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 Post subject: Relay contacts burned out, how to prevent ?
PostPosted: Wed Jun 06, 2012 8:15 pm 
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Hi folks,
the contacts have burned out on the relay I'm using, does any one know if this can be prevented ?

Would a capacitor across the switch help this, or one in series coming off the base of the coil in the relay ?

I tried a magnet on the contacts on the outside of the case to try and quench any sparks inside, but can't say it helped any.

Thanks
Fizzy


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 Post subject: Re: Relay contacts burned out, how to prevent ?
PostPosted: Thu Jun 07, 2012 10:01 am 
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A snubber capacitor will help the contacts it does reduce the radiant as it converts it to normal electricity. Good quality automotive relays do work well and I have had them running for weeks although they are not designed to be used in this way. Powerful magnets will also help but it is difficult to get them close enough to have an effect without effecting the mechanical switching. If you can find an old mechanical voltage regulator this may work better or even a vintage ford model A or T ignition coil of the Tesla design as these coils were designed to work in this way http://www.electrotherapymuseum.com/201 ... nition.htm


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 Post subject: Re: Relay contacts burned out, how to prevent ?
PostPosted: Mon Jun 11, 2012 2:26 pm 
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Thanks for the link :)
What a neat piece of kit that old coil is ! I had planned to make something similar to this before you sent me this. I've ordered a reed switch in a glass tube, it's the heaviest duty one I could find, so hopefully this should last longer. It's normally open contacts I'll close with a small magnet, and hopefully the field from the coil will over power the permanent magnet and open the contacts.

I have a 1/2 pound real of 24 gauge magnet wire for the coil, it's 'q' factor is not too high, but I understand that a high voltage coil has to be long and narrow for best results ?

Thanks again
Fizzy


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 Post subject: Re: Relay contacts burned out, how to prevent ?
PostPosted: Tue Jun 12, 2012 12:56 pm 
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I doubt the reed switch will last long, they are not good with current.


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