During power outages I backpower my house through a transfer switch
with a 4000 watt (5000 watt surge) Coleman generator. In the past, the
generator has easily powered the refrigerator, furnace, well pump etc.
just fine. During the last power failure I was experiencing slow
recovery on my water pressure and I found that when the well pump
kicked on, the voltage dropped from 220 v to 110 v in the wires
feeding the pump. The pump is 220 v, 3/4 HP, 7.0 amp, two wire feed.
Once the grid power is restored the pump works great, so I suspect my
generator is malfunctioning.
I have tested the generator by plugging in two 1800 watt heaters to
the 110 v outlet on the generator and measuring the voltage at the 220
v outlet, which remains at 220v.
By the way I did turn off all the house circuit breakers except the
pump as a diagnosis during the power outage in case I had left some
high wattage appliance on - no change.
Any idea what might be causing the issue? Thanks in advance.