2PDT mech relay that is normally closed?

[terrazza]

Looking for one in the 5 amp+ range... Ideas where to look?

 

[Sawdustguy]

Ebay has a bunch of them....

http://shop.ebay.com/?_from=R40&_tr...&_nkw=dpdt+NC+relay&_sacat=See-All-Categories

 

[Bobby_M]

Just to clarify what I think you're confused about. A double throw mechanical relay is typically "normally" in one of the throw positions so one side is NC and the other is NO. I guess if you're thinking about standalone selector switches that have an OFF center position, it would be easy to mistake a relay for having it also.

 

[terrazza]

Just to clarify what I think you're confused about. A double throw mechanical relay is typically "normally" in one of the throw positions so one side is NC and the other is NO. I guess if you're thinking about standalone selector switches that have an OFF center position, it would be easy to mistake a relay for having it also.

Still don't get it....

 

[SweetSounds]

A 2 pole double throw relay has 2 circuits built in, and 6 contacts (Plus 2 for the coil)

If you look at it like a 2PDT switch where the contacts are aligned like the number 6 side of dice, the center 2 contacts (Middle dots on the dice) are common. The top contacts are normally open, and the bottom contacts are normally closed, all of the time.

When you energize the coil in the relay, it breaks the normally closed contacts and makes the normally open contacts.

So in other words, by definition all 2PDT relays are normally closed AND normally open. It's just a matter of which contacts you connect to your circuit.

 

[Bobby_M]

You can see the two "common" connections on the left. They are connected to the two Normally Closed contacts on the right. When the coil is energized, they both "throw" over to the Normally Open contacts. There is never any connection between the two "poles" or circuits but that dotted line indicates that both throws are coupled physically.

 

[SweetSounds]

Thanks Bobby!
A picture is worth 115 words!

 

[rosier9]

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