Testimony power regulation is superior to temperature regulation, and a summary of what has been presented in this thread:
gonzo
“I find a variac gives me the best temperature control and the most even heating, far above a PID which is above a dimmer. A guy from california is selling a good variac for 38$ shipped, I got his 46$ version (10amp).”
Five ways to precisely regulate power:
1 Variac alone (a 20 amp unit from eBay for about $75 is recommended)
2 Rotary encoder power regulator with solid state relay (Auber DSPR1)
3 Temperature controller with PID or ON/OFF or Limit function with an external heavy duty mechanical relay* to control the temperature when using either a Variac or rotary encoder power regulator (Auber SYL-1512A2 temperature controller)
4 Temperature controller with PID or ON/OFF or Limit function with it’s internal mechanical relay* used to interrupt the solid state relay signal from a rotary encoder power regulator (Auber SYL-1512A2 temperature controller and a Auber DSPR1 power regulator and a solid state relay)
5 Rotary encoder power regulator designed for distillation with solid state relay (Auber DSPR220 or DSPR400)
- How I assembled and set up of a temperature controller with mechanical relay,
https://www.icmag.com/ic/showpost.php?p=8050263&postcount=240
https://www.icmag.com/ic/showpost.php?p=8064606&postcount=241
https://www.icmag.com/ic/showpost.php?p=8067913&postcount=243
https://www.icmag.com/ic/showpost.php?p=8069624&postcount=244
https://www.icmag.com/ic/showpost.php?p=8073018&postcount=246
https://www.icmag.com/ic/showpost.php?p=8074191&postcount=247
https://www.icmag.com/ic/showpost.php?p=8075322&postcount=248
From the final link (setting the controller cycle time for the mechanical relay)
“I don’t think I posted the info for the SPST relay I’m using. It’s the same brand and rating as the little mini power relay Auberins carries without the superfluous normally closed contact.
The initial controller setup is straightforward and simple, and changing between PID, on/off, or limit, and adjusting set point is just as hassle free. One note (this from the controller manual,)
“Note 10. Cycle rate (ot): It is the time period (in seconds) that the controller uses to calculate its output. e. g. If ot=2, and the controller output is set to 10%, the heater will be on 0.2 second and off 1.8 seconds for every 2 seconds. Smaller ot value results in more precision control. For SSR output, ot is normally set at 2. For relay or contactor output, it should be set longer to prevent contacts from wearing out too soon. It normally set to 20~30 seconds.”
Instead of upping the cycling rate to 20-30 seconds to accommodate the mechanical relay, I went with the lowest suggested value I could find, 8 seconds, though I just found another reference stating 5 seconds. I’m not worried about wearing out the relay contacts, I just want to avoid pulsing them, so I may experiment with lower values to find out just what’s actually optimum for this situation.
Five seconds works fine, any lower and the clicking gets annoying.”
That’s all I know, sorry for the rambling presentation, but it should all be there if you go back and dig through the links.