asco 920 relay

[anthony001]

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.

[iwire]

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)

[infinity]

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.

[iwire]

In a simple single switch setup you could use a regular 3-way switch for the control.

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.

[iwire]

Here is a wiring diagram for a 920, it shows many different possibilities.

You will need Adobe reader to open it but that can be download off the web for free.



http://www.ascoswitch.com/Products/drawings/331851_K.pdf

[anthony001]

Thanks guys this will definitely help... P.S. this is a truly amazing site.