12.5 KW Onan generator and inverter

[steve zannella]

I seem to have a problem with my xantrex inverter when the  generator is running with 2 air conditioners operating. When my 3rd air conditioner starts up. The inverter shuts down for about 20 seconds after the air conditioner starts and then the inverter comes back on by itself. The other 2 air conditioners continue to run without interruption.

Any ideas about what is happening?

[Edward Buker]

Steve,

The generator can handle the total load of the coach (may include Aqua Hot Heating element also etc) but when you add the starting current of the third air unit, with the other two running, the voltage must drop enough momentarily for the Xantrex to take itself offline, or simply will not operate due to low AC voltage or momentarily not producing 60 cycles AC. Once the starting current has been satisfied and the total current drops back, the voltage rises again and the Xantrex then comes back online. I cannot tell you for sure if this is exactly what is happening but it makes sense based on your issue. I do not think there is a real issue here if the Xantrex comes back online. You may be able to help the situation by turning off the electrical element in the water heating system at the breaker panel if you have one while you run the air units on the genset.

Later Ed

[steve zannella]

Ed
I tried to check voltage watching TV when the inverter shuts down, unfortunately, the TV went down with the inverter. I'll try using the drivers 12 volt display next time to see if generator voltage drops just before shut down.
I never experienced this problem when connected to shore power. So it sounds like it maybe a generator problem. If I can't isolate the generator problem would adding A/C hard start capacitors be a work around.

Do you have any experience with them?

[Larry Dedrick]

Steve:
             Just to let you know what we have discovered on our coach regarding load and circuits. Our washer and the rear A/C (one of three) will not operate together because they are on the same breaker and they have set the system up to give priority to the washer when it is in use. I don't know if this will be of help or food for thought, but I thought I would mention it. All three A/C's work as long as the washer is not on. My reference is from the coach manual and I then looked at the AC (electric) breaker panel to confirm what appliances are doubled up on a common breaker.
              Once again, just food for thought.
           Good Luck

                Larry D

[Edward Buker]

Steve,

I do not think you have a problem, I think what is happening is quite normal. If you are running the generator it should be passing through 120V and not using the inverter to power your TV. So in that case when the third air kicks on the load from the first two is probably 26 amps and the starting current for the third can be 60 amps or more for a few seconds plus heating elements and anything else that is on. That extra sudden load added to the genset causes the engine to slow momentarily and then the throttle responds to bring the voltage back and the frequency back to 60 cycles at 1800rpm. I think your TV is sensitive to the frequency shift and/or voltage drop and it turns itself off. The only thing that could help is to add a computer APC supply to the TV to supply for a quick response hold of 120V when the generator slows momentarily responding to the added load. Something like this would likely do it for the short term voltage drops you are getting...

http://www.amazon.com/APC-BE550G-Back-UPS-8-outlet-Uninterruptible/dp/B0019804U8

You may or may not be able to see this voltage drop or frequency shiftaccurately on one of the 120V legs of the monitor panel depending on how fast that system senses and displays what is actually happening.

Later Ed

[Steve Huber Co-Admin]

Steve.
I had a similar problem with the TV dropping out when switching from Geni to battery power. I installed the unit Ed suggests and problem was solved. Check the dimensions and make sure it will fit.
Steve