RC Snubber

Hi everyone!

I am learning Arduino and I do have a concern when dealing with AC motors.

With an Arduino UNO R3 I want to control through 3 relays (5V/12V 1 Een Kanaal Relaismodule Laag Niveau Voor Scm Huishoudelijke Apparaten Controle Voor Arduino Diy kit|one channel relay module|channel relaylevel relay - AliExpress) following devices:

I read about voltage spikes, backward current...

A wonderful man, who answered all my questions, said the solution was not a diode (DC), but an RC Snubber. I do want to know what RC snubber would be my best choice. On AliExpress I found two common types:

(1) Which snubber module would be okay?

(2) Do I put RC Snubbers in parallel with each pump and the motorized valve?

(3) Also I would like to know if RC Snubbers would also work for a DC solenoid valve, for which I am using now a flyback diode?

(4) Apparently the relay module can also generate backward current (magnet), but it is protected well with the onboard circuit, right?

I ask many question, but I really want to understand...

Kind regards and thank you for your time.

Nobody?

dimi2710:
Hi everyone!

I am learning Arduino and I do have a concern when dealing with AC motors.

With an Arduino UNO R3 I want to control through 3 relays (5V/12V 1 Een Kanaal Relaismodule Laag Niveau Voor Scm Huishoudelijke Apparaten Controle Voor Arduino Diy kit|one channel relay module|channel relaylevel relay - AliExpress) following devices:

I read about voltage spikes, backward current...

A wonderful man, who answered all my questions, said the solution was not a diode (DC), but an RC Snubber. I do want to know what RC snubber would be my best choice. On AliExpress I found two common types:

(1) Which snubber module would be okay?

(2) Do I put RC Snubbers in parallel with each pump and the motorized valve?

(3) Also I would like to know if RC Snubbers would also work for a DC solenoid valve, for which I am using now a flyback diode?

(4) Apparently the relay module can also generate backward current (magnet), but it is protected well with the onboard circuit, right?

I ask many question, but I really want to understand...

Kind regards and thank you for your time.

Lots of questions, but little effective information.

IF you are using solid state relays to switch the 220 volt mains, nothing else is needed.

The links to the snubbers do not show the component values on the boards, so no one can tell which is best or worse or any thing else about them.

A relay module has all the components necessary to protect itself from the relay coil back voltage.

AC snubbers only work for your AC devices. Why think the added cost is better than a simple single diode?

The problem I see with the Aliexpress units is all the component leads and the circuit board traces expose the 220 VAC to your fingers. I suggest using a single insulated device that has two leads and all the other components are inside the insulating housing. Besides, they are smaller than the circuit board things.

Paul

Does a diode help with AC backward current? I mean the backward current from my 220V garden pump to the relay.

dimi2710:
Does a diode help with AC backward current? I mean the backward current from my 220V garden pump to the relay.

A diode shorts half of the AC wave.
Booom!!!

So I do need an RC snubber. All an aliexpress are not specified, would they be for 'general use' or should I build one myself: what do I need, if I would like to protect my against voltage spikes from my biggest 'consumer': 600 Watt - 220 Volt pump. A resistor and a capacitor? What would be the scheme (series/parallel)?

Thank you so much for the answers.

Have you thought about Varistors (MOVs) or bidirectional TVS diodes?

You need to rate MOVs and TVS diodes appropriately - MOVs in particular can have thermal runaway, and
tend to fail short-circuit.

RC snubbers have to be sized for the current and inductance of the load they snub, however. You basically
form an RLC circuit and you need to ensure it has low Q and is not resonant anywhere near mains frequency.

You also have the choice of placing the snubber across the load, or across the switch. Its tailored to the load,
but it protects the switch, so there are arguments both ways.

Thank you for the answer!

I only found on AliExpress two types of snubbers, without any description. Where would I be able to find a
snubber for my pump (600 Watt, 220 Volt)? I maybe ask stupid questions, but this is pretty new to me.

Kind regards

Eureka! Finally I found more detailled information about the snubber sold on AliExpress:

For AC or DC 5-400V, max 1000 Watt.

So I guess this will be sufficient for my 600 Watt pump or are can inductive loads be higher than the specs of the pump itself?