C6.6 Generator Sets Caterpillar

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DANGER: Shock/Electrocution Hazard-Do not operate this equipment or work on this equipment unless you have read and understand the instructions and warnings in the Operation and Maintenance Manual. Failure to follow the instructions or heed the warnings will result in serious injury or death.

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Personal injury or death can result from high voltage. When power generation equipment must be in operation to make tests and/or adjustments, high voltage and current are present. Improper test equipment can fail and present a high voltage shock hazard to its user. Make sure the testing equipment is designed for and correctly operated for high voltage and current tests being made. When servicing or repairing electric power generation equipment: Make sure the unit is off-line (disconnected from utility and/or other generators power service), and either locked out or tagged DO NOT OPERATE. Remove all fuses. Make sure the generator engine is stopped. Make sure all batteries are disconnected. Make sure all capacitors are discharged. Failure to do so could result in personal injury or death. Make sure residual voltage in the rotor, stator and the generator is discharged.

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Accidental engine starting can cause injury or death to personnel working on the equipment. To avoid accidental engine starting, disconnect the battery cable from the negative (−) battery terminal. Completely tape all metal surfaces of the disconnected battery cable end in order to prevent contact with other metal surfaces which could activate the engine electrical system. Place a Do Not Operate tag at the Start/Stop switch location to inform personnel that the equipment is being worked on.

The voltage regulator is located in the enclosure for the control panel or in the terminal box on the generator.

The Automatic Voltage Regulator (AVR) may control any of the following excitation systems: AREP, PMG and SHUNT. The AVR monitors and corrects the alternator output voltage by adjusting the excitation current.

Illustration 1	g03368326
The voltage regulator is located in the terminal box on the generator or in the enclosure for the control panel. (1) Terminal Box on the Generator (2) Enclosure for the Control Panel

The generator set may include one of the following voltage regulators.

SHUNT excitation system

The generator with SHUNT excitation is auto-excited with an R220, R250, or R251 voltage regulator. The regulator monitors the exciter excitation current as a function of the alternator output voltage.

AREP excitation system

For both AREP and PMG excitation systems, the AVR is the R438. With AREP excitation, the R438 electronic AVR is powered by two auxiliary windings which are independent of the voltage match circuit.

The first winding has a voltage in proportion to that of the generator (characteristic SHUNT), the second has a voltage in proportion to the stator current (compound characteristic: Booster effect).

The power supply voltage is rectified and filtered before being used by the AVR monitoring transistor. This principle ensures that regulation is not affected by distortions generated by the load.

Permanent Magnet Generator (PMG) excitation system

This is fitted at the rear of the machine and connected to the R438 AVR. The PMG supplies the AVR with constant voltage which is independent of the main generator winding. As a result the machine has a short-circuit current capacity and good immunity to distortions generated by the load.

These voltage regulators may have an optional remote potentiometer for voltage adjustment. This potentiometer is 1000 ohms 0.5 W minimum. The adjustment range is 5%. The voltage range is limited by the internal potentiometer "P2". Remove "ST4" in order to connect the potentiometer. A 1000 ohm potentiometer, or 470 ohm potentiometer may also be used on the R438 AVR.

R250 Adjustments

Illustration 2	g03361909

Use the following procedure to adjust the R250 voltage regulator.

1. The engine speed must be changed from the factory setting in order to change the frequency of the generator.

2. Turn potentiometer P1 to the full counterclockwise position.

3. Turn the potentiometer ST4 to the middle of the total rotation for the potentiometer, if equipped. Run the generator at the rated speed. If the voltage does not increase, the field may need to be energized. Refer to the "Special Use" section.

4. Turn potentiometer P1 until the rated output voltage is obtained.

5. Adjust the stability with potentiometer P2.

U/F Function and LAM

Illustration 3	g03363529
Frequency selector

The threshold position (50 Hz - 60 Hz) to activate the U/F function, as well as the LAM setting, is selected using the frequency selector.

Operating at 50 Hz: (U/F gradient)

0 - Threshold at 48 Hz without LAM for impacts between 30 and 40% of the rated load.

1 - Threshold at 48 Hz with LAM 13% for impacts between 40 and 70% of the rated load.

2 - Threshold at 48 Hz with LAM 25% for impacts greater than 70% of the rated load.

Operating at 60 Hz: (U/F gradient)

3 - Threshold at 58 Hz without LAM for impacts between 30 and 40% of the rated load.

4 - Threshold at 58 Hz with LAM 13% for impacts between 40 and 70% of the rated load.

5 - Threshold at 58 Hz with LAM 25% for impacts greater than 70% of the rated load.

Special operating

6 - Threshold at 57 Hz without LAM for speed variations at a steady state greater than 2 Hz.

7 - Threshold at 65 Hz without LAM for variable speed and tractelec/gearlec (U/F gradient).

8 - Special. The factory setting 48 Hz 2 U/F gradient.

9 - Threshold at 47.5 Hz without LAM for speed variations at a steady state greater than 2 Hz.

R438 Adjustments

Illustration 4	g01518013

Use the following procedure to adjust the R438 voltage regulator.

1. Remove wire ST4.

2. Connect an analog voltmeter that is calibrated for 50 VDC on terminal E+ and terminal E-.

3. Connect a voltmeter that is calibrated for 300 VAC to 500 VAC or 1000 VAC.

4. Make sure that the ST3 wire is positioned on the desired frequency. Also, the engine speed must be changed from the factory setting in order to change the frequency of the generator.

5. Turn potentiometer (P2) to a full counterclockwise position.

6. Turn potentiometer (P4) to a full clockwise position.

7. Turn potentiometer (P3) counterclockwise to about 1/3 of the total rotation for the potentiometer.

8. Start the engine and set the engine speed to a frequency of 48 Hz for 50 Hz or 58 Hz for 60 Hz.

9. Adjust the output voltage to the correct value with potentiometer P2. This voltage should be the rated voltage UN for single operation or UN plus 2% to 4% for parallel operation. Use potentiometer P3 to make adjustments if the voltage oscillates. Adjust potentiometer P3 in both directions while you observe the voltage between E+ and E-. The voltage between E+ and E- should be approximately 10 VDC. The best response times are obtained at the limit of the instability. Try cutting or replacing the wire ST2 if no stable position can be obtained.

10. Check the LAM operation. ST5 must be closed.

11. Turn potentiometer (P4) slowly counterclockwise until there is a significant voltage drop. The voltage drop should be approximately 15 %.

12. Vary the frequency of both parts between 48 Hz or 58 Hz according to the operating frequency. Check the change in the voltage that was previously observed.

Use the following procedure in order to run the generator set in parallel operation.

1. Preset the unit for parallel operation by connecting the current transformer to S1 and S2 of the connector J2. Set potentiometer P1 for quadrature droop in the center position. Apply the rated load. The voltage should drop for 2% to 3%. Switch the positions of the two incoming secondary wires of the current transformer if the voltage increases.

2. The no-load voltages should be identical for all the generators that are operating in parallel. Connect the generators in parallel. Try to obtain a 0 kW power exchange by adjusting the speed of the generator. Try to minimize the circulating currents between generators by altering the voltage setting with potentiometer P2 or Rhe on one of the generators.

   Note: Do not change the voltage settings after this step.

3. Apply the available load. The setting is correct only if a reactive load is available. Equalize the Kilowatts or divide the rated power of the units proportionally by altering the speed. Equalize or divide the currents by altering the quadrature droop potentiometer.

R438 Adjustment for Maximum Excitation

Illustration 5	g03361296

The factory setting corresponds to an excitation current that is required to obtain a three-phase short circuit current of 3 X IN at 50 Hz for industrial power, unless this is specified otherwise.

The maximum level of excitation may be reduced by a static method. The static method is safer for the generator and the network. Use the following steps to reduce the maximum excitation level.

1. Disconnect the power supply wires X1, X2, Z1 and Z2.

2. Disconnect sensing leads 0V, 110V, 220V and 380V on the generator.

3. Connect the main power supply 200V-240V, as shown. X1,X2:120V

4. Install a 10 Amp DC ammeter in series with the exciter field.

5. Turn potentiometer P5 to a full counterclockwise position and activate the power supply. If there is no output current from the voltage regulator, turn potentiometer P2 clockwise until the ammeter indicates a stable current.

6. Switch off the power supply. Switch on the power supply. Turn potentiometer P5 until the required maximum current is obtained. The maximum current must not be greater than 10 Amperes.

Use the following steps in order to check the internal protection.

1. Open switch D. The excitation current should increase up to the preset maximum value and the excitation current should remain at the preset maximum value for approximately 10 seconds. The current will decrease to less than 1 Amp.

2. Open switch A in order to reset the internal protection.

   Note: The voltage must be adjusted after the maximum excitation current has been set.

Special Use

The exciter is switched off by disconnecting the power supply to the voltage regulator. The connection is identical for resetting the internal protection for the voltage regulator.

Illustration 6	g00952830

Use a 12 VDC power source in order to energize the field, if necessary. Refer to the following table.

Illustration 7	g00952821

R450 Adjustments

Illustration 8	g02320335
(1) Rotating switch (Excitation type and time response) (2) Rotating switch (Voltage sensing) (3) Rotating switch (LAM and U/F) (4) "P1" Voltage (5) "P2" Stability (6) "P3" Excitation (7) Excitation limiting/overload indicator LEDs (8) 10 Amp fuses (9) Field and excitation supply connections (10) Model designation (11) "P4" (Quad droop) (12) Droop current transformer input (13) Remote voltage adjustment potentiometer input

Excitation Type and Time Response Rotating Switch

Illustration 9	g02352788

0 - "AREP" excitation and normal time response

1 - "PMG" excitation and normal time response

2 - "PMG" excitation and fast time response. For "SHUNT" applications, "AREP" excitation must be selected.

3 - "AREP" excitation and fast time response.

Voltage Sensing Rotating Switch

Illustration 10	g02352789

0 - Voltage from 320V to 530V (5000/6000 series)

1 - Voltage from 80V to 320V (5000/6000 series)

2 - Voltage from 80V to 320V (7000/8000 series)

3 - Voltage from 320V to 530V (7000/8000 series)

LAM and U/F Rotating Switch

Illustration 11	g02352790

0 - Change in the voltage according to the U/F ratio. Knee point position at 48 Hz.

1 - Change in the voltage according to the 2 U/F. Knee point position at 48 Hz.

2 - Change in the voltage according to the self auto-adaptive LAM combined with 2 U/F. Knee point position at 48 Hz.

3 - Change in the voltage according to the U/F ratio. Knee point position at 58 Hz.

4 - Change in the voltage according to the 2 U/F. Knee point position at 58 Hz.

5 - Change in the voltage according to Change in the voltage according to the self auto-adaptive LAM combined with 2 U/F. Knee point position at 58 Hz.

6 - Change in the voltage according to the U/F ratio. Knee point position at 65 Hz.

7 - Special (not used)

8 - Change in the voltage according to the U/F ratio. Knee point position at 48 Hz or 58 Hz according to the selection of the frequency by an external contact.

9 - Change in the voltage according to LAM 1. Knee point position at 48 Hz or 58 Hz according to the selection of the frequency by an external contact.

Integrated Voltage Regulator (IVR)

The Integrated Voltage Regulator (IVR) provides excitation current to the generator. The IVR is controlled by the IVR function in the EMCP4. The IVR function allows the EMCP4 to control the generator voltage, optimize transient performance, and provide feature specification.

The excitation module may interface with any of the following excitation systems: Self Excitation (SE), Internal Excitation (IE) and Permanent Magnet (PMG) excitation systems.

For additional information about the IVR, see Application and Installation, LEBE0006, and Special Instruction, REHS9106.

Illustration 12	g03712568
Excitation Module 10 (EM10) (1) Connector P3 (2) Connector P2 (3) Connector P4

EMCP IVR Connection

To regulate the generator terminal voltage, the EMCP communicates the desired excitation command to the excitation module through a pulse width modulation (PWM) signal. A twisted pair of shielded cable must be used for the communication link. Table 5 details the connections to be made between the EMCP and Excitation Module.

Table 6 provides information on the technical specification of the EM10 and EM15 modules. Selection of the appropriate module must be determined by the following:

• Nominal and maximum generator excitation current at full load (standby 0.8 PF).

• The maximum AC voltage input.

IVR Excitation Module Connections

The EM10 and EM15 excitation modules have three plug type multiple-pin connectors. The connectors are labeled P2, P3, and P4 as shown in illustration 12. Table 7 describes the signal and function of each connector pin.

Note: The X2 and Z1 connections are internally linked within the excitation module. The link provides a point of common connection for the auxiliary windings where an AREP or IE excitation supply is available. Also, the X2 and Z1 connections may be linked externally to the excitation module. Only three connections (X1, X2, and Z2) are needed for the EM. Refer to Systems Operation/Test and Adjust/Troubleshooting, UENR1209, "Integrated Voltage Regulator Connections" for excitation module wiring connections. The wiring diagrams are for self-excitation (shunt), auxiliary windings (AREP/IE), and permanent magnet (PM) configurations.

The voltage regulator knee frequency must be configured for your specific package requirements. The knee frequency for 50 Hz operation will usually be between 48.0 and 49.8 Hz. For 60 Hz operation, the parameter must be set between 58.0 to 59.8 Hz.

Refer to Illustration 13 for an example under-frequency roll-off (loading) profile.

Illustration 13	g03487998
Under-frequency (loading) profile slope1 = 1.0 V/Hz, slope2 = 2.0 V/Hz