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J

jparker86

Hello,
I am new to the forum and would be most grateful if anyone here could help me with a project I am working on.

I have a control panel which I have made that controls 2 x heaters and 1 x pump.

Both heaters are 6kW (three phase) and the pump is single phase.

It all works, and I have on/off push buttons to operate the heaters and pump all run via the emergency stop button.

Where I am stuck is that my three phase heaters have a built in thermostat, which switches the contactor from on to off when the heat exceeds x degrees. My problem is that with my current design, unless someone presses the start button again it wont switch back on!

Under my current design, the thermostat isn't installed I left this until last (I underestimated how easy it would be).

Currently, all that happens is the device will turn on and off.

What I want is for the thermostat to cut in and cut off the power to the heater when temperature gets too high.

In my head I am thinking the best idea would be to have a contactor which is controlled via the on/off buttons, and that powers another contactor that is controlled by the thermostat?... or am I missing something that could help me?

I below attach the wiring diagram for both the heater in question and the control circuit diagram.

Any help would be gratefuly rec'd.
[ElectriciansForums.net] Control Panel for 3ph Heaters

[ElectriciansForums.net] Control Panel for 3ph Heaters
 
My last note would be to avoid confusion and uncertanty you should fit a row of indicator lamps to signal what is on, anyone walking up to the panel wont be any wiser as to the operational state its in, using a N/O contact (aux if necessary) wire a control on lamp, heater 1, heater 2 and pump lamps as well as a initial power lamp....... i think you'll start to appreciate how a good background is needed before designing and building a panel on your own.
Personally i would have fitted a plc programmed it up lost a few relays added a flow sensor and temp read-out as well as a overtemp sensor all controlling the system in case of problems.... yes a little more advanced but giving it the PRO - touch.
Your system is functional but as it stands it is functionally confusing as to what it on and off at any given time and at a minimum id implicate indication lamps.
 
Another thing I would look at, is providing indicator status lamps for the various items, when you get it working.
You could use the spare contacts on the stop/start contactors (terminals 5&6 on Richards drawing).

As DW said it is debateable whether you actually need an E-Stop or more correctly EPO (Emergency Power Off).

Cross posted with DW above lol
 
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My last note would be to avoid confusion and uncertanty you should fit a row of indicator lamps to signal what is on, anyone walking up to the panel wont be any wiser as to the operational state its in, using a N/O contact (aux if necessary) wire a control on lamp, heater 1, heater 2 and pump lamps as well as a initial power lamp....... i think you'll start to appreciate how a good background is needed before designing and building a panel on your own.
Personally i would have fitted a plc programmed it up lost a few relays added a flow sensor and temp read-out as well as a overtemp sensor all controlling the system in case of problems.... yes a little more advanced but giving it the PRO - touch.
Your system is functional but as it stands it is functionally confusing as to what it on and off at any given time and at a minimum id implicate indication lamps.

Hello Darkwood,
Yep I already have the wheels in motion for this- it would have two indicator lamps. One to show the heater is active and another to show it is drawing heat.
Im just thinking on the drawing that has been done, can I use a 2 pole instead of the three shown?
 
If a third pole isn't required then you can fit the 2pole i think you shown earlier, the calling heat lamp can just be connected to the stat sw wire as the same with any other lamp just double up in the circuit where it requires a signal, although when you advance you will design the lamp indication etc through there own aux contacts but no harm in doubling up on your learning curve. Also for future ref.... control voltages are usually reduced to both heighten safety and allow to export control circuits and sensing outside the panel itself in a safe manor...24v dc is common but can vary in the industry.... last note would be to run slotted trunking to neaten your control system it may mean a larger box but looks more pro'.
 
[ElectriciansForums.net] Control Panel for 3ph HeatersTrying to see if can get it larger.

Contactors are generally N/O ..this is the de-energised state the one you have i assume has 2 N/O poles that close when coil is energised, re' this pick it would normally not be as tight and compact but has some space restrictions as it was a sample and will have all its internals removed and fitted into a main cab of a larger control system, also due to this just been a temp' set up ive left out a cooling fan and filter just in case any keen eyes try pulling me on it.
 
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Wow that looks ace Darkwood. This is what I will hopefully one day achieve lol.
So what I will do now is go home and try and figure out what you guys have done and report this evening with another drawing.
 
:blush5:...... believe it or not this is a simpler set up than yours, dont get overwelmed by the drives but it was rushed and i was restricted with spec's on the cab' size so got a little more crowded than i like, only difference here to yours is the trunking and the numbering of all cables but you can see what a ÂŁ10 worth of extra gear can achieve.
 
:blush5:...... believe it or not this is a simpler set up than yours, dont get overwelmed by the drives but it was rushed and i was restricted with spec's on the cab' size so got a little more crowded than i like, only difference here to yours is the trunking and the numbering of all cables but you can see what a ÂŁ10 worth of extra gear can achieve.


You see as much as I would love to pay someone to do the job first time around, I love to know how things work.
When I sell a pce of equipment I love to know how each and everything works. Before I come on this forum I wasn't that clued up on how a contactor worked, etc... and to be honest I am probably still a bit lost but at least now if anything goes wrong or the customer asks me a question I can give him an answer based on my experiences and that in my business is priceless. I hate nothing more than speaking with someone about something and he says "Ill have to ask my boss...".
I have drew the control circuit out on paper and see what you think. Please let me know if I have got all the wires going to the correct place. (please ignore the writing diagram which doesnt have anything going to A1!)

[ElectriciansForums.net] Control Panel for 3ph Heaters
 

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it would function but it is poor design, consider a latching stop button or holding stop in, at the same time push start this will pull the contactor in, your stop button should be before the start in series and take your latching relay source from the outgoing off the stop button, this way it breaks both power to the start button and power to the latch loop.
Put your stop before your start in series then take your supply to terminal marked 2 from the out going of the stop or input of the start (same thing)

If you follow that ....now if you hold stop in and press start it wont pull the contactor in.
 
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