AVR VT Location

[NickParker]

What are the pros and cons of options 1 and 2?

Option 1: VT located within generator terminal box

Option 2:- VT located before the incoming breaker in the Switchgear

 

[waross]

Available space may be an overriding factor

 

[TugboatEng]

If you're going to use fuses, they generally don't tolerate the vibration associated with being mounted on the machine.

 

[waross]

If you're going to use fuses, they generally don't tolerate the vibration associated with being mounted on the machine.

I have had quite a few PTs mounted with 480 Volt generators without vibration issues.
However your concern may be valid at higher voltages.

 

[TugboatEng]

PTs or fuses? Transformers themselves vibrate. They'll be tolerant of what the engine contributes. It's that fine wire inside the fuse that fails. I've had problems with circuit breakers as well. The 3 phase breakers are riveted together and the plastic dividers cut through the rivets which then drop into the windings and blow the generator up. The OEM ships the generators with breakers, the dealers replace the breakers with fuses, the customer gets stuck with failures.

The modern solid state AVRs can sense directly at 480V. If mounted in the enclosure, I prefer designs that don't incorporate any over current protection.

 

[wcaseyharman]

For utility scale generators we have examples of both at the company I work at, and operationally I don’t notice a difference. It seems more common to put the PTs in the switchgear with the breaker - often the gen and line PTs used for synchronizing are in the same cabinet.