Light to indicate ssr closed
- Thread starter redman67
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What's wrong with having an LED in parallel with your load coming off the SSR?
That's what I'd do. You can find lights that operate off of 120V or 240V. Just wire them on the SSR output.
That's what I did 
FYI, you can use a 240V LED on an output of 110V and it will still light. It just might not be as bright.
FYI, you can use a 240V LED on an output of 110V and it will still light. It just might not be as bright.
Better than that you can have a light that comes on only when the heater is actually drawing current. Buy or make a current transformer and wire it to a LED. If you make your current transformer you will have to experiment some.
TungstenBeer
Well-Known Member
Not if the element is plugged in.
Depends on which idea proposed here is implemented. With a current transformer the leakage current on the LED side of the transformer will be too small to light the LED. With a LED connected across the heater terminals you have in series a relatively high impedance (the off resistance of the SSR) in series with the low resistance of the heater and the heater in parallel with the series combination of a pretty high resistance and the LED. Most of the leakage current will flow through the heater. If the heater is unplugged then whether the LED lights or not depends on the relative resistances of the SSR and the resistor in the LED assembly.
You can fix the problem of the LED lighting when the element is not plugged in by putting a 7.5 Kohm to 10 Kohm, 10 W resistor in parallel with the LED. This will shunt enough of the leakage current to keep the LED from turning on. This will reduce your element power by 6 to 8 W, but insignificant in the scheme of things. Larger resistor values may work as well depending on your LED.
Brew on
Or by putting an external resistor in series with the LED assembly. This will, of course dim the LED somewhat during normal use.
Then there was the fellow here who decided not to fix this 'problem' but rather feature it.
LED out = system energized, SSR not gated, heater connected or system not energized
LED dim = system energized, SSR not gated, heater not connected
LED bright = system energized, SSR gated
Then there was the fellow here who decided not to fix this 'problem' but rather feature it.
LED out = system energized, SSR not gated, heater connected or system not energized
LED dim = system energized, SSR not gated, heater not connected
LED bright = system energized, SSR gated
jeffmeh
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Individual choice, but I cannot see being so bothered by the LED being illuminated when the element is not plugged in, and working fine when the element is plugged in and providing a load, that I would feel a need to "fix" it. 
