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RC snubber circuit

Karthik rajagopal

May 9, 2016
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May 9, 2016
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Hello all,
I am planning to design a timer based cut off circuit for my ~230V, 10A water heater. In order to avoid arching at the relay contacts, I thought of using a RC snubber circuit.
I haven't worked with snubber circuits before. I went through lot of documents on the internet but didn't get a clear idea.
I am not sure whether to have the snubber circuit across the switch or load or to entirely go with TRIAC based design for zero cross switching.
Please help me out with my confusion and also with the component value calculation .

Thanks in advance.
 

bertus

Moderator
Nov 8, 2019
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2,722
Hello,

Where does the relay come in this circuit?
Driving a heater (wich is resistive) with zero crossing, you likely do not need a snubber ciruit.
For more info on snubber circuits, have a look at the attached application note.

Bertus
 

Attachments

  • 6785_RC snubber circuit design for TRIACs.pdf
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Bluejets

Oct 5, 2014
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Where does the relay come in this circuit?
Many timers although rated at 16A are recommended to use a contactor for the HWS.
All possibly in conjunction with solar .....turn HWS off at night when the sun don't shine..:):)
Also this end, forget the snubber, not needed.
 

Karthik rajagopal

May 9, 2016
246
Joined
May 9, 2016
Messages
246
The heater element is a resistive load, not inductive, so do you need a snubber?
Yes, the heater element is resistive. Right now it is controlled using a conventional ON/OFF switch. I notice sparking whenever I turn on the heater (a greenish light that illuminates the switch for an instant). Not able to exactly trace the reason for that spark as there is no reactive element to respond to such switching events with an arch. So, I thought of adding a snubber to prevent the same from damaging the relay contacts...if in case anybody knows the reason for the sparking, please share it as it will help me get a better clarity on my problem.
 
Last edited:

Karthik rajagopal

May 9, 2016
246
Joined
May 9, 2016
Messages
246
Hello,

Where does the relay come in this circuit?
Driving a heater (wich is resistive) with zero crossing, you likely do not need a snubber ciruit.
For more info on snubber circuits, have a look at the attached application note.

Bertus
Thanks for sharing the application note.
 
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