Discuss 3 phase immersion heaters in star (no N) or delta in the Commercial Electrical Advice area at ElectriciansForums.net

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Hi all
Been to a micro brewery today .

They have 2 water boilers with 3 phase immersion heaters in them (ie 3 x elements)
Originally they were wired to run single phase will all the lives and neutrals linked out and a 32A single phase supply connected to them.
Now they are wired in a star configuration. .. but with no neutral at the star point.
All cable sizes seem very large to me at 6mm.
The heaters are of the type sold by RS ..or look to be so.
I can't see any part numbers to know their rating .. but im guessing 4 - 6 kw or 12 even.
Now looking at this I was thinking that they should have a neutral to the star point..?.
Then i thought why not change it to delta configuration. ..no neutral needed .. and greater heating capacity. ..I think..
I'm used to star delta for motor starting etc but not really as a heating load.
Some advice would be appreciated.

Cheers

Vito
 
Quite a common design, draw it out you'll see why they need no neutral. Do not change it to a delta configuration. You'll change the characteristics.

Ensure they have adequate load monitoring protection, as if one heating element fails an it becomes unbalanced the other 2 will quickly fail too.

Seen this install numerous times on bitumen heating tanks. Although it is a rather old fashioned way of doing things.
 
if each element is a 240V jobby, wire in delta and you'll fry them with 415V across each.
 
Hi all
Been to a micro brewery today .

They have 2 water boilers with 3 phase immersion heaters in them (ie 3 x elements)
Originally they were wired to run single phase will all the lives and neutrals linked out and a 32A single phase supply connected to them.
Now they are wired in a star configuration. .. but with no neutral at the star point.
All cable sizes seem very large to me at 6mm.
The heaters are of the type sold by RS ..or look to be so.
I can't see any part numbers to know their rating .. but im guessing 4 - 6 kw or 12 even.
Now looking at this I was thinking that they should have a neutral to the star point..?.
Then i thought why not change it to delta configuration. ..no neutral needed .. and greater heating capacity. ..I think..
I'm used to star delta for motor starting etc but not really as a heating load.
Some advice would be appreciated.

Cheers

Vito
If the heaters are rated at 400Volts and connected across 2 phases they won't require a Neutral. Balanced load no N
 
It's not an electrode boiler by any chance did about them at college years ago but never seen one to this day.
 
It's not an electrode boiler by any chance did about them at college years ago but never seen one to this day.

Doubtful in a brewery, they'd ruin the taste.

My guess is ceramic wire wound heater elements. Imagine they are installed in an orifice within the bottom of the tank.
 
i am now getting bombarded with huge ads top of page. everything from motorcycle boots to google gadgets. even got one from cheat-a-trade. what's the crack?
 
It's not an electrode boiler by any chance did about them at college years ago but never seen one to this day.
Used to have three to look after on a large A/C installation, they were providing humidity to a large computer suite,
 
Doubtful in a brewery, they'd ruin the taste.

My guess is ceramic wire wound heater elements. Imagine they are installed in an orifice within the bottom of the tank.
Yeh but no but ..
Ceramic wire wound I think ..just like a standard immersion but x 3 .
But the elements are in a sleeve..maybe stainless looking at it.
 
OK I'm still not sure about star without a neutral.
I understand that they may not be designed to have 400 v across them ... but maybe they are ... but I can't tell without a part numbe ..I see from rs that some are and some arnt .

But I guess in the end it's in star now..it works..with no neutral so it's ok.
If you have an unbalanced load in star and there is no neutral then what happens to the unbalanced portion of the load..?.
The Brewery does require fast heat up times as this would mean they can do more brews a day..at the moment only 1 ...hence I wondered about the delta connections.
But without the part numbers to guide me I think I can't risk finding out..!

Thanks all for the good stuff.

Vito
 
If they end up unbalanced the voltage will change over the 2 remaining elements and they'll go pop pretty quickly.

Just think of it as a 3 phase motor in star, but it has no motive force.

Could be possible to connect in delta, but the current will increase.

An yes, I've seen similar before, they'll be kept in stainless tubes considering it's food produce.
 
Thanks for that contact.
As I said they appear to be of the type sold by RS ..
And looking at the rs wiring diagram they may or may not be suitable for delta connection depending on the part no. So far I can see none.
Maybe I should introduce a neutral. .. to the star point ... but there is not enough cores for this at the moment. .
Or I could use earth .. it's a pme system after all. .
There is a neutral at the controls .. but I think it's only used for 230v coils and thermostats. .
 
Connect the star point to earth!!
Have you been asked to look at these heaters?
 
Maybe I should introduce a neutral. .. to the star point ... but there is not enough cores for this at the moment. .
Or I could use earth .. it's a pme system after all. .

Why do you want to add a neutral connection? All it will do is waste cable as it won’t do anything in normal operation.

I assume you are joking about using the earth?
 
Thanks for that contact.
As I said they appear to be of the type sold by RS ..
And looking at the rs wiring diagram they may or may not be suitable for delta connection depending on the part no. So far I can see none.
Maybe I should introduce a neutral. .. to the star point ... but there is not enough cores for this at the moment. .
Or I could use earth .. it's a pme system after all. .
There is a neutral at the controls .. but I think it's only used for 230v coils and thermostats. .

What have they asked you to do with the heaters?

An please, please tell me you're kidding about thinking of using the cpc as a neutral.

In any form of installation this is prohibited and potentially very dangerous!
 

Reply to 3 phase immersion heaters in star (no N) or delta in the Commercial Electrical Advice area at ElectriciansForums.net

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