clipper

ws9876
ws9876 Solar Expert Posts: 453 ✭✭✭
in Wind Power Generation #1
I was reading Midnite Solar description of their load clipper for wind turbines and they claim its a lot more than just a load resistor...
what do you think is in there that makes it good and would it be that hard to make your own??? Theirs is way overpriced..
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: clipper

    You don't know what's in it but you think it's overpriced? Interesting logic.

    Maybe boB would like to explain the value of it: it's his product. :D

    But yes it is possible to make your own diversion load. May be one or two legal issues if it is a system requiring inspection as anything you devise will not be UL listed.
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  • ws9876
    ws9876 Solar Expert Posts: 453 ✭✭✭
    #3
    Re: clipper

    another 1000 dollar bill..yea thats overpriced.. I was wondering what in the box controls voltage besides the current resistor..
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  • boB
    boB Solar Expert Posts: 1,032 ✭✭✭✭
    #4
    Re: clipper

    Yeah, it sure didn't seem like the Clipper should cost a lot of money but they are not simple or cheap to manufacture.

    They aren't even listed (yet) because there are not enough of them sold (yet) to warrant UL or ETL testing. That won't be cheap.

    The AC clipper includes a 3-phase bridge rectifier (1200 volts, 100+ amps) shorting brake, on-off switch (all breakers really),
    PCB with lightning protection, MOVs, LEDs and related circuitry, auxiliary power supply to power fans and the fail-safe circuitry to drive the
    Solid State Relay (SSR) when Classic Aux out doesn't drive (the SSR is expensive !), all the custom metal-work, and man-
    hours to build and test the Clippers. Also, the power resistors and high temperature wire mounted in a custom heat box with the
    thermal fan switch mounted to it.

    There is also a DC clipper that is slightly different and I ~think~ less expensive than the 3-phase Clipper but is still expensive
    because of similar reasons to the AC Clipper. I'm not sure of exact street prices.

    A simple relay to short the AC side of the turbine, triggered by a voltage set-point could work, would be
    less expensive and wouldn't need power resistors or fans but would not have the advantages of a PWM or
    clipper using a SSR of some sort. SSRs are also synchronous which allows the clipping to commence on
    zero-crossings of the waveforms. A limited AC clipper can be made with SSRs but without resistors but
    control is a bit more complicated.

    One reason that PWM works better than just slamming on a short circuit across the turbine is that some turbines
    really don't like that and can't take much of that abuse. i.e. they have to be eased down in RPMs.

    PWM also allows multi-stage voltage regulated charging while keeping the turbine's required RPM and voltage
    just high enough to do that.

    I hope this helps explain a little bit of why ready-made clippers are not cheap. Sure doesn't seem like they should be
    expensive but they pretty much end up being that way.

    Home made clippers are certainly an option if you have the time and patience. I think that some here or on Otherpower
    have done this successfully.

    boB
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