I have recently completed my osPID project and was testing it out on my kiln. The controller works as expected, so it is not in question. I noticed that when the kiln is wired to the ssr, even though the PID output is 100%, it does not reach desired temperatures as fast as it does when it is wired directly to mains. Is it typical for an SSR to have high internal resistance?
Specs: Kiln runs on 240V mains. Each leg of 120V is connected to neutral. I have two SSRs for each leg connected to my PID controller (based on osPID). SSR1 - RS3-1D40-21 SSR2 - Crouzet GN 84131120 SSRs are connected to aluminum head sink. Fan is blowing on heat sink/ssr.
When the kiln is wired directly to mains, it can reach over 800C in under an hour. When it is wired through the SSRs, it is only around 600C after an hour, even though the PID output is 100%.
Are the SSR the incorrect type? From what I can tell on the datasheets (http://www.cpu.com.tw/kh/m/ssr/gn-series2.pdf and http://www.nteinc.com/relay_web/pdf/RS3.pdf), they are both zero-cross type, which is what I think I should be using.
Please let me know of any other details I can provide if this is unclear.