3 phase immersion heaters in star (no N) or delta

[vitoboy]

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

 

[westward10]

Is each of the three elements actually single phase.

 

[Bobster]

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.

 

[telectrix]

if each element is a 240V jobby, wire in delta and you'll fry them with 415V across each.

 

[Pete999]

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

 

[Toneyz]

It's not an electrode boiler by any chance did about them at college years ago but never seen one to this day.

 

[Bobster]

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.

 

[telectrix]

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.

wouldn't be much use outside of the tank, would it? .

 

[telectrix]

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?

 

[Pete999]

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,

 

[vitoboy]

Is each of the three elements actually single phase.

I guess..they were running single phase at one time...
I imagine 3 x 2kw or 3kw or 4kw Immersions ..

 

[vitoboy]

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.

 

[vitoboy]

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

 

[Toneyz]

Did you get any freebies?

 

[vitoboy]

Did you get any freebies?

Not yet...but as you can tell I'm keen to help them out.!