SSR 40A Off State Leakage


I bought the 40A SSR from the shop and put it into my control box. Now that all is assembled I started testing and found that the Indicator LED is glowing when the SSR is in off state, not bright but visible on.

I connected the N-wire from the general power in N-wire and the L-wire from the output of the SSR, same as the heat element connector.

I can’t measure the A leakage but it looks like it must be something around 5mA as the light just glows and if I turn on the element SSR (via Tinker Photon App) the Indicator LED is bright. Turn it off it glows but it is not off.

Is there a known Off State Leakage of these SSR or are my SSRs broken? Is there anything that I can do to prevent that or resolve the Indicator LED issue?

Thank you,

There is a certain amount of leakage from all SSRs. I believe that is why most recommend a contactor between the SSR and anything high voltage like an element, plus if the SSR fails it usually fails in the “on” state.

Understand but the way that the electric brewery does it for safety reason with a selector before the mechanical relays to guarantee that only one side is on at a time and also if the selector is in middle position that no electricity flows to the elements. If it fails in ON state but selector is in the middle it would not be a problem, any other position the electricity would flow.

How would it stop the small leakage if the SSR would be ON and it will flow through the relay? Has the relay a resistor to filter out that minimal leakage?

I would like to not have a selector, but I would risk that there is a chance that both elements are on at the same time and probably blow my fuse.

Without paying toomuch attention to anything you or others have said; 2 seperate electrical engineers who build Plc based control boxes for a living have told me that adding a contactor to a homebrew setup is super redundant safety wise. Ignoring ill effects to wort, they have convinced me very easily that anything more than the relay is a waste - breakers are safer. If you’re getting leakage there’s a reason. Find out that reason.

The new BrewPi algorithms can add both actuators to a mutex group, of which only one can be active at any time.

This goes down to the pin level, so two PWM actuators can be running at 40% each, but quickly alternate between being active. This will allow you to heat your boil kettle, while maintaining the temperature of your HLT. Configuring this has not been brought to the UI yet. Now all actuators are part of the same mutex group without a UI to change it.

Now on to your question:

  • The LED on the SSR is driven by the control side, not the AC side. Normally, SSR leakage is about the AC side. Did you connect a lamp/LED to the AC side of the LED? A closed SSR can leak enough current to drive a small LED, but as soon as you connect a heating element, the LED will be off because the leakage current goes through the path of least resistance (which will be the element).
  • Connecting the LED in parallel with your element is correct. L to SSR, SSR to element and LED, other side of element and LED to N.

Yes, connecting the element removed the minimum of leakage towards the LED and it is OFF now and only ON when the SSR is in ON state.

I did connect the L wire to the AC side the 2 wires leave the SSR, one going to the connector for the heat element and the other to the AC side of the LED indicator. The N comes from the general power in for the elements.

Thanks for the help.