Effect of unbalance currents on transformers & generator 1

[usman74]

hello everybody...........
i wanna know about the effects of zero and negative sequence currents in transformer as well as in generator???

 

[ScottyUK]

What do you already know about them?

 

[usman74]

-ve sequence current produce reverse rotating MF in stator, that produce double frequency current in rotor. thus increased eddy current losses, hence increases heat.
zero sequence current is in phase, thus trap in delta winding and produce effect on grounding transformer.
now wanna now what happened in transformer due to -ve sequence and zero sequence????

 

[dpc]

Neither of the transformer windings is usually rotating, so it doesn't really care about positive vs negative sequence. It doesn't care about zero sequence either, but unless current can flow in both windings, there won't be any current, save excitation current. This applies to positive, negative and zero sequence. If you draw out the path of the zero sequence current in the windings, you can figure it out.

 

[Hector04]

Std._C37.91-2000
Std._C37.102-1995