I have two generators working in parallel all the time. But recently one generator is losing power in seconds while operating in parallel mode. then finally reverse power trip will act to remove that generator from the bus bar. i checked my fuel pump and governor and are very ok. so please help me what the problem could be.

 

Generator instability

there are a few questions that need to be known before any reliable answer can be given.

What is the prime mover of the generator - diesel engine ??

Are the two generators working in parallel independent of the gird . ( or are they connected to the grid )

What is the governor mode of operation when the machines are in parallel
1. Droop mode
2. load control mode
3. Iso chronous mode - if iso chronous does it have a load sharing scheme ??

blind guess - I am assuming that the machines are operating independent of the grid , then the probable causes are

1. Faulty iso load sharing scheme - this is a common problem , and you say that one generator is losing power in seconds , i assume that the other generator is picking up the power. check to see is this is the case. This can be verified by putting both the machines in droop mode. In droop mode if the governor id functioning properly then the system should be stable.

2. One generator in droop and other in iso - this can also be a recipe for disaster if the iso machine setpoint is high enough than the system frequency , the iso machine tries to take on all the load.

So , the first thing you must do is to check in what mode the governor is operating. Put both the machines in droop and check for stability.