Phasing an induction generator 5

[Rodmcm]

I am to commission an old 11kV 1000kVA induction generator. How can you reliably and easily check that the phase rotation of the rotating generator is the same as the grid?

 

[GTstartup]

I agree with Skogs method. I've done this many times. It doesn't matter how slow you rotate the rotor. I use 3 simpsons so you can see the deflection easily. Connect them directly to the output bus and rotate the generator a few RPM

This is not a check for synchronizing but that's not what the OP asked.

 

[waross]

That's nice Gunnar. Thank you.

Bill
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"Why not the best?"
Jimmy Carter

 

[Skogsgurra]

GT,

Never thought about using analogue meters. I am a 'scope-and-recorder' guy, myself. But three 260's would be quite an impressing sight. I haven't go but one :-(

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[Rodmcm]

Thank you all, looks like I can safely go ahead. What are '3 simpsons' GT?

Many thanks Gunnar.

 

[ScottyUK]

Rod,

A Simpson is a North American analogue meter similar to an AVO 8.


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If we learn from our mistakes I'm getting a great education!

 

[genhead]

Maybe getting off-track a bit, but with regards to "pwrengrds" suggestion of using hot-sticks and synchroscope, this is the method that I used to use (not with induction generators though).

However, would modern safety standards prohibit this method?

Also, there was the problem of finding volunteers to hold the hot-sticks - they're the type of people that volunteer for bomb disposal, or finding the source of major radiation leaks!

 

[ScottyUK]

Phasing across a breaker equipped for synchronising is fairly easy if the load can be disconnected and the breaker closed. From that state it is easy to verify the VT secondary phasing matches by closing the breaker. Obviously there is no possibility of incorrect primary phasing with the breaker closed. The less direct interaction with the HV plant the better.

Re. volunteers:

I'm totally uncompromising if I'm not happy with someone's attitude toward live HV testing: I won't work with anyone who has a gung-ho attitude or treats working on live plant as some kind of rite-of-passage. A substation ain't the place for adrenaline junkies. Most times direct interaction with live HV can be avoided: sometimes it takes a little longer to do it safely, but you are dead for a real long time if the short cut goes wrong.


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If we learn from our mistakes I'm getting a great education!

 

[GTstartup]

Well technically you only need two analog meters but then you have to think a little

 

[cranky108]

From the perspective of testing with the breaker closed, even if the disconnect's are open, the 52b contact is in a position the disconnects many older sync-check relays. This might interfear with some other testing that might be going on (just a note).

I even saw this with a SEL relay, because of a setting (Really confused the tech.).

 

[ScottyUK]

Hi cranky,

I wasn't really meaning to go as far as the sync check relay, just the VTs. I'm quite happy with a meter at the VTs to prove that the phasing is ok, but valid point about the relay. Thanks.


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If we learn from our mistakes I'm getting a great education!

 

[burnt2x]

edison123 already posted a simple way: i.e. starting the generator as induction motor from the grid (11kV) with the hydro intake valves closed. If the rotation of the generator is the same as direction when you run the hydro-generator off-grid (intake valves open but generator breakers off), then you know you're phase-in with the grid.

 

[Rodmcm]

On synch gens we always disconnect the cabes at the generator and close in the 52G breaker, everythimg then gets energised in phase so the VTs ( bus ad gen),synch check, protection synch, gen metering et al can be checked. By closing the 52G under test mode from an autosynch the breaker timing can also be checked. Simple, easy, effective