Switchgear and Motor Control Center (MCC)

DESCRIPTION Switchgear plays an important role in electricity distribution and its performance significantly affects the overall performance of the system. Failure to efficiently disconnect faults elsewhere in the network or failure in switchgear itself is costly, resulting in additional loss of supply, damage to equipment and possibly fatal injury to personnel. It is therefore critically important that switchgear is operated and maintained correctly, within an overall asset management regime that is both economic and effective in securing a high level of system reliability. OBJECTIVE By the end of this course the participants will gain the following;

• Know how to calculate the short circuit level.
• The transient phenomena in power systems.
• Understand the arc phenomena and circuit interruption.
• Know the different types of circuit breakers and industrial switchgears.
• Be able to select the proper specifications of CB and switchgears.
• Know the maintenance procedures.
• Be able to do all tests on circuit breakers.
• Be able to detect circuit breakers troubleshooting.
• Know the methods of system earthing and protection requirements.
• Be able to control circuit breakers with associated relaying systems.

OUTLINE Introduction to Switchgear

• Single line diagrams – what is a power network? Why different voltage levels?
• Network components – active and passive  – typical examples
• Simple busbar and substation layouts – layouts – protection and control circuits
• Fault Levels & MVA rating of equipment
• Measuring transformers VT’s and CT’s
• Circuit breaker utilization, disconnector  operation and earthing switches
• Fuses - LV and HV fuses. Fuse gear
• Air break switches
• MCC’s for LV distribution boards
• Rating of switchgear - normal and fault duties
• Selection and checking for correct  switchgear ratings  - LV, MV, HV and EHV

Distribution Switchgear

• Primary substations – name plate data
• Device function numbers – suffix letters, main devices and auxiliary devices
• Vacuum Switchgear up to 36kV
• Description of equipment  – front, rear, cable entry and busbars
• Vacuum principles of interruption
• Air and SF6 external insulation of busbars and vacuum interrupters
• Oil breakers
• Maintenance requirements air, oil, vacuum and  SF6

Switching, Safety and Earthing Requirements

• Busbar configurations – single, double, sectionalized and breaker and a half
• Main substation earthing and bonding
• Step and touch potentials – danger to personnel
• Routine testing and certification of substation earthing
• Interrupter classification - mechanisms, motor - spring, hydraulic and solenoid
• Switching Requirements – interrupting time
• Auto - reclosing considerations – ring main and radial circuits

The Technology of Circuit Breakers and Switchgear

• Typical substation arrangements and MCC's
• Definitions and terminology
• Fault level calculations
• Motor and generator fault contributions
• Low voltage equipment
• Medium voltage equipment
• High voltage equipment
• Name plate ratings - interpretation
• CT's and VT's
• Basic protection requirements

Operation of various types of interrupting equipment

• Fuses - motor starting types
• Fused switches
• Moulded case type breakers
• Air break switches
• Vacuum contactors - fused
• Vacuum circuit breakers
• SF6 puffer, rotating arc devices
• Special insulating requirements for 36kV
• Solid and gaseous insulation - problems!

Maintenance and testing

• Health and Safety in Substations
• Mechanisms of deterioration of insulation
• MCC testing and refurbishment - contacts and arc chutes
• Trouble shooting  – use of diagrams and manufacturers manuals
• Block diagrams, line diagrams, wiring diagrams, interlock diagrams
• Required maintenance – condition, heaters, fuses, mechanism, overhaul
• Weekly, monthly, yearly program of maintenance – 5 years and more?
• Principles of circuit breaker maintenance – mechanisms and mechanical aspects

The Identification and Repair of Problems/ Failures PARTICIPANT Electrical Engineers, technicians and technologists in the industrial, commercial, and institutions, consulting electrical engineers, and electric utilities who involved in power system design. This course is also appropriate for power system operation and maintenance personnel who require knowledge of electrical system design techniques.   TRAINING METHOD Presentation Discussion Case Study Evaluation   FACILITIES Training Kit Handout Certificate 1 X Lunch 2 X Coffee Break Souvenir