What would put on your control panel?

[Rossey]

I have a few questions about building a control panel.

So far I have put in a PID and ssr that is mounted on a heat sink that will have a fan on it.

Does the PID need to have a permanent supply so it doesn't lose its settings

I was thinking of adding a 12volt supply so I can have illuminated switches and relayed outputs.
The fan could also be 12v then.

Where can I put the end of the thermocouple, I was think the thermostat tube on the immersion but as its facing up I don't want it to fall out.

[Julian]

If it's a decent quality SSR it will need no more than mounting on a metal cabinet.  If you clean the paint off so you get metal to metal contact with a bit of that white heat transferring gloop, the heat sink effect will be more than enough.

I currently use a very old, ICI "built in house" temperature controller and that has the same arrangement.

Not to my knowledge, every PID I've seen powers down and back up without problem.

You don't have to have a 12v supply, especially if you don't have a fan.  It's possible to get indicator lamps running on mains voltage, but obviously safer using low.  The most commonly used control voltage appears to be 24v DC I believe.

I use a copper water cylinder and have my control thermocouple exactly where you describe.  Can't remember what I did to stop it falling out but what ever it was, it hasn't fallen out in 5 years.  Perhaps a blob of silicone if you're really concerned.

[julesandtash]

Here is a little something I put together....

Front view


Inside view


Rear of front panel


All the indicators, and the timers are 24V DC
The PIDs are 240VAC. They dont need a permanent supply to keep their settings as they are stored in non-volatile memory.

I have SSR for the electric heaters which are bolted to the sides of the case (internally) with the paint scraped away and PC heatsink grease as Julian mentioned above.

All the logic and interlocks is done by the four pole double throw relays at the top driving the contactors in the middle. As such, even if an SSR locks on for some reason, the overheat alarm signal from the PID controllers will cut power to the contactor coil and therefore isolate the heater(s)

The panel is still a work in progess with more stuff to add for a couple of extra bits and bobs but works well as it is.

[Rossey]

Didnt think of silicone

I want to use 12v as there's some nice looking switches on eBay


I thought I needed a heat sink so I grabbed a small one out the scrap bin



Think its a bit ott 

[BANDIT2]

I've got lights too for whatever circuit is in use, a pid and a master 'kill' switch which I 'lockoff' when not processing.

[Rossey]

Here is a little something I put together....

Front view


Inside view


Rear of front panel


All the indicators, and the timers are 24V DC
The PIDs are 240VAC. They dont need a permanent supply to keep their settings as they are stored in non-volatile memory.

I have SSR for the electric heaters which are bolted to the sides of the case (internally) with the paint scraped away and PC heatsink grease as Julian mentioned above.

All the logic and interlocks is done by the four pole double throw relays at the top driving the contactors in the middle. As such, even if an SSR locks on for some reason, the overheat alarm signal from the PID controllers will cut power to the contactor coil and therefore isolate the heater(s)

The panel is still a work in progess with more stuff to add for a couple of extra bits and bobs but works well as it is.

That's impressive
Think I'm going to have three switches and a pid lol

I did see an alarm output on the pid, what can I run off it?

I was thinking of a flashing light or strobe so I can see it from the house.

[julesandtash]

The PID alarm contacts are not an output as such, just relay contacts which close when the alarm set point is reached (or exceeded) and open again when the temperature falls below the alarm temperature

As such, they can be used to switch whatever you want. Their contact rating is quite low though so best to use them to control a larger relay then use that to switch your strobe/klaxon or whatever.
If you use a simple latching circuit (easily achieved with a Double Throw relay then, once it has been activated by the PID alarm, it will stay activated until cleared manually, even if the temperature falls below the alarm point again.

On my PIDs, the alarm temperature setting is not an absolute temperature, rather it is a number of degrees above the set value.
Ie, if I want the set value to be 65C and the alarm to go off at 70C, I have to enter +5 as the alarm figure as opposed to 70. That took me a while to decipher from the translated chinese instructions. Thankfully I tested it by putting the thermocouples in boiling water and wondered why the alarm wasn't activated.
By putting +70 in, I was basically setting the alarm to be 135C !!

[Tony]

Wow Jules

Trying... not... to... be... envious!

[Jamesrl]

I'll bet Sizewell B Nuclear plant ain't got that much wiring.

Being VERY envious, at least I can't put a plug on the end of a lead were as Jules seems to have a problem with that.

[Rotary-Motion]

jules that is sweet!

very nice...

 

[Julian]

Didnt think of silicone

I want to use 12v as there's some nice looking switches on eBay


I thought I needed a heat sink so I grabbed a small one out the scrap bin



Think its a bit ott 

It is a little OTT, but you could cut it down to a little bit bigger than the SSR, cut a hole in the cabinet the same size as the SSR, bolt the heat over the hole and fix the SSR to the heat sink.  Personally I wouldn't bother.

Jules, still on my mission to tidy my garage and I keep coming across items I'd squirreled away for my panel.  I was just on the cusp of planning it out when I saw your effort again, reminding me of what we all have to compete with.  Might just pack all the parts away again!

[Head Womble]

If you can't step up to Jules's standard, don't post photos of it and we'll never know.

An electrition looked inside my control pannel, once he figured out what went where it was decleared safe,
but not up to "standard",
it will soom be replaced by a bigger one that houses everything as at pressent I'm using two boxes.

[Julian]

Mark ...I really don't think you ought to be planning so far ahead.  Just put your affairs in order and await the inevitable.

Rossey ... It might seem a little extra work but consider using something like this ...



It takes a little time to get your head round programming one, but there are so many things you can do with it, timers, clocks, counters, interlocks ... almost endless.

I bought one for the processor years ago and used it on the central heating and it's worked faultlessly for several years and I've recently bought another two to run the bio plant.  But you do need a lead to make the programming easer.

Best bit about it is Jules hasn't got one in his panel!
I bought one for the processor years ago and used it on the central heating and it's worked faultlessly for several years and I've recently bought another two to run the bio plant.  BUt you do need a lead to make the programming easer.

Best bit about it is Jules hasn't got one in his panel!

[Rotary-Motion]

am i seeing double? lol

[Rossey]

It is a little OTT, but you could cut it down to a little bit bigger than the SSR, cut a hole in the cabinet the same size as the SSR, bolt the heat over the hole and fix the SSR to the heat sink.  Personally I wouldn't bother.

Jules, still on my mission to tidy my garage and I keep coming across items I'd squirreled away for my panel.  I was just on the cusp of planning it out when I saw your effort again, reminding me of what we all have to compete with.  Might just pack all the parts away again!
[/quote]


The heat sink is mounted over the 4" fan hole that was already in the box, and I have fans at work anyway.