raffles
Member
So a contactor for all 6 and a SCR on one heating element (after the contactor)?
Toggle the other 5 heat elements at different deviation stages and use the SCR to maintain?
Yep - one smaller SCR and 6 smaller contactors is going to be far more cost effective than one larger SCR and one Contactor
The output of your control loop will be 0-100% master signal /6 = 16.67% per stage. The first 16.67 % gets scaled to 0-100% PWM signal to modulate the SCR controlled heater. When the output of your loop passes 16.67% the second contactor pulls in and the PWM signal is back to 0% - 100% for the next section 16.67%-33.33% of the master if that makes sense.
What PLC are you using? I'll dig out some sample code and post it on here, I think its in RSLogix500