Electrical ? for BuickandDeere

Hello Buick and Deere.

If a home generator is rated at say 20 kilowatts and the amperage rating of the generator is 83 amps then I would have to guess that is in 220VAC.....Yes?
Cause 83 amps x 220 volts = 18,320 watts, or basically 20KVA.
And then in 110 volts it would be equal to 165 amps.....Yes? cause 110 volts x 166 amps = 18,320 watts.....
Why is a 20 KVA generator rated at 83 amps? and not listed as 166 amps at 110vac?

In this case I would use 240 volts and then yes it is 83 amps. The reason is that the 240 is A phase to B phase, but when split up it is A phase to neutral and B phase to neutral giving you 41.5 amps per phase or a total of 83 amps.

Ok.
It seems that you would get 83 amps per phase, not 41.5.
I do not like the fact that if I pay for a 20kw gen set I should get 83 amps per phase, not 41.5.

But..........I am not an electrical engineer.

20 kw is 20 x volts x amps x power factor (phase relationship between voltage and current which changes with generator type and whether or load is resistive, inductive (voltage leading the current) or capacitive (current leading the voltage).

My machines have a pair of regular US 120v receptacles rated at 20 amps, a round 3 terminal receptacle rated at 30 amperes, and a round 4 terminal receptacle rated also at 30 amperes but 240 volts.

So for mine (20 x 120) + (30 x 120) + ( 30 x 240) = 13,200 watts with a PF of 1 which it has. However, the unit is not rated to supply full power to all outlets simultaneously. It is rated at 50% duty or usage and conservatively rated at 6500 w, but does have a surge rating of somewhat more than that for things like compressor starts.

Due to wiring limitations, including protective fusing (circuit breakers) you can only supply the UL listed rated power from each receptacle.

HTH,
Mark

I don't see my friend the good Buick man responding, but its sort of the same as the transformer mounted outside on a utility pole. It is 240 volts across it two outermost terminals, but in its mid center point there's a tap which is connected to a GroundING Electrode Conductor (No 4 bare copper wire) that leads down the pole to a GroundING Electrode (driven into earth cooper rod). From that center point, its ONLY 1/2 OR 120 VOLTS from EITHER outside terminal and therefore, only 1/2 of the total power dissipation is available. That's for a cheaper single winding transformer or genset. However, if you were to have two windings (would be more expensive) and had the ability to place them in series (240 volts) or parallel (120 volts) then you can dissipate the same power (I Squared R heat) at EITHER voltage, as each winding still dissipates its 1/2 share.

Surge ratings and KW versus KVA and dual voltage etc are important considerations when selecting a genset.

John T I AM an Electrical Engineer but retired and pretty rusty on this, so NO WARRANTY. Buick is younger and currently practicing and the question was for him, so see what he has to say.


DISCLAIMER, This is merely an opinion, and like ALL opinions posted here, it may be right or it may be wrong, I'm not saying it is or it isn't, some others may agree some others may disagree. Its worth what you paid NOTHING take it or leave it, its your choice