Today I pulled an ssr from a versalaser air compressor and wanted to test if it was working.
l started just as you would with an electro mechanical relay, l stuck a 9v battery across it and nothing. Then l remembered it was an ssr so l wouldn’t hear anything and I put my meter across the load terminals in continuity mode and got nothing.
Hmmm a quick google reveals all solid state relays need a powered load as they use some of that power to operate and a multimeter doesn’t provide enough.
So hooking a desk fan to the load side of things with the live wire connected to the terminals and a 9v battery to switch the relay results in the fan turning on, result working ssr.