid-immersed distribution transformers. This test is specified in 10.4 IEEE C57.12.90.
Test voltages listed in the following table are the most common utilized within Saudi Aramco. Table IV - Transformer Applied Test Voltages Levels Winding Nominal Voltage (kV rms) 0.48 2.4 4.16 13.8 34.5 69.0 115.0 230.0
28 October 2006
Basic Impulse Level (BIL) (kV crest)
Induced Potential (kV rms) (7200 cycle duration)
Applied Potential (kV rms)
45 60 75 110 200 350 450 900
0.96 4.8 8.3 27.6 69 138 120 (phase to gnd) 240 (phase to gnd)
10 15 19 34 70 140 185 395
Revision Summary New Saudi Aramco Best Practice.
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Document Responsibility: Consulting Services Dept. Issue Date: 28 October 2006 Next Planned Update: 28 October 2011
SABP-P-005 Transformer Factory Acceptance Tests
Appendix A Impulse Tests Impulse Test Sequence: Lightning impulse voltage tests, when required, shall precede the low-frequency tests. Switching impulse voltage tests, when required, shall also precede the low-frequency tests. For Class II transformers, the final dielectric test to be performed shall be the induced voltage test. If not otherwise specified by the buyer, the test sequence for an impulse test should be in the following order: 1)
Switching impulse test, if applicable
2)
Lightning impulse test.
Chopped wave should be at 110% of the BIL value and the front-of-wave should have amplitude according to Table 5 of ANSI C57.12.00. For chopped-wave tests, the minimum time to flashover shall be 3.0 µs except for 110 kV BIL, in which case the minimum time to flashover shall be 2.0 µs. Applied Voltage Test Level 1
0.5 50 µs
Time 1.2 µs
Figure A.1: Lightning impulse full wave; IEC and IEEE
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