November 23, 2016 at 9:43 am #7966
Hello Galco, I would like to know, what are the differences between Relays and Contactors?
They seem to be the same thing.
November 23, 2016 at 10:19 am #7967
Hello Pete, thanks for visiting our web forum today. I would be happy to help you with the differences.
First of all they are basically the same thing, but there are also unique differences.
Contactors are generally made for high power use in 3 phase applications, but are also available 2 pole for DC applications. Because of the high currents they are made to handle they usually have magnetic arc chamber to extinguish arcs in shortest possible time. They will also have the ability to mount auxiliary contacts for low power signalling to the control circuits.
Relays are much more simple in nature, they just have a number of poles controlled by the coil to open or close them when energized. Relays don’t necessarily have auxiliary contacts but some types will have stackable contact blocks to be able to add poles if needed.
Both are operated by a coil that is available in different voltage ratings, and both operate contacts to open or close when energized.
Hope this helps
Regards and Happy Thanksgiving
November 23, 2016 at 10:24 am #7968
Thanks John, this is very helpful, but have another question.
So what kind of power are they rated for and what are the coil voltages?
How do I know which type to use?
November 23, 2016 at 10:54 am #7969
These are great questions Pete.
Ok well relays will generally be used to switch low power like 10volt, 24volt, 115volt AC or DC signals at less than 20amps of current.
Contactors, on the other hand, are made to handle much higher currents and voltages. A small contactor might only be rated up 20 amps of current. Where a large contactor will do 10 times that or 200amps up to a thousand volts.
To decide which to use, simply identify the number of poles needed for your application, the coil voltage needed (many different volts available for coils, 24Vdc minimum usually, and up to 480Vac) and then the maximum amount of amps to switch on and off.
November 23, 2016 at 11:20 am #7970
Yes John that is better, reason I’m asking is I have an old ABB DCS800 drive and it looks like the contactor went bad. 1 of the terminals is all discolored looking like it got really hot for a while and this thing hasn’t run in almost a year. Well now we need it running, can you guys help?
November 23, 2016 at 11:26 am #7971
Do me a favor though, first gather the name plate data of the drive in question.
We will need the whole part number ok?
Then give us a call at 248-336-4591, this is Randy Barbret’s direct line. He is our ABB product manager and has many years of experience with ABB products. He will be able help you figure out what that contactor was and get a replacement ordered.
Good luck and thanks again for asking Galco
November 23, 2016 at 11:27 am #7972
Very good, I will do just that.
Thank you very much
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