no neutral phase power (phase to phase) ice show chillers

[svincent]

Hi there

 

Currently have an ice show in and wondered how the chiller power works!!

 

It’s running off power lock and they don’t have a neutral just 3 phases and earth

 

One of the Russian techs tried his best to explain it but only got as far as saying it runs phase to phase instead of phase to neutral (live to live instead of live to neutral is how I translate this)

 

I'm now confused as to how that is possible and was just wondering if anyone can explain how this works!!!

 

The closest thing I can think of is that the earth is being used as the neutral

but I’m not sure that’s right after putting this to their tech and him just saying no (in Russian)

 

Any clue anyone

 

Just for my general knowledge base really

 

Cheers

Sam

 

(p.s. sorry if I have put this in the wrong place but I couldn’t think where it would belong unless I really am blind and missed the power section)

 

 

A concurrent post has been automatically merged from this point on.

 

ok I'm really blind went back and looked and found the power section

 

I’m very sorry mods could you please move this for me

 

cheers

A very embarrassed Sam

[themadhippy]

balanced 3 phase loads dont need a neutral,and as most chillers are just motors then the phases will be balanced.The theory behind it and equations are is lost in the dark recesses of my memory.

[dekw1]

It must be working off 415v (the voltage between two phases) as opposed to 240v (the voltage between phase and neutral)..........

[dbuckley]

The single phase 240V power you are familiar with at home is just one phase of a three phase system.

 

At work you have all three phases to your dimmers, so still giving 240V phase to neutral.

 

What you may not know is that if you measure between phases you get 415V. You can draw power directly between phases at 415V between any two phases.

 

Pretty much all industrial motors run directly off three phase with no neutral.

[mrcog]

Surely the chiller unit is going to be a motor running the refrigeration system pumping the coolant round? Therefore likely to be a three phase motor which therefore means that each phase would be identically loaded when eliminates the need for a neutral... Off topic a little bit, but in the UK, is phase to phase power used much to get that 415V? I understand its popular in America but not so sure about the uk?

[KevinE]

Yes, used alot in industry. Alot of older factories in particular don't have neutrals wired to machinery points so they use eithe 2 or 3 phase 415 and sometimes a local 415-240V transformer for controls or auxilliary power.

 

It doesnt matter if the load is balanced or not if you're only using things that use 415; it's just better practice if it can be done.

[Tris]

used a lot on farms as well, grain stores and such like for their heaters and conveying machinery

 

More amusing when you are trying to borrow such power for a wedding in a barn and discover the cable comes straight out of the floor to the dryers not going via any kind of distribution board or meter, they just pay a flat rate to the electricity company (not sure how common that bit is though)

[Andrew C]

I think we've been here before, and I think I found a better picture. Have a look here for an introduction to motor control on 3ph systems.

[paulears]

The magic words when Googling for three phase answers are DELTA and STAR.

[adam2]

Any common 3 phase motor does not need a neutral, each winding of said motor will be designed for the correct phase to phase voltage, normally 400 to 415 in the UK.

 

Machinery incorporating 3 phase motors sometimes needs a neutral for control circuits or other ancillary parts.

Large AC chillers are normally 3 phase and earth only. Large cables are required for such machines, and are often lengthy with roof mounted chillers and basement intakes.

There is an appreciable saving in installation costs by use of 3 core cable rather than 4 core.

The chiller will normally contain a small transformer with a 415 volt primary, and 120 or 240 volt secondary in order to supply controls.

The controls transformer often has a range of input voltages to allow for use in different countries, the ones at work are for 208/220/240/277/380/400/420/480 volts.

The manufacturer would have to supply compressor motors for the local supply voltage, but at least the controls section will be the same for every market.

 

In my youth I worked in a factory with a 550 volt 3 phase supply without neutral.

Machines worked directly on this voltage.

Lighting was at 50 volts from transformers, special lamps of 50 volts 300 watts being used.

[dbuckley]

The magic words when Googling for three phase answers are DELTA and STAR.

But for avoidence of doubt: A star arrangement without a neutral is still a star arrangement.

 

A delta load can be plugged into a star supply, but the reverse is not true if the star load needs a neutral.

[Samwise]

Hi Sam,

 

If you work alot with lighting and sound you might well notice that all the motorised chain hoists you use for rigging your equipment run on 3Ø and earth.

 

Have a look! :-)

 

Sam.

[TomM]

Hi Sam,

 

If you work alot with lighting and sound you might well notice that all the motorised chain hoists you use for rigging your equipment run on 3Ø and earth.

 

Have a look! :-)

 

Sam.

 

[PEDANT] Not all. Many are also available in single phase versions as well! [/PEDANT]