9403 to control a relay (on/off heating)

[andrea11hr]

Hello,

I am building a temperature control system, I already have the PT100 measurement using the module 9205 (16bit analog input). For the controlling of the temperature:

I am using 300W heaters connected to 230V and the 9403 module , as well as SSR Crydom ED24D3R. I am trying to do this "phase fired controller" in Labview. But I do not know how to get it arranged so that the PWM starts together with the AC .

Am I right with this reasoning? I don´t have much experience in this.

Any other ideas how to control the temperature with the heater-relay set-up?

Thank you! 🙂

[Henrik_Volkers]

Getting in sync with the line phase migth get tricky, your SSR doesn't seem to have a zero crossing detector .

Depending on the termal mass I would start with a first and easy try: a pulse packet control, say a slow PWM 🙂  with 10s (or 2s)  periode and 10 power steps.

300W isn't that much load, so flicker shouldn't be a problem.

If your system allow to measure a step response ( from a cold system, turn on the heater and measure the temperature until a limit is reached )
 this would help to design a controller.

If you really need a line phase sync you can use a small transformer and one analog in , or just a optocoupler (with some additional circuitry search the EDN design ideas for some hints) with a DI. 

Using an SSR with zero detector will help.