Control Panel for 3ph Heaters

[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.

 

[spark 68]

Spark what you say is exactly what I want.
What I did on the paper above is what I think your drawing is telling me to do.
My drawing will be replicated for the 2nd heater as per your post, except for emergency stop which kills all three (2 pumps and heater)
What I'm asking is what's wrong with how I've drawn it out?

All of the contactor/relay contacts on my drawing are normally open (N/O)

 

[jparker86]

All of the contactor/relay contacts on my drawing are normally open (N/O)

Hi Spark,
Yeah my contactors are all NO. I have removed the auxillary but Tony said in his previous post that the stat will kill the power to the controlling contactor. That is what has confused me.

 

[spark 68]

Hi Spark,
Yeah my contactors are all NO. I have removed the auxillary but Tony said in his previous post that the stat will kill the power to the controlling contactor. That is what has confused me.

Iam not sure if Tony was referring to your drawing (I suspect he was), as with mine the start/stop relay will remain closed (unless the stop or E-Stop is activated) regardless of the stat status.

On my drawing K1 is the control element to K2, K2 is the stat controlled switch which actully turns the heater on and off when the stat dictates.

 

[spark 68]

Does this help any ?

I have drawn the box around K1 contacts, and the coil for K1 is shown seperate, as is K2 coil, I have added the A1 and A2 labels too.

 

[jparker86]

Yes I think it does. I will give you my "amateur" drawing and see if it looks good.

 

[Richard Burns]

Sorry to jump in here, but I think Spark68 has the easiest solution with your control setup, I am not sure on your diagrams how you have set this up.
Each heater has a latching contactor control by momentary start stop buttons.
This controls another contactor, through the stat control to operate each heater.
The pump control is a straightforward single latching contactor.


I think that this diagram is a simple layout (from a simple person) of what Spark68 has said.

 

[jparker86]

Sorry to jump in here, but I think Spark68 has the easiest solution with your control setup, I am not sure on your diagrams how you have set this up.
Each heater has a latching contactor control by momentary start stop buttons.
This controls another contactor, through the stat control to operate each heater.
The pump control is a straightforward single latching contactor.


I think that this diagram is a simple layout (from a simple person) of what Spark68 has said.

View attachment 13991

Excellent- The only thing I do not have is a panel start and panel stop. Just an Isolator switch, then the e/stop finally start and stop buttons for each control.

 

[Darkwood]

View attachment heater circuit.pdf

Here try following this chopped down version as its in standard wiring format and youll need to learn to read them its a copy of Tony's plan with only 1 heater and no pump or E-stop just to allow you to follow it easier.
Ive explained how the marking system functions and hopefully will enlighten you to be able to follow them.

 

[Richard Burns]

Excellent- The only thing I do not have is a panel start and panel stop. Just an Isolator switch, then the e/stop finally start and stop buttons for each control.

That is immaterial, your panel start and stop switch are just combined in one isolator and are not momentary.

 

[jparker86]

View attachment 13992

Here try following this chopped down version as it in standard wiring format and youll need to learn to read them

Hi Darkwood,

Richard Burns has given me a broken down drawing with contactors and if possible I want to stick with them. I really do appreciate all your help. If any of you are interested in making these for me in future I am open to quotes. This has taken up already too much of my time and think in future ill leave it to the professionals.

 

[jparker86]

That is immaterial, your panel start and stop switch are just combined in one isolator and are not momentary.

So I do not need a panel start and stop?

 

[Richard Burns]

Your panel start / stop is the isolator.
I have modified the diagram to show a single switch (which is the isolator).
It would help you to be able to understand the proper wiring diagrams so do not discount Tony, darkwood and Spark68 contributions, these are the ones that will make the difference and be of most use in the future. Do try and read and understand them, even if only for future reference.

 

[Darkwood]

Ok JP but do have a gander and see if you start to follow what its all about, this will be the type of plan usually found with machinery and control boxes and if you expect to have future interests in that area its well worth learning the basics....

well done Rich' succeeded where many have failed arty: OP seems happy with it but he'll rarely come across such a layout in the real world....well maybe on the wiring bumf with a start stop contactor manufacturers connection plan and cheers JP for the challenge of doing a 1day wonder course on on the teachings of schematics

 

[jparker86]

Ok JP but do have a gander and see if you start to follow what its all about, this will be the type of plan usually found with machinery and control boxes and if you expect to have future interests in that area its well worth learning the basics....

well done Rich' succeeded where many have failed arty: OP seems happy with it but he'll rarely come across such a layout in the real world....well maybe on the wiring bumf with a start stop contactor manufacturers connection plan and cheers JP for the challenge of doing a 1day wonder course on on the teachings of schematics

lol Thanks Darkwood. The problem I have/had is just understanding these drawings, but again if anyone is interested in making these for me in future please inbox me.

 

[Darkwood]

I lack the time unfortunately you could ask tony as he dont do alot all day :lol:

next things to look at regarding your control is E-stop, and whether its required as you have only fitted it as a latching stop button and not wired it as a true e-stop circuit, for the basics of your water heater and pump im not too sure you'll actually need one, as mentioned before a risk assessment needs doing as to the level of possible injury and/or death by an operator and the resulting catagory will give the degree of protection needed.... as your system has been explained it dosn't sound like it warrants an E-stop option.

 

[Darkwood]

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.

 

[spark 68]

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

 

[jparker86]

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?

 

[Darkwood]

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'.

 

[Knobhead]

you could ask tony as he dont do alot all day :lol:

Cheeky sod!

JP a latching stop P/B does not meet the requirements of an emergency stop.

 

[Darkwood]

Heres a recent one i did just to express the slotted trunking suggestion and how neat a simple cheap addition actually looks.

 

[jparker86]

View attachment 14003 Heres a recent one i did just to express the slotted trunking suggestion and how neat a simple cheap addition actually looks.

Can you enlarge it?

 

[Darkwood]

Can you enlarge it?

im trying bare with me

 

[jparker86]

im trying bare with me

Darkwood thanks for bearing with me.
As I said I only need two poles so you think that contactor I posted earlier with 1,2,3,4 + A1 + A2 will be ok? It doesn't have any NO contacts though. But looking at this drawing it doesnt matter? Correct?

 

[Darkwood]

Trying 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.

 

[jparker86]

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.

 

[Darkwood]

: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 £10 worth of extra gear can achieve.

 

[jparker86]

: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 £10 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!)

 

[Darkwood]

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.

 

[Knobhead]

When I sell a pce of equipment I love to know how each and everything works.

Out of curiosity what do you normally sell?