Can I detect when my HRS-2 Series Solid State Relay is energized?

Question

I am using a HRS-2 Series solid state relay. I am trying to determine whether I can use a simple continuity logger to determine when this relay is activated. I've attached the circuit from the data sheet below.

The idea is that I'd attach continuity leads between the trigger leads 1 and 2. The input circuit would already be wired up so that when power is applied to the input circuit I would hope it would be able to see that power was applied with my data logger on the trigger circuit 3 and 4. In practice however I'm not seeing any continuity between terminals 1 and 2 when the relays are turned on. These are dry contacts as of right now with no voltage going across 1-2.

Answer 1

This looks like an AC switching SSR which triggers on the zero crossing of the loads AC voltage supply. So if you only apply a continuity tester (DC) it won't start conducting.

Answer 2

The idea is that i'd attach continuity leads between the trigger leads 1 and 2.

The "trigger" is on terminals 3 and 4. The load is connected to 1 and 2.

The input circuit would already be wired up so that when power is applied to the input circuit i would hope it would be able to see that power was applied with my data logger on the trigger circuit 3 and 4.

You supplied no information on the data logger but we'll assume it applies a low voltage DC to the device under test.

In practice however I'm not seeing any continuity between terminals 1 and 2 when the relays are turned on. These are dry contacts as of right now with no voltage going across 1-2.

You have a few problems:

1. It's an AC SSR. It won't switch steady DC.
2. It will only switch on shortly after a zero-cross is detected.
3. If you do get it to turn on you need 150 mA to hold it on.

Figure 1. From brochure.

^{simulate this circuit – Schematic created using CircuitLab}

Figure 2. Full-wave, unsmoothed DC test rig.

The SSR should switch with this test circuit - perhaps at 12 V AC. You will need to ensure that your logger can handle the peak voltage or add an attenuator or voltage clamp.

See my answer to SSR not switching dimmed load for an explanation of how zero-cross detection works internally.