asco 920 relay

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anthony001

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I am installing an asco 920 relay that shuts down the lower half of a 208 three phase panel. The relay has three terminals L, O, and C.I have a n.o. key switch and a n.c. push button, followed by other push buttons. Im really not sure where to start my feed. Most of the other relays i have done have had terminals for my line in. I know that the o and c are for normally open and normally closed but im not sure about where to begin. any help would be greatly appreciated.
 
An Asco 920 is a mechanically held contactor.

You need a set of contacts to open the 920 and another set of contacts to close the 920.

A typical switch used for these is a single pole double throw switch. Usually you will need to get this in a center off momentary contact.

The terminals are as follows.

L = common assuming it is a 120 coil this will be connected to the neutral of the control power source.

O = Open, apply power momentarily to this terminal and the Asco opens.

C = Close apply power momentarily to this terminal and the Asco closes.

Do not wire the system in a way that applies power to both O and C at the same time.

If you are stuck using single throw operators you will need to install a SPDT pilot relay.

(Edit; Made it clearer as my coffee kicked in)
 
Bob's right. We usually use center off momentary contact switches when we are switching the Asco on and off from more than one location (wire them in parallel) or if we're using a momentary time clock and a switch as an override. In a simple single switch setup you could use a regular 3-way switch for the control.
 
infinity said:
In a simple single switch setup you could use a regular 3-way switch for the control.
Click to expand...

That is a good point in a single control position the switch can be a maintained contact.

As soon as you go to multiple control locations you must use momentary contacts.
 
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