contactor rating

[Shaun12]

When looking at contactors, does the coil voltage refer to auxiliary a1/a2 such as 24v supplied from a plc output and contact voltage rating refers to the feed/load being switched? If a contactor is rated to 690v/3-pole could it be used for 415v/3pole or 230v single pole?

 

[tazz]

A1 & A2 are the coil voltage to operate the contactor, the voltage switched is only relevant to the current being switched. So the voltage is not a issue, as the contactor rated for 690v will switch any voltage below its rating. The current rating will however decrease on lower voltage and if used for DC switching

 

[ian.settle1]

Any voltage can operate a controlling coil for a contractor switching any voltage.

It should noted though that many old contactors may still have a 240/415v coil

You must make sure though that all supplies are from the same main source of supply even if a transformer is used, if not it should be indicated that there are 2 sources of supply.

 

[Lucien Nunes]

The current rating will however decrease on lower voltage

Don't understand this bit Tazz, did you mean to say the power rating?

 

[Shaun12]

Thanks for the replies.

Would this be classed as a contactor?
What is the part sitting out from the main unit?

 

[Deleted member 72666]

No, that's a relay and the diode across the coil to counter back emf.

 

[Shaun12]

Thanks.

Oh what's the difference then? They both operate in the same way with the same idea a coil making contacts when energised. So when does a relay become a contactor?

 

[davesparks]

Looks like a contactor,

 

[Deleted member 72666]

Contactors have the ability to switch higher currents and are made to suit whilst relays normally switch much lower currents such as control circuits etc. You can purchase mini contactors which are the same form factor as the relay you have there.
What is it you are wanting to do with this?

 

[Darkwood]

These are seimens range of compact contactors and usually for the lower loads ...as for the difference between them well I never really thought about it, but often relays tend to be limited load handling ...

This isn't technical but if clicks, its a relay and if it clunks, its a contactor (Excluding solid state device before I get a smart comment )

 

[davesparks]

Thanks.

Oh what's the difference then? They both operate in the same way with the same idea a coil making contacts when energised. So when does a relay become a contactor?

Generally speaking a contactor is used to switch a load and a relay is used within control circuits.
But there is no hard and fast definition to either.
Generally contactors have higher current ratings and switching duties, but you can also get relays capable of switching 100's of amps.

 

[Deleted member 72666]

The tell-tale sign in your picture are the markings, these denote normally open and normally closed contacts which are usually found on relays of that type, contactors on the other hand are marked up differently L1, L2, L3 etc.

 

[davesparks]

The tell-tale sign in your picture are the markings, these denote normally open and normally closed contacts which are usually found on relays of that type, contactors on the other hand are marked up differently L1, L2, L3 etc.

That doesn't necessarily make it a relay though, it could still be a contactor.

Some of the other writing on there is a bit more useful in getting reliable identification, specifically the part number. A quick google brings up a data sheet clearly tilted 'contactor'

 

[telectrix]

These are seimens range of compact contactors and usually for the lower loads ...as for the difference between them well I never really thought about it, but often relays tend to be limited load handling ...

This isn't technical but if clicks, its a relay and if it clunks, its a contactor (Excluding solid state device before I get a smart comment )

clunk -click. thought jimmy saville was brown bread.

 

[Darkwood]

clunk -click. thought jimmy saville was brown bread.

We don't talk about him... :38:

 

[Deleted member 72666]

That doesn't necessarily make it a relay though, it could still be a contactor.

Some of the other writing on there is a bit more useful in getting reliable identification, specifically the part number. A quick google brings up a data sheet clearly tilted 'contactor'

I'm going to be diplomatic on this occasion and call it a 'contactor relay'.

 

[davesparks]

I'm going to be diplomatic on this occasion and call it a 'contactor relay'.

The manufacturers describe it as a contactor, what more do you need?

 

[Deleted member 72666]

The manufacturers describe it as a contactor, what more do you need?

.....Okay then what do you personally think it is?

 

[Hellmooth]

I'd say it's a contactor, that's what I ask for when I need one of these lol, relay and contactor are essentially the same thing, as has been said it is usually higher switching currents with a contactor, but whatever the manufacturer calls it.......

 

[Guest77]

I didn't realise a contactor could be switched using Normally open Or normally closed contacts like a relay can be switched, I thought they were coil controlled?

 

[davesparks]

.....Okay then what do you personally think it is?

A contactor as that's what the part number is listed as by the manufacturer.

 

[Guest77]

I didn't realise a contactor could be switched using Normally open Or normally closed contacts like a relay can be switched, I thought they were coil controlled?

that said you can get clip in auxillary contacts.

 

[Deleted member 72666]

A contactor as that's what the part number is listed as by the manufacturer.

Do you have much experience with automation and control gear?

 

[andyb]

Interesting thread, my thoughts are that a contactor is either open or closed and used to switch on/off and for switching high loads.
whereas a relay is for control switching with a common and n/o n/c. So a relay can be used as a contactor but not the other way round.

So if I'm right, the picture is of a contactor as it has no common, although it has independent n/o n/c contactors it cant switch from one to the other.

 

[DPG]

Interesting thread, my thoughts are that a contactor is either open or closed and used to switch on/off and for switching high loads.
whereas a relay is for control switching with a common and n/o n/c. So a relay can be used as a contactor but not the other way round.

So if I'm right, the picture is of a contactor as it has no common, although it has independent n/o n/c contactors it cant switch from one to the other.

Relays can have single contacts or any combination of contacts though. Daz