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Path: utzoo!decvax!bellcore!ulysses!allegra!princeton!caip!seismo!umcp-cs!eneevax!hsu
From: hsu@eneevax.UUCP (Dave Hsu)
Newsgroups: net.analog
Subject: Re: MOV's with fuses
Message-ID: <788@eneevax.UUCP>
Date: Wed, 9-Jul-86 20:13:01 EDT
Article-I.D.: eneevax.788
Posted: Wed Jul  9 20:13:01 1986
Date-Received: Fri, 11-Jul-86 00:09:09 EDT
References: <1380@voder.UUCP>
Reply-To: umd5!don@eneevax.UUCP (Chris Sylvain)
Distribution: na
Organization: Imperial Widget Research Center, Kingdom of Maryland
Lines: 26
Keywords: MOV, failsafe transient protection


In article <1380@voder.UUCP> paul@voder.UUCP (Paul Dietz) writes:
>Can MOV's really be protected with fuses?
>--- phd		{nsc!voder!paul} 

Fuses operate thermally, and the metal alloys used take a while to heat up
enough to melt (or at least become elastic). The duty cycle of the pulses
that MOVs clamp are generally very low. Fuses will conduct large pulse
currents without much heating. I suppose you could connect multiple varistors
in parallel with small value current equalizing resistors in series with each
varistor (one per MOV). But why bother?
Varistor protects, wears out, shorts, fuse blows, equipment off.
What more could anyone ask for?
Varistors are insurance that's soooo inexpensive.

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