3000W Chinese Gensets Info.

purchased a contractor line genset from ebay rated at 4000 peak and 2800 watts. But when I try to run my a/c unit in my 5th wheel the voltage meter on the genset drops to 50-60 volts, and the 27 amp breaker on the genset trips. I thought maybe I have a problem with my a/c unit so I plugged my air compressor into it and the same thing happens!( rated at 12.5 amps at 110 volts). Any thoughts about what could be wrong with this generator?

While I have not seen your generator, I have a pretty good feeling about what is happening. This is an issue that has been extensively discussed on this forum for well over a year - I wish you could have read the discussion sooner and saved yourself a lot of grief.

Most all of these "contractor" generators deliver both 240 and 120 volts. Thus, the windings in the generator are in series. This means that you only have 1/2 of the total available power at 120 volts, which is 1,400 watts or around 12 amps. Starting current on your AC and air compressor can be more than double the run current. The peak power rating is meaningless. You see, the 2,800 watts is an RMS value, to get peak current or voltage on ANY AC source, we multiply the RMS value by 1.414, which will equal your 4,000 watt peak rating (give or take a little). This is NOT a surge current rating. The only reason for putting the peak power rating on the generator is to confuse you and make you think you are buying something more powerful than it really is. Unfortunately, a lot of advertisers are doing this. I cannot begin to fathom why you would have a 27 amp breaker on your unit. At most, you should have two 12 amp breakers.

Your only hope is to return your generator or undertake a rewiring to place the coils in parallel.

Sorry!