RC Snubber question

Discussion in 'General Electronics Chat' started by lokeycmos, Feb 9, 2013.

  1. lokeycmos

    Thread Starter Active Member

    Apr 3, 2009
    Looking for some help with calculating the proper resistance and capacitance for an RC snubber for arc suppression and protecting relay contacts. voltage across the contacts is about 25-35 volts and upto about 750mA of current. Thank you for your time.
  2. #12


    Nov 30, 2010
    Blind leading the blind here...
    Snubbers are one of the nastiest little problems I have examined.

    For protecting against dI/dT, you put an inductor in series with the contacts.
    For peak voltage, the handiest equation is 1/2 LI^2 = 1/2 CV^2, then, there are MOVs that quench high voltage spikes.
    If you put a capacitor across the contacts, inrush current when re-closing the circuit needs to be limited by a resistor in series with the capacitor.
    Not knowing what you're protecting against is part of the problem.

    I'm going to tack on something from my inventory. See if you can make sense of it!