types of contactor

[ectbigboss]

Dear all ,
i am new to this forum. i hope you all are fine and enjoying life.

please tell me types of contactors. because i seen many but didnt understand their types and rating.

secondly what is the difference between relay and magnetic contactor.

Thanks,

Best reagards,

 

[jraef]

First, relay vs contactor: the difference is basically just current rating. Relays are only expected to handle control circuits, contactors handle power circuits. At the low end of contactors, the difference is negligible but generally we stop calling anything handling over 30A a contactor and anything designed for under 9A is a relay. In between, it's a matter of application.

As to "types" of contactors, in what context? Construction? Application? Voltage? Duty cycle?


"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington

 

[itsmoked]

we stop calling

"we start calling"


Keith Cress
kcress -

http://www.flaminsystems.com

 

[ScottyUK]

I guess the major categories of electromechanical contactors are the commonplace 'block' type, the old-fashioned-looking bar and shaft design for severe service and DC applications, and exotic types like vacuum contactors for high power applications.

Feel free to pitch in with more.

 

[itsmoked]

The ever lovely mercury contactors.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[ScottyUK]

Wow, haven't seen any of them for a long time. Hasn't your government banned mercury switches?

 

[itsmoked]

Not sure they're banned, just frowned upon.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[ectbigboss]

Thanks

 

[REDDOG]

NEMA or IEC rated contactors

 

[itsmoked]

REDDOG has pointed out the "types of contactors".

NEMA contactors are much heavier duty than IEC contactors rated the same. They also tend to cost about 3X more than IEC. They are also larger than IEC. They tend to take more abuse than IEC. The theory is that if you've invested in these expensive NEMA contactors you will be rewarded by long life and the ability to repair them as you can order all the various bits when they wear out. The reality of it is that it's very hard to figure out the part numbers needed to order the various bits and then finding someone who has them to sell you. About half the time you end up with the wrong parts that cost a serious percentage of the price of the original contactor. It may be well less expensive to just replace an entire IEC contactor that has an issue than the time and cost required to fix a NEMA contactor.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[ScottyUK]

If you order IEC contactors based on their AC-4 rating rather than the normal AC-3 rating you get something much closer to a NEMA contactor in size and capability. Cost goes up, but so does contactor life.

 

[itsmoked]

Good point Scotty. If they're going to operate more than 5 or so times a day I've always just selected the next contactor up from the one recommended. Still way less money and faster to come by than a NEMA.

Keith Cress
kcress -

http://www.flaminsystems.com