Firman generators

[Tractorat]

Nope, giving the mitsu to my son.

 

[Tractorat]

So now you have two?

Oops, no. I cancelled the generac as soon as I realized it wont pull start without a battery.

 

[Dan_69GTX]

Here is a link to something I posted about generators
https://www.turbodieselregister.com...-pics-of-some-wave-forms.239085/#post-2309804

The Generac XG8000E required the fuel tank to be removed to replace the battery.

 

[Dan_69GTX]

The Champion gens are OK, but parts and reliability are issues - from my experience. Hondas are quieter.

There have been a lot of China brand knock offs of Honda that have come and gone - Kipor ring a bell?

 

[Tractorat]

I wonder what the acceptable hz variation is for household current.

 

[Dan_69GTX]

That depends upon the device that requires the power. Motors are designed to operate at a specific frequency. They do typically allow some variation w/o hurting the motor. What will really affect the motor isn't the frequency as much as how dirty that frequency is. (how smooth is the wave). The dirtier the waveform, the faster the motor will fail.

Now a resistance load - doesn't care.

 

[brods]

I wonder what the acceptable hz variation is for household current.

Can't answer that, but you bring up a good point that most, including myself, tend to overlook: the quality of the electrical output of the generator. We had a Craftsman 6500 from 2005 until 2015 when the Briggs engine decided there were too many teeth on the cam gear. We used it several times a year and whenever the computer battery backup/surge protector was plugged in it would click constantly switching from line to battery and back signifying that the power from the generator was dirty. Bought a Rigid 5700 from Home Depot and the battery backup is happy as a clam.

Maybe someone with an electrical background can give what specs should be looked for on the electrical output side of a gen set. Ideally it should be based on whatever device you'll be powering that has the most stringent power requirements.

If your power goes out regularly, a transfer switch is well worth the cost, especially if you can install it yourself. For the superstitious, once the transfer switch is installed, the power will go out half as often. Having the genset gassed up and not buried in the back of the garage reduces outages another 25%. Ok, maybe its because of the aggressive tree trimming the utility started doing.... either way I'm happy with the power going out less frequently!

 

[Dan_69GTX]

Certainly electronics can be affected by any of it - voltage variations, frequency variations, dirty waveforms. One time we were dry camping with some friends. He brought along a construction generator and I had my Hondas. His wife brought along a kuerig coffee maker. The coffee maker did'nt work on the construction generator but worked fine on the Honda.

For dirty waveforms think of it this way - an oversimplified description - A motor is spinning. It has to spin according to the waveform. If the waveform changes at all, the motor has to change too. So, if there is a slight change to the waveform the motor has to try and change too. The motor is spinning a lot of mass, this mass doesn't change as fast as the wave does, so it hurts the motor to do so.

The very early Priuses had issues with dirty waveforms. Their transmissions (electrical motors) started to fail around the 150K mile mark. Toyota did much digging in to it and found it was because of the dirty waveforms. They greatly improved the waveform and now the Prius is much more reliable.

 

[Tuesdak]

I wonder what the acceptable hz variation is for household current.

Not sure this is the question you want to ask. We used to run synchronous motor clocks off the utility main power and expect them to be accurate. Regardless the grid is very tightly controlled for HZ as all kinds of bad happens to the utility if the HZ varies. For example overload slowing the HZ down starts brownouts and blackouts to keep the HZ spot on. HZ to a utility is more important than voltage.

The Onan generator I listed above is 59-63 HZ depending on the load on it and it's governor control. Extreme idle stop is set at 54 HZ although it should never run at this HZ. Typical adjustment is for 59HZ minimum at full load: ideally 60 HZ at full load. (The engine governor needs some RPM (HZ) change to work properly.)

Most modern "Global" stuff, TV, computer, etc... their power supplies are rated for 50-60 HZ so it can run in other countries without changes. These are no longer sensitive electronics due to modern power supply designs.

AC Motors will simply follow the HZ and run at that speed although they may be out of their design range at some low or high HZ and could overheat or stall out.

I suggest you are asking about "Dirty Power" and specifically if a device you plug in will have problems on a generator.

For example I plugged in a HZ meter on my RV generator and found a surprising 400HZ reading. I turned on the air conditioner and found a normal 60 HZ. Turns out the 400HZ was "noise" from the "battery charger" converter interacting with the generator. It caused the old microwave in the RV to not power up on gen power and makes a new GFI light up an unhappy red light. If I run a AC motor the "noise" goes away and things work... It's said that some microwaves use the line HZ as a "clock" signal for their electronics. Clearly the old microwave was overwhelmed by the 400HZ noise.

@Dan_69GTX linked his post of waveforms showing clean vs. dirty waveforms. Noise from a bad load is beyond that, but, another angle of dirty power. Some generators are better than others in design of the regulator from CHEAP capacitor regulators to high end electronic regulators. "Sensitive" computers run very well on the awful APC UPS output waveforms.

As noted above there is no hard and fast rule on what is sensitive anymore and further the source of the "noise" or problem may not be the generator itself.

 

[Tractorat]

Well, the reason I asked is this new firman gen I bought has a meter that can show voltage, hz, and one other metric (I forget what that is, but I dont think it is amps. Just for grims Im going to run my old mitsu gen and test it with my volt/amp/hz meter to see what it says, then run the new gen against the same meter. Never had any problems running anything with the old gen, and just havent tried the new one yet.

 

[Tractorat]

With no load, the firman puts out 243v at about 62.5hz. I didnt look at the volts on the old mitsu. But with no load, it is putting out 60.1 hz.

 

[Tractorat]

Well, it looks like the hz is adjustable

 

[Tractorat]

I got the frequency adjusted to 60.1hz. Support initially had me turning the wrong screw which adjusted the V, not the freq. After I realized that problem, I had to adjust the volts. I put it to where it was from the factory, 244v with no load. Is that OK ?

 

[Tuesdak]

Sounds like the Firman is set ok. Old governor spring on the mitsu maybe needs a little tightening. I used to set my old genset to 60 HZ, 3600 RPM, no-load till I found a service manual for it that gave me a higher No-Load HZ/RPM number. Never hurt anything running a little slower under load.

 

[Dan_69GTX]

A VOM will give you good info, but just so you know - to check out how "dirty" the power is you will need a scope.

 

[Tractorat]

A VOM will give you good info, but just so you know - to check out how "dirty" the power is you will need a scope.

Right, which is something I dont have. But, not too concerned about that. If voltage and freq are correct, there really shouldnt be a problem.

 

[Tractorat]

Factory tells me the total harmonic distortion on this thing is 11-14% I dont know what it is on the old mitsubishi

 

[Tuesdak]

With no load, the firman puts out 243v at about 62.5hz. I didnt look at the volts on the old mitsu. But with no load, it is putting out 60.1 hz.

I got the frequency adjusted to 60.1hz. Support initially had me turning the wrong screw which adjusted the V, not the freq. After I realized that problem, I had to adjust the volts. I put it to where it was from the factory, 244v with no load. Is that OK ?

What does their manual call for? IMO the factory 62.5 HZ No-Load was correct. My mistake if this is the "Full Load" HZ adjustment number you are posting.

 

[Tractorat]

What does their manual call for? IMO the factory 62.5 HZ No-Load was correct. My mistake if this is the "Full Load" HZ adjustment number you are posting.

At the time of posting it was no load (mentioned in the post). However, although it didnt occur to me that freq might be affected by load, this morning I hooked it up to the house with all the lights on, refri running, dishwasher on heat dry mode, 2 52" tvs and dvr on, and anything else I could think of that might be on during a power outage. Voltage at the outlets I tested was about 120-121v. freq was right at 60hz on the nose.