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Chapter – 1
CONCEPTS OF SWITCHGEAR

1.0

INTRODUCTION :

Switchgear - The Importance of Switchgear Protection in Electrical System - List of Different Types of Switchgear - Switchgear Equipment - List the Switchgear Equipment - Very Short Questions - Short Questions - Broad Questions.

Electrical Energy Management system ensure supply of energy to every customer at all times at rated voltage, rated frequency and specified wave form, at lowest cost with minimum environmental degradation. The Switchgear, Protection and Network Automation are integral part of the Modern Energy Management System and National Economy. The modern 3 phase, 50 Hz, interconnected power system has several conventional and non conventional power plants, EHVAC and HVDC Transmission Systems, Substations, MV and LV distribution Systems and Connected Loads. The energy in electrical form is supplied to various consumers located in a vest geographical area, instantly, automatically and safely with required quantity at all times. The service continuity and high quality of power supply have become very important.

Generation planning, Transmission planning, System expansion, Installation, Operation Control and Maintenance of Electrical Energy System, Fault Calculation, Network Calculation and Load Flow Studies have been very essential function of Modern Power Engineers. Switchgear and Control gear are also essential with every power consuming devises at Utilization level.

Switchgear and Protection/Control-Panels are installed at each voltage levels at each switching point for

(i) Normal routine switching, control and monitoring and

(ii) Automatic switching during abnormal and faulty operating condition such as short circuit, under voltage, overloads.  

1.1

Switchgear:

The apparatus used for controlling, regulating and switching on or off the electrical circuit in the electrical power system is known as switchgear. The switches, fuses, circuit breaker, isolator, relays, current and potential transformer, indicating instrument, lightning arresters and control panels are examples of the switchgear devices.

The switchgear system is directly linked to the supply system. It is placed in both the high and low voltage side of the power transformer. It is used for de-energizing the equipment for testing and maintenance and for clearing the fault.

Switchgear and Protection :

We are all familiar with low voltage switches and re-wirable fuses in our home. The switch is used to manually open and close the electrical circuit in our home and electrical fuse is used to protect our household electrical circuit from over current and short circuit faults.

In same way every electrical circuit including high voltage electrical power system needs switching and protective devices. But in high voltage and extra high voltage system, this switching and protective scheme becomes complicated one for high fault current interruption in safe and secure way. In addition to that from commercial point of view every electrical power system needs measuring, control and regulating arrangement. Collectively the whole system is called switchgear and protection of power system. The electrical switchgear has been developing in various forms.

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