3 phase to single phase supply

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nagasahitya

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Hiii ,

I require a single phase ac supply in my LAB with volatge rating (1000 V)rms ,current rating 600 A. 3 phase 415v supply is available in my LAB.please tell me the best methods to convert my 3 phase supply in to single phase.Important thing is i must maintain balanced load on the 3 phase side.


Regards
sahitya
 
nagasahitya said:
Hiii ,

I require a single phase ac supply in my LAB with volatge rating (1000 V)rms ,current rating 600 A. 3 phase 415v supply is available in my LAB.please tell me the best methods to convert my 3 phase supply in to single phase.Important thing is i must maintain balanced load on the 3 phase side.


Regards
sahitya
Click to expand...
There is no way that I know of to make single phase from three phase using all three phases.
 
1000 VAC x 600 A = 600 kva
input at 415/3 is 835 A

600 kva 415:1000 3 ph xfmr
feeding a 1000 VAC 1000+ HP VFD (expensive VFD lol), 1000 vac is a common mining voltage and drives are available
use two phase legs of the output
input will be balanced since rectified to a DC bus
 
Just such a transformer connection has been described in a thread here. It produces single phase drawing equally from all three source phase lines.
 
the common way with xfmrs is a 2 winding primary open delta and a 2 series winding secondary
but it is not balanced
2 phases are equal, the third is 1/2 the load iirc

I'd like to see how it is done balanced
3 phase primary coupled to a single sec coil?

here's the post that purports to get 3 ph-1 ph balanced operation no drawings or real info though http://forums.mikeholt.com/showthread.php?t=146298
 
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use the 3 phase to feed a VFD with a sinewave filter at it output because VFD output is not sinusoidal. Needless to say, it is not straightforward, you need professional engineers to do all the design.
 
160518-1319 EDT

A transformer method is based on the mathematical identity that the sum of multiple sine waves of identical frequency and phase locked together produces a single sine wave of the same frequency, and some phase angle.

If A to N is 120 V, B to N is 240 V, and C to N is 240 V, then by properly connecting these secondaries in series, they are not joined at a neutral point, the summed voltage is 240 V and in phase with A to N The real power loading on each transformer is the same. Thus, a balanced real power load is presented to the source.

.
 
gar said:
160518-1319 EDT

A transformer method is based on the mathematical identity that the sum of multiple sine waves of identical frequency and phase locked together produces a single sine wave of the same frequency, and some phase angle.

If A to N is 120 V, B to N is 240 V, and C to N is 240 V, then by properly connecting these secondaries in series, they are not joined at a neutral point, the summed voltage is 240 V and in phase with A to N The real power loading on each transformer is the same. Thus, a balanced real power load is presented to the source.

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Click to expand...

3 sec coils
ph A 120/0
ph B 240/120
ph C 240/-120

series connected

how are the 'dots' oriented?
A and B the same, C opposite?
all the same?
etc

if in series all carry the same current, correct?
but if the V is different (120 and 240) the power must be different per coil?
 
GoldDigger said:
Just such a transformer connection has been described in a thread here. It produces single phase drawing equally from all three source phase lines.
Click to expand...
I only remember some unsubstantiated claims that it is possible.
 
It would be the same connection that you use on a 12 lead generator....a double delta or a zig zag connection of the secondary side, however you would need the secondary side of each of the 3 transformers to have all 4 leads brought out.
 
Ingenieur said:
the common way with xfmrs is a 2 winding primary open delta and a 2 series winding secondary
but it is not balanced
2 phases are equal, the third is 1/2 the load iirc

I'd like to see how it is done balanced
3 phase primary coupled to a single sec coil?

here's the post that purports to get 3 ph-1 ph balanced operation no drawings or real info though http://forums.mikeholt.com/showthread.php?t=146298
Click to expand...

It is not a simple as three primaries and one secondary.
Basically you interwire three individual secondary windings in a complicated way. It is similar to the complicated interconnection of the Scott T circuit between two phase and three phase.
 
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