Generator Frequency Fluctuations - Whats safe?
Submitted: Wednesday, Feb 06, 2013 at 18:50
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Palaeoboy
As mentioned on another thread I recently got a second-hand Honda eu10i and am very happy with it. While reading other threads a member mentioned a usage meter that you could get from Jaycar and it tells you voltage, frequency and watts being used. Definitely worth the 20 bucks as I have been testing how many watts are used all my appliances around the house.
The Honda tested at an absolute constant 50Hz and 239 volts. The house mains power tested at the same consistent 50Hz and 244 Volts. I was definitely impressed by the Honda in this respect. So as a comparison I then tested my 750 watt GMC 2 stroke. I wasn't expecting the same result as its not a pure sine wave inverter. It tested at a varying 215 to 220 volts and a frequency varying from 47 to 50Hz. This didn't seem too bad as I have heard other horror stories of some getting upward of 280 volts ad 60Hz. It did make me stop and think as I was about to give the GMC away to my brother, with its fluctuations, what things can you run off this generator without doing damage? What's safe to run with these fluctuations and what's not?
Reply By: Ross M - Wednesday, Feb 06, 2013 at 19:19
Wednesday, Feb 06, 2013 at 19:19
Palaeoboy
On the GMC you can use anything which isn't voltage and frequency sensitive.
ie, Globes, conventional, battery charger, kettle (if wattage large enough), fan heater too, possibly, but it may not like 60 "HURTS".
Anything designed to run on 240 v ac which has a voltage sensitive power conversion or switching can only be use on the Honda with safety for the appliance.
Laptop supplies, these are switch mode types and only a few will run on other than full 50 HZ sine wave, most like the sine wave and possibly will not start and become stalled and may burn out or blow their internal fuse if connected to a varying voltage, off frequency wave form..
Switch mode battery chargers, usually multi stage units also like 50 hz full sine wave.
If a switch mode device does happen to start and run, on something other than clean power, it usually cannot switch properly and the poor waveform can cause the unit to run hotter than normal because it can't make proper use of the shape of the energy being fed into it.
If the GMC happens to run at 50 hertz and 240 v while under load, then nearly everything should be ok, it is just when these two are not held constant the delicate stuff may not like it. No good if it is an expensive device.
Ross M
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Follow Up By: patsproule - Thursday, Feb 07, 2013 at 07:36
Thursday, Feb 07, 2013 at 07:36
Modern multi-voltage switchmode power supplies are actually a lot less sensitive than most people think. They are designed to handle a large range of input voltages and frequencies (Hertz by the way). The main thing they dont like is a full square wave input as it makes the laminations in the transformer buzz (SM supplies still run a small transformer). I've had a bit of experience with this running OB trucks on the odd dubious genny and on all but one occasion (dodgy welder genset) it was fine. And I'm talking about a unit with about 100 SM supplies or more.
I too can vouch for the output of the Honda EU range - we run the current OB truck off a pair off EU65i's and no matter what you do to them the output is a beautifully stable sine wave even when loaded to the limit on each. We prefer them over the mains.
Pat
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Follow Up By: Ross M - Thursday, Feb 07, 2013 at 13:47
Thursday, Feb 07, 2013 at 13:47
Pat
Didn't you like my little hurts joke.
What is an OB truck? Some of use probably don't know what they are.
I have two old laptops and one will run on a less than suitable wave form but does run hot ie both from mod square wave inverter and low frequency generator. The other laptop SW supply just like it clean and no fuzz and won't run at all, where the other one will.
The Honda will keep on giving clean power because of the inverter output and unless the electronic control gets out of spec, the wave form and voltage will remain within specs.
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Reply By: 08crd - Wednesday, Feb 06, 2013 at 23:52
Wednesday, Feb 06, 2013 at 23:52
Just remember with a generator, it can only put out what the prime mover can put in.
I could put a 10kva generator on the end of a 150cc motor. It will still only put out approx 2kva, actually it will probably put out less because of the extra weight of the 10kva rotor.
Power out = power in - losses
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