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General => Lighting & Load Control => Topic started by: shrathod on October 29, 2013, 08:12:54 am

Title: Fibaro Double Relay Switch Module - FGS221 - LED Load
Post by: shrathod on October 29, 2013, 08:12:54 am
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?
Title: Re: Fibaro Double Relay Switch Module - FGS221 - LED Load
Post by: AndersH on October 29, 2013, 02:06:58 pm
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.
Title: Re: Fibaro Double Relay Switch Module - FGS221 - LED Load
Post by: shrathod on October 30, 2013, 02:24:43 am
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.
Title: Re: Fibaro Double Relay Switch Module - FGS221 - LED Load
Post by: AndersH on October 30, 2013, 02:58:34 am
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.
Title: Re: Fibaro Double Relay Switch Module - FGS221 - LED Load
Post by: RexBeckett on October 30, 2013, 04:07:50 am
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.
Title: Re: Fibaro Double Relay Switch Module - FGS221 - LED Load
Post by: shrathod on October 31, 2013, 04:20:43 am
@AndersH

Quote
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.

Quote
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.

Quote
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.
Title: Re: Fibaro Double Relay Switch Module - FGS221 - LED Load
Post by: shrathod on October 31, 2013, 04:24:03 am
@RexBeckett

Insert Quote
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?
Title: Re: Fibaro Double Relay Switch Module - FGS221 - LED Load
Post by: RexBeckett on October 31, 2013, 05:10:36 am
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 (http://www.ebay.co.uk/itm/FE-SP-HDR23-100-47-Contact-Suppressor-0-1Uf-47R-AMPOHM-WOUND-PRODUCTS-/200971674999?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item2ecad86577) 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.

Title: Re: Fibaro Double Relay Switch Module - FGS221 - LED Load
Post by: shrathod on November 01, 2013, 02:09:35 am
Thanks AndersH and RexBeckett for your help.

@RexBeckett
Will a MOV also provide the same protection as snubber in this case?
Title: Re: Fibaro Double Relay Switch Module - FGS221 - LED Load
Post by: RexBeckett on November 01, 2013, 06:48:34 am
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.
Title: Re: Fibaro Double Relay Switch Module - FGS221 - LED Load
Post by: shrathod on November 11, 2013, 03:28:47 am
@RexBeckett

Thanks.
Title: Re: Fibaro Double Relay Switch Module - FGS221 - LED Load
Post by: dark on October 23, 2014, 03:00:58 am
Is this correct?
Title: Re: Fibaro Double Relay Switch Module - FGS221 - LED Load
Post by: RexBeckett on October 23, 2014, 05:03:03 am
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.

Title: Re: Fibaro Double Relay Switch Module - FGS221 - LED Load
Post by: dark on November 30, 2014, 02:38:49 am
Hi Rex when i connect the suppressor  to terminal IN & 01 my Led start blinking???
any solution for this?

Thanks.
Title: Re: Fibaro Double Relay Switch Module - FGS221 - LED Load
Post by: RexBeckett on November 30, 2014, 01:20:49 pm
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.
Title: Re: Fibaro Double Relay Switch Module - FGS221 - LED Load
Post by: silasbruder on February 09, 2015, 06:06:04 am
Hi, I am having the same problem in different clients, I just read this post and i will try the suppressor between O1 and N.
Using a contactor wouldn`t help aswell? Or the only solution is the suppressor?

King Regards
Title: Re: Fibaro Double Relay Switch Module - FGS221 - LED Load
Post by: RexBeckett on February 09, 2015, 02:13:44 pm
Quote
Using a contactor wouldn`t help aswell?

It would if the contactor was rated for a large-enough reactive load. It is sometimes necessary to fit snubbers/suppressors to contactors, though. Also the coil of a contactor is largely inductive and, if it is a large one, may still require a suppressor to protect the contacts of the Z-Wave switch.

Reactive loads cause many switching problems...
 
Title: Re: Fibaro Double Relay Switch Module - FGS221 - LED Load
Post by: balboa on July 06, 2015, 03:03:30 pm
Hi. I'm having the same problem. I've already connected a snubber with C=100nF(X2) and R= 100 ohm (3W) to O and N, and it didn't work. Am I doing something wrong? Info: 230V supply connected to a LED strip (with drive - 12V - 7,2W/m); 0,835A nominal at the switch.
Title: Re: Fibaro Double Relay Switch Module - FGS221 - LED Load
Post by: Alexia on July 21, 2015, 07:23:42 am
Has anyone really overcome this problem using snubber or any other simple solution?
Title: Re: Fibaro Double Relay Switch Module - FGS221 - LED Load
Post by: rotman253 on November 20, 2015, 10:56:12 am
Hey ,
so glad I stumble upon this thread , I thought my fibaro relay is gone.
knocking on the relay released the relay.

so can someone please explain what exactly should I buy and connect to the fibaro relay in order to solve this issue?

Thanks
Title: Re: Fibaro Double Relay Switch Module - FGS221 - LED Load
Post by: KMorley on December 03, 2015, 07:24:40 am
I have an engineering background and this is an interesting problem, so I thought that I would chime in ;)

It sounds like arcing is causing the relay contacts to stick together in the closed position regardless of the relay actuator.  The root cause of the problem may be that the contacts are made of some soft/easily melted material, which inherently makes that material a poor choice for use as relay contacts.  Simply put, the root cause of the problem may be poor design of the relay.

The power supply may be a contributing factor as it may have a high inrush current that significantly exceeds the design of the relay.  I don't know what kind of power supply is being used for this, but high inrush current is a characteristic of conventional, non-switching type power supplies.  Correctly-size switching power supplies should not have the same problem or at least not to the same degree.  A properly-sized resistor placed in series with the power supply should help reduce in-rush current.

The power supply design may also have some reactive/inductive design that causes an arc when the contacts open.  This particular issue is characteristic of conventional non-switching power supplies that have a transformer primary wired across the mains.  A disk capacitor placed across between the two relay contacts should suppress arcing when the contacts open.  Adding a gas tube in parallel with the capacitor would also help.  Gas tubes are fairly slow to ionize, so the capacitor would be mandatory and the gas tube would just provide additional suppression.

Rather than analyze and experiment, it might be better to eliminate the problem by adding a Solid State Relay (see https://en.wikipedia.org/wiki/Solid-state_relay).  Use the Fibaro relay contacts to send mains voltage to control the SSR and let the SSR do the heavy lifting to start/stop the power supply.  SSRs have an inherent advantage in that when they switch mode (on to off or vice versa), they do so during the mains sine wave zero crossing point.  At the zero crossing, there is zero voltage and current available on the mains and so there is no current in-rush or high-voltage inductive arc possible.

SSRs are relatively cheap and effective.  Additionally, it should be easy to retrofit to the existing configuration - at least for testing and experimentation purposes.

Ken

Title: Re: Fibaro Double Relay Switch Module - FGS221 - LED Load
Post by: ohdan on July 19, 2017, 06:48:55 am
In case anyone still wants to resurrect their Fibaro FGS221 and FGS222 double relay, I connected a thermistor in series from the "light" to the relay. The thermistor prevents the surge of current when the switch is turned on (inrush current) and prevented the contact points of the Fibaro relay from welding together.

Please use with care as thermistor runs hot so when you put it back into the socket box, do make sure there is some distance between the thermistor, wires and the relay itself.
Title: Re: Fibaro Double Relay Switch Module - FGS221 - LED Load
Post by: Cor on July 19, 2017, 08:25:22 am
I have this issue as well occasionally on one of my relais , and always with the same lights- relais.

Do you have some more info about this thermistor.

Thanks,
Cor
Title: Re: Fibaro Double Relay Switch Module - FGS221 - LED Load
Post by: ohdan on July 19, 2017, 11:17:09 am
There you go...

http://uk.farnell.com/ametherm/sl15-10006/thermistor-ntc-radial-10ohm/dp/2113005

My AC supply is at 220V/240V so this thermistor should be suitable for UK use as well.