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Modified Sine Wave Inverters

Discussion in 'Photovoltaics' started by John Dunkley, Apr 26, 2006.

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  1. John Dunkley

    John Dunkley Guest

    What electronic equipment is it NOT recommended to run off of modified sine
    wave inverters?

    Appreciate some advice on this.

  2. Audio mixing desks. Buzz like buggery !

    Cheers, J/.
  3. Doubt it. Exactly the same grounding and shielding techniques worked
    fine with a sine wave inverter dropped in as a replacement.

    As to the power supply being poor, (presumably you mean in the
    mixer ?), it's certainly true that it's not designed or sold to cope
    with non sinusoid power supplies.

    Does using a non sinusoid inverter make it a poor power supply, or is it
    a poor choice of power source ?

  4. If you mean run the mixer power supply from DC, the transformer won't
    last too long...

    If you mean that the mixer electronics could be run off a DC supply, I'm
    sure you're right, but

    a) that doesn't help if you want to use a non sinusoid AC supply,


    b) the noise may not be coming through the power supply anyway.

    I put my banana up a tree and it didn't rain.

    Maybe ethylene promotes fruit senescence ?

    Well yes. You might specify a preamplifiers rejection of supply noise.

    But I fail to see how that makes operating a power supply outside its
    design envelope the fault of the power supply - indeed in this
    instance, there is no reason to assume that the noise that makes it to
    the output of the mixed even comes via the mixer PSU.

    All we actually know is that it wasn't a problem with a sine wave
    inverter, but it was with a non sine wave inverter.

    The OP wanted to know "What electronic equipment is it NOT recommended
    to run off of modified sine wave inverters?". On the basis of my
    experience in the field, I'm nominating audio equipment, because it can
    be a problem, at least some times. You can talk about your children if
    you want.

  5. You

    You Guest

    Laser Printers.......
  6. Well, can't say it does it for me, and I'm not sure the association was

    Well, I didn't put the system together so I'm not sure I had much
    'ownership' of the configuration.

    None the less, unless you are referring to the grounding, shielding or
    equipment design of the inverter itself, there was no difference between
    the wiring for the sine and MSW inverters.

    Indeed. It could be down to the grounding, shielding or equipment
    design of the inverter itself. Do you think the inverter manufacturers
    frequently get this stuff wrong ?

    Well, obviously quite a lot manages it in practice.

    These were audio systems put together as part of festival sound stages.

    It's entirely possible that if plugged together in some less than
    obvious way, the grounding could have been improved.

    None the less, the upshot is that the use of a non-sinusoid supply may
    be more problematic.

    Indeed. Back in the real world...

    Upshot remains that non sinusoid supplies may cause more problems with
    audio equipment.

    It was nearly four years ago. Don't think I'll be trying to rework the
    signal paths and grounding. Didn't need to anyway as we just used a
    1960s sine wave inverter instead.

    Cheers, J/.
  7. sonny Power

    sonny Power Guest

    Hi JD,
    I've been using a Trace DR1524 modified sine wave inverter for about 8
    years. I have yet to find something it won't run. It runs computers, TV,
    satellite modems, Cisco router, fridges, etc.
  8. CampinGazz

    CampinGazz Guest

    i've got something that wont run on it... the washing machine in my
    motorhome, refuses to start up on a msw inverter output and the circuit
    board gets hot,

    put a pure sine wave inverter on it, and it works exactly the same as it did
    on shore power, it's coz of the fuzzy logic crap in modern washers, warying
    hte water levels according to the load, farting about distributing the
    clothes evenly before doing a high speed spin etc.

    seems to be owt that uses a thyristor in the design dosent like msw inverter

    At the moment i keep my msw inverter (antares 1600 soft start.. and old un
    with a big torodial transformer in it, bullet proof) as it runs the
    microwave (mechanical timer) central vacuum system, hair dryer, bug zapper,
    fans, inkjet printer, laminator etc fine, little more buzzing on the
    microwave but that's to be expected as a transformer expects a nice pure
    sine wave, so the abrubt chopping of a msw will create a bizz)

    The pure sine wave inverter just powers the washing machine (Candy aqua
    1000T, one of those compact washers, like a home model but a 3.5 kilo load
    capacity instead of the usual 6 or 7)
    when i get round to it i'll be replacing the main antares and washer
    inverter with a single 1500 watt pure sine wave inverter, just because i can
    get a decent one for about £200 from a bloke i trust and knows what he's
    talking about with inverters.
  9. Blue Cat

    Blue Cat Guest

    About 10 years ago (before sine wave inverters were inexpensive) I did some
    experimenting with motors and square wace inverters. I found that if you
    connect a capacitor in parallel with a motor load, you will improve the
    power factor and also the probability that a motor load will start properly.
    Capacitance depends on the current drawn by the motor at rated speed. Such a
    capacitor must be capable of functioning in ac power.

    I assume that if this works with square wave, it will also work with
    modified sine wave.
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