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06-11-2014, 06:43 PM
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#1
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Senior Member
Join Date: Sep 2013
Location: Upland, CA
Posts: 425
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Floating Neutral
So...I have a Champion 3500 RV generator, which means it is set up already to run with the trailer, and it does well for several months now. But....what is the terminal marked "Floating Neutral" on the front panel used for? I've looked up this in search, but nothing explains in laymen terms, what this does and what it is used for and when is it used? Anyone?
OK, so what prompted the question, I have a Craftsmen Professional Air Compressor 3 HP / 1.5 HP, 120v 15amp, and this generator will not run it. It tries to run but cannot get up to speed. The generator works fine off of house current or in my last Motor Home. Just having the problem now. I take it with me and want to be able to use it for various situations, kids toys, my tires, etc.
__________________
2015 Four Winds Super C, Class C Motorhome
4 - 100w mono solar panels with MPPT40 to charge four 6v batteries with 440amp hours.
Progressive Industries HW50c surge protector
1800 / 3600 inverter with auto transfer switch,
The bosses: My wife and two Labradoddles 80 lbs each
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06-11-2014, 09:41 PM
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#2
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Senior Member
Join Date: Jul 2013
Location: Box Elder
Posts: 2,897
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Floating indicates it's not bonded to the ground. Most electric systems have the neutral grounded at the source, such as the electric meter panel where the ground rod is driven. Normally, from the meter panel out, the ground is isolated from the neutral, so that is why on your 50 amp cables, there is two hot legs, a ground, and a neutral. The neutral is current carrying, and the ground is a safety bond back to earth. Because the ground and neutral are tied together at the meter panel, you can check voltage at a pedestal between both the neutral or the ground to either of the hot legs. The only thing I can think of that the floating neutral terminal would be used for would be connecting to a ground source to be similar to a utility power pedestal.
As for your compressor, you have way more startup load just to get the compressor up to speed than the generator can handle. The 15 amp rating is the running load, but for a very short time during startup, you are trying to pull much more than the generator can supply, at least what the supply cord can carry. You might try a 10 gauge extension cord, but if the generator can't handle it, that might be a waste of money.
__________________
Bob & Becky
2012 3402 Montana
2012 Chevy 2500HD D/A CC
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06-12-2014, 12:27 PM
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#3
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Senior Member
Join Date: Sep 2013
Location: Upland, CA
Posts: 425
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Bob, thank you for your reply, it does make a lot more sense to me now. OH, and I did find out more about the air compressor, and of course you are dead on. I work for the county and I talked to a motor guy this morning and he told me much of what you said.Most compressor motors require three times their rated draw to power up. He told me as well, as your compressor motor is attempting to start it is most likely drawing a significant load on the generator and bogging the engine. Check the compressor motor's electrical specifications tag. The running amperage times three is what's required to start it. But, the floating neutral terminal, I still a bit fuzzy as to it's use.
I know the compressor motor is 120 volt 60Hz and if the amperage or "A" is 15 then amps x volts = watts. So 15 x 120 = 1800 running watts and startup watts is 1800 x 3 = 5400 watts. The compressor is outside the generators peak rating. When plugged into your garage receptacle you
have a minimum of 6000 starting watts if your home has 100 amp service. If you have 200 amp you have 12000 starting watts protected by a 15 amp breaker. As the generator in my past MH was 5500, the compressor worked well. So me thinks I'll be looking for a smaller air compressor with a smaller start up usage.
thanks again
__________________
2015 Four Winds Super C, Class C Motorhome
4 - 100w mono solar panels with MPPT40 to charge four 6v batteries with 440amp hours.
Progressive Industries HW50c surge protector
1800 / 3600 inverter with auto transfer switch,
The bosses: My wife and two Labradoddles 80 lbs each
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06-12-2014, 04:43 PM
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#4
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Senior Member
Join Date: Jul 2013
Location: Box Elder
Posts: 2,897
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I never have done this, but you could drive a temporary ground rod, and run a jumper from the rod to the terminal on the generator. When plugged in to the trailer, you are grounded to the rod and the generator and the trailer are all bonded together. That would be the closest to getting power from a pedestal that you can get when using the generator.
__________________
Bob & Becky
2012 3402 Montana
2012 Chevy 2500HD D/A CC
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