CIRCUIT BREAKERS AND SURGE ARRESTERS (SA)

OBJECTIVES:
• Select circuit breakers and surge arresters for HV/MV applications.
• Understand breaking capacity, insulation coordination, and duty cycles.

KEY TOPICS:
• Circuit breaker types (SF6, vacuum, GIS, AIS).
• Breaking capacity (asymmetrical, symmetrical, making current).
• Operating mechanisms (spring, hydraulic, pneumatic).
• Surge arrester selection (MCOV, energy rating, discharge voltage).
• Insulation coordination and BIL.

PRACTICAL FOCUS:
• Prepare CB specification for 33kV 25kA application.
• Exercise: Select a surge arrester for the 132kV line entrance.
• Case study: CB failure due to incorrect breaking capacity.

SUGGESTED DIAGRAMS:
• CB nameplate parameters.
• Surge arrester V-I characteristic.
• CB operating duty cycle.

KEY TAKEAWAYS:
• Ability to select CB and SA for projects.
• Understanding of switching and lightning over voltages.

STANDARDS & REFERENCES:
• IEC 62271-100 (CB), IEC 60099-4 (SA).
• Client CB specifications.

CERTIFICATION & DELIVERY:
• Certificate of Completion awarded.
• Delivery Mode: Online (On-demand).

PREREQUISITES:
• Basic knowledge of fault levels and overvoltages.