[Arnold Ziffel]

I have a Robin Subaru 7500 portable generator that I use as an emergency backup. I use it to run two furnaces,, a fridge, a freezer and a well pump. It can handle them all, as well as the other miscellaneous electrical stuff in the house.

The surge power is 7300 and the full load is 6700 watts.

The AVR blew and I had it replaced. The power is running at 112 unloaded in both of the 120 volt outlets. I didn't check the 240 volt outlet, but I can with a multimeter. I checked the outlets with simple, plug in digital meters; these indicated that my utility power in the house was 120 volts, so they seem accurate.

I just tested it by plugging a 1700 watt hair dryer and a 1500 watt space heater into one outlet and a 1500 watt space heater into the other outlet.

On the outlet with both appliances connected, the voltage dropped to 110, perhaps to 109 volts for a moment. Correct me if I'm wrong, but I think I'm safe in that voltage range, but if I can easily raise it, I'd like to (more time on my hands with the Coronavirus freeze for projects like thhis ...).

On the outlet with only a 1500 watt space heater connected to it, the voltage was unchanged, or even went up a volt.

I found a Youtube video and some instructions on Champion's web site that showed how to adjust a screw on the AVR to increase the voltage, and it looks like a simple process.

However, I read on another site that I should first ensure that the frequency should be checked and adjusted first before modifying the voltage. I have no way of adjusting frequency - my multimeter doesn't do that.

Should I simply reset the frequency to 122 volts, or should I wait until the repair shop re-opens and have him check the frequency first?

 

[seharper]

Get a $20 Kill-a-Watt power logger. Among its displays is frequency. And it has many other uses.

 

[Arnold Ziffel]

I didn't know they only cost $20. Worth the money.

I do want to know what the frequency range is on this thing.

Should the frequency be tested before adjusting voltage? Is that accurate?

 

[Arnold Ziffel]

Turns out that my multimeter does read frequency. The generator is running at 64 hz unloaded, and 63 hz with a 1500 watt space heater plugged into each outlet. (My in-house utility power reads 59.99 or 60 hz on the meter).

What are the risks of having the frequency running that high?

Should I adjust the frequency first, and then the voltage?

 

[AllanJ]

I would say that plus 10% to minus 5+ for AC current frequency would cause no problems except for clocks running a little fast or slow. Some very old TV sets might require re-adjustment of vertical hold or horizontal hold.

 

[Bud9051]

Let me apologize first, but you are worrying too much.
Your generator probably produces 240 volts, give or take, which is split into two 120 circuits. The power rating you quoted should be balanced half on each circuit when running 120 loads. You can't put the full load on just one 120 side.

I suspect any extension cords you use will increase the loss more than what you are reading. Never good to run a generator near full capacity so plan to run ONLY what is absolutely needed. Example, a cold freezer can hold for many hours as long as you do not access it frequently. And two furnaces? At best alternate their use or just shut one down, whatever your house will allow. Emergency situations sometimes require a compromise.

Bud

 

[Arnold Ziffel]

Thanks. I do try to moderate what I run when I'm on the generator (I get hot water from the gas grill or wood stove, for example). I usually turn alternate furnaces. The biggest draw is the well when it surges.

I try to run some of the electronics from marine batteries through inverters.

I plug the house into the 240 volt power supply, so I get both legs of the 120v outlets (which are giving me 112 to 114 volts each right now). Do you think I'm OK there, or should I raise the voltage on the two legs to about 122 to 124 volts (unloaded),a nd leave the frequency as is?

 

[Arnold Ziffel]

Thanks for your advice, folks. I was able to raise the voltage to 122 volts. I haven't messed with the frequency, so it'll be 64 hertz unloaded and 63 loaded for now. Hopefully that won't damage anything. I do run some computers with the generator at times; I haven't run my ham radio with it - I would probably use a car battery for that, but in a short-term emergency, I wouldn't need that. If all other means of contact go, the ham radio is a means of reaching the rest of the world, but I really don't see Armageddon coming. A recession, yes.