Portable Generator - - Voltage/Frequency Tolerances

[RCW]

For some of the new folks, I've gone to a 12 kW portable generator for when we have outages. We've covered all of it in previous thread(s).

It's all a manual hook-up. I need to get the generator outside and hook the 50A connection to it.

It's covered a couple tests and short outages.

I've altered loads some before.

Today we face a long-term outage. We've been out 12 hours already, and I'm betting for 36 hours at a minimum.

I left the Electric Water Heater on the load because we need hot water. Seems to work okay on the genny.

My thoughts/questions:

1. I'm not savvy with the tolerances of frequency. Just don't know enough about it. Frequency typically reads 60-61 Hz, but noticed can vary 59-63Hz with/without instantaneous load demand of the water heater today.
2. I'm not concerned, but should I be?
3. IF I were to adjust Hz - - I believe it's throttle adjustment on engine?
4. If I were to adjust throttle linkage for Hz, would it also affect voltage output?
5. Pretty sure the following is a non-issue. Alternator reads 239-242 volts consistently. I'm happy with that. My older genny was doing 110 or so volts. Our Electrical Utility couldn't deliver maybe 60V early this morning..............
   

 

[North Idaho Wolfman]

Your within the normal variance for a small generator.

 

[Mark_BX25D]

My thoughts/questions:

1. I'm not savvy with the tolerances of frequency. Just don't know enough about it. Frequency typically reads 60-61 Hz, but noticed can vary 59-63Hz with/without instantaneous load demand of the water heater today.
2. I'm not concerned, but should I be?

Don't be concerned. Only the most sensitive equipment might be affected in the real world.

Theoretically, the things that would be bothered are computers and things with computers (digital controls).

Resistance loads (electric dryer, water heater, space heater, hair dryer) and motors don't care.

1. IF I were to adjust Hz - - I believe it's throttle adjustment on engine?
2. If I were to adjust throttle linkage for Hz, would it also affect voltage output?

There is no way to compensate for frequency fluctuations by messing with the throttle on a consumer grade backup generator. Fuggedaboudit. The fluctuations happen FAR too quickly. You need millisecond response time, and you CANNOT get that out of a carburetor even with a fancy digital control. The engine just cannot respond that quickly.

Instead, concentrate on making your loads resistant to such fluctuations.

A laptop is already fairly immune, due to the fact the actual circuitry is powered by the battery, which is being charged by the AC. The charging circuit can tolerate sloppy power. Same for your phone

A desktop computer with true UPS (Uninterruptible Power Supply) is in great shape if it is a zero-switching time UPS.

A UPS is not going to work with something like a modern electric dryer, because it will draw more power than a UPS can handle, and you don't have the opportunity to run the controls from a separate power supply. If you are concerned, you can just flip the breaker and not use those appliances.

But really, you are probably just fine. I run my desktop, cable modem and router on a zero-switching UPS so I don't drop my Internet at all, and I just don't worry about the rest.

Pretty sure the following is a non-issue. Alternator reads 239-242 volts consistently.

Correct. It's a non-issue. My grid power fluctuates more than that on a regular basis!

 

[chim]

Probably not a concern, but I have an inverter welder that gets run on my generator more often than utility power and wants a max of 5% THD. I've read about guys having issues with worse distortion.

 

[Magicman]

Adjust your engine speed to obtain 60 Hz with your maximum load. There should/will be a screw. You will be OK.

 

[RCW]

Your within the normal variance for a small generator.

Thanks.
Thought so as well.

 

[RCW]

Don't be concerned. Only the most sensitive equipment might be affected in the real world.

Theoretically, the things that would be bothered are computers and things with computers (digital controls).

Resistance loads (electric dryer, water heater, space heater, hair dryer) and motors don't care.



There is no way to compensate for frequency fluctuations by messing with the throttle on a consumer grade backup generator. Fuggedaboudit. The fluctuations happen FAR too quickly. You need millisecond response time, and you CANNOT get that out of a carburetor even with a fancy digital control. The engine just cannot respond that quickly.

Instead, concentrate on making your loads resistant to such fluctuations.

A laptop is already fairly immune, due to the fact the actual circuitry is powered by the battery, which is being charged by the AC. The charging circuit can tolerate sloppy power. Same for your phone

A desktop computer with true UPS (Uninterruptible Power Supply) is in great shape if it is a zero-switching time UPS.

A UPS is not going to work with something like a modern electric dryer, because it will draw more power than a UPS can handle, and you don't have the opportunity to run the controls from a separate power supply. If you are concerned, you can just flip the breaker and not use those appliances.

But really, you are probably just fine. I run my desktop, cable modem and router on a zero-switching UPS so I don't drop my Internet at all, and I just don't worry about the rest.



Correct. It's a non-issue. My grid power fluctuates more than that on a regular basis!

Mark - appreciate your response.

Thought I was okay, but appreciate your feedback regarding some of the appliances.

I’ve had to replace a couple circuit boards on my pellet stove recently.

We were definitely receiving much less than standard power from the utility earlier today. I figured I would rather supplant that with generator power, even if a little off spec from what the utility is supposed to provide.

 

[Mark_BX25D]

120v with slightly out of spec frequency variation is a lot better than 60v with perfect frequency!

 

[RCW]

Adjust your engine speed to obtain 60 Hz with your maximum load. There should/will be a screw. You will be OK.

@Magicman - many thanks.

Will obviously need an oil change after this session so I’ll look for it then. Maybe adjust next session…..and I know there will be one.

Right now just want to put it away…..

33 hours out with temperatures around 40 degrees F….

Thankfully pellet stove only draws 3-400 watts running. Pretty easy load.