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PT open delta and Wye wirings

PT open delta and Wye wirings

PT open delta and Wye wirings

Hello all.
I have some issues with PT wirings. your help is appreciated in advance.
1- can Wye PT wiring (3 PTs) provide phase angle measurements?
2- the figure below shows the connection of a single PT to Schneider Vamp40 feeder protection relay. the manual says that with this configuration, all voltage functions such as:
27- undervoltage
59- overvoltage
32- reverse power protection
Are all these functions possible with this pt config?

RE: PT open delta and Wye wirings

27 and 59 can be performed on the L1-L2 voltage. Anything involving L3 or anything that shifts the L1 and L2 relative to ground without changing the phase-phase voltage will be missed. Assuming relatively well balanced currents and voltages the 32 function should work as well, but will probably have a wider dead band around zero.

RE: PT open delta and Wye wirings

Should the primary voltages be unequal it is possible to have reverse power on only one phase. Such an event may be missed with this connection.
With four wire wye:delta transformer banks reverse power on only one phase is an known issue.

"Why not the best?"
Jimmy Carter

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