Power System Protection and switchgear Minia Univ Faculty

Power System Protection and switchgear Minia Univ. , Faculty of Engineering Electrical Eng. Department th 4 Power & Machines Section Prof. Dr. Abou-Hashema Mostafa El-Sayed

Power System Protection and switchgear Part 1 Introduction to Protection System Part 2 Protection System for Power system Elements

Part 1 Introduction to Protection System

THE PROTECTION SYSTEM PHILOSOPHY The primary aim of any electricity supply system is to meet all customer’s demands for energy. Power generation is carried out wherever it achieves the most economic selling cost overall. Relaying is the branch of electric power engineering concerned with the principles of design and operation of equipment called relay or protective relay’s which detect abnormal power system conditions, and initiate corrective action as quickly as possible in order to return the power system to its normal state.

Protection Requirements Reliability Selectivity Simplicity Speed Cost • The protection arrangements for any power system must take into account the above basic principles

Reliability Dependability Security

Reliability: The ability of the protection to operate correctly. It has two elements: 1. Dependability: Which is the certainty of a correct operation on the occurrence of a fault. 2. Security: Which is the ability to a void incorrect operation during faults or normal stats.

Selectivity: maintaining continuity of supply by disconnecting the minimum section of network necessary to isolate the fault.

Simplicity A protection system should be kept as simple : and straightforward as possible while still accomplishing its intended goals.

Speed Minimum operating time to clear a fault in order to : avoid damage to equipment.

Cost Maximum protection at the lowest possible cost :