Gravimetric Feeder

DOCUMENT COVER SHEET PROJECT NAME

: SIPAT SUPER THERMAL POWER PROJECT

STAGE-I (3 x 660MW) CONTRACT NO.

: CS-9518-108-2(PART-A)-FC-COA-4313

ITEM

: COAL FEEDER

DOCUMENT DOCUMENT TITLE : GRAVIMETRIC FEEDER CONTROLS WRITE UP

Stock St ock Equipm Equipment Company

ATPD32400-140 OPERATION

SYSTEM COMPONENT DESCRIPTION Feeder Microprocessor Controls

The microprocessor feeder electronics control system is designed to op erate in industrial and power plant environments where harsh conditions and frequent power disturbances exist. It uses special circuits, software subroutines, and nonvolatile memories to store store data, programming and operating parameters. This allows the system to recover and keep the feeder running under control after after a momentary momentary power loss. The microprocessor electronics are contained in a NEMA rated electrical control c abinet with a glass door for keyboard access. The keyboard/display assembly is part of an environmentally sealed panel that is gasketed against the enclosure door. The feeder control consists of four four hardware packages: a power supply, a CPU board, a keyboard/display assembly and a motor speed control. Additional input and output devices are available and can be formatted to a variety of requirements, both digital and analog.



SYSTEM COMPONENT DESCRIPTION Feeder Microprocessor Controls

The microprocessor feeder electronics control system is designed to op erate in industrial and power plant environments where harsh conditions and frequent power disturbances exist. It uses special circuits, software subroutines, and nonvolatile memories to store store data, programming and operating parameters. This allows the system to recover and keep the feeder running under control after after a momentary momentary power loss. The microprocessor electronics are contained in a NEMA rated electrical control c abinet with a glass door for keyboard access. The keyboard/display assembly is part of an environmentally sealed panel that is gasketed against the enclosure door. The feeder control consists of four four hardware packages: a power supply, a CPU board, a keyboard/display assembly and a motor speed control. Additional input and output devices are available and can be formatted to a variety of requirements, both digital and analog.





input current. The light output of the diode is optically coupled to the base of a phototransistor. The collector lead of the transistor sinks current from the microprocessor microprocessor to ground. Thus, inputs and outputs are electrically isolated. A typical isolated output operates as follows. CPU signals are used to bias a light emitting diode and an optically coupled transistor, as with inputs. However, the transistor emitter sinks current to energize a relay coil and the relay contacts provide the output signal. Input Signal Converter Card (A1)

The function of the input signal converter card is to convert the customer fuel demand signal to a normalized 0 to 10 kHz signal for interfacing with the microprocessor system. system. The fuel demand signal can be any standard control signal: current, voltage or potentiometer. The voltage and current current

Stock Equipment Company

ATPD32400-140 OPERATION digital form are located on this board. The keyboard assembly with vacuum fluorescent (VF) display is directly cabled to the CPU board assembly. The CPU board is the principal mechanism through which control of the system is achieved. Digital inputs and keyboard commands are processed by software algorithms which then route signals either to digital outputs or to the display as required. All digital I/O interfaces are isolated by circuits on the power supply board which prevent damage due to transients and prevent operational malfunction due to noise. Interfacing between the microprocessor and the analog parts of the system is accomplished by conversion circuits. Signals which pass from an external analog device to the microprocessor first must pass through an analog to digital converter (voltage to binary number). When the microprocessor must operate an external analog device, its output is sent in the form of a frequency to a frequency to voltage or current converter card. This device is a digital to analog converter since



The microprocessor control configuration is shown in Figure 2. A transparent portion of the configuration is the software contained in a permanent memory. The software is written so that the most important system activities (such as the motor speed loop and demand signal input) are processed fast enough to allow good control to be achieved, while less important signals (such as relay outputs) are processed at a slower speed. This time multiplexing concept in the software program allows for better control of the process when a great number of tasks must be performed. As can be seen from the illustration, the only inputs directly accessing the CPU board are the keyboard and the load cells. All other I/O signals pass through optical isolation circuits located on the power supply which gives the system excellent noise immunity. Microprocessor Memory

Programming of the microprocessor is done in the C programming language, which fully utilizes the 16 MHz operating speed of the



power failure is detected. This allows the feeder to recover and keeps the system operating in an orderly manner when power is restored after a failure. Alphanumeric Display/Keyboard

Commands are entered to the controls via the keyboard on the front panel of the microprocessor cabinet as shown in Figure 3. To operate the keyboard, it is necessary to open the small outer door by loosening its two thumbscrews. This door must remain tightly closed when the keyboard is not being used to maintain the NEMA rating of the control enclosure. The clear window allows the operation of the feeder to be checked without opening the door. The keyboard consists of small switches which input data digitally by creating a low signal level (GND or binary number 0) when they are pressed. This signal is first stored in a specific memory location which is different for each key of the


ATPD32400-140 OPERATION function table. That function may require further data (numbers) which are also read from the queue. At the same time that pressed key signals are being stored in a decoded form in the queue, a de-multiplexer (decoder) reads the queue for any data which is numerical and drives the keyboard display with alphanumeric data. Thus, as numbers and function keys are entered, they are displayed. The keyboard contains keys of two colors: white and blue. The white keys are the standard REMOTE/OFF/LOCAL selection of feeder operating mode and will be the keys most frequently used. To activate a mode selection, press the bottom center of the key below the LED light. The blue keys are functions and numbers that are activated by pressing the key in the exact center in the proper order. When a key is pressed, the VF display will change to acknowledge that the



Keyboard Commands

The three white keys with LED indicators at the upper center of the keyboard select the feeder operating mode, REMOTE, OFF or LOCAL. REMOTE allows the feeder to be controlled from the customer run permissive contacts and demand signal. OFF deactivates the feeder. LOCAL operates the feeder at a selectable speed. If there is material on the belt during LOCAL op eration, the feeder will trip after a two-second delay. NOTE Pressing any of the white keys all ows the feeder to operate i n the selected mode. I t also resets any alarm or tri p in dication, tur ni ng off the red panel in dicators and openi ng t he appropri ate relay contacts.



From time to time it may be desirable to reset the three totalizers back to zero. To do this, press and maintain: TOTAL RESET IMPORTANT Th ere is no way to recall total izer amoun ts once they have been r eset.

The lower forty-character line of the VF display shows RATE, DENSITY or SPEED by pressing the INFO SELECT key. The display will cycle and can be stopped by releasing the key on the selected mode which appears at the left of the display. RATE shows the operating feed rate of the feeder when in the gravimetric mode, or the equivalent feed rate using the average density of the material when in the volumetric mode.



c. ALARM (red) indicates that a problem exists which requires attention, but is not serious enough to immediately stop feeder operation. d. TRIP (red) indicates that a serious problem exists and feeder operation has been stopped. e. VOLUMETRIC (red) indicates that a fault exists in the weighing system or its electronics which prevents the feeder from operating the gravimetric mode. Diagnostic Error Codes

Whenever an ALARM or TRIP condition occurs, an error code number is stored internally to identify the source of the problem. To access the error code, press: ERROR RECALL .



The microprocessor will select a default address if one is not selected by the operator in 4 seconds. Other addresses can then be accessed by pressing the UP or DOWN arrow keys. For each address, the display shows the address number, the current parameter's value, units of measure, and a brief description. For example, the display may appear as follows for Address 05.

The microprocessor controls are capable of displaying units of weight in pounds, kilograms, U.S. tons, and metric tons. To choose alternate units for setup parameters that are values, press the SETUP key until the desired units are displayed. The microprocessor recalculates the displayed value to accommodate the new units. Each of the setup parameters that are values have independent units. Changing units for one parameter does not affect the other parameters.



4.

The microprocessor displays three decimal places for most values, but internally keeps six digits of accuracy (ANSI/IEEE single precision). If more than six digits are entered at the keyboard, the microprocessor round or truncate the value entered.

5.

If a decimal point is used at a setup address which requires a coded entry, the microprocessor will ignore the decimal point.

6.

If a mistake is made, press CLEAR to erase the entry and start again.

7.

Press ENTER to store the value in memory.

8.

If a value for a setup parameter is entered which exceeds the usable range of the specific setup parameter, the microprocessor displays the message OUT OF RANGE, and the original value for that specific setup parameter is used. Changing the units (e.g., pounds to kilograms) automatically changes the usable range.



Example:

If the feeder will operate in the REMOTE mode controlled by the 18.25 feed rate set point, press: tons/hr ENTER If the feeder will operate in the REMOTE mode controlled by the analog customer feed rate demand signal, this address is not recognized. Speed Set Point RPM (Address 01)

This is the operating speed of the belt drive motor in the LOCAL and CALIBRATION modes, and also in the REMOTE mode when the feeder is controlled by speed set point (see Address 03, option 5). The value must be less than the value entered for the motor maximum speed (see Address 29) and greater than the value entered for the motor minimum speed (see Address 30). Example:

If the feeder is to operate at 1000 rpm, press:



1

procedure in Section 3.3.1 before operating the feeder. The limits on the feed rate demand signal are set by the minimum (Address 06) and maximum (Address 05) feed rates of the feeder. Raise/Lower Customer Feed Rate Demand. This mode increases or decreases an internal feed rate set point depending upon the raise or lower contact closures. The limits on the raise/lower control are set by the minimum (Address 06) and maximum (Address 05) feed rates of the feeder.

2

Feed Rate Set Point. The feeder will deliver material at the rate contained in the feed rate set point (Address 00).

3

Analog Customer RPM Demand. The feeder will seek to match a speed demand from the analog customer demand input. The value entered in Address 29 determines the maximum



Display Select (Address 04)

This parameter specifies which units of measure the microprocessor will use to display feed rates, densities, belt travel and totals. Units of Measure Selection Chart

Unit Options

Description

Units of Measure

0

Feed rate; Density; Belt travel; Totals

U.S. tons/hour; pounds/cubic foot; inches; U.S. tons

1


pounds/hour; pounds/cubic foot; inches; pounds

2


metric tons/hour; kilograms/cubic meter; meters; metric tons



parameter are pounds/hour, tons/hour, kilograms/second, kilograms/hour and metric tons/hour. Example:

If the minimum permissible feed rate is 4.68 tons per hour, press:

until < SETUP 06 > appears, then 4.68 ENTER Remote Data Logging Totalizer Increment (Address 07) This sets the amount of material registered on a remote totalizer for every pulse of the data logging output. A typical value is 100 units (pounds, U.S. tons, kilograms, or metric tons). Press: until < SETUP 07 > appears, then 100 ENTER Demand Mode (Address 08)



1

40-Tooth Gear

2

Ac Tachometer - 18 cycles (36-pole)

3

Ac Tachometer - 12 cycles (24-pole)

Example:

If a 24-pole ac tachometer is in use, press:

until < SETUP 09 > appears, then 3 ENTER Weigh Span (Address 10)

The weigh span is the distance between the centers of the weigh span rollers expressed in one of the following units: inches, centimeters, millimeters or meters. Enter up to two decimal places if necessary.



= 153.99 sq. in. 2. Convert square inches to square feet. 144 sq. in. = 1 sq. ft.

3. Volume on weigh span = Cross sectional area x weigh span length = 1.07 sq. ft. x 3.191 ft. = 3.41 cu. ft. To enter this sample value, press: until < SETUP 11 > appears.



Then press SETUP until the units appear as "lbs". Press 50 ENTER



Motor Speed Control Servo Loop Gain (Address 14)

This parameter is predetermined for each particular motor/control combination and should not be altered without consulting Stock Equipment Company. Typical values are listed in the following table: Value

Motor/Control Combination

4800

Eddy Current Clutch Speed Control

2000

DC Motor Speed Control

4000

AC Variable Frequency Drive

Example:

If the feeder motor is equipped with an eddy current clutch, press:



Discharge Pluggage Delay (Address 16)

If the feeder is equipped with a discharge pluggage sensor, this parameter sets the delay after closure of the discharge pluggage switch contacts until the feeder is tripped. To disable this function if a discharge pluggage sensor is not provided, enter "0"; otherwise, the delay must be entered in seconds as: 1/2 second 2 seconds 5 seconds

= = =

0.5 2.0 5.0 (this is the maximum allowable delay)

Example:

If the feeder is to be stopped after a 2-second delay, press:

until < SETUP 16 > appears, then 2.0 ENTER Belt Motion Monitor Delay Time (Address 17)



As an example, the following data are required for this calculation: downspout radius, downspout height (from level monitor elevation to coupling) and maximum feeder operating pressure differential. The following example uses units of feet: Downspout radius: 1 ft. Downspout height: 12 ft. (from level monitor elevation to coupling) Max. feeder operating pressure differential: 25 inches of water Example using the sample dimensions listed: 1.

Volume in downspout

= π x radius of downspout squared x height 2 = 3.14 x (1) x 12 = 37.68 cu. ft.



Weight Signal Filtering (Address 19)

This sets the amount of filtering between load cell measurement. It is used where there is considerable mechanical vibration at the feeder or when the belt has an inconsistent weight. The recommended initial setting is 4. Increasing the value by one, doubles the degree of filtering; decreasing it by one, halves the degree of filtering. A value of zero provides no filtering, and 8 provides the maximum degree of filtering available. Example:

Using the recommended initial setting. Press:

until < SETUP 19 > appears, then 4 ENTER Feedback Signal Filtering (Address 20)



Belt Travel Revolutions (Address 22)

This sets the total belt travel (in belt revolutions) used for simulated material tests (see Self Test 13). Best test results will be obtained if multiples of one complete belt revolution are entered, although partial belt revolutions will be accepted. Example:

To set the material test duration to five belt revolutions, press:

until < SETUP 22 > appears, then 5.0 ENTER (Address 23)

This setup function address is not used in this application. Paddle Feedback Permissive (Address 24)



Mode Select Enable/Disable (Address 26)

This parameter specifies the source of control for the feeder REMOTE, OFF, or LOCAL operating modes according to the following table: Value

Mode Input(s) Enabled

0

Feeder operating mode can be established only by pressing one of the three white keys on the microprocessor keyboard.

1

The operating mode and white keys on the microprocessor keyboard are governed by a remotely located mode selector switch when the microprocessor control cabinet is feeder mounted, or a feeder mounted mode selector switch when the microprocessor control cabinet is remotely installed. When the selector switch is placed in the REMOTE position, the feeder



FRI Output Frequency (Address 27)

This parameter specifies the frequency of the feed rate indicator output which corresponds to hertz per ton per hour, hertz per kilogram per second, hertz per metric ton per hour feedrate. Example:

Using the standard feed rate indicator with output of 10 hertz per ton per hour. Press:

until < SETUP 27 > appears. Then press SETUP until the units appear as "Hz/tph" Press 10 ENTER Raise/Lower Contact Input Response Time (Address 28)



When the feeder is running in rpm demand mode (Address 03, option 3) or the RAISE/LOWER rpm mode (Address 03, option 4), this minimum rpm value will correspond to the minimum demand signal. Example:

The minimum motor rpm is XXX rpm, press:

until < SETUP 30 > appears, then XXX ENTER (Address 31)

This setup function address is not used in this application. (Address 32)

This setup function address is not used in this application.



(Address 34)

This setup function address is not used in this application. Remote Totalizer Pulse Width (Address 35)

This address specifies the duration of the remote totalizer (K8 relay) output pulse. This value is rounded to the nearest 50 ms by the microprocessor. It has a range of 0.005 to 2.0 seconds. The relay OFF TIME must be at least as long as the ON TIME. If this register is set up incorrectly, the remote TOTALIZER INDICATOR (TCI) will not display the actual totalized amount. The value of this register multiplied by the value of address 07, specifies the MAXIMUM feed rate that the feeder can deliver. Example:

Maximum Feed Rate = 200000 Lbs. per hour.



test), this address should be set to a value of zero. Units available for this parameter are: pounds/inch, kilograms/meter, kilograms/centimeter, kilograms/millimeter . The weight of each test chain is stamped on the end of the chain assembly. Example:

A set of six test chains has the following weights marked in Lbs./in: 0.7212, 0.7214, 0.7213, 0.7215, 0.7214, 0.7212. Enter the TOTAL SUM of each chain rounded to four decimal places.

↑ until appears, then Press: SETUP until the units appear as “Lbs./in”.

Then Press: 4.3280 ENTER Feeder Operation Specifications (Refer to the original manual OPERATION Section)



The following table summarizes all the operating parameters of the microprocessor control system. The values entered in the preliminary value column are to be copied from the existing microprocessor control and are used for guidance during equipment start-up. They should be checked and changed as required in accordance with actual job site conditions and, when verified, recorded in the final value column for permanent reference.

Address

Function

00

Feed Rate

01

Speed Set Point (rpm)

02

Initial Density Estimate (pounds per cubic foot)

03

Run Mode Select

Preliminary Value

Final Value



Address

B

Function

30

Minimum Allowable Motor Rpm

31

(Not used in this application)

32


33

Weight Signal Gain Factor

34


35

Remote Totalizer Pulse Width

36

Test Chain Weight

Acoustic Flow Monitor

Preliminary Value

Final Value



The microprocessor then begins to measure the volume of material passing over the weigh span by using the material density it has internally calculated to derive the volume of material from its weight. When the volume that has been programmed into the set-up parameter at Address 18 in the microprocessor has been fed, the microprocessor examines the input to see if material flow has been re-established or if the stoppage still exists. If material flow has resumed, feeding continues normally; if it has not, the feeder is tripped immediately and an error code (Code 13) giving the reason for the trip is displayed.

For: Doosan Heavy Industries American Corp. Project: SIPAT Units #1, #2 & #3 India Purchase Order No.: 110104180/N003-05KX Stock Equipment Company Sales Order: S.O. 10102-0000, 10103-0000, 10104-0000 File: SIPAT_Logic_rev_0.doc Date: 12-12-2005

Stock Equipment Company 196NT Controller Logic (Reference Logic Diagram, Stock 196NT Microprocessor Dwg. No. A1-001517)

Microprocessor Memory

Output Signals

Output signals to the CPU consist of analog signals (such as feeder feed rate feedback, or speed control signal to the motor speed control), or feeder status contact outputs (such a s ALARM, TRIP, FEEDER IN REMOTE) provided for customer use. Feeder Modes

The feeder is capable of being operated in three modes: OFF, REMOTE, or LOCAL/CALIBRATE. OFF deactivates the feeder. REMOTE allows the feeder to be controlled from the customer run permissive contacts and demand signal. LOCAL operates the feeder at a selectable speed or puts it in the CALIBRATE mode when used in conjunction with the CAL 1 and CAL 2 keys.

FEEDER OUTPUTS

7. After a two second delay the motor speed control has been determined to not be running and the feeder is in the RUN mode. ERROR CODE 11 “Motor starter” is displayed on the vacuum fluorescent display. Tachometer Select Relay K2

Energized under the following conditions: 1. With the feeder running in either REMOTE, LOCAL, or CALIBRATE mode, a signal has not been received by the microprocessor from the primary tachometer for 3 seconds. ERROR CODE 21 “Primary Tachometer Failure ” is displayed on the vacuum fluorescent display. Remote Relay K3

Energized under the following conditions:

unstable; possible loss of the +10 VDC supply. ALARM relay K7 is also energized. This alarm resets when the electronic calibration results are consistent. Running Speed, Totalizer, and Feed Rate Feedback signals are all Volumetric when VOLUMETRIC relay K4 is energized. Feeding Material Relay K5

Energized under the following conditions: There is material on the belt and the feeder motor is running Feeder Run Relay K6

Energized under the following conditions:

5.

6.

7.

8.

9.

differs from the demand feed rate by more than 5% for 2000 seconds. This error will reset if the difference falls below the 5% threshold. ERROR CODE 10 “Feedrate ” is displayed on the vacuum fluorescent display. There is an Event Processor Array problem. Possibly caused by failure of frequency outputs to feed back cards or the speed control loop. ERROR CODE 14 “EPA watchdog” is displayed on the vacuum fluorescent display. The total material integrator data logging pulses have exceeded 5 pulses per second and some pulses are being lost. ERROR CODE 09 “Remote TCI” is displayed on the vacuum fluorescent display. The primary tachometer signal has not been detected after 3 seconds. ERROR CODE 21 “Primary Tachometer Failure ” is displayed on the vacuum fluorescent display. The CPU could not write data to the EEPROM and then read the same data. ERROR CODE 05 “EEPROM write ” is displayed on the vacuum fluorescent display. The checksum of the data read from the battery backed-up RAM is incorrect,

Gravimetric Feeder

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