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MV Feeder Earth-fault Protection

Distribution Automation Handbook – Power System Protection Practice // MV Feeder Earth-fault Protection – by ABB
Distribution Automation Handbook – Power System Protection Practice // MV Feeder Earth-fault Protection – by ABB

Introduction

This chapter contains a description of the earth-fault protection of MV feeders. A feeder may consist of:

  1. An overhead line with bare conductors,
  2. An overhead line with covered conductors,
  3. An aerial cable,
  4. An underground cable or
  5. A combination of such line and cable sections.

The feeder is a part of a distribution system that may be:

  1. Effectively earthed or
  2. Non-effectively earthed.
Phase overcurrent relays and residual overcurrent relays are often used to provide main earth-fault protection of MV feeders.

The relays may have independent time or dependent time characteristics and may or may not be combined with a directional element. Neutral displacement voltage and neutral point current are the most common polarizing quantity for directional elements. Backup protection is often provided by a neutral displacement overvoltage relays.


Faults and Abnormal Conditions

Various forms of earth-faults are common on distribution systems. The most common fault is the single phase-to-earth fault but other types of earth fault also occur. They are:

  • Phase-to-phase-to-earth faults
  • Cross-country faults
  • Back-fed earth faults

A long discussion on phase-to-phase-to-earth faults is not necessary. This fault may be detected by either the short-circuit protection or the earth-fault protection or by both.

Title:Distribution Automation Handbook – Power System Protection Practice // MV Feeder Earth-fault Protection – ABB
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Size:642 KB
Pages:20
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Distribution Automation Handbook - Power System Protection Practice // MV Feeder Earth-fault Protection - AB
Distribution Automation Handbook – Power System Protection Practice // MV Feeder Earth-fault Protection – AB

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Page edited by E.C. (Google).