Is there a such a thing as a D.P. C/O contactor? (electrical)

[dave]

I'm looking for a contactor that can switch 15A (mains 230VAC) and that has double pole change-over contacts.

All I can find can easily handle the current but all have just N poles x N/O. ie no c/o contact sets. I did find one with an "aux. c/o" contact but that particuar contact was for control and rated at at only 5A.

I can simulate the dp-c/o by using two contactors but then one of them will always have to be energised (unless anyone has a clever way around that). If you know the whereabouts of such a beast I'd appreciate the address. thanks

[Dave Plowman (News)]

Do you need the full 15 amps? RS do a relay which does what you want but only with a low voltage coil. (5, 12 or 24v) If you could make do with 10 amps the range is vast.

[fred]

In article , dave writes

Does it have to be a contactor or will suitably rated relay do?

bigger:

that a 240V ac switch rating is not suitable for switching sources between phases or between a generator and mains.

[harryagain]

If money is no object you could buy a star-delta motor starter & make a few slight alterations.

[NT]

how do you set them up so one is always energised?

The normal way to have a DPCO is to use a 2Pole 2 way. However I dont know what's reaily available in the 15amp region.

I'd be slightly wary of making one up out of 2x 1 pole changeover relays, simply cos if one gets slower than the other, flashbang can result.

Maybe if you tell us the app there might be some other approach.

NT

[mick]

They exist, but they are as rare as rocking horse s**t.

Merlin Gerin/Schneider Electric do a modular contactor (similar to the mcbs in distribution boards) rated at 25A with 2no and 2nc contacts &

230vAC coil. Their part number is 15964. You should be able to order it through Newey & Eyre or any other Merlin Gerin dealer. Note that these are not rated for inductive loads like motors (they are AC7a).

[cynic]

The old style modular MTE contactors could be configured for a variety of contact arrangements. I can't find them on the current market but

shows a sample (although the sale is ended you can get an idea of what they looked like).

[Steve Walker]

Telemechanique LC1-K09008## (the ## is the coil voltage code).

2 NO and 2 NC poles, 20A rated.

SteveW

[Andrew Gabriel]

What you're asking for doesn't make a lot of sense. A contactor has a fast-make slow-break contact, generally for inductive loads. It relies on strong electromagnet force to generate high contact pressure for higher current operation. It is not mechanically symmetrical and so can't be made into a change-over arrangement.

As someone else commented, the nearest you are likely to find is the star-delta relay from a 3-phase motor starter, although that isn't symmetrical, so don't expect to pull the full contact rating continuously through the star side N/C contacts, which only have return spring pressure closing them and will be slow-make (which doesn't matter in a star-delta starter as there's no current flowing during the N/C contact closure).

So, do you need a contactor (as opposed to a relay), and if so, why?

[Andy Burns]

Could the O/P achieve what they want with a pair of mechnically interlocked contactors on a DIN rail? Often used (with electrical interlock too) for mains/generator failover.

[dave]

You don't know the application so what you said doesn't make a lot of sense.

Thanks for the lecture. I was using them extensively from ~ 1973 onward.

Yes - surprising ly I know what they are too - but expensive and too big physically.

You wouldn't understand - much electrical experimental theory.

Thanks to all for the actual detailed help and item ID - much appreciated. Pity some on this NG are so patronizing.

[Dave Plowman (News)]

The problem with this group is you've usually no idea of the knowledge or skills of the OP when a question is asked, and many refer to all relay type thingies as contactors.

A patronising reply would be more along the lines of 'if you have to ask you shouldn't be attempting this'...

[robgraham]

=A0 London SW

+1 - I've found that if you are asking a question here, it is necessary to give as much information of the requirement and your capability. It is only reasonable if you are searching for technical assistance that you help your advisor as much as possible.

Rob