Ensuring Safe Operation and Maintenance of Circuit Breakers and Switchgear

Introduction:

Circuit breakers, fused switches, switchgear, and other devices located in Motor Control Centres (MCC) are important components of any electrical management system in a plant. Their suitability is determined both during the initial selection phase and throughout their operation and maintenance.

Understanding the operational limits and maintenance requirements of circuit breakers and switchgear is crucial for deploying this equipment. Knowing the ratings of the local substation and system, along with the underlying principles of operation for various breakers, is vital for effective repairs.

The course on safe operation and maintenance of circuit breakers and switchgear aims to prepare participants with new or reinforced skills to install, operate, and maintain these devices safely.

Participants will learn to accurately diagnose faults and identify appropriate remedies, thereby minimizing the risk of future failures. The curriculum encompasses essential components of operational and maintenance management while emphasizing the principles of safety in operations and maintenance.

Objectives:

At the conclusion of the course on safe operation and maintenance of circuit breakers and switchgear, participants should be able to:

• Appreciate the operational characteristics of circuit breakers and switchgear.
• Formulate and pursue effective troubleshooting processes for circuit breakers and associated switchgear.
• Improve competence in using multifunction test equipment.
• Study possible modes of failure and conduct failure analyses of fuses, circuit breakers, and switchgear, focusing on air brake, vacuum, and SF6 troubleshooting.
• Review basic electrical safety knowledge applicable in substations and control rooms.
• Estimate fault levels in substations.

Training Methodology:

• Presentations and demonstrations led by the instructor
• Forums and case studies in groups
• Simulations and role plays
• Quizzes and exams
• Visits to functional substations
• Technical and library services
• Learning from one another
• Safety training and exercises
• Reflection and feedback

Course Outline:

Unit 1: The Technology of Circuit Breakers and Switchgear

• Describe common types of substation arrangements and MCCs.
• Define relevant terminology in the industry.
• Compute and explain the importance of fault levels.
• Understand how motors and generators contribute to faults.
• Discriminate between equipment types: LV, MV, and HV.
• Read nameplate data.
• Explain the roles of CTs and VTs in electrical systems.
• Understand basic protection requirements for safe operation and maintenance.
• Engage in case studies for practical insight.

Unit 2: Operation of Various Types of Interrupting Equipment

• Explain various fuse types and their applications, including motor starting fuses.
• Operate fused switches and molded case breakers.
• Handle air break switches and vacuum contactors.
• Describe vacuum circuit breakers and SF6 puffer devices.
• Discuss special insulation requirements for 36kV lines.
• Address problems related to solid and gaseous insulation.

Unit 3: The Operation and Maintenance of Circuit Breakers and Switchgear

• Accurately use Digital Voltmeters (DVM).
• Utilize oscilloscopes for maintenance procedures.
• Define the Megger and its purpose.
• Explain the use of frequency meters.
• Monitor temperatures using probes/IR pyrometers.
• Take readings with ammeters and power meters.
• Understand load bank testing.
• Apply techniques using cable fault locators.

Unit 4: Specialized Measures

• Employ NEC checklists for correct installation.
• Conduct advanced troubleshooting of electrical equipment.
• Explain methods, terminologies, and principles.
• Develop new techniques to solve problems.
• Create single-line diagrams of electrical networks.

Unit 5: The Interpretation and Use of Drawings

• Translate system overviews from drawings.
• Identify control drawings for operation and maintenance.
• Outline core generic wiring for usage.
• Read nameplate specifications.
• Use standard terminologies and symbols.
• Address step and touch potentials in safety.

Unit 6: The Development of a Job Plan

• Identify stepwise sequences for troubleshooting.
• Prepare procedures for operational readiness.
• Document best practices from lessons learned in operation and maintenance.
• Ensure continuity of practices.
• Address safety issues and training during operations.
• Analyze case studies for practical applications.

Unit 7: The Identification and Repair of Problems/Failures

• Consider common modes of failure and associated problems.
• Discuss issues related to phase imbalance and phase sequence checks.
• Describe contact pitting/arcing and its causes.
• Review load and fault ratings for electrical equipment.
• Troubleshoot failures in electronic components and their repairs.
• Conduct functional checks of switches and control circuits.
• Troubleshoot ground faults in cables and busbars, including line-to-ground, line-to-line, and ground-to-ground short circuits.
• Review safety requirements, area classifications, NEC, and electrical codes.
• Regularly update safety information regarding energy operations and maintenance solutions.