Genrator out of phase...

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xformer

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Dallas, Tx
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Master Electrician
How many degrees out of phase can a 3-phase and a single-phase generator reach?

This is for discussion and not field application. Ideally generators need to be in phase in order to be synchronized to utility.
 
I was inquiring how much out of phase can they be in general. Not how much out of phase they can be when synched. :)

If the lines are not connected together, then 180 degrees would be the maximum phase angle.

If synced to a utility, the power angle has to be under 90 degrees ( if I am remembering correctly ) for the sync condition to be stable. I am thinking 30 degrees is more normal.

I cannot tell if from here if this link is still good.

http://www.youtube.com/watch?v=3Mwy07lLZnE&feature=relmfu
 
Just for info....paralleling generators. Learned this while in the Navy on a nuclear sub. We had two turbine generators. 180 deg out of phase means max current. 120 deg out means max torque. I saw out of phase paralleling roll a 2500 ton sub about 45 deg due to out of phase parallel. Scary. Breakers tripped, adding to the fun. Ever been in a sub at 750 ft and had ALL of the lights go out? Gets really quiet...
 
Just for info....paralleling generators. Learned this while in the Navy on a nuclear sub. We had two turbine generators. 180 deg out of phase means max current. 120 deg out means max torque. I saw out of phase paralleling roll a 2500 ton sub about 45 deg due to out of phase parallel. Scary. Breakers tripped, adding to the fun.
Wow! That is one of the most chin dropping things I have read here. Seriously, no joke.














Ever been in a sub at 750 ft and had ALL of the lights go out? Gets really quiet...
So did anybody get caught making out? (that was a joke)
 
Here's another true story....while I was in the Navy electrician training school, there were two (60 hz 3600 RPM) motor generator sets that were used for training on parallel operation of generators. I don't remember how big they were, but they stood about 2 ft high and four feet long. Bolted to a concrete floor. Well....somebody (not me) paralleled 'em out of phase at just the right time to get max torque. It ripped one out of the floor, threw it against the wall and then it rolled up the wall about three feet before it crashed to the floor. I didn't see it happen, but we all had to go look at the damage. Made a lasting impression.

Oh, making out? Naw! On a sub the new guys had to "hot rack". Not enough beds for all of the crew. Which means share the same bed with two other guys because we worked three 6 hour shifts and you slept only during your six. I slept in my clothes on top of the blanket. No way I was gonna crawl between somebody else's warm sheets (unless it's my wife). YUK!
 
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