Portable Generator Question

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DaveHo
DaveHo Posts: 3,481
in The Clubhouse
Power was out last night. PowerCo estimate was several hours, so I fired up the gen. Connection to my house is via a proper inlet & back-feed breaker with interlock in the main panel. Load was fairly low, a full size fridge, chest freezer, mini fridge & whatever lights happened to be on, mostly LED. Out of curiosity I plugged my Kill-A-Watt in to check the generator output. The voltage out of both legs was fine, around 122V, but the frequency was a shade over 65Hz.

This is the generator in question: https://honeywellstore.com/store/products/honeywell-hw7500e-portable-gas-powered-generator.htm

After the PowerCo restored power I checked again & got a dead-on 60Hz, so I believe the Kill-A-Watt reading is accurate. While on gen power lights & appliances were operating fine. I know the generator output can vary slightly with load. Is 65Hz within an acceptable range or should I have the gen looked at?

@lightman1 ?
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  • mhardy6647
    mhardy6647 Posts: 33,049
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    Check the specs on your generator. You're within 10%; my guess is your generator's spec is being met (but it's just a guess!). I couldn't find the manual on the link you sent, and the spec sheet that is provided there doesn't contain info on the quality of the output.

    NOW comes the editorial part.
    The big "issue" with generators is THD :) The cheap ones put out very dirty AC and can be disastrous for sophisticated, modern computer controlled hardware. Not just the obvious stuff -- if you have a modern "high tech" heater/heat pump/HVAC system, you put it at risk with dirty power from a generator. If you have any expensive, sophisticated (more to the point, expensive to repair!) appliances or 'fixtures' (heater, well pump controller, etc.) in your home, you should really think about (IMO) the not inconsiderable investment in an inverter-type generator. Sorry! :/

    The massmarket/old fashioned generators often have THD specs of 20 or 30%.

    We have a (too) sophisticated 'boiler' system in this house, so I ended up biting the bullet and going with one of these.
    https://powerequipment.honda.com/generators/models/eu7000is

    But... around here, a prolonged power failure in the winter could be fatal. :(


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  • zingo
    zingo Posts: 11,258
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    Can you adjust the governor, that is connected to the throttle, to slow down the engine, just a tad? If you can slow the engine rotation a bit, the frequency should come down also.
    Jake
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  • decal
    decal Posts: 3,205
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    It's running too fast, adjust the throttle a little. 57Hz to 62Hz is the generally acceptable range.
    If you can't hear a difference, don't waste your money.
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  • mhardy6647
    mhardy6647 Posts: 33,049
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    So, I looked at the manual for the above-mentioned Honda and they don't mention power quality specs :(
    I did find this, albeit in a review -- NOT from Honda!
    Power Quality
    One of the problems with more inexpensive generators is that the power isn’t always great. Under load, the sine wave of AC power tends to distort. But the Honda eu7000is is capable of producing a very clean sine wave. The total harmonic distortion is a shocking 4%. For reference, the grid power in New York is commonly rated at 6%. This makes it ideal for anyone who’s trying to wire in a backup generator for a home, or run some kind of high end electronics that require a clean sine wave, the Honda eu7000is is a clear winner.

    Even under load, we noticed that the frequency and voltage of the power rarely dropped. If it wasn’t for the power regulator, we’d suspect that you could get much more than the rated output out of this generator. Most start to crack at around 70% capacity, but even when pushing this generator to the limit we saw consistently high voltages. That being said, when you can push this much power it’s important to make sure everything is connected properly. You’ll want to get a heavy duty extension cord if you have any intention in running this generator near it’s limit. With a cord not rated for the appropriate capacity, you could cause damage to it.

    source: https://shedheads.net/honda-eu7000is-generator-review/
    Yeah. Sorry. I am a generator snob, too. :(
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  • DaveHo
    DaveHo Posts: 3,481
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    I'm aware of the pitfalls powering sensitive electronics. This is only the second time I've used it other than test running every couple months. First time was during Sandy back in 2012. I never power any stereo gear or the HVAC with it. Luckily we've never needed it in the dead of winter.
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  • DaveHo
    DaveHo Posts: 3,481
    edited February 2019
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    zingo wrote: »
    Can you adjust the governor, that is connected to the throttle, to slow down the engine, just a tad? If you can slow the engine rotation a bit, the frequency should come down also.
    decal wrote: »
    It's running too fast, adjust the throttle a little. 57Hz to 62Hz is the generally acceptable range.

    That's what I was leaning toward doing. Thanks!

    Edit: Woot! Found a PDF of the service manual. Now I know what I'm looking for.
    Post edited by DaveHo on
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  • mhardy6647
    mhardy6647 Posts: 33,049
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    decal wrote: »
    It's running too fast, adjust the throttle a little. 57Hz to 62Hz is the generally acceptable range.

    Sounds good to me.
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  • CoolJazz
    CoolJazz Posts: 569
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    Bigger generators adjust for differing loads to keep the speed closer to desired. Throw on a heavier load, like a big AC unit kicking on, and listen to it load and slow and then pick back up. All normal.

    I'd suspect that unit adjusts for load too. But I've ran very sensitive loads on speeds much further off than that without issue. Generally, not much cares too much about a few hertz off. Look at some of the discussions about the varying speed rate of the power regenerators to dig in a little.

    I'd not worry to much about it.

    CJ
    A so called science type proudly says... "I do realize that I would fool myself all the time, about listening conclusions and many other observations, if I did listen before buying. That’s why I don’t, I bought all of my current gear based on technical parameters alone, such as specs and measurements."
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  • DollarDave
    DollarDave Posts: 2,575
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    I've gone the portable generator route and then went with a whole-home solution from Generac. Good move for me in the Houston area.
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  • gudnoyez
    gudnoyez Posts: 8,066
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    https://powerequipment.honda.com/generators/models/eu7000is
    A Honda EU series is the way to go, with a eco throttle and a inverter you won't experience those problems plus you don't have to worry about electronics. In the case of yours being good sized putting a bigger load on it or adjusting the throttle should solve your problem, as others have stated. I have run 2 Eu 2000's in parallel with a parallel cable running a cabin with a heater electronics, no problems.
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