Relay Coil Input

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fifty60

fifty60

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Can a loose wire on the input coil of a relay cause the output to draw to much current and overheat? Or would the loose wire need to be on the output to cause the output to draw excess current?
 
fifty60 said:
Can a loose wire on the input coil of a relay cause the output to draw to much current and overheat? Or would the loose wire need to be on the output to cause the output to draw excess current?
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If something prevents the armature of an AC coil relay from fully moving to close the gap in the magnetic circuit the AC impedance of the coil will be lower than expected and could draw excess current and overheat.
That something might be a bad connection in the coil circuit.

It takes a high current to get the armature to move in the first place, so the coil DC resistance is designed to allow that high current. But once the relay is in the fully closed position the increased coil inductance is supposed to limit the current to an acceptable steady state value.

If the circuit is designed for mechanical latching with aux contacts converting a steady applied voltage to a pulsed actuating voltage on the coil then failure of the aux contacts to open will also allow the coil to overheat.
 
Yes

Yes

Yes a loose connection on the coil can cause the output device to draw too much current. If the coil connection is loose it will cause the relay to chatter off/on. This will cause the load to turn off/on and the high starting surge can cause your problem
 
just the cowboy said:
Yes a loose connection on the coil can cause the output device to draw too much current. If the coil connection is loose it will cause the relay to chatter off/on. This will cause the load to turn off/on and the high starting surge can cause your problem
Click to expand...

That's true, but absent this condition a loose wire on the coil input won't cause the load side to draw excess current if the coil input is still high enough to let the relay change state without chatter.
 
just the cowboy said:
Yes a loose connection on the coil can cause the output device to draw too much current. If the coil connection is loose it will cause the relay to chatter off/on. This will cause the load to turn off/on and the high starting surge can cause your problem
Click to expand...
+1 :thumbsup::thumbsup:

gadfly56 said:
That's true, but absent this condition a loose wire on the coil input won't cause the load side to draw excess current if the coil input is still high enough to let the relay change state without chatter.
Click to expand...
I've seen it where the "chatter" was not very noticeable, it was more like a loud hum because the coil didn't totally let go, but the contacts were (likely) separating just a scoche*. Destroyed the contacts in less than a week.

* Bonus for anyone who can tell me where they first heard that term...
 
Jraef said:
+1 :thumbsup::thumbsup:


I've seen it where the "chatter" was not very noticeable, it was more like a loud hum because the coil didn't totally let go, but the contacts were (likely) separating just a scoche*. Destroyed the contacts in less than a week.

* Bonus for anyone who can tell me where they first heard that term...
Click to expand...

It is properly spelled "skosh", and at first I thought it was another Yiddish loan word. I was wrong. http://www.straightdope.com/columns/read/1032/whats-the-origin-of-skosh-meaning-a-little-bit

My first memory of hearing it was from a great aunt back in Chicago, talking about a small amount of something in a recipe.
 
GoldDigger said:
It is properly spelled "skosh", and at first I thought it was another Yiddish loan word. I was wrong. http://www.straightdope.com/columns/read/1032/whats-the-origin-of-skosh-meaning-a-little-bit

My first memory of hearing it was from a great aunt back in Chicago, talking about a small amount of something in a recipe.
Click to expand...

I don't think there is a consensus on the spelling...
http://www.urbandictionary.com/define.php?term=scosche
http://www.urbandictionary.com/define.php?term=skoch (also skoche)
http://www.merriam-webster.com/dictionary/skosh
 
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