XQ175 Rental Generator Set 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. Make sure residual voltage in the rotor, stator and the generator is discharged. Failure to do so could result in personal injury or death.

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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.

For generators with a PMG excitation system (permanent magnet generator), the PMG excitation system is added to the rear of the generator. The PMG supplies the voltage regulator with a voltage that is independent of the main generator winding. The PMG has a short circuit capability of 3 X In for 10 seconds. The PMG also has good immunity to distortion from the generator load.

The voltage regulator monitors the output voltage and the voltage regulator corrects the output voltage of the generator by adjusting the excitation current.

Illustration 1	g01837333
The voltage regulator is located in the enclosure for the control panel. (1) Enclosure for the Control Panel

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

R448

R448 Adjustments

Illustration 2	g01212000

Illustration 3	g00996011

Use the following procedure to adjust the R448 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.

R448 Adjustment for Maximum Excitation

Illustration 4	g01016266

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

Illustration 5	g00952821

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.

Set-up

A qualified engineer must make adjustments during tests of the AVR. The drive speed specified on the nameplate must be reached before starting the adjustment. After operational testing is completed, replace all access panels and covers.

The AVR adjusts the equipment.

Initial Potentiometer Settings

"P1" - Voltage minimum fully anti-clockwise (Factory setting 400V - 50 Hz)

"P2" - Stability (Not set)

"P3" - Excitation ceiling (Factory-sealed) 10 Amp maximum

"P4" - Voltage quadrature droop (Operation with current transformer) 0 quadrature droop fully anti-clockwise (Not set (fully anti-clockwise))

Stability Adjustments (Stand Alone Operation)

1. Install a DC analogue voltmeter (needle dial) calibrated 100 V on terminals "F+", "F-" and an AC voltmeter calibrated 300 to 500 V or 1000 V on the alternator output terminals.

2. Check the rotating switch selection.

3. Voltage potentiometer "P1" at minimum, fully anti-clockwise.

4. Stability potentiometer "P2" around 120° from the anti-clockwise stop.

5. Start the engine. Set the speed to a frequency of 48 Hz for 50 Hz or 58 Hz for 60 Hz.

6. Set the output voltage to the desired value using "P1".

   1. Rated voltage for solo operation (such as 400 V)

   2. Or rated voltage (such as 410 V-)

7. If the voltage oscillates, use "P2" to make adjustments. Adjustments may be made in both directions. Observe the voltage between "F+" and "F-", which is approximately 10 VDC. The best response time is obtained at the limit of the instability. If no stable position can be obtained. select the fast position.

8. Check the LAM operation depending on the rotating switch selection.

9. Vary the frequency below 48Hz or 58 Hz according to the operating frequency. Check the change in voltage from the voltage observed previously.

10. Readjust the speed of the generator set to the rated no-load value.

Stability Adjustments (Parallel Operation)

Note: Make sure that the speed droop is identical for all engines before working with the alternator.

1. Preset for parallel operation with the current transformer connected to "S1", "S2".

   Note: Potentiometer "P4" (quadrature droop) in 1/4 position in the case of 5A CT and at 1/2 position in the case of 1A CT.

   Apply the rated load (PF = 0.8 inductive). The voltage should drop by 2% to 3% (400V). If the voltage increases, check to make sure that one of the following have been reversed: "V", "W", "S1" and "S2"

2. The no-load voltages should be identical for all the alternators which run in parallel.

   1. Couple the machines in parallel.

   2. Attempt to obtain 0 kW power exchange by adjusting the speed.

   3. Attempt to cancel or minimize the current circulating between the generator sets by alternating the voltage setting "P1" on one of the generator sets.

   4. Do not adjust the voltage settings after the above procedure is completed.

3. Apply the available load by one of the following methods. The setting is only correct if a reactive load is available.

   1. Alter the speed. Match the kW or divide the rated power of the units proportionally.

   2. Alter the quadrature droop potentiometer "P4". Match or divide the currents.

Maximum excitation adjustment

In the standard setting, the potentiometer "P3" is in maximum position. For applications requiring an overload protection, use the following procedure to adjust the excitation ceiling in AREP and PMG.

Method 1

1. Connect the AVR to the alternator.

2. Apply the load to 100% of rated generator set rated at power factor =0.8. The greed lamp is illuminated and the red lamp is off.

3. Adjust "P3" until the red lamp is flashing and the green lamp is illuminated.

4. Decrease the load to 100% and make sure that the red lamp is not illuminated.

5. Increase the load to 115%. Make sure that the red lamp flashes for 90 seconds. Make sure that the excitation current is brought back to the above adjusted value (l ex adjusted)

Method 2

Multiply the rated excitation current by 1.1. Use the obtained value to set the potentiometer P3. Use the following table.

Illustration 7	g02355098

In the case of a permanent short-circuit, the excitation current must reach 2.9 × hex adjusted (clamped to 9.5 A) during 1 second in AREP or 10 seconds in PMG. The current must shut down to a value less than 1 Amp.

Note: When the excitation current is set to the rated value, a voltage dip is observed in the excitation current limit when the limitation is activated and the current limit is reached.

For information about electrical faults, refer to the Systems Operation/Testing and Adjusting, "Troubleshooting" information for the generator set.