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PID wiring to an SCR voltage regulator?

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Mogwa4

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I'm currently using a digital SCR to control a 3 phase 5500w element in my brew kettle, what i would like to do away with the manual control and have a PID running the element, or better yet a switch where i can go from manual to (pid) temperature controlled.

I am trying to avoid investing in a ssr/heatsink etc as seems to be the standard set up.

Attached a pic of the SCR i am using, the 4 wire that lead to the digital display are labeled as (SCR) (GND) (ZERO) (5V+). My thought is to tap into these wires and attach to a switch leading to the original manual input and to the PID.

Does anyone have experience with doing this, how can this be accomplished?

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ajdelange

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It is certainly possible to do this. Typically the controller sends a 4 - 20 ma or 0 - 5 V signal to a device which fires the SCRs varying either their conduction angle or pulse frequency (for example 50% output would cause the SCR to conduct 50 out of 100 half cycles. Various 'controllers' also accept TTL level logic signals or a relay closure signal. Most of the 'controllers' discussed here are SSR's which take the TTL signal from the PID devices the guys use and conduct for part of the PID controller's output cycle which is in seconds (as opposed to half cycles of the A/C line). What you can do depends on what kinds of outputs the PID controller has available and what the thing in your picture actually is and what it does. What are the buttons for? What is connected to the four terminals? What does the display indicate?

It is certainly possible to have AUTO - OFF - ON control over a heater. In my system, as an example, 24 VAC is wired to the common contact of a three position switch. The ON contact is wired directly to coil of a steam valve and the AUTO contact is wired to the valve coil through an SSR fired by the logic level output of the PID controller.
 
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Mogwa4

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Thank you for the reply. The buttons are simple up and down buttons that set the display from 0 (being off) to 100 (full power) I liked this over a simple potentiometer knob for accuracy. Currently with my element i get a nice rolling boil at 24% stepping up to 25% and it is much too vigorous.

I've attached a few other pics of the unit, i currently do not have a PID as I am not certain what would work best on this unit, or if i should just look to eventually build a SSR style unit as most have.

I've attached a few more pictures if that helps, I could also get some of the unit i built.

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