Need 3 phase 480v SSR with aux contact ?

[I_Automation]

2. You can add in logic to make sure the SSR has not failed. For some reason that I don't understand, when an SSR/SCR fails it more often than not fails "closed". With the CT you can measure the current when command is 0, and if the current is not 0 (or close) then you know you have an issue

One good reason to not follow the 'standard' I have seen in machines from Germany and Russia to only use a single pole contactor or SSR for single phase heaters and motors.


I have even discovered [the hard way] only the lead going through the contactor fused, the other lead goes directly from the heater/motor to the service disconnect. That was on a cooling tunnel with a small collection of 240V axial 'computer' fans. With the circuit breaker off there was still 240V at each fan on the other lead. All the single phase heaters on the machine were wired the same way.