Compressor switching transients a problem?

System
System Posts: 2,511 admin
in Advanced Solar Electric Technical Forum #1
A friend has a 24VDC Nova Cool fridge and an Outback charge controller. The controller has fried twice since adding the fridge to the system. I'm wondering if high-voltage fast transients generated by switching on/off the compressor could be damaging the output of the controller.

Is this a general problem, or are DC fridges pretty good about not generating conducted emissions back onto the DC bus?

And, if the fridge is a plausible culprit, any suggestions for transient suppression devices to help solve the problem?

Thanks for the help,

Alan
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Comments

  • crewzer
    crewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    #2
    Re: Compressor switching transients a problem?

    This seems odd to me... The battery bank between the controller and the loads is usually pretty good at absorbing kickback loads. How about installing a big ol' anti-kickback diode in parallel with and adjacent to the fridge's DC input?

    HTH,
    Jim / crewzer
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  • Brianellul
    Brianellul Solar Expert Posts: 95 ✭✭
    #3
    Re: Compressor switching transients a problem?

    Hi
    If the 24V fridge is connected directly or very close to the controller output, and there is a long run to the batteries or the connecting wires to the batteries are not thick enough, then yes, the batteries would not be able to absorb the switching transients.
    There are 2 options;
    1) Connect the fridge as close as possible to the battery terminals.
    2) Connect across the supply (as close to the fridge as possible) a couple of 30V MOV.

    Also, a large capacitor across the supply (as close to the fridge as possible) will help in absorbing any switching transients.

    I had this problem on a boat some time ago, with all types of electronics failing for no reason. After installing a couple of MOV and a large capacitor across the fridge supply, the problem seems to have been resolved.

    Regards
    Brian
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