RC snubber circuit

[Karthik rajagopal]

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.

 

[Kiwi]

The heater element is a resistive load, not inductive, so do you need a snubber?

 

[bertus]

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

 

[Bluejets]

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]

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.

 

[Karthik rajagopal]

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.

 

[Bluejets]

if in case anybody knows the reason for the sparking

Yes, it's due to the sudden 10A current flow and the position of the sine wave as it turns on, nothing abnormal about that.