SSR with Arduino Input Failing to Light up Lightbulb

I have a 100A DC/AC zero-switching SSR rated for 3-32 VDC input and 24-480 VAC output. My load is a 150W, 24V lightbulb, the positive wire of which is connected to Terminal 1 of the SSR, and negative wire connected to the black neutral wire of a laptop charging cable. The white live wire of the cable is connected to Terminal 2 of the SSR. Input voltage is being provided by two Arduino Uno output pins set to High. I’ve measured the voltage difference across input Terminals 3 & 4 of the SSR to be ~4.65 VDC, which is sufficient to turn the SSR LED on. The problem is my lightbulb isn’t lighting up. A continuity test across output Terminals 1 & 2 with my multimeter shows it’s an open circuit. Any ideas or insights would be much appreciated!

See below for code and picture of setup.

const int plusPin = 2;
const int minusPin = 4;

void setup() {
  // put your setup code here, to run once:
  pinMode(plusPin, OUTPUT);
  pinMode(minusPin, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  digitalWrite(plusPin, HIGH);
  digitalWrite(minusPin, LOW);
  delay(1000);
}

Based only on the specifications you gave for the SSR, do you see a problem connecting the output connections to a DC circuit? Read, again what the output rating is! 24-480 VAC, that means AC, alternating current, your mains house AC supply, not a 24 volt DC supply.

1 Like

Short across the ssr output leads and see if bulb lights. if yes, SSR spec is wrong. If no, problem is with power to bulb, bulb, or associated wiring.
...
Just read SSR output spec printed on relay. As has been said, an AC OUTPUT SSR won't control DC. Your SSR is for AC ONLY.

2 Likes

Ah-ha! That would definitely explain my problems. I won't be making that mistake again. Thank you!!

If you buy a new relay, it only needs to be rated at 24VDC and 10A

1 Like

Ok, thanks for letting me know!

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