Wiring question

[rudylyon57]

Need some advice from you electrical wizards out there. I'm wiring my new panel to power a three 4500W elements at 220V, as well as one selectable between 220V and 110V to control max power. Two elements will be driven via SSR/PID and the third will be driven manually via SSVR to control boil. The heaters are all wired through a DPDT relay with one leg (L1) always hot and the other leg (L2) switched on/off by the SSR via PID control. Pretty much standard stuff.

Now the question. I would like to wire in a few 110V LED lights (L2 to neutral) to flash along with energizing of the element but I'm not sure how to wire them in as they will always see 110V from the L1 leg always being hot through the heater.

Any suggestions or is this just not doable. Will 220V LED's do the trick if available?

 

[jeffmeh]

220v leds, wired in parallel with the elements. That will work at 220v. Not sure about when you switch one to 110v.

 

[rudylyon57]

220v leds, wired in parallel with the elements. That will work at 220v. Not sure about when you switch one to 110v.

Thanks Jeffmeh. I'll do just that but on the element that gets switched 220v/110v I'll use an additional 110v led wired to neutral. It will be on all the time at 220v but fire with the SSR on 110v...that will be okay.

 

[Brumateur]

Most 220V LED works OK on 120Volts. So one 220V LED wired in parallel with your heater should do what you want

 

[rudylyon57]

Most 220V LED works OK on 120Volts. So one 220V LED wired in parallel with your heater should do what you want

Great! That will mean I don't have to drill another hole with all the gear mounted and wired! 220v LEDS are on order.

 

[jeffmeh]

Most 220V LED works OK on 120Volts. So one 220V LED wired in parallel with your heater should do what you want

So would you connect both the 120v neutral and one hot leg of the 220v feed (after the switch, so only one is in a closed circuit) to one leg of the 220v led? Thanks.

 

[rudylyon57]

So would you connect both the 120v neutral and one hot leg of the 220v feed (after the switch, so only one is in a closed circuit) to one leg of the 220v led? Thanks.

I have two DPDT relays that switch the SSR and common heater legs between 220 (L1/L2) and 110 (L1/N). I will simply have one 220v LED wired across the heater legs.

 

[lschiavo]

It has been a while but I remember having leakage issues through the SSR - it would let enough current through to light the led dimly at all times when put on the supply side. With my builds, I monitor the control voltage. It is already DC for the SSR anyway so all you need is a standard LED and a resistor.

 

[JoshuaW]

It has been a while but I remember having leakage issues through the SSR - it would let enough current through to light the led dimly at all times when put on the supply side. With my builds, I monitor the control voltage. It is already DC for the SSR anyway so all you need is a standard LED and a resistor.

Power -> SSR -> Contractor, Put your LEDs after the contractor, in parallel with the element. If your SSR is leaking current, that is important to be able to see as well, IMO.

 

[lschiavo]

Power -> SSR -> Contractor, Put your LEDs after the contractor, in parallel with the element. If your SSR is leaking current, that is important to be able to see as well, IMO.

That would solve it unless you want to run PWM. Then you wouldn't want your contactor cycling. I believe SSR's just DO leak a small current. Its the nature of the beast. It is probably less than a few milliamps as it doesnt fully light an led and they need 15-20mA to light fully. They certainly do not have 0V at the output like a contactor would. I remember this issue before and am just trying to help anyone from learning the hard way like I did

 

[JoshuaW]

That would solve it unless you want to run PWM. Then you wouldn't want your contactor cycling. I believe SSR's just DO leak a small current. Its the nature of the beast. It is probably less than a few milliamps as it doesnt fully light an led and they need 15-20mA to light fully. They certainly do not have 0V at the output like a contactor would. I remember this issue before and am just trying to help anyone from learning the hard way like I did

I agree that SSRs are very prone to leaking. Now, what impact would running PWM have on the contractor? The contractor would be in the closed position, via your switch (or whatever control method you are using for it), and wouldnt be impacted by the PWM, correct?

 

[lschiavo]

I agree that SSRs are very prone to leaking. Now, what impact would running PWM have on the contractor? The contractor would be in the closed position, via your switch (or whatever control method you are using for it), and wouldnt be impacted by the PWM, correct?

I agree but that is not how I understand the description of the ciruit by the OP. And your LED would only be fully off when the contactor is off. It would still see the leakage between cycles. I guess a circuit diagram would help.

 

[rudylyon57]

Interesting chat gents. For purpose of this discussion, I'll refer to the DPDT mechanical relay as the "contactor" and the controlling relay as the "SSR". In my case one leg of contactor is positioned between the SSR and heater and the other contactor leg between line and heater. Since the contactor is closed during the period of interest, I'm not sure its relevant to LED function. The voltage across the LED when the SSR is "off" will be the SSR leakage current (which appears to be micro-amps to several milliamps) X the heater resistance (4500W @ 240v so 12.8 ohms). So, at 3 milliamps the voltage may be on the order of 40 mv. I doubt that is anywhere close to being able to illuminate a 220v LED.

 

[rudylyon57]

I agree but that is not how I understand the description of the ciruit by the OP. And your LED would only be fully off when the contactor is off. It would still see the leakage between cycles. I guess a circuit diagram would help.

I did not answer your question about a circuit diagram. I see all these nice electrical schematics that people post but have no idea what software is used to draw them? Wish I could help. But hopefully my description will suffice.

 

[lschiavo]

Interesting chat gents. For purpose of this discussion, I'll refer to the DPDT mechanical relay as the "contactor" and the controlling relay as the "SSR". In my case one leg of contactor is positioned between the SSR and heater and the other contactor leg between line and heater. Since the contactor is closed during the period of interest, I'm not sure its relevant to LED function. The voltage across the LED when the SSR is "off" will be the SSR leakage current (which appears to be micro-amps to several milliamps) X the heater resistance (4500W @ 240v so 12.8 ohms). So, at 3 milliamps the voltage may be on the order of 40 mv. I doubt that is anywhere close to being able to illuminate a 220v LED.

Well, the voltage across the LED and Element will be the same if they are in paralell. The lower resistance of the element should pull the majority of the leakage current away from the LED. As long as the element is plugged in, you probably will not see any illumination of the LED. This thread seems to indicate that:

https://www.homebrewtalk.com/f170/ssr-current-leakage-447276/

I may be alone in the camp that monitoring the voltage at the element is redundant. I can see and or hear if my elements are powered. Monitoring the control input to the SSR seems easier and should the element not fire, it gives more indication of where the problem might be. Must be the SSR or downstream if the indicator is flashing...and upstream on the control side if not.

Just my $0.02. Have fun with the build.

 

[rudylyon57]

Just my $0.02. Have fun with the build.

It has been a blast putting all this together. The main objective behind the LED's that energize with the heaters was simply to provide a more direct and visible indication of what the process is doing. It may be a little overkill or redundant, we'll see.