Control Panel for 3ph Heaters

[jparker86]

Hi JP,

Glad you got the basics working.

As DW and Tony have said though, this is far from the finished article.

If you noticed on my drawing, and I think Tony's too, we never marked the control circuits with a L or N, this was because generally it is better not to use 230V for the controls (unless all controls are staying inside the panel), as DW pointed out too, it is usually much better to use say 24V DC for these circuits, this would have made it much easier, for example to add your floats or other safety/inhibit sensors which may be remote from the panel.

Using SELV for the controls makes it far easier to comply with electrical regs, where sensors etc. are to be used outside of the control panel, also consider seperate fusing of the controls, as well as the heater side of things, there are other things too to consider, such as earthing the metal work of the panel, a seperate earth strap to any doors and/or any removable covers/gland plates, IP ratings of the panel, safety and voltage labels. As you can see the list just goes on and on, and this is far from easy, if not impossible on an internet forum.

As Tony and Dw also pointed out, it is a massive legal can of worms to design and build an electrical panel which will have to satisfy a number of different statutory regs, and pass mandatory general electrical safety tests too, from a legal point of view, when offering such items for sale.

I do wish you good luck with your project, and Iam also sure different people will have many different views on the best way forward (many ways to skin a cat).

Thanks- how could I get 24V inside my panel?
Do I use an inverter or something similar?

 

[spark 68]

Thanks- how could I get 24V inside my panel?
Do I use an inverter or something similar?

If there is room inside of the panel you could fit a suitable 24V DC switch mode PSU, suitably fused on both the 230V AC input, and the 24DC output sides, sometimes if there is no room in the panel this would have to be fitted externally.

If you do go this route you will need to change all of your contactors to types with 24V coils, as well as your indicators to 24V types.

Edit: it may be possible to just add 24V relays for the safety inhibit parts of the system, leaving the existing contactors and indicators as 230V types.

 

[jparker86]

If there is room inside of the panel you could fit a suitable 24V DC switch mode PSU, suitably fused on both the 230V AC input, and the 24DC output sides, sometimes if there is no room in the panel this would have to be fitted externally.

If you do go this route you will need to change all of your contactors to types with 24V coils, as well as your indicators to 24V types.

Definitely worth a look! Doubt I have room in the panel to be honest so maybe have to outsource a PSU unless it worked from a battery?

 

[spark 68]

See my now edited post above ^^^

 

[jparker86]

See my now edited post above ^^^

Good idea. Relays to be honest are something I am researching into- as stupid as it sounds, I have no idea how they work inside so am currently reading up on them to see exactly that

 

[Darkwood]

I can see alot of unused parts and high costs as you discovers each area we address JP, on this occasion you would be best to have the panel built professionally and peruse the finished item and understand the reasoning for each area, also gives you the opportunity to try follow the wiring plans, im bowing out here as i feel you are attempting something beyond your experience and knowledge and your leaving yourself wide open to having this project haunting you further down the line.

Before you design any control system you need to be fluent in :-

Schematic wiring diagrams (reading and design).
Risk assessment.
Regulations of the various aspects of design and running of your panel, little of this falls under the 17th and is a minefield if you are not familiar with them.
Available products out there and how they work with the pro and cons of each product.

If i was to employ anyone to design and build me a panel i would expect them to have at least 10yrs in the industry unless they were exceptional and recommended, ive got 20yrs combined in both standard electrical and electrical engineering and it was only 5yrs ago i considered my knowledge of the industry at a level where i started designing my own systems, i commend your enthusiam but keep it to the hobby level for a good 5yrs yet and that is with onsite guidence from a colleage who excells in this field.

 

[jparker86]

I can see alot of unused parts and high costs as you discovers each area we address JP, on this occasion you would be best to have the panel built professionally and peruse the finished item and understand the reasoning for each area, also gives you the opportunity to try follow the wiring plans, im bowing out here as i feel you are attempting something beyond your experience and knowledge and your leaving yourself wide open to having this project haunting you further down the line.

Before you design any control system you need to be fluent in :-

Schematic wiring diagrams (reading and design).
Risk assessment.
Regulations of the various aspects of design and running of your panel, little of this falls under the 17th and is a minefield if you are not familiar with them.
Available products out there and how they work with the pro and cons of each product.

If i was to employ anyone to design and build me a panel i would expect them to have at least 10yrs in the industry unless they were exceptional and recommended, ive got 20yrs combined in both standard electrical and electrical engineering and it was only 5yrs ago i considered my knowledge of the industry at a level where i started designing my own systems, i commend your enthusiam but keep it to the hobby level for a good 5yrs yet and that is with onsite guidence from a colleage who excells in this field.

The idea behind me building this panel is to see exactly how it works behind the scenes, as then at least when/if it goes wrong I can be best placed to understand how to repair it.
I am however already on with employing a professional panel builder, as everything you say above is true and correct.
for me this is a great learning curve and think ill even build myself a panel for my garage at home, for lighting etc :-D

 

[Darkwood]

The idea behind me building this panel is to see exactly how it works behind the scenes, as then at least when/if it goes wrong I can be best placed to understand how to repair it.
I am however already on with employing a professional panel builder, as everything you say above is true and correct.
for me this is a great learning curve and think ill even build myself a panel for my garage at home, for lighting etc :-D

I understand your position better now and yes keep it to the hobby level but be careful not to use the family as guinea pigs , safety of your designs shouldn't be tested in the real world but virtually if possible.
A tip is ask yourself what would happen if each item failed etc like contactors sticking or a broken connection; would the safety of your system be compromised or that of anyone else, a well design system would be fail safe, self monitoring, and easy to use and understand but to what degree depends on what job and who is using it.

 

[jparker86]

I understand your position better now and yes keep it to the hobby level but be careful not to use the family as guinea pigs , safety of your designs shouldn't be tested in the real world but virtually if possible.
A tip is ask yourself what would happen if each item failed etc like contactors sticking or a broken connection; would the safety of your system be compromised or that of anyone else, a well design system would be fail safe, self monitoring, and easy to use and understand but to what degree depends on what job and who is using it.

Well the way in which I have wired this system now is... I have two heaters. Both are at the same level in the tank.
One heater has a manual thermostat in (like you see in an immersion heater).
Second heater will have a PID temperature controller sensor/phile inside.
The above will control both heaters, going on and off. So in effect giving a digital readout but at the same time will cut in and out the main live going into A1 on the main 4 pole contactors.
The main thermostat is set to a high level, so should the PID fail or give inaccurate reading it will kill power to two pole contactor. I had debated weather to wire this into my e/s circuit, but wouldn't want to kill the pump because this would ensure the heat is evenly distributed.

 

[spark 68]

Hi JP,

Not knocking your enthusism at all, but I agree with DW here, in seeking professional advice with something you are intending to market, this will work out much cheaper and safer in the long run.

This is a fascinating side of the electrical industry, and one of my personal favourites, I love 'playing' with the various building blocks and you never stop learning.

There are many ingenious ways to achieve things, often limited by your own imagination, once you are conversant with the basic principles, it is like a giant lego set with basic building blocks.

I think it is great that you have shown the enthusiasm that you have, and your willingness to learn, maybe when you get a panel builder working for you they will let you help and ask questions (the only way to learn), as other posters on this thread have said previously, ask the underlying reasons why something is done the way it is.

Good luck!

 

[jparker86]

Hi JP,

Not knocking your enthusism at all, but I agree with DW here, in seeking professional advice with something you are intending to market, this will work out much cheaper and safer in the long run.

This is a fascinating side of the electrical industry, and one of my personal favourites, I love 'playing' with the various building blocks and you never stop learning.

There are many ingenious ways to achieve things, often limited by your own imagination, once you are conversant with the basic principles, it is like a giant lego set with basic building blocks.

I think it is great that you have shown the enthusiasm that you have, and your willingness to learn, maybe when you get a panel builder working for you they will let you help and ask questions (the only way to learn), as other posters on this thread have said previously, ask the underlying reasons why something is done the way it is.

Good luck!

Exactly! This is why I love forums like this which is a wealth of knowledge and information. The only question I ever ask myself in life is "why". When you ask why you understand and when you understand you move on.

 

[Darkwood]

Panel building is big mans lego but it has the added advantage that it can blow up or kill you , got a love a hobby with a risk factor :nuke: