This chapter contains a description of the earth-fault protection of MV feeders. A feeder may consist of:
- An overhead line with bare conductors,
- An overhead line with covered conductors,
- An aerial cable,
- An underground cable or
- A combination of such line and cable sections.
The feeder is a part of a distribution system that may be:
- Effectively earthed or
- Non-effectively earthed.
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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Please could you give me some information on Earth Feeders. We have been asked to quote for a earth feeder for 3 aerials at the back of a building.
No problem what ever the Power rating of the generators may be. We can connect them parallel no doubt, but it has to satisfy the parallel operation conditions like
1. Same Voltage at 2 Generators
2. Same Frequency at 2 Generators
3. Same Phase Sequence.
After fulfilling the above conditions you can generators of any power rating in parallel.
Is it possible 500kva and 140 kva generators in parallel connection.