AVR

[jalover]

Hi! pls i need some help re AVR of generator. I have 1 unit of gen set rated 140kw, 400volts , 50 hz.I dont know what is the reason why the AVR always damaged. I already changed 2 times but now again damaged, i noticed that the voltage has increased. I adjusted the trimmer to 400 volts during start-up. Any thoughts what could be caused by this.
thanks in advance.

 

[waross]

I am assuming that you don't have a PMG, and that you have a brushless exciter. Check your exciter field windings and the rotating diodes and varistor. If there is diode damage also check the revolving field.
Also check the AVR voltage rating and the source voltage for the AVR power and sense (sometimes the same terminals).
Many AVRs have a MINIMUM allowable connected resistance. This value will be in the spec sheet. Check the exciter field resistance as well as checking for grounds.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[jalover]

Hi Warros! thanks for your quick reply. Yeah it uses brushless exciter. But why it normally work at about 4 hrs, if there is a damaged diode , could it be working in normal at the beginning. anyway, i will check accordingly. Thanks for your valuable info.

 

[waross]

Thank fangas for this link in another thread. (Electric motors & motor controls engineering Forum
how to select the right varistor for a syncronous generator)

http://www.marathonelectric.com/

Drill down through;
Generators, Service & Support, to Service Procedures.

http://www.marathonelectric.com/generators/serviceProcedures.jsp

Bill
--------------------
"Why not the best?"
Jimmy Carter