1-phase load connected to 3-phase generator

[etalaat]

what is the maximum single phase load can be connected to a three phase generator rated 30 KVA, 220/380 volt

 

[Dennis Alwon]

Think of it this way. What size single phase load can you hook to a 100 amp 3 phase breaker? The breaker is good for 100 amps on each phase. Now the generator may not be rated to run at 100% but thats another question.

 

[tom baker]

It may be dependant on the generator windings and wiring. The generator may have an smaller neutral which would limit the connected load to neutral. Check with the mfg

 

[dbuckley]

I used to think this was an easy question, but now I know I don't know.

I was all relaxed about unbalanced loads on gensets, even just using one phase of three, until I saw a forum post (elsewhere) that said

Also, 3 phase gennies do not like being unevenly loaded. In electrical power theory, it cause NPS currents (negative phase sequence). These are bad news and cause stator over heating. In big gennies 3% nps is really bad news and 5% can cause the generator to fail. This isn't the same as saying you must have the phase loads within 5% of each other, but my previous post of keep the phases balanced as best you can is good advice.

So now I'm confuzzled. I don't understand about NPS, and all my googling has lead me to is that if you lose phases off a loaded generator then the NPS currents cause temperature rise in the stator, and you use I2T protection devices so the thing doesn't melt.

Is there anyone out there who both understands this stuff and speaks English not math?

 

[robbietan]

Also, 3 phase gennies do not like being unevenly loaded. In electrical power theory, it cause NPS currents (negative phase sequence). These are bad news and cause stator over heating. In big gennies 3% nps is really bad news and 5% can cause the generator to fail. This isn't the same as saying you must have the phase loads within 5% of each other, but my previous post of keep the phases balanced as best you can is good advice.


this is bad if you have other loads sharing the genset. otherwise, if that single load is to have the genset all for himself, why not?