If I have a zero-crossing SSR switching 240VAC (e.g. this LS240D12), will the zero-crossing detection function if the load side is shorted?
I know that zero-crossing SSR's can't be used with DC loads because the load never crosses zero. What I'm wondering is if with an AC load the SSR only cares that the voltage is zero, or if it actually needs the voltage to cross zero.
E.g. in the following schematic:
If the switch is already closed and the SSR receives an activation signal on the control side will it actually activate, or will it only activate once the switch is opened?
I'm asking because I'm hoping to use a combination of SSR and mechanical relay in parallel (per advice received elsewhere). The idea is to prevent arcing in the mechanical relay, and to prevent heat buildup in the SSR.
To turn on: SSR activates at zero crossing, small delay, mechanical relay activates, small delay, SSR deactivates.
To turn off: SSR activates, small delay, mechanical relay deactivates, small delay, SSR deactivates at zero crossing.
My concern is that the "turn off" procedure described above may not in fact reduce arcing in the mechanical relay if the SSR fails to truly activate without alternating voltage on its outputs.