Generator Set Load Sensor Caterpillar

Expected Result: The linkage moves through full travel smoothly until the linkage is against a stop screw. The linkage moves without binding or excessive force.

Results:

• OK: Check backlash. Refer to the governor Service Manual, Service Procedures, "Linkage Calibration". If backlash is acceptable, go to 2. If backlash is not acceptable (more than specified wear limits), repair the worn components. STOP.

• NOT OK: The linkage does not move through full travel to a stop screw. The linkage is stuck, or has binding and takes excessive force to reach a stop screw. Refer to the governor Service Manual, Service Procedures, "Linkage Calibration". STOP.

1. Run only one engine.

2. Load the engine until speed slows to 50 rpm less than rated speed.

3. Check fuel linkage to determine if linkage goes completely to maximum fuel position. If not enough load is available to move fuel linkage to maximum fuel position, look at fuel linkage during acceleration from low idle to rated speed to obtain maximum FUEL ON position against the stop screw.

   Expected Result: Linkage moves to maximum fuel position.

   Results:

   • OK: Go to 3.

   • NOT OK: Linkage does NOT move to maximum fuel position. Refer to the governor Service Manual, Troubleshooting, "Engine Will Not Carry Load (Low Power)". STOP.

1. Run only one engine in Isochronous Mode at part load to full load.

2. Disconnect any external speed control components (such as synchronizer) from the generator set load sensor.

3. Adjust the engine speed control governor potentiometers for stable operation. Refer to the governor Service Manual, Service Procedures, "Adjust for Stable Operation".

4. Set the "LOAD GAIN" voltage the same as all other isochronous units are set for at full load. Usually, the voltage is about 4 to 6 volts. Now check the engine speed control governor and its response to load changes.

   Expected Result: Engine speed is constant at constant load, and response to a load change is acceptable.

   Results:

   • OK: Go to 4.

   • NOT OK: Engine speed change is NOT constant after a load change (is not isochronous). Check output voltage of generator as the load is changed. Refer to the governor Service Manual, Service Procedures, "Speed Setting". STOP.

Note: Refer to Testing And Adjusting, "Phasing - Check" for current transformer phasing check instructions.

Note: The generator set load sensor contains internal current transformers. Due to their low impedance, shorting their inputs (T4 to T5, T6 to T7, T8 to T9) is NOT effective.

1. Perform the phasing check.

   Expected Result: Load signal voltage drops by 1/3 for each phase ("A", "B", "C") tested.

   Results:

   • OK: Go to 5.

   • NOT OK: Load signal voltage does NOT drop by 1/3 for each phase (A, B, C) tested. Make a correction to CT phasing. See Testing And Adjusting, "Phasing - Adjust". STOP.

1. Put the engine into operation. As necessary, make adjustments to all of the following settings so that they are the same as all other units.
   • Speed

   • Speed Droop

   • Load Gain

   • Generator Voltage

   • Voltage Droop

   • Voltage Gain

2. Perform 5.a with the other generator sets.

   Expected Result: Engine will take and share the load.

   Results:

   • OK: Problem is solved. STOP.

   • NOT OK: Engine will NOT take or NOT share the load. Verify wiring, initial checks and adjustments. Go to 6.

1. Inspect droop/isochronous circuit. Inspect load sharing lines and connections to all generator set load sensor terminals. Verify that shield has been properly connected. Verify that wires are not routed near EMI (electromagnetic interference) sources.

2. When operating in parallel, measure the DC voltage between terminals T15 and T16 on the generator set load sensor. T15 is a positive terminal. T16 is a negative terminal.

   Results:

   • If the voltage measured is approximately 10 VDC, then repair or replace the circuit breaker auxiliary contact or the droop-isochronous switch or wiring to them. STOP.

   • If the voltage measured is near 0 VDC, the problem is resolved. STOP.

   • If shield is improperly connected or wires are routed near an EMI source, then connect shields properly and/or reroute load sharing lines as required. STOP.