Go Down

Topic: SSR relays not flipping (Read 754 times) previous topic - next topic


As Wawa mentioned, you will not get a zero resistance across an SSR when it is on. More importantly, you're not measuring resistance on that meter setting, you're measuring voltage drop as the "diode" test function being used does not measure resistance.

The reading of 682 on the meter diode setting would indicate the SSR is switching on, that's the voltage drop across the triac, 682 millivolts is what you'd see for a typical silicon device.

You stated you where trying to switch 25 watt led's on and off but you never stated what their rated voltage was. If they are not rated at 100-240 vac, you cannot switch them with that SSR.

Nothing is adding up here. Have you actually trying switching a proper load on and off with the SSR?
Everything I'm trying to switch is 127V. I tried 127V LEDs between 5W to 100W. I had EMRs (regular relays) working in my design, then I replaced them with SSRs, but it just won't work.

PS: I have no idea how you're making the measurement that displays the 682 as the black meter probe is nowhere to be seen. Just another mystery that may never be answered.
The measure I'm making is conductivity. In the selected meter switch, if I touch the 2 poles, I get 0. If they are apart, I get 1 (infinite). 682 is somewhere between 0 an infinite.


Sep 20, 2020, 09:57 pm Last Edit: Sep 20, 2020, 10:26 pm by WattsThat Reason: Added continuity explanation
I suspect as a non-native English speaker you are confusing "conductivity" with  "continuity" which are two very different things.

You are not measuring continuity and you are not measuring resistance.

You are using the "diode test" function of the meter. It is a voltage drop test. Google "DMM diode test".

There are several possibilities for why the ssr's do not work.

1. They are defective.
2. They are are incompatible with the led loads
3. They are off spec devices and don't work at lower voltages

Test them with a 50 to 100 watt incandescent lamp and you might have some answers.

Or, you could just abandon the idea and return to using electromagnetic relays.
Vacuum tube guy in a solid state world

Go Up