It's not appropiate to use a SSR to switch on/off magnetic ballast (used with HID lamps), because it's an inductive load and the Triac inside the SSR cut off while there is still current flowing. That produce flickering.

Can I use an SSR to switch on/off an electronic ballast without adverse side effects?

  • 1
    \$\begingroup\$ I would look at zero-cross current sending SSRs for an inductive application like this. \$\endgroup\$
    – jwh20
    Jul 28, 2021 at 20:47
  • \$\begingroup\$ "Triac inside the SSR cut off while there is still current flowing." No, not possible. The triac conducts until the current drops to zero. The flickering is caused by the delay until the triac is triggered again. \$\endgroup\$
    – Dave Tweed
    Jul 29, 2021 at 3:08

1 Answer 1


The easiest way to solve that is use SCRs. They have 1/2 cycle to commutate. We did that with 500V 100 horsepower DC motors, no problems. There were 8 of them on extruders. I do not know if you can purchase them any more. You can also add to the snubber circuit.

  • \$\begingroup\$ It sound good (and Aliexpress carry SCR) and I will try it. \$\endgroup\$
    – Candid Moe
    Jul 28, 2021 at 22:05
  • \$\begingroup\$ Good luck and let us know how you do. Glad I could help! \$\endgroup\$
    – Gil
    Jul 28, 2021 at 22:06
  • \$\begingroup\$ Using a SSR to switch a ‘iron’ ballast might be problematic, but switching an electronic ballast should not be a problem. An electronic ballast is effectively a switch mode power supply so should be no different from , say, your PC. I would suggest you consult the ballast manufacturer to confirm. \$\endgroup\$
    – Kartman
    Jul 29, 2021 at 0:05
  • \$\begingroup\$ It have been working flawlessly for several month. \$\endgroup\$
    – Candid Moe
    Mar 1, 2022 at 23:47

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