Generator Amp (Again)

[Guest Wayne77590]

Dang! The Generator Amp Question was interesting.

If'n ya'll have worked out the differences, a post would be good.

Question:

In the simplicity of it all, it was stated that watts divided by voltage equals amps. Let me ask this please.

In a 7500 Watt system, providing two independent 120 volt sources, wouldn't the way to determine what the current (amps) is would be to divide the 7500 by 2, then divide by voltage? That would put both legs having an amperage of 31.25 each. If two air conditioners were tied to one leg of the source, then it would be that the combination of current being drawn would exceed the one leg source output.

This is a legitimate question. I'm looking for an answer, please.

I have a different situation that works. I have a basement AC with two compressors. I know for a fact that the basement AC works off of L1 and that other appliances work off the other leg, L2. Now when I am hooked up to 50 Amp, both AC compressor's run. When I am hooked up to my Generator, both AC compressors seem to run (I need to check that more.) But, I do have an Electrical Management System that will shut down appliances to balance a load.

When I am hooked up to a pedestal with 30 amp service being supplied through a dog bone adapter to my 50 amp cable, only one compressor runs on the AC. There is a meter in my coach that shows which compressor is turned on. Number 1 AC compressor is the priority one and will run at all times. Compressor #2 comes on when power is available.

So that is why I'm confused about the 7500 watt generator providing power. In my case, everything operates when the generator is running. So I'm not sure if the 7500 watts is split in half or not.

[wolfe10]

Wayne,

Actually VERY few differences in either of our understandings in that other thread, just use if different terms that were starting to confuse many-- Herman wasn't the first to observe that! And as you identify in your post here, whether the generator is wired 120 VAC or 240 VAC was in question-- that is why I posted the link to Onan generator website to show that all the 6.5/7.0 KW Onans are wired 120 VAC.

Let me try to go through your questions one by one-- My response in SOLID LETTER CAPS (no, not yelling, just easier to separate ANSWER from the question):

"...it was stated that watts divided by voltage equals amps.: YES, OR MORE COMMONLY STATED (SAME MATHEMATICALLY-- VOLTS TIMES AMPS= WATTS).

"In a 7500 Watt system, providing two independent 120 volt sources...": WAYNE, I ASSUME YOU ARE TALKING ABOUT AN ONAN 7500 WATT GENERATOR. IF A DIFFERENT UNIT, PLEASE POST. NO CURRENT SPECS FOR IT ON ONAN'S WEBSITE, BUT HERE ARE THE SPECS FOR THE NEWER 8000 DIESEL http://www.cumminson...111&detail=true. IT SHOWS TO BE SET UP AS 120 VAC ONLY-- NO 24O OPTION. SO START BY CHECKING THE SPECS FOR YOUR GENERATOR TO SEE IF IT IS 120 VAC, 240 VAC OR ALLOWS THE COACH MAKER TO CHOOSE BETWEEN THE TWO.

"So that is why I'm confused about the 7500 watt generator providing power. In my case, everything operates when the generator is running". WAYNE, SORRY ONE WOULD HAVE TO LOOK AT YOUR WIRING DIAGRAM, INCLUDING HOW THE Electrical Management System WORKS TO BE ABLE TO ANSWER THAT ONE. CLEARLY A 7500 WATT GENERATOR PROVIDES MORE POWER THAN 30 AMP SHORE POWER-- 30 AMPS TIME 120 VOLTS= 3600 WATTS-- FAR LESS THAN 7500 PROVIDED BY YOUR GENERATOR).

"So I'm not sure if the 7500 watts is split in half or not." IF BY SPLIT IN HALF YOU MEAN TO HOTS L1 AND L2, YOU WOULD NEED TO LOOK AT YOUR WIRING DIAGRAM AND/OR GENERATOR BOOK. AS POSTED IN THE ONAN LINK ABOVE, THEIR CURRENT 8000 DIESEL GENERATOR IS 120 VAC ONLY.

IF THIS LEFT QUESTIONS UNANSWERED OR BROUGHT UP OTHERS, LET US KNOW-- HOPEFULLY SOMEONE ELSE WITH A SIMILAR ENERGY MANAGEMENT SYSTEM AND GENERATOR (PLEASE POST WHAT GENERATOR YOU HAVE AND WHETHER IT IS 120 OR 240) CAN DIG UP A SCHEMATIC AND BE ABLE TO ADDRESS YOUR QUESTION MORE COMPLETELY.

Brett

[Butch39]

BRETT,

We have an "ONAN 8000 diesel generator", in a 2007 Monaco Diplomat, and according to it's manual and it's data plate, is rated at 66.7 amps, and 120 AC voltage.

Butch

[wolfe10]

Butch,

Thanks. Yes, that matches the specs of the current generation 8000 posted in the link I posted above.

Again, on the larger generators (Like the Onan10,000+ watt generators) 240 is possible, but controlling voltage on BOTH legs is difficult enough that few coach makers wire them as 240.

[Guest Wayne77590]

Aw shux! I was being hypothetical with the 7500 watts and I should have stated that. I have the Onan 6.0kw generator. (RV QD 6000). I found the manual on the same site as the 8000

The principles will still be the same. Thanks.