Wifi relay three phase power supply problem

(dBC) #21

What’s the nature of that 12V LED supply? Is it a big iron transformer with some diodes, or is it a switch mode power supply?

(Bernardino Morillo Merino) #22

The power supplies are integrated in the different light points. It depends of the model, but mainly they are like this:


(Robert Wall) #23

You cannot use a diode when switching a.c!
You need a resistor and capacitor in series - something like this.

(You cannot use any capacitor, it must be “X-rated” for mains use: Papel metalizado X2, 250 Va.c.)

(Bernardino Morillo Merino) #24

I have to consult an specialist but how much important is this resistor? could be my problem of stop switching or not?

(Robert Wall) #25

I only made the suggestion. It is for you to decide whether you want to try it, or not.

When you wrote that the relay stopped working for a few seconds when it switched off, I deduced that at that instant, you might have an arc strike as the contacts part, as stored energy in the transformer inside that power supply has nowhere else to go. The arc generates interference that causes the WiFi relay to crash and restart itself.

If you put the component I suggested across the relay contacts, the capacitor allows the fast spike of current to flow and be dissipated harmlessly in the resistor, instead of generating a high voltage and interference.

(dBC) #26

They look like “electronic transformers”, i.e. not really transformers at all but rather switch mode power supplies. I wouldn’t expect them to present as an inductive load.

(Robert Wall) #27

Neither would I, in fact I’d expect one of those to appear capacitive with a big splash of current at switch-on rather than at switch-off, but a big splash at switch-off is the only scenario that seems to fit the available evidence, and it’s probably worth trying for the sake of the cost of a contact suppressor.

(Bernardino Morillo Merino) #28

Thanks everyone for your support.

Finally I am ordering a contact suppressor for my problem but I don’t know exactly which one?

Any help in this decission?


(Robert Wall) #29

Here: Wifi relay three phase power supply problem

(Bernardino Morillo Merino) #30


My question now is how to install it in the current relay. By connecting pieces, in a board?
I have to connect two wires now (relay only have to control one) and I didn’t before


(Bernardino Morillo Merino) #31

According to the scheme of a cotact supperssor I have to introduce in the relay wire cables as this scheme shows. That’s right?


(Bernardino Morillo Merino) #32

My second question

Why not introduce it inside the WIFI RELAY board?

I think it is totally possible and this device will be prepare for any circuit: inductive too.

That’s right isn’t it?

(Bernardino Morillo Merino) #33

I can solder the 100 nF cappacitor to relay 2 external pins (i am using only NC option for the lighting line)

Could this capacitor damage the board? better outsie? What do you think?

I don’t understand why this component is not installed in the board now!

(Robert Wall) #34

You must have had two wires before. It is impossible not to have.[quote=“bernamorillo, post:31, topic:1153”]
as this scheme shows. That’s right?

That is correct.[quote=“bernamorillo, post:32, topic:1153”]
Why not introduce it inside the WIFI RELAY board?

There might be a situation where the very small amount of current that passes through the contact suppressor will cause a problem. Therefore, it is impossible to say that the suppressor should always be fitted. It could be the case that a suppressor MUST NOT be fitted.

Are you sure? You ENERGISE the relay to turn the lights OFF?
NO means Normally Open, open when not energised, closed when energised…
NC means Normally Closed, closed when not energised, open when energised.

You put the contact suppressor in parallel with the contacts that you are using.

If you apply too much heat for too long when soldering, you could certainly damage the board. I would connect it to the terminals that go to the relay contacts. Remember to put some insulating sleeving on the bare wires to prevent an electric shock if you touch them.

(Bernardino Morillo Merino) #35

Ok, everything thats right.

I will introduce the capacitor in the terminals, it is easier.

I am ENERGISE the relay to turn the lights OFF because if the relay doen’t works the user could use thermal protection as a switch on-off button (as they are using now)

Is there any problem with this solution? Could it increase the problem or something?

If I connect the wires in NC position as you say if the relay fail they can turn lights on manually.

Thanks a lot Robert.

(Bernardino Morillo Merino) #36

I have 2 wires of course, but they are from the same line, I didn’t explain it properly, I was asking about the use of the second wire of the line (Neutral and Phase in AC 220V line).

Now I am controlling one wire with relay (logically) and the other wire goes directly to lighting line from thermal protection.

Previously I didn’t understand the capacitor conection scheme, now this question is not interesting.


(Bernardino Morillo Merino) #37

I still working on that.

Finally we have check that:

  • The 240V to power the unit is the problem. We have 250V connection (electrical company issues) and after some uses the relay stop to work. You can hear how it try to move but it sounds very quiet, it is like a very tiny “click”
  • We are trying to solve introducing directly 5V in the board trought an external transformer.

I will keep you informed. Tomorrow we finish the work.

(Bernardino Morillo Merino) #38

We still trying to solve 250V problem.

Finally use 5V input to feed relay did not solve the problem

I have 2 options:

1- Decrease 250V to 220V
2- Change the on board relay.

Both solutions are very problematic

Any idea?


(Robert Wall) #39

@Martin_Harizanov is best placed to solve this problem. It might be a faulty component that is out of tolerance. The standard domestic mains supply for Europe is 230 V ± 10%, giving a lower limit of 207 V and an upper limit of 253 V. The UK standard prior to harmonization was 240 V ± 6%, giving an upper limit of 254.4 V. The relay should work properly at any voltage between 207 V and 254.4 V.

(Bernardino Morillo Merino) #40

Sometimes we can measure 255-258 V, and when it happends the relay stuks in OFF position. I will change the relay for 2 250V relays alternatives:

I have only 2Amps so I hope to solve the problem using them

Fingers crossed :slight_smile: