# Thread: 6 phase forked star secondary wound transformer

1. Junior Member
Join Date
Mar 2017
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Exeter
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5

## 6 phase forked star secondary wound transformer

Does anyone have information on how to calculate the secondary line voltages for this type of transformer? Information generally would be gratefully received!!!

2. Originally Posted by RogerRoger25
Does anyone have information on how to calculate the secondary line voltages for this type of transformer? Information generally would be gratefully received!!!
How about an explanation of how you are using this and why you need to know? Because if it's just the 6 phases you want to know about, that's easier to describe than the 9 possible connections available.

3. Originally Posted by RogerRoger25
Does anyone have information on how to calculate the secondary line voltages for this type of transformer? Information generally would be gratefully received!!!
Got a diagram?

4. Originally Posted by Jraef
How about an explanation of how you are using this and why you need to know? Because if it's just the 6 phases you want to know about, that's easier to describe than the 9 possible connections available.
Do you think he means hexaphase?

5. 6 phase
ph-ph voltage = ph-neut/gnd voltage

6. Originally Posted by Ingenieur
6 phase
ph-ph voltage = ph-neut/gnd voltage
Got a diagram of a forked star?

7. ## Diagram

8. That lower diagram is something I was aware existed in theory, but have never needed to implement. 6 phase (hexaphase) as shown in the upper diagram on that page, used as an input to a 12 pulse rectifier, yes. But the "forked wye" thing is not necessary for that. Still, there are people who sit around thinking about this sort of stuff for all kinds of off beat uses.

9. Is this xfmr used to do something similar?
D - DDD
4160-1400/1400/1400 0 deg/+20 deg/-20 deg
3500 kva labeled scr application
ties a 4160 bus to a large vfd that powers a 4160 3500 hp motor
only used for starting then a contactor transfers in

10. Originally Posted by Jraef
That lower diagram is something I was aware existed in theory, but have never needed to implement. 6 phase (hexaphase) as shown in the upper diagram on that page, used as an input to a 12 pulse rectifier, yes. But the "forked wye" thing is not necessary for that. Still, there are people who sit around thinking about this sort of stuff for all kinds of off beat uses.
Hexaphase is commonly used for six-pulse rectifiers for high current low voltage rectifiers. There is one device (SCR typically) in each leg. The merit is that you have just one semiconductor voltage drop as opposed to two with a full wave rectifier. The devices are subjected to a higher PIV but if the system is just a few tens of volts that is not usually a critical factor.

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