[AMPS] Relays hanging up

measures 2@vc.net
Sat, 12 Aug 2000 06:48:17 -0700

>> >> When we did that we could hear virtuallu hundreds
>> >> of relays clickking off held by residual magnetism.
>Well he "says" it was residual magnetism. I guess we have to 
>believe somehow he knows that's what it was, and not weak 
>springs or other mechanical problems.
Because the relay stopped hanging up when I reversed polarity.  

>> >Mechanical non-mercury wetted relays in a telephone switching 
>> >system?
>> >
>> >What a system. No wonder the materials in the relay magnetic 
>> >parts were poor!
>> >
>>   ''poor''?  All relay armatures contain iron.  Hello.  If the spring
>> isn't strong enough, it can hang up.  >........
>That's right. With a weak enough spring, the relay won't have any 
>return force.
The relay did not hang up after I reversed the magnetic field.

>But if the iron is soft it should also have no flux storage. 

All types of iron can be magnetized.  

> If it does 
>have flux storage, it would take a damn big hammer to 
>"demagnetize" the metals in the relay.
>I haven't seen ANY amplifier relays stick from "residual 
>magnetism". I suspect the most common flaws...dirt or other 
>contaminants....contact welding from hot switching...are written off 
>to "sticking relays from residual magnetism".
The contacts were not welded, Tom.  Reversing the polarity fixed the 

>I'm not saying it can't happen, just if the iron is too hard the relay is 
>toast. It will immediately fail over and over again.


-  Rich..., 805.386.3734, www.vcnet.com/measures.  

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