# contactor v breaker



## John Valdes (May 17, 2007)

Sorry friend. I have no idea of what you speak. We have some very good DC motor and control guys around here that would like to help you. But we must understand you first.


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## JayH (Nov 13, 2009)

tamilbabu said:


> what is the fundamental difference between DC control supply power contactor and self control supply power contactor?Is it possible to design DC control supply contactor with DC off condition contactor will not trip.


If I understand you correctly you are asking if it is possible to maintain a contact when a loss of power supply occurs.

If so, this would be possible with mechanical latching relays.


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## micromind (Aug 11, 2007)

If you're talking about circuit breakers that have a separate DC supply for the trip coil, the solution is a capacitive trip supply. Also known as a cap-trip. 

It's just a box with a rectifier (to convert AC to DC), and a capacitor. Or, simply a capacitor, if the supply is DC only. It'll store enough DC power to trip the coil when the normal power supply fails. Most of the ones I've worked with will actually trip the coil several times, though once is enough. 

A word of caution, wire the output of the capacitive trip supply through a relay or switch contact then to the trip coil only. Don't use it to power anything else, or the capacitor charge will be lost. 

I usually mount them in the breaker cubicle, to keep the wire as short as possible, and to eliminate the possibility of broken wiring causing it to fail. I use one per breaker. 

If this isn't what you're looking for, please post a more detailed request. 

Rob


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## tamilbabu (Dec 29, 2009)

Thanks






micromind said:


> If you're talking about circuit breakers that have a separate DC supply for the trip coil, the solution is a capacitive trip supply. Also known as a cap-trip.
> 
> It's just a box with a rectifier (to convert AC to DC), and a capacitor. Or, simply a capacitor, if the supply is DC only. It'll store enough DC power to trip the coil when the normal power supply fails. Most of the ones I've worked with will actually trip the coil several times, though once is enough.
> 
> ...


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## Mr.C (Dec 20, 2009)

If your looking for an example of this cap-trip look up product info for GE-Zenith transfer switches and you might find a schematic there


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