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#43738 - 10/21/04 02:27 PM motor starter heater ratchet thingy
maintenanceguy Offline
Member

Registered: 12/02/01
Posts: 303
Loc: Southern NJ, USA
On a square D motor starter. What's the function of those ratchet wheels on the side of the heaters?

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#43739 - 10/21/04 03:25 PM Re: motor starter heater ratchet thingy
HotLine1 Offline

Member

Registered: 04/03/02
Posts: 6804
Loc: Brick, NJ USA
A mechanical function of the 'trip' mechanism that "opens" the contacts on overload seems to come to mind.

John
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John

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#43740 - 10/21/04 03:50 PM Re: motor starter heater ratchet thingy
maintenanceguy Offline
Member

Registered: 12/02/01
Posts: 303
Loc: Southern NJ, USA
One heater melts and breaks and the "trip" pawl is released opening up the other two poles. I get that. But why a ratchet wheel? It doesnt seem to turn...or does it turn when it overheats?

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#43741 - 10/21/04 03:56 PM Re: motor starter heater ratchet thingy
resqcapt19 Offline
Member

Registered: 11/10/00
Posts: 2209
Loc: IL
 Quote:
It doesnt seem to turn...or does it turn when it overheats?

Yes, it turns when it gets hot. There is a low melting point metal around the gear shaft and when it melts it lets the gear turn and that in turn opens the overload relay contact.
Don
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