> From:         spam_OUTcarlosmarcano78TakeThisOuTcantv.net[SMTP:.....carlosmarcano78KILLspam@spam@CANTV.NET]
> Sent:         Tuesday, June 29, 2004 10:46 AM
> To:   PICLISTKILLspamMITVMA.MIT.EDU
> Subject:      [EE:] Harmonics in a Generator.

> Hi list. I have this little problem I would like to share to see if any of
> you have known of something similar. I work at an hidroelectrical dam, Guri
> Dam (Raul Leoni Dam to be more precise), in Venezuela. I am part of the
> Regulators Section for about 6 months now. We are on charge of the
> excitation systems of the generators among lots of other stuff. We also are
> on charge of the syncronizers of the machines. These devices check the
> phase and voltage coming from a generator (through the step-up transformer)
> and the phase and voltage of the line (the rest of the electrical system)
> and sends the orders to the generator to raise or lower the freq or voltage
> of it to match the system and when these parameters are as close (or equal)
> as posible sends an order to the breaker switches and "syncs" the generator
> with the system, alouding to pump the power from the machine to the system.
> Recently we were having trouble with one of the generators (there are 20
> here, for a total installed capacity of 10.000 MW) when syncronizing (I
> dont know if this is spelled right). It was absorbing a huge amount of
> MVAR, which is ussually and indication of a difference between the
> generators voltage and the system's voltage when syncronizing, difference
> that should not be more than around 1 volt. We calibrated the syncronizer

> Instead, we are
> getting a clean, 60 Hz 120 VAC rms signal from the line's side and a pretty
> much like wave from the generator's side but with little peaks         that look
> like harmonic distortion. We got the generator desyncronized (switches
> opened) and measured the signals at A and B again, the B signal (system's
> side) was exactly the same clean one and the other one from the A point
> (generator's side) was more distorted, with a bigger harmonics component.
> The thing is: Is it possible (well it seems like it is!) to see two
> different signals from the same line conection? Isn't the system a "bigger
> voltage source" than the generator so the signal should be the system's
> one? I am a little confused... Hope someone could give me some light in
> this matter. TIA,

> Regards,

>   *Carlos*
> -- Guri, Venezuela --