Posted: 12/5/2012 10:04:31 AM EDT
| During the Sandy power outage I made a list of all the circuit breakers that we ran off the generator. We have an interlock rather than a transfer switch so we turned on only the breaker that we needed. This past weekend I just put little red stickers next to the breaker so I won't need to look for the list next time the power goes out. While I was doing this I realized that 6 of the 8 of the circuits used were on only one of the legs or bus's. This means there was a fairly large imbalance in the draw from the generator. Except when we used the coffee maker or the microwave we probably drew 2000-3000 watts total. If we are drawing 2000 watts from 1 leg and 100 watts from the other is this going to be a problem for the generator ? |
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We've got a 1800RPM 6000 watt light tower that I haven't rewired the gen head for 120 yet, like I've been putting off for awhile.
Right now it puts out 120/240 and I've wondered the same thing about unbalancing the load on the stator pulling say 3000 watts. I do know that it won't start my smallish air compressor at times.. It's mostly IMHO a mechanical issue with stresses on the stator windings and although occassional unbalanced loads might not hurt it, long term is anyone's guess. You might want to relocate the wires going to a couple of breakers and that shouldn't take more than a couple minutes if the wires aren't too short. |
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Imbalanced loads aren't really a problem unless you are tripping the breaker for one leg on the generator. Imbalanced loads can keep you from utilizing the generators full capacity, i.e. a 5KW generator is only going to supply 2.5KW per leg and if most of your loads are on one leg you can trip that breaker before you actualy reach the generator's capacity. Some generators are actually built unbalanced, I have such a generator that is a 5KW unit, 20.8A per leg nominal, but has the windings for one leg doubled up to allow you to draw 30A from that leg.
Also realize that circuit breaker count in no way relates to balance, the actual loads on the circuits are what matters. You can have 10 circuits on one leg that are drawing a combined 15A and 2 circuits on the other leg drawing a combined 15A i.e. in balance. A clamp on Amp meter is very handy for figuring out the actual loads, but it requires access to the individual circuit conductors. You can also install permanent Amp meters for the two generator power legs in an enclosure next to the panel. Some of the small gnerator transfer panels include such meters. |