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Where should the feedback of AVR be taken in a synchronous generator?
Where should the Feedback for an AVR be taken in a Synchronous Generator? Also what are the consequences of taking the voltage feedback from the Busbar instead of the Generator terminals themselves?

Hi all,

Where should the Feedback for an AVR be taken in a Synchronous Generator?

This is a shipboard generator which has an Electronic Automatic AVR installed. The AVR takes its feedback (voltage) from the generator itself and not from the Switchboard Busbar to which the Generator wiring (3 phases) is terminated.

The OEM states that it is ok. What does the standard say? Please help me with the standard name and number in case one such exists.

Also what are the consequences of taking the voltage feedback from the Busbar instead of the Generator terminals themselves? The Busbar voltage is nominal and rated and to be maintained at 415 V @ 50 Hz.

This is a Cummins (India) Prime mover with Kirloskar Alternator tied to it. The AVR is supplied by Kirloaskar Electric India.

Please help me on this.
--
Regards,
Surya
mirage@fastmail.fm

2 out of 2 members thought this post was helpful...

Surya,

From my experience AVR sensing is usually accomplished using the generator output terminals--not the bus to which the generator is connected. Usually, the generator is isolated from the bus by a breaker so it's not really a good idea to take the voltage measurement from the bus (especially during start-up, when the breaker connecting the generator to the bus would be open).

Also, if other generators are synchronized to the bus one wouldn't necessarily want to control a generator based on the bus voltage (yes; the voltage is technically the same, but when sharing VArs (reactive current) it's not).

What kind of issues are you having that make you think the sensing location is not correct?

CSA,

>"voltage measurement from the bus (especially during start-up, when the breaker connecting the generator to the bus would be open)"<

Please elaborate on this sentence!
Thank you,
Vivek.

1 out of 2 members thought this post was helpful...

Vivek,

>>"voltage measurement from the bus (especially during
>start-up, when the breaker connecting the generator to the
>bus would be open)"<

The major part of the statement is: "From my experience AVR sensing is usually accomplished using the generator output terminals--not the bus to which the generator is connected."

This simplified, one-line (meaning all three phases are NOT shown; only one) "picture" might help:


Generator
3-Phase Breaker
Generator -----------------------| |--------------- - - - - - - -

INCOMING RUNNING
BUS BUS


In the above diagram, the generator phase leads are connected to the "INCOMING BUS" (meaning the generator would be synchronized to the RUNNING BUS), and the rest of the shipboard generators and loads would be connected to the RUNNING BUS (because at least one generator would already be running to supply the loads connected to the RUNNING BUS).

In my experience, the AVR sensing would be connected to the generator side ("upstream") of the generator breaker--and more specifically, to the generator output terminals connected to the INCOMING BUS, so there is as small a voltage drop between the sensing terminals and the AVR sensing input.

One would NOT connect the AVR sensing terminals to the RUNNING BUS (downstream of the generator breaker).

Hope this helps!