we've 8.5 MW engine for our industrial purpose. say engine is running and delivering 5MW electrical load. My question when we increase load from 5 to 7 MW then a sound arises in the engine for few seconds and engine tends to be blocked.

My question why engine i.e rotor of the alternator tends to block when we suddenly increase the load. can any body help me? please give me details conception.

 

mua,

I've heard of rotor blocking before, but not in this context; usually it refers to work done to the generator rotor during maintenance or repair. If by "blocking" you mean that the engine-generator is unable to be loaded above approximately 7 MW, then I feel pretty confident in saying that the problem is the engine or the engine fuel delivery system.

If the unit continued to run at rated speed and frequency and to produce approximately 7 MW but the load couldn't be increased, then it's likely not the alternator that is the problem. The alternator is just a device for converting torque into amperes and if the amount of torque being supplied to the alternator won't increase then the amount of amperes won't increase either.

You didn't say if this is a new problem or something that has been happening for some time. If it's a relatively new problem, what has changed recently? Was some maintenance or repair work recently done to the engine? To the engine control system? To the engine fuel delivery system?

So, it's not exactly clear from your post and terms what the problem is or how long it's been happening or what has recently changed which might be contributing to or be the source of the problem which seems to be that the engine-generator can't be loaded above approximately 7 MW, which means that the engine can't be loaded above approximately 7 MW for some reason.

Since you didn't tell us what kind of engine, it might not even be the fuel delivery system. It could be some auxiliary or protective system that is operating, prematurely or because of some condition that has been detected, rightly or wrongly.

But one thing's pretty certain: It's not likely the alternator that's the cause of an inability to increase load above 7 MW, if that is a correct interpretation of the problem.

 

Are you stalling the engine? I think there is a limit to how fast the engine can increase torque (accept increased load without stalling).

I'm not an expert in this field, so I won't try to offer you any advice on this. However, your description of the symptoms is very unclear and I suspect that many people will not understand what you are trying to say.