Loss of exciation(40) and Voltage Restrained Overcurrent for Generator

[shkim2000]

I'd like set protection setting for generator protection relay but I'm not familiar with setting for Loss of exciation and voltage restrained overcurrent. What information is required to be obtained for setting and how can I calculate to set both protections ?

 

[dpc]

The best starting point is the instruction books that come with the relays.

A good reference book like "Protective Relaying" by J.L. Blackburn is something that would also be helpful.

If you have specific questions after reviewing the instruction books, you can post those, along with the specifics of your relays and generator installation.

 

[tommy75]

Shkim2000,

While dpc brings up a valid point, this should be a rather simple procedure. Loss of excitation will come right from the generator manufacture's spec. When you loss excitation, the relay will drop the GCB. This is typically a hard wire from the generator exciter. As far as the voltage restrained overcurrent goes, you should have acess to the original relay study to help guide you or if this is a new install, again the manufature's spec for your system or dpc's reply on the book "protective relaying" should help you solve this.
Good luck... Tommy

 

[jtkirb]

getting the generator capablity curves is a good start.

Setting the 51v is easy- ignore the lowered voltage settings and focus on the full voltage settings. The current trip point is just lowered when the voltage is reduced.

40 protection is a little more tricky, but calculating the secondary vars using the vars capable by the machine is a very conservative starting point.

JTK