×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Replacing a reverse acting AVR with forward acting AVR

Replacing a reverse acting AVR with forward acting AVR

Replacing a reverse acting AVR with forward acting AVR

(OP)
Hi all,

We currently have a requirement to investigate replacing our existing Jeumont Schneider reverse acting AVRs.

The existing alternator is an indirectly self excited machine. The stator part of the generator excitation system comprises a differential compound winding arrangement (a shunt field and a differential series field winding). The shunt field is the main field winding and is fed from a normal compound excitation circuit. The differential winding is excited by the AVR.

If I wanted to just feed the shunt winding with the compounding circuit plus a forward acting AVR. What else would need to be looked at?

Alternatively, instead of it being a differential compound wound machine, could I get a forward acting AVR and wire up the series field winding for a cumulative effect? What are the specific things I need to look at to achieve this?

RE: Replacing a reverse acting AVR with forward acting AVR

Do you have the instruction manual?
Link
I have seen saturable reactor or transformer regulators with series boost with and without an AVR.
Basically, the constant voltage transformer or saturable transformer supplies the field and the no load voltage of the generator is determined by the output voltage or current of the saturable transformer.
If the generator voltage is less than the desired generator voltage, the machine may be operated with no AVR or with a forward acting AVR.
If the generator voltage is more than the desired generator voltage, the machine may be operated with a reverse acting AVR.
There may be a rheostat in the circuit to reduce and adjust the voltage applied to the brushless exciter, and as a result, the generator output voltage.
A series boost may be added, and if the machine is to be operated without an AVR, a series boost must be added. The output of a current transformer monitoring the load current of the generator is dropped across a resistor and the resulting voltage is added to the output of the saturable transformer to set the generator output voltage and to compensate for the internal impedance of the generator.
Adjusting the value of the resistance across the CT output will determine the amount of compensation and influence whether the system will run with a forward acting AVR, no AVR or a reverse acting AVR.
To change from a reverse acting AVR to a forward acting AVR, the output of both the saturable transformer and the series boost CT must be trimmed to a little less than 100%.

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

RE: Replacing a reverse acting AVR with forward acting AVR

(OP)
Thanks waross,

Is there any benefit in connecting the AVR to the series winding over connecting it to the shunt (compound) winding? Will the response of the excitation system benefit in any way?

I imagine that connecting the AVR up to the shunt winding as the series boost will require the AVR to provide the current compensation wholly. Whereas, if it was decided to leave the existing current compensation circuit as it is, and leave the AVR acting on the differential or cumulative series winding that it would then just be used to perform fine control wrt current compensation.

Hence, if the AVR only has to perform fine control is it more likely to respond more quickly than if it is performing the full series boost? Is this beneficial?

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources