Why Diesel Generator Set Trip?

by Generator D. Diesel Generator

Tripping phenomenon

A.If diesel genset operates under rated conditions for a few minutes, the automatic air switch trips, after recloses, then trips a few minutes later with a burning odor.

The cause:

The main contact of the automatic air switch is not well contacted or the spring pressure is insufficient. and the lead-out wire of the switch is not well contacted. The above two reasons will increase the contact resistance of the main circuit of the automatic air switch and cause serious fever, which will lead to the action of the thermal release and lead to wrong tripping.

Methods of resolution:

At this time, we should clean the main contacts of the automatic air switch and flatten them with a fine file or fine sandpaper; Adjust contact spring pressure to make good contact; clean contacts, apply conductive paste if necessary, and lock connection screw.

B.Diesel generator trips immediately after connecting load.

After the unit starts, the generator terminal voltage is normal, but when the external circuit is connected, the load automatic air switch will trip immediately.

The causes:

External circuit short circuit and too heavy load.

Methods of resolution:

Find out the short circuit point of the external circuit and repair it. Reduce load to reduce load current output of generators.

But when we do not know what is causes of genset tip, what should do? After power generator set tripping, first check genset to judge the cause of this trip, and then take appropriate measures, the specific steps are as follows:

1.Check whether there is a problem of wrong operation, and whether the secondary circuit will cause tripping;

2.When the main circuit breaker at the outlet of transformer set of generator trips automatically, first check whether the generator indicator has any obvious fault symbols, if have, should cut off the excitation immediately; if not abnormal symbol, under the situation of good furnace condition, the electrical attendant should adjust the generator voltage and frequency in the normal range, check whether the high-voltage auxiliary power with the generator set trips, whether the start-up transformer is put into linkage, and whether the auxiliary power is normal;

3.According to accident phenomena, to judge the nature and scope of the fault, and clearly inspect the external of transformer set of generator and related equipment, to identify whether there are external fault characteristics;

4.Need to pay attentions, If switch tripping occurs in incomplete phase, need to remove start of switch protection failure; if it is not failure protection problem, it is necessary to open all switches connected to the same bus in time;

5.If because of busbar differential protection operation, or generator is over-current protection and other over-step tripping due to faults in substations, check the generator's external, it is normal, after fault isolation, the connection network is adjusted and connected to the grid;

6.Before tripping, if there is forced excitation and current shock. Reflecting the main protection (differential, heavy mashgas, etc.) action of the internal faults of generator-transformer unit, while the power grid is running normally, should shut down at this time;

7.And that’s another one that will quickly shut down a generator: alternator or prime mover over-temperature, as heat causes lubrication to break down and bearings to swell, increasing friction, causing more heat, and potential total failure or more fire;

8.If there is no strong excitation action and no impulse current before tripping, the operation of power grid is also normal. The generator's hydro-oil system and main transformer are also normal. The following treatment should be done: check the generator and its circuit, check the protection of the action, if all is normal, generator can be boosted at zero. When boosting, if everything is normal, the generator can be connected to the grid, and then continue to find out the reasons. When boosting, the strong excitation and automatic adjustment device shall not be put into operation. The neutral point of the high-voltage side of the generator-transformer unit shall be grounded. If abnormal phenomena are found, the generator-transformer unit shall be stopped immediately for inspection.

If it is found that the tripping is not caused by the failure of diesel generator set, it may be caused by the wrong operation of the relevant personnel. At this time, the demagnetization switch is often still in the closing position. Operators should first manually trip the demagnetization switch and immediately re-connect generator set to the grid.

Starlight diesel generator set covers Cummins, Perkins, Volvo, Yuchai, Shangchai, Ricardo, MTU, Weichai etc. If you have purchase plan recently, please feel free to contact us by email

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About Generator D. Senior   Diesel Generator

99 connections, 1 recommendations, 628 honor points.
Joined APSense since, September 11th, 2017, From Jiangsu, China.

Created on Dec 12th 2020 00:01. Viewed 35 times.


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