I-V Phase Offset > 90 Degrees in Transformer Secondary Coil from Loads?

[wwhitney]

If we treat transformer secondary coils as idealized voltage sources, can we have an arrangement of secondary coils and linear loads on them for which the current through a coil will have a phase offset of greater than 90 degrees from the voltage across that coil? And does that mean that the circuit configuration is causing power to flow into that coil, rather than out of it?

These questions are from the part of an example I'm uncertain about, see https://forums.mikeholt.com/threads...-coil-transformer-secondary-circuits.2577504/ for details.

Thanks,
Wayne

 

[JoeStillman]

Negative-sequence current certainly would imply reverse power, but the downstream "load" connection that would cause that has me stumped.

 

[jim dungar]

Negative-sequence current certainly would imply reverse power, but the downstream "load" connection that would cause that has me stumped.

Negative sequence has nothing to do with direction of power in regards to the normal 'flow'. It is one of the 3 components (positive, negative, an zero sequence) used to analyze symmetrical components.

 

[JoeStillman]

Negative sequence has nothing to do with direction of power in regards to the normal 'flow'. It is one of the 3 components (positive, negative, an zero sequence) used to analyze symmetrical components.

I thought that negative sequence measurement was how a feeder protection relay senses import and export.

 

[jim dungar]

I thought that negative sequence measurement was how a feeder protection relay senses import and export.

The relay takes the current waveform and mathematically converts it into the three components. Once the components are determined they can be used as set points for the relay.

A reverse power relay function can be used for import/export.

The last time I used negative sequence was to determine if the utility had blown a fuse and was effectively providing an open wye feed to to their wye-wye service transformer.