What voltage does your generator run at?

[JerryK]

Most home owner generators run at 3600 RPM's. Other popular RPM's on bigger units is 1800 [ not as annoying ]. Anyone that has spent long times listening to the 60 cycle hum or around a running generator could probably set the proper RPM from sound memory..... Once your get the motor running at the proper speed [ or near it ], your voltage should read up around 120/240 volts RMS [ what your Fluke measures, that and their DC accuracy is what made Fluke famous ] without a load, plus or minus a handful or so of volts. As you place a load on the generator, the voltage tends to get lower.... just like in your home with store bought power from the electric company.

 

[90cummins]

HZ & Voltage are interdependent.
On most generators the correct voltage is attained when the engine is running at the correct speed.
Low engine speed = low voltage.
Anyone using a portable generator should have a Killawatt meter to monitor Hz & voltage anytime it is being used to power your home.
Stand-by units have over/under voltage & frequency shutdown protection unlike portables.
When ever I service or repair a unit I check the Hz and voltage and have found low voltage in more than a few because of a bad capacitor.
The owner was totally unaware of the problem but left unchecked could have damaged expensive electronics.
Motors in freezers & refrigerator's are very voltage sensitive.
No portable generator provides perfect 60Hz 120/240 volt power, there are limits on both you need to be aware of.
I used my Kilawatt meter to measure the current draw (watts) on all my electronics so there is no guessing about capacity when I use a device.
My 2 cents
90cummins

 

[buickanddeere]

Some generators use a cheap and awful system of field excitation with a rectifier instead of a regulator. I have a crappy Generac with no load voltage is too high at 145 volts and full load voltage is too low at 102volts. I have a proper aftermarket regulator on the bench to install someday .

 

[TractorGuy]

Not sure how this relates but my diesel generator adjusts voltage through a solid state regulator with potentiometers. I adjust the hertz by adjusting the governor speed of the engine.

My utility power measures 248v, 60 hz at the panel so I try to match that at the genset. My hertz will drop a little under load so I set the no load hertz to 61.5. At 40 amps load it drops to around 59.8 hz. My voltage remains constant at any load.

 

[daybreak1998]

Howdy,
You want 60Hz, the voltage can be in a range from 110-120volts. UL rating makes manufacturers build in usage of a guaranteed reference variation of 5%. Manufacturers build in usually 7% variance to ensure the products work as advertised. When someone speaks of a voltage of a products, they could say its a 110 volt unit. You might find things saying its a 115 volt product. You will also see it called 120 volt. Do not get all hung up on the voltage. The most important is going to be Hz. USA products are made for 60Hz. Just because someone says a clock plugged in to 50Hz will just run slow. That is a very simple powered item. Your refrigerator was made for 60Hz. It will end up dying if you keep running it on 50Hz. There are a lot of household items which do not care about Hz. Standard incandescent light bulb. That is not the only thing using power in your house. Have you looked at the outbound 30amp socket on your unit? it probably says 30 amp 125/250 on it.

A good clean 60Hz and 115volts is fine.

 

[TomSeller]

Not sure how this relates but my diesel generator adjusts voltage through a solid state regulator with potentiometers. I adjust the hertz by adjusting the governor speed of the engine.
.

So adjust the governor on the engine to get 60 Hz out of the generator, then adjust the potentiometer on the voltage regulator to 120/240V out of the generator? Then check under load?

 

[Mendonsy]

So adjust the governor on the engine to get 60 Hz out of the generator, then adjust the potentiometer on the voltage regulator to 120/240V out of the generator? Then check under load?

Yes, that is the best procedure.
The frequency tolerance is 5% so 57-63hz is the range. You want to start with about 62hz at no load because it will drop a bit as the engine is loaded up.
Voltage is the same deal. If your generator has a voltage adjustment then set it for 125 volts at no load. It will drop some as the generator load is increased.

 

[JerryK]

Always remember that the important voltage is what you actually provide the device you are powering. Long extension cords, poor connections/worn out plugs or even house wiring, may be delivering too low of a voltage to the frig/pump/etc.

 

[techman]

A couple of points. Generators fall into 2 categories. One type have (electronic) regulators. They have a board which will have an adjustment to set voltage. This type will maintain voltage under varying load and frequencies. They are the "better" and generally more expensive generator. The other type are "self regulating" generators. They will have one or more capacitors connected to the generator. This type of generator has a voltage to frequency relationship and are configured for a nominal voltage at the desired frequency (60 hz typical). Faster (higher frequency) will output higher voltage and vice versa. The only way to change the relationship is by capacitor value change. With this type regulation is not as good. If the voltage is low (or high) it typically indicated that the capacitor is out of tolerance or going bad, and should be replaced with a new one of the proper value. This type of generator is usually lower cost.

One other point. It was mentioned that US specs the voltage and frequency. UL does not require or set the requirements of these values.

paul

 

[TomSeller]

My house (built in 1988 ) had the "Quickwire" push in terminals when I bought It in 2015. I dislike those for load carrying circuits. So I have now replaced all of the primary feed circuit outlets but have 20 or so "bedroom" type load outlets to go at some point. Wire size seems to be All 12+ AWG so I should not have much voltage drop going on.