??? 05/04/10 17:35 Read: times |
#175675 - Yes, but... Responding to: ???'s previous message |
Stefan said:
You mentioned 2 times here about surges. It's not advisable to use varistor against them? Yes, a varistor can used against surge. Unfortunately, when being hit by too many surges a varistor gets more and more low ohmic and can dramatically heat up one fine day. So, todays design practise is to use a varistor in combination with a temperature fuse, put in series with the varistor and in close contact to it. The big disadvantage is, that you won't notice the damaged temperature fuse, so that you never know whether the varistor is "online" or not... The best methode is to use parts which can withstand surges by design. Kai Klaas |