Switchgear is a term used to refer to combinations of switching devices and their interconnection with associated control, measurement and protection equipment. It allows the interconnection of various parts of the electrical network by means of transformers, overhead lines or cables to allow control of the flow of electricity within that network from power station to customer. Switchgear is also designed to be able to safely interrupt any faults that might occur in any part of the network to protect the network itself, associated equipment and operational personnel. It also provides, by means of disconnectors, facilities for isolating sections of the network and, with the provision of earthing switches, to allow the safe application of devices to ensure that the isolated sections of the network are earthed and made safe for maintenance activities or possible fault repair.

Chapter Contents:

• 9.1 Introduction
• 9.2 Substations
• 9.2.1 Substation types
• 9.2.2 Substation layouts
• 9.3 Distribution system configurations
• 9.3.1 Urban distribution systems
• 9.3.2 Rural distribution systems
• 9.4 Ratings
• 9.4.1 Rated current
• 9.4.2 Rated short-circuit-breaking current
• 9.4.3 Rated short-circuit-making current
• 9.4.4 Rated asymmetrical breaking current
• 9.4.5 Rated short-time current
• 9.4.6 Rated voltage
• 9.4.7 Rated insulation withstand levels
• 9.4.8 Rated transient recovery voltage
• 9.5 Switching equipment
• 9.5.1 Circuit-breakers
• 9.5.2 Distribution circuit-breaker types
• 9.5.3 Disconnectors
• 9.5.4 Earth switches
• 9.5.5 Switches
• 9.5.6 Switch disconnector
• 9.5.7 Switch fuse
• 9.5.8 Fuse switch
• 9.5.9 Fuses
• 9.5.10 Contactors
• 9.5.11 Ring main units
• 9.6 Circuit protection devices
• 9.6.1 Surge arresters
• 9.6.2 Instrument transformers
• 9.7 Switchgear auxiliary equipment
• 9.8 SF6 handling and environmental concerns
• 9.8.1 SF6 breakdown products
• 9.8.2 SF6 environmental concerns
• 9.9 The future (as perceived in 2000 and again in 2011)
• 9.9.1 The future 1 - by B.M. Pryor in 2000
• 9.9.2 The future 2 - by H.M. Ryan in 2011
• Disclaimer
• Summary
• References
• Appendices - by H.M. Ryan
• A: Additional CIGRE references
• B: Distribution systems and dispersed generation (after CIGRE [8]) - summary of key CIGRE information mainly from SC C6 2011 AGM [8] - compiled by H.M. Ryan

Inspec keywords: power cables; power distribution protection; power distribution faults; load flow; power system measurement; earthing; power transformers; switchgear protection; power overhead lines; power system interconnection; maintenance engineering

Other keywords: overhead line; protection equipment; electricity flow control; cable; distribution switchgear device; fault repair; transformer; electrical network interconnection; maintenance activity; power station; faults interruption; earthing switch

Subjects: Power cables; Distribution networks; Transformers and reactors; Switchgear; Power system management, operation and economics; Overhead power lines; Protection apparatus; Power system measurement and metering