wiring up a three phase compressor

[minibizz]

Hi got a problem I am sure someone can solve, I have a work shop on a farm that has both single phase (lighting 240v electric sockets) and three phase supply. The three phase supplying elec to a vehicle lift. I have recently purchased a three phase compressor which has brown blue black and the normal yellow/green which I assume to be earth coming from the on/of switch. The three phase supply is wired through an isolator switch but only two of the wires are being used brown and grey, the black wire has been left and marked as 'not in use' I would like to wire the compressor into the isolation switch so do I in turn only use two of the wires from the compressor and if so which ones.

 

[Spark123]

You cannot run a 3 phase machine on two phases, best get yourself a sparks in who knows what they are doing, brown blue and black seems an odd combination to me?

 

[crystal ball]

Brown Blue black sounds like SY cable

 

[ColJack]

brown, blue, black, earth is old 4 core flex colours too..

where is this isolator located? is this the same isolator that runs the vehicle lift? if so then the vehice lift is not 3 phase.. it's single phase....


photo's would help loads...

 

[minibizz]

Yes the isolator switch is on a wall this switch also runs a spot welder, wiring from this switch then goes to the lift which also has an on/of switch together with one up and one down switch. Is it possible for the third phase to be coming in by way of the normal domestic supply, because this isolator switch has also a separate supply. However I will endeavour to take some pics

 

[Spark123]

So you don't have a 3 phase distribution board?

 

[minibizz]

dont think so, wiring is very old. The board is in another building next to mine and is on what is probably chip board with an old box with the three leads running into it red blue and yellow I beleave. One of them supplying the single phase to the various out buildings, from memory I think yellow but I can have a look tomorrow. The blue and red coming in to the isolation box.

 

[Spark123]

You'll need some sort of isolation in your building to kill all the power where it enters, you should not use a number of single phase boards to supply 3 phase, you need a proper 3 phase distribution board.

 

[ricicle]

Also,is all the control gear with the compressor? If not you will have to fit contactor and overload (if the motor is bigger than 0.37kW)

 

[minibizz]

yes all the switches for the compressor are intact it has an on/of switch with the wiring coming out of the bottom of this switch, the feed cable has just been cut short. With regards to the correct three phase board there is no way the owner of the farm will lay out the money as it is only me who needs three phase. Probably be easier to just change the motor on the compressor to single.

 

[RF Lighting]

....or fit an invertor?

 

[toasty]

...or fit a rotary converter

 

[ricicle]

....or fit an invertor?

The motor on the compressor would have to be of the dual wound variety, which means it can be connected in Delta at 230/240V driven by a single phase to three phase invertor.
I would be surprised if the motor was of this kind!

 

[briwire]

The motor should have a plate on its casing with information on the frame size, voltage, current, speed, kilowatts etc. Can you post on here exactly what it says, then we can tell you if it is a single or 3 phase motor.