I don't know whats going on...or...I don't trust my multimeter....

[Dualfuel]

Well just in case I cannot find my Kill a Watt....how would I go about measuring frequency of a generator if I cannot go higher then 30 volts AC?

[vdubnut62]

Buy a $10 or so digital Hz meter from Asia Engineers? Above my pay grade.
I'm sure someone here has the knowledge for a simple work around.
Ron

[Thob]

You should be able to get a step down transformer, 120VAC primary, something less than 30V on the secondary.  Like an old style doorbell transformer, filament transformer from an old tube radio, etc.

Transformers should work just fine with higher frequencies than they were designed for (up to a point).  A 60HZ transformer will work OK on 400HZ.  That doesn't mean that a device with a transformer designed for 60HZ will work at 400HZ, however; other components in the device might not work properly.

Check the tag on the generator.  Based on the manual you linked, it *SHOULD* be a 60HZ generator, IF that's the correct manual.

[glort]

Fleabay has loads of frequency meters from $14 up.

There are Multimeters, panel meters that only do around the 60Hz range which you could install permanently or use in the field, There are lab type frequency meters.... not shortage.
I have never heard of a meter that measures frequency only to 30V. All my chinese cheapies measure at over 400V as I have done when running up my Induction motor generators.

I subscribe to the theory you can't have too many multimeters ( I think I have about 5 now)  so just go buy another that does the job properly.

[BruceM]

30VAC max for frequency is a joke.  Use a low voltage transformer, or a resistor divider.  To divide by 11, use  100K to 10K, with 10K connected to the neutral leg, preferably. (not essential but safer) Read across the 10k resistor. 

The cheapest usb o'scope would suffice to not only determine frequency but other power quality problems as well.

[Jens]

The concept that a transformer made for 60 Hz should work at 400 Hz is just flat out wrong. The magnetics of transformers are designed to run at a certain frequency and that is that. Heck, even a 60 Hz transformer run at 50 Hz has to be de-rated (yes it works but you need to de-rate!)

[M61hops]

I would bet that that Leroy Sommer was built to a price point and they were just thinking of it running resistive loads.  It just might not work for inductive loads.  I have seen that a lot of small generators wont run transformer type battery chargers hardly at all.  I don't know exactly what is lacking in the generators that have these limitations, maybe not enough windings or the regulation system might be to blame.                           Leland

[Dualfuel]

Dear Jens,
When I first read  Bruce's post, I have been questioning the idea of whether it would work at all. That has been one my main questions to come from this...what happens to transformers that are exposed to frequencies they aren't built for....but since then I found a thermostat transformer and am going to wire it up, AND, I am going inside my old battery charger and measure the frequency off the transformer, before the diodes. It could very well be that I have made some fundamental error in how I measure the frequency. I copied the model number exactly on the Leroy and its number matches the .pdf I posted. I am good at researching stuff. Not so good as an electronics expert. So the confusion is most likely self created. I am thinking...What could it hurt?
Two interesting things come out the test....1. The generator is indeed working at 60hz and the Inverter doesn't like it because it trips the low voltage drop out function...Or 2. I do indeed have generator operating at something other then 60hz and the inverter can't deal with it because of that.
If I wasn't so full of turkey and pie, I'd leap off the couch, test meter in hand, and do something, but for now, I am benched, simply armchairing it up.
yours,
BPJ

[mobile_bob]

this from an engineering dept of a leading transformer manufacture

and please don't ask me which one, it has been about 7 years or so, and i don't recall
so check it out to confirm

60hz transformers can be used on 400hz with little loss, actually they can be used up to about
a khz before you start to see losses coming up.

in practice as far as my testing, three 60 hz transformers connected in three phase, successfully step down voltage from a 3 phase alternator running at between 400 and 600 hz... they did not heat and the losses as measured worked out to be about 5% which is likely very close to what the losses would be running at 60 hz.

now having stated this

my first impression was there would be no way that 60hz transformers could be used at 400 plus hz without serious losses, i only inquired to find out what the losses might be expected to be, because i had a need to step down 3 phase 400plus hz from ~120vac to 24vac to do some testing.... i thought maybe i would call on a transformer manufacture to check it out and was very surprised when i was told to go ahead and use them.

anyway i have no problem using 60 hz transformers of quality construction on up to 600hz, and have no reason to believe there would be any problem until one exceeds about a khz.

fwiw
bob g

[Ronmar]

+1 on the killawatt...  Nobody who makes their own power should be without one...  harbor freight tools usually carries them, so does home depot and other places that sell electrical related hardware.

[Jens]

Well it looks like I was out of line with my transformer theory and statements.
Looking at the magnetics, there is more of an issue with core saturation going from 60 Hz to 50 Hz then there is going the other way. When a core saturates, you basically end up with a short circuit across your transformer which will let the magic smoke out. This is why the transformer needs to be de-rated. Going in the other direction, it would appear that the transformer can actually handle more power before the core saturates but I don't know if this is true and to what degree. I am quite surprised though that the range of operation is as large as it is because the magnetics are designed for the lower frequencies and I would expect substantial core heating at anything over 120 Hz (a WAG on my part). Nevertheless, an actual test trumps my theory. I can't say that I ever had the pleasure of running anything at 400 Hz.
The question that comes to mind though - since increasing frequency reduces the size of a transformer and makes rectification easier, why is 50/60 Hz chosen for power distribution ? Are there heating losses? Are there radiation losses? .... very curious ....

[BruceM]

Our US power system was designed originally around 1900.  Eddy current losses in the earliest transformers drove the frequency decision.  Once 50/60 Hz induction motors were in place,  and incapable of running at higher speeds (the inductance of the rotor is fixed to the max speed), the die was cast. 

The early distribution systems had little in the way of lightning surge protection, and motor wire insulation quality was so poor that high voltage spikes were destroying the then very expensive new induction motors.  The WYE distribution system ''hard'' grounding practice of multiple point earth grounding and no transformer isolation, patterned after Edison's DC distribution, was thus employed in a crude attempt at reducing motor failures.  It is a piece of pathetic 1900 engineering that causes neutral current to flow through the earth and aquifers, water and gas mains (measured at typically 25% of the return current to the power plant coming back through the earth).  It causes magnetic field levels in homes and businesses that are 100 times higher than those found in DELTA served areas (Delta systems have proper transformer isolation of the customer neutral.)

[Dualfuel]

Dear Bruce, Thanks for the history lesson. I would like to read more about it. I have read some of the various Tesla biographies, and one about George Westinghouse. Nothing about the history of engineering the grid...That sounds fascinating.

Alrighty then, I tore apart the battery charger and measured frequency from the 12volt side of the transformer....and.....ahem....the generator is giving 61.7 hrz @118 volts. I confirmed the measurement by measuring other AC sources with the meter/batterycharger setup...all the inverters are 60.4 hrz +/- .1 hrz sooooo my conclusion is that I am glad I decided I needed a sanity check.

So I am back to square one...the Magnum MS2812 inverter will not pass the Leroy Somer current through nor will it use it to charge the batteries....I monkeyed with the various dropout VAC settings but never have got the two to mesh like the Honda/Magnum does.
I think the answer for this lies with the nice Magnum Tech Support guru, as its obviously something the inverter doesn't like.
Still thanks everbody for all the fun suggestions. I actually love these kind of problems...they are so much more fun then things like putting the skid chains on the loader, or digging a hole.
BPJ

[Jens]

It is a piece of pathetic 1900 engineering that causes neutral current to flow through the earth and aquifers, water and gas mains (measured at typically 25% of the return current to the power plant coming back through the earth).  It causes magnetic field levels in homes and businesses that are 100 times higher than those found in DELTA served areas (Delta systems have proper transformer isolation of the customer neutral.)

Thanks for that background and especially this bit of absolutely amazing detail ..... WQW !!!!

[BruceM]

Standard WYE distribution grounding practice is a pet peeve.  There is nothing inherently wrong with the WYE system, only with the multiple earth grounding practice and violation of transformer isolation by the ''ground tie".   WYE grounding practice is so technically barbaric that most EEs won't believe that it's actually done that way, since it violates such basic engineering practice, as well as the NEC. 

What's WQW ?