Magic Blue Smoke » Varistor http://www.magicbluesmoke.org When good electronics go bad. Fri, 27 Jan 2012 18:03:37 +0000 en hourly 1 http://wordpress.org/?v=3.3.1 Part 431KD20 Varistors blow http://www.magicbluesmoke.org/259/part-431kd20-varistors-blow http://www.magicbluesmoke.org/259/part-431kd20-varistors-blow#comments Sun, 24 Jan 2010 06:11:29 +0000 MagicBlueSmoke http://www.magicbluesmoke.org/?p=259
Part 431KD20 Varistor blows

Part 431KD20 Varistor

Part 431KD20 Varistor blows

Part 431KD20 Varistor

These varistors were protecting a transformer when they died.  The transformer was protected as the fuse blew – thanks to the varistors.  Credit:  bhungy

]]> http://www.magicbluesmoke.org/259/part-431kd20-varistors-blow/feed 0 Varistor on UPS cracks http://www.magicbluesmoke.org/218/varistor-on-ups-cracks http://www.magicbluesmoke.org/218/varistor-on-ups-cracks#comments Fri, 11 Dec 2009 23:16:06 +0000 MagicBlueSmoke http://www.magicbluesmoke.org/?p=218

Continue reading »]]> UPS Capacitor fried

Board with blown MOV

UPS Capacitor fried - closeup

Closeup of failed MOV

The burned part shown appears to be a MOV (Metal-oxide Varistor).  The purpose of a MOV is to have a very high resistance until a certain voltage is reached at which point it will conduct current, in this case from “Hot” to “Neutral.”  This property is useful for surge protectors.  Original poster says this UPS was involved in an electrical fire.  Credit:

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