Generator output 250v?

[Saywatt]

We just installed a 20kw generator with a service rated xfer switch and load shedding capability on a home.

Checked the hz. 59.5-60, but the voltage L-L was 250-251, L1-N 124.5 and L2-N was roughly the same.

This was with no load, but does this not seem a little too high? I would like to tweak it down to around 240...but there was no mention of voltage output adjustment in the manual. Do I just idle it down?

Another question:
The generator is only a 20kw/83a but comes with a 100amp breaker. Using the 75deg. column I used #4, but after reading 110.14(c), that was brought up in a previous thread, I'm wondering if I should have used #3.

Thoughts?

 

[qcroanoke]

We just installed a 20kw generator with a service rated xfer switch and load shedding capability on a home.

Checked the hz. 59.5-60, but the voltage L-L was 250-251, L1-N 124.5 and L2-N was roughly the same.

This was with no load, but does this not seem a little too high? I would like to tweak it down to around 240...but there was no mention of voltage output adjustment in the manual. Do I just idle it down?

Another question:
The generator is only a 20kw/83a but comes with a 100amp breaker. Using the 75deg. column I used #4, but after reading 110.14(c), that was brought up in a previous thread, I'm wondering if I should have used #3.

Thoughts?

Do not turn back the govenor! That controls the freqrency and not the voltage. You should be able to tweek the voltage but I wouldn"t do that either. Under load the voltage will drop back and I've seen many homes with 245-248 VAC from the utility. So I wouldn't be too concerned with that.
The wire size issue I will defer to others .....

 

[hurk27]

Make sure your battery is not weak in the DVM you used, also if your not using a true RMS DVM it's normal to read a little high, I always use my Triplet 310 when I check generator voltage, and my amp probe 610 for frequency, Generac has a voltage adjustment on the mother board, a small square pot, but its factory marked and you will void the warranty if it's messed with, without the factorys ok, 124/248 is not that high, if you have the 250-251, then your line to neutral would have been 125-126 volts, still not that high.

 

[broadgage]

Agree with others who state that 250 volts is fine.
It will drop a little under load and should end up very close to the utility voltage which is often slightly over the nominal voltage.

 

[G._S._Ohm]

Does the manuf. even specify open circuit voltage? They may specify a minimum load, though.

 

[don_resqcapt19]

The Illinois Commerce Commission rules require that a utilty correct for high votage at a 120/240 volt service only if the line to neutral voltage exceeds 127.5 volts. It is not unusual to see 125 line to neutral in my area.

 

[K8MHZ]

Take another look with a load connected.

 

[Saywatt]

Does the manuf. even specify open circuit voltage? They may specify a minimum load, though.

Nothing referring to a minimum load for proper voltage, but it does state that the range should be between 238-242.

I did put a 20a load on the generator and the output dropped to 247-248.

Also, the markings on the generator's 100a breaker says 60/75c, so with the 20kw max, I should be fine with the #4, right? I couldn't get anything larger than a #4 in the neutral bus anyway.