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previous: Tracy HiI replace alot of output ... -- 9/25/2000 6:01 AM

Re: Crate amps: Inrush current limiting

9/25/2000 3:32 PM
MBSetzer	Re: Crate amps: Inrush current limiting If its an inrush current limiter in series with incoming power, they are negative temperature coefficient varistors, they look like disk capacitors or spike-protecting MOV's. They start at significant resistance when cold and simply limit current depending on the ohms, then after heating up to operating temperature some have very little if any significant resistance. Turning the power off then back on before the limiter has had time to cool off can fry a circuit if the design completely depends on these instead of just using them for extra reliability. If you find out that's the case, you could either add some additional fixed resistance in series, maybe some fraction of the limiter's cold value, or make it switchable, essentially adding a standby switch, then you could use a larger ohm value than the cold limiter for extra protection. hope this makes sense, Mike They say every man need protection . . . - - BDylan & The Band

9/25/2000 3:32 PM

MBSetzer

Re: Crate amps: Inrush current limiting

If its an inrush current limiter in series with incoming power, they are negative temperature coefficient varistors, they look like disk capacitors or spike-protecting MOV's. They start at significant resistance when cold and simply limit current depending on the ohms, then after heating up to operating temperature some have very little if any significant resistance.

Turning the power off then back on before the limiter has had time to cool off can fry a circuit if the design completely depends on these instead of just using them for extra reliability.

If you find out that's the case, you could either add some additional fixed resistance in series, maybe some fraction of the limiter's cold value, or make it switchable, essentially adding a standby switch, then you could use a larger ohm value than the cold limiter for extra protection.

hope this makes sense,
Mike
*They say every man need protection . . .* - - BDylan & The Band

Replies:

Tracy Re: Thanks -- 9/25/2000 8:41 PM