Zero sequence current source for transformer having a nonwound tertiary
AssigneeGeneral Electric Company
InventorsWilliam J. McNutt, James R. Wilson
Life of this patent
Estimating the term…
Abstract
A three-phase electrical transformer utilizes a conductor independent of the transformer windings for sensing zero sequence current upon the occurrence of a ground fault. A current transformer coupled with the independent conductor provides polarization to protective relay devices. One embodiment utilizes the transformer internal tank shield in combination with the current transformer for providing zero sequence current.
Claims12
A zero sequence current source for use with transformers comprising:
- a nontertiary autotransformer within a casing and having primary and secondary windings arranged around a core;
- an auxiliary conductor within the transformer proximate said casing and surrounding both said core and said windings for intercepting zero sequence flux from the core and the windings during an external ground fault occurrence;
- and
- a current transformer surrounding a part of the auxiliary conductor for sensing zero sequence current.
A zero sequence current source for use with transformers of the type consisting of a three-legged core and primary and secondary wye-connected windings arranged around the legs of the core within a casing and an electrically conducting shield within the casing comprising:
- a current transformer in magnetic proximity with the shield for inducing zero sequence current within the current transformer during a ground fault condition.
Dependencies are inferred from the claim text.