SKU: COM-13015 Solid State Relay

Looking at SKU: COM-13015 Solid State Relay for a project and I’m confused about what the data sheet says,

As I understand SSRs there are two types, Zero Cross and the oddly named Random Phase.

Zero Cross turns on at the next zero crossing after the ‘coil’ input is made active, stays on while input is active and turns off at the next zero after the input goes inactive. Output is 1 or more complete 1/2 cycles.

Random Fire turns on immediately the input is active and is capable of outputting fractional 1/2 cycles.

The data sheet for your SSR describes two modes of operation, “Zero Cross Trigger Method” and “Variable Resistance Control Method”. A pair of waveform diagrams show the input/output relationship. First diagram shows zero crossing mode as described, second diagram shows phase angle control and suggests a 500k variable resistor is required but gives no circuit.

How is a zero cross relay capable of phase angle control?


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I thought they were 2 different relays. Be aware when using these devices that if you are switching an AC load of very little current it may not switch off. There is a “snubber” circuit of a capacitor and resistor across the “contacts” which will leak enough to keep very light loads activated.
Cheers Bob

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Hey everyone,

Welcome to the forum Ken! :partying_face:

For those following along at home, we’re talking about page 2 of this datasheet on the SSR Ken was talking about earlier (I’ve also linked it below)

Excellent question, as Bob said, they are two different relay models in the same datasheet, but as far as I’m aware they both have a Zero Crossing Control circuit built-in. The English in the datasheet is a little hard to interpret, but it’s interesting that the Zero Cross Method is referred to as a Trigger Method while Variable Resistance Method is referred to as a control method rather than also being a Trigger Method or vice versa? This leads me to think that this relay can only perform Zero Crossing Control, as there doesn’t appear to be anything in the schematics, nor listed anywhere else about the relay that states that it can perform phase angle control. I hope that answers your question, although I’d be glad to be proven wrong if anyone has used one of these relays before :smile:


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The V series is resistor-controlled for variable phase. It’s not clear if this is what is meant by ‘random’.


Yes, The V series data sheet specifically mentions phase angle control (which is random. as I said oddly named), the D series says zero cross.

Looks like my confusion is due to showing both control methods on both data sheets when only one of them applies.

The SKU: COM-13015 Solid State Relay is a Zero Cross relay.The Variable Resistance Control Method on the data sheet is irrelevant.

I think we’ve sorted that out, thanks to all,


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Hey everyone,

Thanks for the help on this one Robert and Bryce, if you run into any issues or had any other questions or queries Ken just jump straight back in on here.

Good luck with your projects!