2 PHASE supply to machine

[mike the sparky]

I'm carrying out an EICR to a machine shop ( they make machine guns!). One machine is a sciaky P282 hot riveter. This starts out as a 3 phase, neutral & earth set up at the DB; then terminates in a rotary isolator 30 metres away where it changes to what I assumed was a single phase supply. This single phase supply is supplied from the red and blue cables in the isolator. Another 20 metres away is a MEM switched isolator next to the machine. A check inside this confirms 400volts. The machine has a built in transformer but no wiring diagrams are available. To me it seems to be a 230 volt machine but the operators tell me that there have been no operating issues. Is there such a machine that is 400volt, 2 phase, no neutral or is this potentially dangerous

 

[shanky887614]

230 between any phase and neutrel.

or 400 between any two/three phases

if i remember right some outside lights use two phases. (no need for a neutral if it uses two phases)

if it uses red and blue then its definatly two phase as the old colours were red,blue and yellow for three phase

 

[babylonsBurning]

Seen welders that a 400v 2 phase.

 

[mike the sparky]

At the rotary isolator on old colours 400v R-Y, Y-B, B-R; 230v R - BLACK, Y - BLACK; B - BLACK. The RED feeds to new colour BROWN; the BLUE feeds to new colour BLACK & the armoured sheath feeds to new colour GREY. Across BROWN & BLACK new colours is 400v

 

[shanky887614]

At the rotary isolator on old colours 400v R-Y, Y-B, B-R; 230v R - BLACK, Y - BLACK; B - BLACK. The RED feeds to new colour BROWN; the BLUE feeds to new colour BLACK & the armoured sheath feeds to new colour GREY. Across BROWN & BLACK new colours is 400v

where a lot of people fall foul is the old colour for neutral is black which is now used as one of the phase colours

 

[44ALLAN]

I'm carrying out an EICR to a machine shop ( they make machine guns!). One machine is a sciaky P282 hot riveter. This starts out as a 3 phase, neutral & earth set up at the DB; then terminates in a rotary isolator 30 metres away where it changes to what I assumed was a single phase supply. This single phase supply is supplied from the red and blue cables in the isolator. Another 20 metres away is a MEM switched isolator next to the machine. A check inside this confirms 400volts. The machine has a built in transformer but no wiring diagrams are available. To me it seems to be a 230 volt machine but the operators tell me that there have been no operating issues. Is there such a machine that is 400volt, 2 phase, no neutral or is this potentially dangerous

Is there such a machine that is 400volt, 2 phase, no neutral or is this potentially dangerous
How about a transformer...............welders spring to mind

 

[ipf]

Installed big spotwelders 2 phase 400v, 3 of them, 160 amp MCCBs
1. red/yell
2. red/blue
3. yell/blue

Just to spread the load as evenly as possible.

 

[ipf]

230 between any phase and neutrel.

or 400 between any two/three phases

if i remember right some outside lights use two phases. (no need for a neutral if it uses two phases)

if it uses red and blue then its definatly two phase as the old colours were red,blue and yellow for three phase

That bloody noitrul again

Thet's batter

 

[Lucien Nunes]

If I understand you correctly, the supply is taken from two of the three line conductors of a 3-phase supply, without a connection to neutral. This makes it a single-phase machine, not two-phase. It just happens to be 400V, therefore the necessary voltage is found between two line conductors, rather than line and neutral. The idea is that by working at 400V where this is available, the current rating is reduced without the complexity and cost of a three-phase machine. Others have mentioned welders, indeed my own portable single-phase welder is switchable between 230 and 400V. At the workshop, I have many 16A 3-phase supplies and it will run on one of those on its 400V setting. However when set to 230V it requires a 32A single-phase circuit.

Two-phase systems were used in the past, they have two phases and a neutral or even two phases and two neutrals, and give a rotating field in a motor much like a 3-phase supply but with different phase angles. Two phases out of a 3-phase supply are not the same thing.

Lucien

 

[gazj82]

I have fitted 2 phase light fittings before in greenhouses

 

[Rockingit]

This is exactly the same principle that I've had to use before when in the States on tour and had some bit of kit that will only work on 230 (and no tx available)...simply use two phases of 110 3ph and ditch the neutral. Confuses the heck out of a red neck yankee spark when you ask them to do it!

 

[Lucien Nunes]

use two phases of 110 3ph

Not sure why they would be confused. Many US supplies consist of 120-0-120 even in homes and they have 240V gear too, which connects between the two outers without a neutral. A dryer or stove might have a 240V receptacle or circuit wired this way. 120V 3ph gives 208V line-line which gets used as a last resort as you say.

L

 

[Darkwood]

I cant understand you issue here... you EICR ends at the rotary isolator the machine, its connection and control fall under different regulations to the BS7671 although there is a grey area about the cross-over point can sometimes be classed as the termination on the machine but either way where is your problem..... is their not a plate on the machine regardless of missing schematics?

 

[Darkwood]

If I understand you correctly, the supply is taken from two of the three line conductors of a 3-phase supply, without a connection to neutral. This makes it a single-phase machine, not two-phase. It just happens to be 400V, therefore the necessary voltage is found between two line conductors, rather than line and neutral. The idea is that by working at 400V where this is available, the current rating is reduced without the complexity and cost of a three-phase machine. Others have mentioned welders, indeed my own portable single-phase welder is switchable between 230 and 400V. At the workshop, I have many 16A 3-phase supplies and it will run on one of those on its 400V setting. However when set to 230V it requires a 32A single-phase circuit.

Two-phase systems were used in the past, they have two phases and a neutral or even two phases and two neutrals, and give a rotating field in a motor much like a 3-phase supply but with different phase angles. Two phases out of a 3-phase supply are not the same thing.

Lucien

If it is supplied by 2 phases of the supply only then its a 2phase system not single phase.... look up your basic definitions
1ph is L and N
2ph is in the OP case is 2 line conductors from L1/L2/L3

How can you state this is still single phase?

2 phase systems dont have a neutral by definition unless specified dont get confused with DNO supplies here and user final circuits with which the OP is discussing

 

[shanky887614]

If it is supplied by 2 phases of the supply only then its a 2phase system not single phase.... look up your basic definitions
1ph is L and N
2ph is in the OP case is 2 line conductors from L1/L2/L3

How can you state this is still single phase?

2 phase systems dont have a neutral by definition unless specified dont get confused with DNO supplies here and user final circuits with which the OP is discussing

you only need a N in single phase to complete the circuit or you would have a dead short.

if you have 2/3ph and neutrel its usually because the machine can be run in single or multiple phases.