Fibaro Double Relay Switch Module - FGS221 - LED Load

[shrathod]

I am having a peculiar problem with the FGS221 switch module.
When the FGS221 switch module is connected to LED load (panel / strip ? which uses a 12V dc supply), sometimes, when I try to turn OFF the LED load using home automation, it fails. Even turning it OFF using a physical switch doesn?t help. I can hear the ?click? sound though.

This has happened 3-4 times over a period of 6 months on different FGS221 switch modules. I then have to tap on the module to make it work. I also interchanged the outputs O1 and O2 just to check.

Is it because of some problem with the internal relay connection of the 2X1.5kW switch module?
Maybe it gets stuck, and doesn?t open up? Maybe inrush current of the dc supply?

[AndersH]

I am having a peculiar problem with the FGS221 switch module.
When the FGS221 switch module is connected to LED load (panel / strip ? which uses a 12V dc supply), sometimes, when I try to turn OFF the LED load using home automation, it fails. Even turning it OFF using a physical switch doesn?t help. I can hear the ?click? sound though.

This has happened 3-4 times over a period of 6 months on different FGS221 switch modules. I then have to tap on the module to make it work. I also interchanged the outputs O1 and O2 just to check.

Is it because of some problem with the internal relay connection of the 2X1.5kW switch module?
Maybe it gets stuck, and doesn?t open up? Maybe inrush current of the dc supply?

What happens if you turn off power completely (to reboot the Fibaro) ? I had a similar problem, although I do not control LEDs, but 6x36W fluorescent lamps. I could not turn the light off, neither by Vera nor via the connected switch. After a reboot of the Fibaro it was OK, everything has worked as it should ever since. I have had this setup since May (4-5 months now), it has happened once so far.

[shrathod]

By 'Reboot Fibaro' if you mean remove the supply of the module and reconnect it, yes i tried that. It did not help.

Only when tapped on the module slightly it started working again.

I also observed some type of arcing inside of the Fibaro module - in the internal relay - whenever I turned on the lights. This happened only with LED load which used a 230V to 12V SMPS. Not with CFL or Fluorescent Tubelight.

[AndersH]

By 'Reboot Fibaro' if you mean remove the supply of the module and reconnect it, yes i tried that. It did not help.

OK. Yes, that is what I meant.

Only when tapped on the module slightly it started working again.

I also observed some type of arcing inside of the Fibaro module - in the internal relay - whenever I turned on the lights. This happened only with LED load which used a 230V to 12V SMPS. Not with CFL or Fluorescent Tubelight.

In that case I agree that it have to do with your SMPS and the way it behaves when turning on/off. I think you are right that there is a in-rush current that's quite a bit higher than the constant load current (which would be quite small). Perhaps this current is higher than the rating of the relay?
In that case, I think you have to try to limit the in-rush current by some means. If you don't use the other relay for something, you could have a resistor in series with the SMPS on one relay contact and a direct connection on the other. By switching them on in sequence, you would reduce the in-rush.

You could of course try another power supply.

As the Fibaro has a separate input (apart from the L terminal), another option would be to use the relay on the low voltage side, but I presume your cabling isn't prepared for that.
You might also try a Fibaro Dimmer, as that one does not contain a relay.

[RexBeckett]

You could also try putting a contact arc suppressor (aka Snubber) across the relay terminals. One with a 0.1uF capacitor and 47R resistor would be worth a try. Make sure it is rated for your full supply voltage.

[shrathod]

@AndersH

In that case, I think you have to try to limit the in-rush current by some means. If you don't use the other relay for something, you could have a resistor in series with the SMPS on one relay contact and a direct connection on the other. By switching them on in sequence, you would reduce the in-rush.

I am using the other relay also. So this option is out.

You could of course try another power supply.

I tried a couple of different power supply, but all gave the same problem. Also, I found a post where similar issues were reported (http://forum.fibaro.com/viewtopic.php?t=1965). So I guess the problem might be with majority of power supply.

As the Fibaro has a separate input (apart from the L terminal), another option would be to use the relay on the low voltage side, but I presume your cabling isn't prepared for that.
You might also try a Fibaro Dimmer, as that one does not contain a relay.

I am afraid both options are not suitable. The number of circuits is too large. I am using close to 40 Fibaro Double Relays in one installation.

[shrathod]

@RexBeckett

Insert Quote

You could also try putting a contact arc suppressor (aka Snubber) across the relay terminals. One with a 0.1uF capacitor and 47R resistor would be worth a try. Make sure it is rated for your full supply voltage.

What should be the wattage rating of the resistor? Also, the supply voltage we use is 230V. So the parts should be rated at 250V?

Also, between which terminals should the snubber be inserted?

[RexBeckett]

I recommend that you buy a proper contact arc suppressor rather than use separate components. They use special capacitors that are rated for continuous use at line voltage, they are encapsulated and they should be UL approved. See here for an example.

You connect the suppressor directly across the relay contacts right at the module. For the FGS221 this would be between terminals I and O1 for the first relay and I and O2 for the second one.

Arc suppressors are available in various combinations of capacitor and resistor value. I cannot tell you which would be most suitable for your situation. I suggest trying the 0.1uF/47R version because it is commonly used in domestic appliances and usually easy to obtain. For a 230V supply the suppressor should be rated for at least 250V AC. I've attached a document that explains how to calculate the required values.

[shrathod]

Thanks AndersH and RexBeckett for your help.

@RexBeckett
Will a MOV also provide the same protection as snubber in this case?

[RexBeckett]

An MOV is not an alternative to a snubber - they work in different ways.

The point of the snubber is to conduct the load current for the brief period it takes for the relay contacts to open. This limits the voltage across the contacts to a low level so that an arc cannot form.

An MOV only reacts to transient voltages that are higher than its rated clamp-voltage. It will not stop an arc at the point where the contacts are just opening.

[shrathod]

@RexBeckett

Thanks.

[dark]

Is this correct?

[RexBeckett]

Is this correct?

You appear to have the suppressor connected between O1 and S1 on the FGS221. It should be connected between O1 and IN if you are trying to protect the relay contacts.

[dark]

Hi Rex when i connect the suppressor  to terminal IN & 01 my Led start blinking???
any solution for this?

Thanks.

[RexBeckett]

Hi Rex when i connect the suppressor  to terminal IN & 01 my Led start blinking???
any solution for this?

Thanks.

You could try connecting the suppressor across the load - i.e. between O1 and N. This will still provide some protection for the contacts and will not cause the LED to flicker.