I need an AC contactor for a 1 hp motor. For the contactor safety I'm goint to use the suppression device on the both coil and contact side. Please suggest me which suppressor device will be use!

I have read all question and answer about suppressor for contactor from your forum, that was a good understandable.

Which would have a good suppresor nature for both side (contact & coil) like diodes, RC snubber or Varistor Coil Suppressor? If Yes of these once (diodes, RC snubber or Varistor Coil Suppressor), please explain why?

My desired AC contactor details are given below: Coil voltage :240v Pole :2 Contact type :DPST

Any suggestions would be greatly appreciated? Kindly clear and explain above question, share your suggestion.


1 Answer 1


There are cons and pros for each type of suppressor. Since you use the AC then the diode as well zener+diode are excluded. You can choose between RC snubber and MOV. Usually the MOV suppresors are embedded into a contactor itself, you need just to order the correct one. RC snubber is more bulky and has to be mounted as add-on.

You can find details on: Simatic contactor

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Using RC snubber on contacts, will produce a leakage current trough. A device connected to the contactor will always have some voltage, also the electric tester will show you a voltage presence even when contactor is disengaged. Usually you won't find any real application with suppressor mounted on switching side, it is done only for high inductive loads.

  • \$\begingroup\$ If i would be use RC snubber for a suppression ,how to select the resistance and capacitance value of the my desired ? \$\endgroup\$ Commented Nov 15, 2018 at 10:51
  • \$\begingroup\$ For 1hp motor , 2pole 240v voltage coil contactor , which RC value is suitable for contactor ? and please explain ,how to calculate ? also \$\endgroup\$ Commented Nov 15, 2018 at 10:55
  • \$\begingroup\$ I had never calculated it, since I buy the contactor with built in MOV. What you have to do is to select the suitable contactor, first. This is quite simple, each manufacturer has a list of contactors vs motor power kW/HP. But you won't find a single phase, rather look for three phase. \$\endgroup\$ Commented Nov 15, 2018 at 11:06
  • \$\begingroup\$ @SENTHURAMOOERTHY Here it is a similar contactor: TeSys D - LC1D0935B7 with 24VAC coil. Which is the control voltage? \$\endgroup\$ Commented Nov 15, 2018 at 11:11

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