How Do Heater Contactors and SSRs Control Heating Elements?

[ismat143]

1.If i apply voltage 440volts at L1,L2,L3 the K3 (contactor) will get on automatically?
2.How this SSR work and what should be the voltage at 4,5,6 and 7,8,9(X1 terminals)?

The main thing i want to ask is how this heating 1 and heating 2 gets ON and OFF and at what voltage?

Thank you.

 

[dlgoff]

Welcome to PF ismat. It looks like the heaters are being controlled by SSR (which is a silicon controlled rectifier, I think) and its ouput is controlled by pluses supplied to the + and - terminals. These pulses could be coming from a PID controller. And K3 appears to be contacts for a relay. Are there other parts of the circuit you are not showing?

The voltage at 4,5,6 is just your 440V line voltage. The voltage at 7.8.9 will be pulsed 440V.