Elementary Relay Question

[eaglewood]

I need a double-pole single-throw relay in my application. I simply need two sets of N.O. contacts that close when the coil is energized. Nothing else. When the coil is not energized, I want no circuit energized.

When I go to purchase a DPST relay, I find them relatively unavailable, as opposed to DPTD relays, which are far more common.

I don't see any harm in using a DPDT, it's just that the power voltage will be present at the unused contacts.

No big deal, I'm just curious why DPST seem to be relatively scarce. And I also thought I'd make sure I'm not missing something. Like... NOOOOOO for god's sake don't use a DPDT when you really need a DPST!

 

[Steve Bailey]

To offer a full range of options for a DPST relay, the manufacturer would need three versions, one with two NO contacts, one with two NC contacts, one with 1 NO and 1 NC. Offering a DPDT accomplishes that with a single model.

 

[Bit_Bucket_07]

I think you're overthinking this. DPST relays are less common than DPDT relays simply because there is less demand for them.

 

[parky]

That's funny, I went to RS Components & the first page showed 9 of them there were over 70 pages although many may not be suitable surely there are a vast array of DPST.

 

[eaglewood]

See why I'm a member here?

Thank you, Steve.

 

[joseph_e2]

I think you're probably overthinking it too (hey, no judgement...I do too)...but if you're worried about the power voltage being on "extra" terminals when the relay is de-energized, you can wire the power to the NO contact and the load to the common.

 

[eaglewood]

Guilty as charged about the overthinking. I guess that's my MO.

 

[ndzied1]

We use a lot of the Phoenix contact
PLC-RSC- 24DC/21-21

And it’s single pole version as well …

 

[kamaroman68]

What about supplying power to the N.O. contact? When that relay coil is not energized power is not available on the common or N.C. contact. The N.O. contact still acts as a switch with load carrying capability?