AVR replacement for coumpound field main exciter

[PaulCurrie]

Hi guys, could I please get some advise on dc generators?

We are currently replacing the Voltage regulator for a synchronous generator that uses a compound field dc generator to supply the main field current. The existing voltage regulator is a mueseum piece that controls a rheostat to change the shunt field circuit resistance.

The plan is to remove the existing regulator and disconnect the field windings to allow rewiring the exciter as a seperately excited dc generator and use a current source AVR.

So I know that I can calculate the armature emf and resistance by measuring the series field resistance, amature circuit current and the armature circuit voltage.

However, what I am not too sure about is the process for then calculating the required field current and voltage for seperate field excitation.

Also when we break out the existing field windings, will we need to run the shunt and series windings together in series to form the new field or can we retain only the series windings?

Thanks in advance,
Paul

 

[waross]

The maximum shunt field voltage will be the maximum voltage of the DC generator.
If this is a smaller machine, less than 1000KVA, measure the shunt field resistance. You will find many AVRs need a minimum resistance load.
Feed the shunt field with the new AVR. One typical voltage value is 63 volts max from the AVR but there are other voltage ratings.


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

 

[Ceast]

You should be able to rig up a Basler DECS 200. Awesome regulator! Go to their website it's all there. I've installed a bunch of DECS. I believe the max current output is 15amps DC.

 

[ksreddy35]

field voltage will be maximum of DC generator & current can be calculated from ohms law by finding the ressistance. The AVR should be 1.6 times more in voltgae & current than the calculated value