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.

 

[jparker86]

The control relay will still drop out when the thermostat operates. The stop is in the wrong place and there's no need for the Aux on the contactor.

Yeah sorry I just realised that I wont need that Auxillary anymore because their will be a constant supply to A1.
Why will the control relay still drop out when the thermostat operates? How can i change it?

 

[jparker86]

How does this look

 

[Knobhead]

I give up!

Follow the last drawing I've given you. It will work with no problems.

 

[jparker86]

I give up!

Follow the last drawing I've given you. It will work with no problems.

Tony I don't mean to offend you but your drawing makes no sense to me. I'm here because I need help. Again something that seems relatively straight forward to you is in actual fact very difficult to me.

 

[Darkwood]

I think you are struggling because you cant interpret tony's wiring diagram because you dont understand what the R1/1 etc means ....
R1 relates to relay 1
R1/1 relates to relay 1 and the first pole/way so looking at the diagram when you press the start button R1 will close.... this will close R1/1(pole no1) and because its in parallel with the start button it holds R1 closed.
R1/2 is the second pole of R1 so when R1 closes R1/2 becomes energised supplying the next part of the control circuit.

Try reading the wiring plans now with this info..... my worry is you will need to supply a wiring schematic with your control panel yet you can't initially read them yet alone draft one up.

 

[jparker86]

I think you are struggling because you cant interpret tony's wiring diagram because you dont understand what the R1/1 etc means ....
R1 relates to relay 1
R1/1 relates to relay 1 and the first pole/way so looking at the diagram when you press the start button R1 will close.... this will close R1/1(pole no1) and because its in parallel with the start button it holds R1 closed.
R1/2 is the second pole of R1 so when R1 closes R1/2 becomes energised supplying the next part of the control circuit.

Try reading the wiring plans now with this info..... my worry is you will need to supply a wiring schematic with your control panel yet you can't initially read them yet alone draft one up.

Hi Darkwood, I am confused because Spark's drawing doesn't mention a relay. This one does? I have loads of contactors, but no relays in my stock and wanted to make it this week? So are we saying Sparks drawing will not work?

 

[Darkwood]

Tony has supplemented relays to do the control side as they are cheaper, less room etc, the contactors are just larger versions of relays for the heavier loads.... take the both as meaning the same if you have all contactors.

 

[jparker86]

Tony has supplemented relays to do the control side as they are cheaper, less room etc, the contactors are just larger versions of relays for the heavier loads.... take the both as meaning the same if you have all contactors.

Thanks,I apprechiate that but just want to work it with contactors.
8 don't want to confuse myself any more lol.

What wwould I need to do to get my current drawing work? I thought I did it just like spark said?

 

[spark 68]

You have shown a diagram with 2 contactors on, K1 is you initial latching contactor (k1/1), k2 is your first heater control and using the common connection K1/2 to supply you 2nd heater would be fine, less expensive and leave more room as it removes the need for the extra contactor. (excluding E-stop and pump controls)

Hi DW,
K1 could easily be a relay instead of a contactor (cheaper) as the control element in my drawing, K 1-1 and K1-2, are 2 pairs of contacts on the K1 relay, K2 is a 3 or 4 pole contactor which has the stat or cutout in series with the control coil.

I had cut this drawing down to it's most basic skeleton, the OP could have used extra contacts on the start/stop relay for status indicators and the like.

I had initialy assumed the OP was controlling both heaters from one stop/start circuit, but then he wanted to control both heaters seperately, hence the mention of three contactors initially, revised to four, to give independent control to each.

Half the trouble I had was the actual drawing with the software package (Tinycad), as Iam not used to drawing in software.

This was the circuit for one heater, as I said he would need to duplicate this circuit (apart from the E-stop) for additional heaters.

 

[jparker86]

Hi DW,
K1 could easily be a relay instead of a contactor (cheaper) as the control element in my drawing, K 1-1 and K1-2, are 2 pairs of contacts on the K1 relay, K2 is a 3 or 4 pole contactor which has the stat or cutout in series with the control coil.

I had cut this drawing down to it's most basic skeleton, the OP could have used extra contacts on the start/stop relay for status indicators and the like.

I had initialy assumed the OP was controlling both heaters from one stop/start circuit, but then he wanted to control both heaters seperately, hence the mention of three contactors initially, revised to four, to give independent control to each.

Half the trouble I had was the actual drawing with the software package (Tinycad), as Iam not used to drawing in software.

This was the circuit for one heater, as I said he would need to duplicate this circuit (apart from the E-stop) for additional heaters.

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?

 

[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.