I have two question?

1. I have one alternator of 3 MW, 3 phase, 50 Hz, 3300 volt, the direction is clock wise at NDE, i have new prim-mover of direction DE, can i run this alternator on wrong side safely?

2. if i put AVR output to fields of alternator exciter, on wrong polarity, what happened with alternator if do this?

 

1. To generate "electricity" with an alternator, all that is required is motion between two conductors and a magnetic field on one of the conductors. IN GENERAL, the direction of rotation doesn't matter, <b>BUT</b> most alternators have internal cooling that <b>IS</b> based on one direction of rotation. You will have to look at the drawings or the physical generator and rotor to determine this.

You should probably contact the alternator manufacturer about reversing effects of reversing the direction of the generator rotor.

2. You have not provided enough information about the type of alternator exciter. If the output of the alternator exciter is applied to brushes and slip rings on the generator rotor, then, IN GENERAL, the polarity of the DC being applied to the slip rings is not important. Again, it's relative motion between two conductors, one of them with a magnetic field associated with it.

But, the exciter alternators provided with many "smaller" alternators is generally of a brushless design and so the polarity of DC that is being applied to this type of exciter may be important. Again, we just don't have enough information to help, and it's likely you can't provide enough information in this type of forum for us to be of help.

 

Hussain... in general reversal of the source of excitation to a brush-type alternator has no effect. And now the Caveat:

UNLESS the rotating part has some sort of over voltage protective component located on the field coil side of the field circuit breaker... such as a diode, an MOV transient surge suppressor, or for older machines, what is called the crow-bar protection circuit!

Regards, Phil Corso

 

Hussain... further to my earlier 02-Nov-10 (10:12), reversing field connection may inadvertently "kill" residual magnetism if system is fitted with a field-flash setup!

Phil Corso