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Topic: PID, ground and fuse (Read 2398 times) previous topic - next topic

francescor

#15
Nov 27, 2016, 11:46 pm Last Edit: Nov 27, 2016, 11:58 pm by francescor
About the second unit to heat, I will ask in case how to connect the wires.

Thank you for your amazing help

How can I connect the heat mat to the power supply without taping wires together? Sorry for the dumb question.
No taping wires together, no bare wires laying about, no twisting connections together.


tinman13kup

The right way would be a mechanical connection that is protected from shorting. That can be accomplished a few different ways;
-solder the wires together and use heatshrink tubing to cover the exposed wire
-use automotive barrel or spade crimp connectors that have the plastic covers on them
-use a terminal strip and attach the wires to the lugs (similar to the connections on the rear of the controller)

There are many ways to accomplish the task. The solder/shrinktube is probably the best, but the terminal strip is the easiest to add/remove wires (another heatdisc??), and the crimp connectors are the easiest to continuously plug/unplug for disassembly to move or change components.

All of them mechanically hold the wires to a connection and isolate the bare wires from each other.  Twisted wires have nothing to prevent them from being pulled apart
Tom
It's not a hobby if you're not having fun doing it. Step back and breathe

francescor

Ok, clear. The last two look feasible.

Just for future application. How did you know that I need to connect the heater to a 12 V power supply? In the manual, the only 12 V I read is for another version of the PID to be connected with a SSR. How could I get to know this detail?

tinman13kup

Oh, forgot about the second unit.

Your heat disc is 1(.)25W.  The formula for it is P=IxE where P=power in watts, I= current in Amps, and E= Voltage in, well volts.  1.25W/12V= .104A, or 105mA. Your supply can give 1000mA, but it is wise to stay around 50% of max, so make that 500mA. 500mA/105mA= 4.7 units can be hooked up, and by rounding up to 5, you are only at 52.5%. No problem. That means you can actually hook up 5 of those same heaters if you wanted, giving you 5W of heat.

Every one of them would be hooked up the same way, with one wire going to the relay and the other going to the 12V supply wire. A terminal strip would come in handy for that. It might have exposed terminals, but the connections are all mechanical and isolated from each other. Touching them wouldn't be an issue because of the low voltage.
Tom
It's not a hobby if you're not having fun doing it. Step back and breathe

tinman13kup

Ok, clear. The last two look feasible.

Just for future application. How did you know that I need to connect the heater to a 12 V power supply? In the manual, the only 12 V I read is for another version of the PID to be connected with a SSR. How could I get to know this detail?
The controller unit you have is a relay unit. Relays are specified as to how much power they can handle, which is the 250V 3A listing in the datasheet and on the sticker on the side of the unit.  That being said, it doesn't supply power, it only turns it on/off (close/open) depending on the thermocouple reading and the temp set.

 Knowing you needed 12V for the heatdisc came from your initial post. You said it is a 12V 1W heater. You could wire the heater straight up to the 12V supply if you want, but it would never turn off.
Tom
It's not a hobby if you're not having fun doing it. Step back and breathe

tinman13kup

You also have 1 alarm on that unit too. It is also a SPDT NO relay, but only rated at 1A. You could use that to light a lightbulb, sound a buzzer, or even use it to turn on an additional couple discs.

As for the 12V for the SSR you are reading about, that is a solid state relay, that would be located in whatever equipment is being controlled. That wouldn't work well for what you are doing.
Tom
It's not a hobby if you're not having fun doing it. Step back and breathe

francescor

I have got the terminal stripper and connected the 12 V, 1.25 W silicon heater just to see how hot it gets.

I have also this mica heating pad, 80 W
http://uk.rs-online.com/web/p/mica-heating-pads/7904842/

In case I would instal this heater instead, which modification should I do? Shell I just plug the heater in to grounded (the pad has three connectors) power supply and the PID?

tinman13kup

I have also this mica heating pad, 80 W
http://uk.rs-online.com/web/p/mica-heating-pads/7904842/

In case I would instal this heater instead, which modification should I do? Shell I just plug the heater in to grounded (the pad has three connectors) power supply and the PID?
No. That is a 230VAC heater. The 2 braided wires are the 2 hot leads, but I am unfamiliar with the yellow/gr wire. It should be a ground wire and is probably attached to the outer plate. In the US, insulated ground wires are green, and often are bare conductors. You need to see what the are in Europe.

As for a power supply, you would need to put a plug end on it and plug it in the wall outlet. One wire would go to the heater, while the other would go to the control unit on terminal 1, and terminal 2 would be the other braided lead for the heater.

80W might make some unhappy ants. Since the heater will be either on or off (no middle ground), it will be too hot while it is on if the ants can come into contact with it. It also might cycle the PID regularly.

What medium are you trying to heat, and how large an area?
Tom
It's not a hobby if you're not having fun doing it. Step back and breathe

tinman13kup

If you decide to go with the 80W, keep this in mind. That is mains power. You do not want to have open connections, and you sure don't want them to come together and short. Solid mechanical connections and insulated.

  If you want, you can actually use the terminals on the rear of the PID to get the mains. Terminals 9/10 are the mains input, and you would take a short length of wire from terminal 9 and connect it to terminal 1.
The heater would have 1 braided wire to terminal 2, and the other to terminal 10. Doing that would be the easiest, and it means only having to put protection on the rear of the PID to protect the mains. Actually, it's protecting you from touching the mains. It can kill you. It can start fires. It can do good/bad things to cats.

I'm thinking you would be better off using 5 of the smaller heaters spread apart. You would get more even heating, or could leave an area unheated and see if the ants prefer it. If you place the thermocouple about the same distance from a heater as the heaters are placed apart, it will heat evenly. Place the thermocouple closer to a heater than they are apart, and you will start getting cool spots in between.
Tom
It's not a hobby if you're not having fun doing it. Step back and breathe

francescor

Hello tinman13kup,

they are 7 queen ants, they will be hosted in single test tube not in contact with the heater. I will place the test tubes at the bottom of the polystyrene box and the heater on the lid (do you think I can place the 80W heater in direct contact with the polystyrene lid?). The ants are in the fridge now +10 C to simulate winter season. To trig egg laying, I need to simulate spring and summer. Since I am in Germany, but the ants come from South Italy, I need to recreate their optimal temperature.
The medium that will be heated is air in the box. I can fill the empty space with other polystyrene, if that helps.

The yellow connector on the 80 W heater should be the "Protective Earth". I have found the color code for Europe. I guess the other two do not matter.

What do you think of adding a grounded plug to the 80W heater and then connecting a pig tail to the terminals 1 and 2? I could buy an extension power cord, cut it in half and connect everything with spade crimp connectors (male of the power cord with the heater). I just do not know where to connect the ground of the pig tail.

thank you

 

francescor

I have placed the 1.25 W Silicone Heater in my polystyrine box and left it for 180 min. The temperature on the termocouple was 25.6 degree. I need either to buy a more powerful heater, a smaller box, or attach several heaters.

tinman13kup

You can get a feel for what the 80W heater will do by going and grabbing an incandescent lightbulb in the 60W range. It gets hot and you will burn your fingers, but at several inches, nothing. You might end up cooking your queens.

 Over here, they sell fishing worms in little styrofoam boxes with a tight fitting lid. They might be a pint in volume. Something of that size should be easy enough to heat with your small discs. The smaller, the better. If yours is a bit too large, you can try making it smaller by putting tight fitting foam sheets in it. Seal the gaps with tape. The idea is to eliminate as much air and surface area to have to heat.

As for putting the big heater in contact with foam......I wouldn't.

As for your 80W  heater ground, The best is to get a grounded cord and attach to the pid (9/10/gnd screw), and then attach the heater as I described before, using a jumper from 9 to 1, and connecting the heater wires to 2, 10, and the yellow to the gnd screw on the case of the pid. All your wires will be tidy, and you only have 1 plug. It has to be a grounded plug though (attached to pid gnd)
Tom
It's not a hobby if you're not having fun doing it. Step back and breathe

francescor

For this project, I will try a smaller box firts, if not enought I will buy a 5 W - 12 V silicone heater. Thank you, without your help I would not be able to proceed.

In case I will need the 80W for a future project. I did not understand how to safely attach the ground to the PID. There is not any ground screw.


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