Pid Newbie Stuff

[labels]

Simple explanation

It's a low voltage switch that switches a high voltage switch

(in this case, please don't get into currents)

 

[Mattyau]

Would the wiring look like this.

 

[squirt in the turns]

Assuming i have that right, how much better are the rtd pt100 probes, compared to the "k" type?

K type thermocouples are supposedly accurate to 1 degree, at best. I compared the ones I got with the Sestos PID kit to the RTD probes I got from Auber, and the RTDs were a lot more responsive and accurate.

Mattyau's diagram is correct (although the colour conventions for DC and 240 VAC are arse-about). As others have explained, the SSR is a switch that's triggered by the PID. The principle is basically the same as the STC-1000 but the 240 V switching component is external instead of built in.

It's not rocket science, but at the same time a stuff-up could kill you. Get a multi-meter to check all of your wiring before you connect it to the mains, and make sure everything that needs to be earthed is, and has continuity to the earth pin on the plug that powers the whole thing. If you aren't already using one, get an RCD type circuit breaker. Most fuse boxes will already have them, but I use one on the GPOs I use for brewing too.

 

[bignath]

OK, so how's this look??



Drawn up in "paint", and i'm not sure what colours to indicate for the control power feed to the ssr, but I THINK everything looks good otherwise.

Comments please??

Also, if this diagram is correct, (based on Mattyau's pic - cheers mate), and i wanted to put a switch in it to manually overide the element so i can turn it on or off independant of the pid/ssr....where and how would that all hook up?

Cheers in advance,

BN

 

[goid]

OK, so how's this look??

View attachment 58625

Drawn up in "paint", and i'm not sure what colours to indicate for the control power feed to the ssr, but I THINK everything looks good otherwise.

Comments please??

Also, if this diagram is correct, (based on Mattyau's pic - cheers mate), and i wanted to put a switch in it to manually overide the element so i can turn it on or off independant of the pid/ssr....where and how would that all hook up?

Cheers in advance,

BN

The diagram looks correct. If you want to put your switch in, place it after SSR between it and the outlet to element. I would put the switch on the active (+) and neutral (-).

Goid

 

[bignath]

The diagram looks correct. If you want to put your switch in, place it after SSR between it and the outlet to element. I would put the switch on the active (+) and neutral (-).

Goid

thanks mate, this stuff seems to be starting make some sense to me.

re switch...

literally would the switch have one pole connected to positive and the other pole to negative?

i was VAGUELY thinking about it being inline on the positive side only?

 

[booargy]

In my opinion it is best to use a double throw relay. the SSR side gets wired to the normally closed and power to the normally open. the element is wired to the common. When the relay is energized it disconnects the SSR and provides power straight to the element.
This way you are not switching a high current directly. You may notice when an element is plugged directly into power point it sparks when turned off that is not what you want.
Will see if I can find a photo to explain it better.

 

[bignath]

In my opinion it is best to use a double throw relay. the SSR side gets wired to the normally closed and power to the normally open. the element is wired to the common. When the relay is energized it disconnects the SSR and provides power straight to the element.
This way you are not switching a high current directly. You may notice when an element is plugged directly into power point it sparks when turned off that is not what you want.
Will see if I can find a photo to explain it better.

Is there any reason why it's not possible to put a switch in the control power feeds between the pid and ssr?
That way you'd be switching a low current wouldn't you?

 

[goid]

literally would the switch have one pole connected to positive and the other pole to negative? No

You are right in your thinking that it is inline with the active. So it will switch the active line. But I would get a switch that will switch both. A switch that allows 2 inputs and 2 outputs.

 

[bignath]

literally would the switch have one pole connected to positive and the other pole to negative? No

You are right in your thinking that it is inline with the active. So it will switch the active line. But I would get a switch that will switch both. A switch that allows 2 inputs and 2 outputs.

Is that a double pole double throw (DPDT) switch you're talking about?

 

[Mattyau]

lIs that a double pole double throw (DPDT) switch you're talking about?

Id say it would be easyer to use a dpst (double pole single throw switch)

 

[Adam Howard]

Is there any reason why it's not possible to put a switch in the control power feeds between the pid and ssr?
That way you'd be switching a low current wouldn't you?

The wiring diagram you've drawn up Nath is exactly how I wired mine.

Might be hard to tell in that pic but you should be able to follow the wiring...

Works perfectly. Fricken love it. Got a few more things to tidy up in my control box though for my HLT control and pump switching.

 

[MastersBrewery]

RE: SWITCH if it were me i would switch the low voltage between the PID and SSR

 

[m3taL]

So im building a Fridge thermostat controller at work for my brew fridge, Could anyone tell me if this Live BUSBAR will carry enough amps to power my fridge





Ok Ok a bit of a joke!!!! For those who want to know its a Main Switchboard for a large multistory building.... 1600A Incoming btw this is what i build on the daily.....

 

[goid]

RE: SWITCH if it were me i would switch the low voltage between the PID and SSR

The only issue with switching the low voltage is in the bad case of the SSR malfunctioning and becoming constantly on. Someone may be under the wrong impression that you have isolated the element from AC with the switch.

I know most people would isolate the AC to the whole unit but what if you weren't thinking and had a brain fart moment and thought the above. You could be in some hurt when playing around with the element.

 

[MastersBrewery]

The only issue with switching the low voltage is in the bad case of the SSR malfunctioning and becoming constantly on. Someone may be under the wrong impression that you have isolated the element from AC with the switch.

I know most people would isolate the AC to the whole unit but what if you weren't thinking and had a brain fart moment and thought the above. You could be in some hurt when playing around with the element.

thats what the E Stop switch is for, really supose it comes down to how you set up the control box.

 

[bignath]

thats what the E Stop switch is for, really supose it comes down to how you set up the control box.

Have seen some boxes with emergency stops on them...

where would they go then, pre pid on the mains in, inbetween pid and ssr..

 

[labels]

In my opinion it is best to use a double throw relay. the SSR side gets wired to the normally closed and power to the normally open. the element is wired to the common. When the relay is energized it disconnects the SSR and provides power straight to the element.
This way you are not switching a high current directly. You may notice when an element is plugged directly into power point it sparks when turned off that is not what you want.
Will see if I can find a photo to explain it better.

That just makes so much sense and I wouldn't have thought of it had you not posted it here

Steve

 

[Lakey]

Have seen some boxes with emergency stops on them...

where would they go then, pre pid on the mains in, inbetween pid and ssr..

Yeah I would put it pre pid to cut power to the whole box for an e-stop

 

[QldKev]

Hacked ya diagram





The SSR can be earthed for extra protection, especially since the heat sink often sticks out of the enclosure. You will notice on the SSR it has a screw hole in the middle between the terminals that has a metal base.

If you are going to switch the output to isolate the heating element, why not just switch the 12v line.

Disclaimer crap: I'm not an electrician, please get your electrician to verify this.


QldKev