SWITCHGEAR AND CIRCUIT BREAKERS: SELECTION, DIAGNOSTICS, TESTING AND MAINTENANCE

SYNOPSIS

Switchgear and circuit breakers are very important components in electrical power systems. The importance of electric supply in everyday life has reached such a stage that it is desirable to protect the power system from harm during fault conditions and to ensure maximum continuity of supply. For this reason, switchgear provides a means to switch on or off generators, transmission lines, distributors, and other equipment under both normal and abnormal conditions.  Failure in any of these electrical components in electricity distribution network can result in serious financial losses. Their reliability, longevity and optimal performance which are of great concern can only be achieved by understanding the characteristics, selection criteria, common problems, and repair techniques for their preventive and predictive maintenance. This two-day course/workshop is aimed at equipping learners with in-depth knowledge of selection, applications and maintenance of switchgears and circuit breakers.

Workshop outline

Day 1

MODULE ONE: INTRODUCTION TO SWITCHGEAR

• The spectrum of switchgear
• Switchgear drawings
• Switchgear ratings
• Difference between switchgear and switchboard
• Principles of Current Interruption
• Interruption techniques
• Industrial switchgears: Fuses, Auto-reclosers, Automatic sectionalizer, Circuit breakers, Isolators switches and Load switches

• Video demonstrations
• Course activities

MODULE TWO: LOW-VOLTAGE SWITCHGEAR AND CIRCUIT BREAKERS

• Introduction to Low-Voltage Circuit
• Basic types of low-voltage switchgear structures
• Sections of Switchgear
• Low-Voltage Circuit Breakers
  • Miniature Circuit Breakers (MCB)
  • Molded-case circuit breakers
  • Air circuit breakers (ACB) /Power circuit breakers
• Trip Curves - trip characteristics for miniature circuit-breakers
• Different Types of Trip Curves
• Insulated-Case Circuit Breakers
• Power Circuit Breakers
• Fused Power Circuit
• Overcurrent Protective Devices
• Static- and Electronic-Trip Units, Monitoring and Protection Packages
• Low-Voltage Fuses, Disconnect Switches, Low-Voltage Switches
• Smart Low voltage switchgear
• Main Switchgear of LV electrical installation
• Large Industrial and Commercial Installations
• Arrangement of bus-section switches on LV switchboard
• Emergency Generators & UPS
• Final Distribution Boards
• Types of Distribution Boards
• Positioning of Distribution Boards
• Feeding Distribution Boards
• Course exercise

DAY 2

MODULE THREE: HIGH-VOLTAGE & MEDIUIM-VOLTAGE SWITCHGEAR AND CIRCUIT BREAKERS

• Types of switchgear
• Medium-Voltage Switchgear Construction Features
• Metal-Clad Switchgear
• Metal-Enclosed Interrupter Switchgear (MEIS)
• Station-Type Cubicle
• POWER CIRCUIT BREAKERS
• Classification of Circuit breakers
• Classification based on location
• Classification by External design or construction
• Classification by Interrupting Media
• Air Circuit Breaker (ACB)
• Oil Circuit Breaker
• Vacuum Circuit Breaker
• SF6 Gas Circuit Breakers
• GIS or Gas Insulated Switchgear
• Course activities

MODULE FOUR: RATINGS AND SELECTION OF SWITCHGEAR AND CIRCUIT BREAKERS

• Introduction
• Switchgear selection
• Ratings
• Short-Circuit Considerations and Power Circuit Breaker Ratings
• Selection and Application of Power Circuit Breakers
• Why Fault Analysis ?
• How do you analyze faults
• Per-Unit Calculations
• Fault Level at breaker position
• Medium-Voltage Switchgear Construction Features
• Bus bars
• Course Activities

 MODULE FIVE: TESTING AND MAINTENANCE OF ELECTRICAL SWITCHGEAR AND CIRCUIT BREAKERS

• Low-Voltage Switchgear Maintenance and Care

• • General Guidelines for Inspection and Maintenance of Switchgear
  • Maintenance of Power Circuit Breakers,
• • • Mechanical Maintenance Factors,
    • Electrical Maintenance Factors
    • Inspections Procedure
    • MCCBs: Mechanical Factors, Electrical Factors, Inspections Procedure
    • Switchgear Enclosure
    • Air Disconnect Switches, Fuses, and Insulators: Air Disconnect Switches, Power Fuses, Insulators
    • Maintenance and Testing of Low-Voltage
  • Maintenance of Power Circuit Breakers
  • Maintenance of Air-Magnetic CB, OCBs, VCBs, Switchgear Enclosure and Bus
  • Electrical Switchgear Testing
  • • Insulation resistance test
    • DC or AC hi-pot test
    • Power factor or dielectric loss test
    • Circuit breaker contact resistance test
    • Circuit breaker time–travel analysis test
    • Contact Resistance test
    • Timing
    • Minimum pick up
    • Travel
    • Power factor
    • Modern Switchgear; Diagnostics, Testing and Maintenance of electrical switchgear
    • • Why switchgear innovation is crucial
      • Case Studies: Schneider switchgear; ABB switchgear; Siemens switchgear
      • Testing of HV & EHV Circuit Breakers
      • On-line Monitoring of Partial Discharge
      • Course activities
      • A visit to a company dealing with Switchgears for practical demonstration