Pid Newbie Stuff

[bignath]

cheers Kev,

another thing i don't understand though is earthing components.

Do i need to earth the box to anything?

If i just have that wiring all hooked up like that diagram (assuming it's electrically sound) inside a plastic enclosure with a heat sink on the outside, is everything gonna be ok?

cheers for everyones input on this thread so far, it's really helping me get my head around a whole heap of stuff.

BN

 

[woodwormm]

Hacked ya diagram


View attachment 58629


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

as far as i can tell a pid and an ssr are just like a car headlight switch and relay (albeit a very intelligent switch)

i'm struggling to see how any of these manually switching options allow Big Nath to manually override the element on and off? as far as i can tell all it allows is the element to be overridden when the pid has turned it on? what about when the pid thinks it should be off? am i completely out of the loop (bearing in mind i dont know pid's very well)

 

[bignath]

as far as i can tell a pid and an ssr are just like a car headlight switch and relay (albeit a very intelligent switch)

i'm struggling to see how any of these manually switching options allow Big Nath to manually override the element on and off? as far as i can tell all it allows is the element to be overridden when the pid has turned it on? what about when the pid thinks it should be off? am i completely out of the loop (bearing in mind i dont know pid's very well)

sorry mate, i think i may have led you up the path a bit. Probably shouldn't have said "independently".
I don't need the element to be able to be switched on when the pid has turned it off, just more the ability to turn it off when the pid has it turned on. Safety for boil dry and all that...

 

[labels]

Booargy has definitely come up with the best so far. Essentially very safe by switching both active and neutral.

Lets face it, anybody could have wired up something preceding your controller and you could be switching on neutral instead of active *thinking* you're switching on active. Especially if taking your you-beaut controller around a fellows brewers premise for a try-out. (the pid controller may not work in reverse polarity - I don't know)

Secondly, by switching out the SSR when the element is on by going direct to through the double pole relay is sensible IF you don't really trust Chinese cheap solid state relays (which should be earthed as previously mentioned)

Steve

 

[booargy]

Any exposed metal including the heatsink, pot, plumbing, etc has to be earthed. Make sure your earth connections are tight and strong. The earth loop does nothing but save your life.

The SSR can be manually switched off from the PID face by stopping the process. A relay bypasses or overrides the SSR allowing the element to get full power. to do the same with the SSR it needs a low voltage supplied to it from another source.

I am re-wireing my mash tun panel at the moment. the pump and RIMS element will be run through N/C alarm relay contacts. the relay is powered through the alarm relay on the PID. when the PID alarms the relay will energize cutting power to the pump and element and turning on a buzzer. A latching contact with keep the relay energized until reset.

 

[bignath]

Any exposed metal including the heatsink, pot, plumbing, etc has to be earthed. Make sure your earth connections are tight and strong. The earth loop does nothing but save your life.

The SSR can be manually switched off from the PID face by stopping the process. A relay bypasses or overrides the SSR allowing the element to get full power. to do the same with the SSR it needs a low voltage supplied to it from another source.

I am re-wireing my mash tun panel at the moment. the pump and RIMS element will be run through N/C alarm relay contacts. the relay is powered through the alarm relay on the PID. when the PID alarms the relay will energize cutting power to the pump and element and turning on a buzzer. A latching contact with keep the relay energized until reset.

I appreciate your help booargy, but i'm completely lost with your post mate. As i said in the OP, i need this stuff in layman's terms if possible as i don't understand the terminology.

with regard to the earthing...i don't understand where it all stops. In my head, i'm being told to earth the ssr to the heatsink, but they are made of metal aren't they? So what earth's the heatsink?
If i use a plastic (ABS) enclosure from Jaycar or similar, and hook it all up as per Kev's or my (mattyau's) original diagram, with no further connections added, is it electrically safe? I'm thinking of not worry about the switch, as i am using those cheap kettle elements for my mash, and i have retained the on/off switch assembly on the chassis of the element so i can turn it off right at the element if needed. That's what i do now atleast anyway..If i don't bother with the switch, can i just use one of those diagrams posted earlier?

As i said, i really appreciate your help, i just don't understand the terminology and reasoning why things have to go a certain way, but i am comfortable with following an approved wiring diagram.

 

[labels]

Any exposed metal including the heatsink, pot, plumbing, etc has to be earthed. Make sure your earth connections are tight and strong. The earth loop does nothing but save your life.

The SSR can be manually switched off from the PID face by stopping the process. A relay bypasses or overrides the SSR allowing the element to get full power. to do the same with the SSR it needs a low voltage supplied to it from another source.

I am re-wireing my mash tun panel at the moment. the pump and RIMS element will be run through N/C alarm relay contacts. the relay is powered through the alarm relay on the PID. when the PID alarms the relay will energize cutting power to the pump and element and turning on a buzzer. A latching contact with keep the relay energized until reset.

Makes a lot a sense to me, love it.

 

[m3taL]

Would the Intergration of a RCD plug on the Lead that go's to your powerpoint be a good idea?? Bout $30ish and would give you that bit more Piece of mind, I'd also be inclined to install some kind of load breaker on the line too incase the element was to fail and short.....

Im Not a Sparky but i build switchboards Im an Electrical fitter so i know all too well what kind of protection protocols are put in place to save lives...... power usually doesn't ask.... just kills....

 

[booargy]

Electricity likes to go to the ground and it will take the easiest path. So what the earth loop/circuit does is provide an easier or lower resistance path than a human.
So all the exposed metal parts should be connected to the Green cable on the supply lead. A plastic box has no need to be earthed but it is important that the heat sink is.

mattyau's diagram is spot on and will work. once you work out how to use the PID mods can be done later.

 

[bignath]

Electricity likes to go to the ground and it will take the easiest path. So what the earth loop/circuit does is provide an easier or lower resistance path than a human.
So all the exposed metal parts should be connected to the Green cable on the supply lead. A plastic box has no need to be earthed but it is important that the heat sink is.

mattyau's diagram is spot on and will work. once you work out how to use the PID mods can be done later.

Ok, thanks mate, so does that mean i should go off Kev's modification of my diagram as it shows the earth connection to the heatsink via the ssr?

Also, just with ssr and heatsink connection....Does the heatsink screw to the control box's chassis, and the two screw holes between the pairs of connectors on the ssr, screw into the back of the heatsink?

 

[beerdrinkingbob]

If somebody wouldn't mind, what does a heat sink look like and how is it attached to the SSR, can't relly get a mental pic going..

Cheers

BDB

 

[mxd]

If somebody wouldn't mind, what does a heat sink look like and how is it attached to the SSR, can't relly get a mental pic going..

Cheers

BDB

http://www.sourcingmap.com/ssr25da-25a-sin...k-p-177678.html

 

[Cocko]

If somebody wouldn't mind, what does a heat sink look like and how is it attached to the SSR, can't relly get a mental pic going..

Cheers

BDB

Here mate

You can see in the pic the heat sink mounted to the SSR - You use a thermal paste between them... Then you can see the 4 screws in the corner of the heatsink, thats how you mount it to your project box or whatever...

Cheers

 

[booargy]

This is my old box it was running 5.4kw of elements
You can see the green earth attached to the heat sink with a self tapper. The easy way is with an eye lug under the fixing screw like kev said.
The 2 small black wires on the SSR are the low voltage from the PID
The orange wire is the element power circuit. The SSR will not cut power completely so I like to use a mechanical relay but is not needed.

 

[bignath]

Does the heatsink screw to the control box's chassis, and the two screw holes between the pairs of connectors on the ssr, screw into the back of the heatsink?

FAIL.

You use a thermal paste between them... Then you can see the 4 screws in the corner of the heatsink, thats how you mount it to your project box or whatever...

AH HA!

View attachment 58633
This is my old box it was running 5.4kw of elements
You can see the green earth attached to the heat sink with a self tapper. The easy way is with an eye lug under the fixing screw like kev said.
The 2 small black wires on the SSR are the low voltage from the PID
The orange wire is the element power circuit. The SSR will not cut power completely so I like to use a mechanical relay but is not needed.

Gotcha, thanks booargy. Your pic makes sense to me.

 

[bignath]

OK, i'm getting ready to order my parts i need for this PID control box build.

Here are the things i want to be able to do...

PID to run and control a 2000-2400W element in the mash. This element will be plumbed in similar to QldKev's u-bend type element.

I want two independant mains feeds going into the box, one to control the pid side of things, and one that basically just goes in and then out again with a switch on it that i can run a second element that will NOT be controlled by the PID.
Also on this second mains power input, i would like to be able to run my little brown pump.

I would like switches for all three items; Mash element, Pump, and second element used for the boil.
I would like these switches to illuminate when on too.


Here is a diagram i've drawn up in paint, based on my earlier diagram, but also adding in the SSR earth, second 240V circuit, and switches.

I am not sure if what i've done is possible. I think it is, but not 100% sure yet.

I think it's advisable to earth the SSR yes?
What about switching the 240V before the element? Is that safe to do?
How about using the terminal blocks to split the 240v to the second/third 240v output sockets? Same blocks we use when we all wire up our stc's....is that safe to do?

Can someone take a look and offer feedback?

Cheers,

Nath

 

[QldKev]

Sorry I though this thread had been quite, I've only just got an update from AHB.

Looks good so far.

100% definitely put an earth on the SSR/heat sink. If that thing leaks voltage you want it to use that earth path and not you.

If you also use a metal enclosure put an earth lead onto it.

Only addition I would consider is a SSR with resistance input for your second line (ie non PID). Something like this. (may not be best price, just first one I saw) Then you wire in a pot to control the output voltage. You **may** find without the element the boil is too soft, but with it it is too full on. This will allow you to adjust the heat output of the second element to get a great boil.

Terminal blocks are ok for the jump to your brown pump supply. I would also consider just jumping it from where they screw into the outlet.
Have you considered circuit breakers, just if your splitting 1 x 10amp supply into 2 x 10amp outlets, it may be easy to forget and plug elements into the both of the outlets.

You could also consider putting the 12vdc power pack within the enclosure and have a nice easy plug for the 12 supply. (don't use a 240vac style plug), then you cannot accidentally plug 2 elements into the one feed.


Your electrician can advise on my ideas above. <_<

QldKev

 

[bignath]

Sorry I though this thread had been quite, I've only just got an update from AHB.

Looks good so far.

100% definitely put an earth on the SSR/heat sink. If that thing leaks voltage you want it to use that earth path and not you.

If you also use a metal enclosure put an earth lead onto it.

Only addition I would consider is a SSR with resistance input for your second line (ie non PID). Something like this. (may not be best price, just first one I saw) Then you wire in a pot to control the output voltage. You **may** find without the element the boil is too soft, but with it it is too full on. This will allow you to adjust the heat output of the second element to get a great boil.

Terminal blocks are ok for the jump to your brown pump supply. I would also consider just jumping it from where they screw into the outlet.
Have you considered circuit breakers, just if your splitting 1 x 10amp supply into 2 x 10amp outlets, it may be easy to forget and plug elements into the both of the outlets.

You could also consider putting the 12vdc power pack within the enclosure and have a nice easy plug for the 12 supply. (don't use a 240vac style plug), then you cannot accidentally plug 2 elements into the one feed.


Your electrician can advise on my ideas above. <_<

QldKev

Thanks Kev...again! appreciate your thoughts mate.

So re: metal enclosure and earthing that...

If i put a nut and bolt through the enclosure chassis close to the SSR, and earthed the main supply on the top circuit to that, then ran a wire from that to the SSR, is that the idea? So i'd have an earth point on the enclosure with two wires on it. One is the main supply in earth, and a jumper from the same point to the SSR?

 

[booargy]

Looks good.
the earth will be common to both the circuits. But less joins is better.
Also it would be a good idea to have someone check it with an insulation resistance tester.

 

[bignath]

Actually just another question i have.....

if it's best to earth the enclosure too (if it's a metal one), i was gonna mount this control box via a metal arm bolted/screwed to my stainless brew table.

Is there anything i need to do after that regarding earths?

ie: Earth SSR to heatsink, Earth all that to the actual enclosure.....is that done and dusted if i do that? My table has rubber/plastic castor wheels....if that makes any difference.

Obviously i don't know much about earthing circuits, i just don't want to end up making my brew table "live"...

Cheers in advance,

N