Secure application of transformer differential relays for bus protection

Author

Thompson, Michael ; Folkers, Ralph ; Sinclair, Amy

Author_Institution

Schweitzer Eng. Lab., USA

fYear

2005

fDate

5-7 April 2005

Firstpage

158

Lastpage

168

Abstract

The greatest challenge of bus differential protection is dealing with false differential current due to CT saturation. Percentage-restrained differential relays are often applied for bus differential protection applications. The percentage restraint principle provides security by requiring that the differential current exceed some percentage of the current flowing through the zone. There are few application guidelines for choosing a secure slope setting when applying this type of relay for bus protection. This paper reviews basic concepts of differential relays and current transformers and then describes a study that was performed to determine secure settings for a relay in a specific bus protection application. Results of the study and recommendations are included.

Keywords

current transformers; overcurrent protection; power transformer protection; relay protection; bus protection; current transformer saturation; differential protection; overcurrent security; transformer differential relays; Circuit faults; Cogeneration; Current measurement; Current transformers; Fault currents; Guidelines; Laboratories; Protection; Protective relaying; Security;

fLanguage

English

Publisher

ieee

Conference_Titel

Protective Relay Engineers, 2005 58th Annual Conference for

Print_ISBN

0-7803-8896-8

Type

conf

DOI

10.1109/CPRE.2005.1430430

Filename

1430430