After Maintenance No-load Operation of 250KW Diesel Generator Set

Reasons for No-load Operation

In practical use, the no-load operation state of 250KW diesel generator sets is usually used to test whether the unit operates normally. If the no-load operation is normal, the power output state of the 250KW diesel generator set is basically normal.

The no-load running time of diesel generator sets should generally not exceed 5 minutes. It is recommended to warm up the engine for 3 minutes first, then increase the speed to the rated speed, and connect the load after the voltage is stable. The generator set should operate with a load of at least 30% to ensure that the engine reaches the operating temperature required for normal operation, so that all matching gaps reach the optimal state, avoid oil burning, reduce carbon deposition, prevent early wear of cylinder liners, and extend the service life of the engine.

Steps of No-load Operation for After-sales Maintenance

1.Disconnect the oil circuit breaker at the generator outlet.

2.Start the generator and keep it running at the rated speed.

3.Close the excitation switch, and then gradually adjust the resistance Rn to increase the excitation current. At this time, the terminal voltage Vo will also increase until the terminal voltage rises to about 1.25 times the rated voltage. During the adjustment of Rn, 9 to 10 points should be selected, and Vo, Il, and the corresponding speed should be recorded simultaneously. More points should be taken near the rated value.

4.Adjust the resistance Rn to reduce the excitation current until it reaches zero. Record the corresponding Vo and Il according to the points in step (3). When the excitation current Il drops to zero, read the residual magnetism voltage value.

5.Based on the recorded Vo and Il values, draw the rising curve and falling curve respectively, and then take the average value to obtain the no-load characteristic curve of the generator.

Precautions for No-load Inspection

After the generator set runs under no-load for a few minutes, if a fault occurs, the unit should be shut down immediately. After shutdown, the following items should be inspected in detail:

1.The oil pressure reading of the engine should generally be 2.8kg/cm2 (40lb/in2) or higher.

2.Check whether the engine fan blades and fan frame are detached or touching the casing.

3.Check the actual load reading on the battery charger or discharge meter.

4.Check whether there is fuel leakage in the engine.

5.Ensure that the system's ventilation openings have sufficient fresh air supply.

6.Check whether the cooling water pipes are leaking.

7.Check whether there is gas leakage in the exhaust system of the diesel generator set.

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