Anyone used a thyristor controller with a PID? thoughts

[AnthonyUK]

And I have to say that they do not switch the power very quickly at variable frequencies to control power.

I should have clarified that that was regarding the PWM controller mentioned but SCRs (thyristor) work similarly in that they adjust the waveform and subsequently the power factor.
A simple PID should be able to achieve what is required though without making it overcomplex and as you mentioned, you'd only need a heat sink on the SSR.

[Fil]

a lot of this thread is over my head and could keep me busy googling for a month or more to catch up.

Ive tried to use a pid to control power, my model allowed me to set 50% 75% and 100% fairly easily with the aid of 2 x manuals.. but i found it much easier to simply get a resistance controlled ssr a 0-500 (k?) ohm potentiometer (pot or variable resistor / ebay electric guitar volume control + knob) the ssr will be clearly marked for the control resistance..

adding a cheap ebay volt/amp meter provided an easy to read and monitor indicator of the power output too, an easy intuitive control that needs no controller reference checking plug n boil vigorously/simmer or anywhere in-between ..

[themadhippy]

ebay electric guitar volume control + knob

most volume controls are log taper,in this application your after a linear taper

[Fil]

ebay electric guitar volume control + knob

most volume controls are log taper,in this application your after a linear taper

Cheers for qualifying that, the few ebay ads ive seen for guitar knobs (maybe not volume knobs??) generally have a few combo box options one being type linear or logarithmic i have assumed its the linear type needed. I was lucky in finding an ebay seller of kits that included the ssr, heatsink, pot, knob, and most valuable a sticky back dial 0-100% in steps of 10 that matches the rotation limits of the pot.. i have searched since but the seller isnt on ebay anymore unfortunately..

[alix101]

Haven't filtered all the bumff in the post, but are you looking for a simple manual control of your elements?
I achieved this on my set up using a pot and a PSR from United automotive....works a treat on my 4 kw elements, responsive not over complicated and durable.

[VANDEEN]

Taking a cue from Graham's suggestion to series the elements & reduce W per inch I considered adding a 4P 2NO 2NC AC1 suitably rated contactor to the circuit to give me that feature but initially went with a simpler idea, my series adapter....



Heats and boils fine with the 2 x 2.4Kw elements in series but no big mega heated bubbles like you get when using just one, cheers Graham

Rest of the build progress is over on my VANDEENS BREWMISER build thread here

viewtopic.php?f=6&t=75085#p782648

[Wonkydonkey]

I've had a PWM after the PID but it was a bit pointless. It wasn't easy to take manual control of the PID output so I used it to control the boil.

If you can control the PID output I can't see any reason why you would want the thyristor additionally unless it's a zero crossover type it might cause voltage spiking and damage the PID.

I'm still using the PID but I changed the wireing so that I can switch over to the PWM during the boil.


Atb aamcle

That's what I have done, pid to control temps, then once boiling for 15mins switch over and use the dial to easily control the boil.
But I'm not sure if I have enough cooling on the PWM as it has got stuck once or twice, I could see it got stuck on or off (it's done both) as I have an amp meter in line. Which is great cos you can see the power being used.