Lecture Notes on Electrical Equipment Isolation and Maintenance

Key Concepts

Importance of Isolation in Electrical Maintenance

• Essential to maintain objectivity on equipment and substations.
• Equipment must be completely isolated before performing maintenance.
• Applies to all chapters of grounding.

Types of Isolators and Disconnectors

• Isolators: Used to isolate equipment in substations.
  • Allows maintenance activities without affecting other parts of the system.
• Disconnectors: Different from circuit breakers.
  • Used to isolate a specific part of the substation.
  • Not capable of breaking a load; must be opened after the circuit breaker is open.
  • Can be operated mechanically or electrically.

Circuit Breakers vs. Disconnectors

• Circuit Breakers: Can operate under load conditions.
  • Can disconnect main supply anytime.
  • Require higher operational specifications.
• Disconnectors: Cannot operate under load conditions.
  • Must be opened only after the circuit breaker is open.
  • Available as horizontal, double break, pantograph, and other types.

Operational Considerations

• Sequence of Operations: Critical in technical tasks and interviews.
  • Correct sequence: Open disconnectors first, then circuit breakers, and vice versa.
• Types of Disconnectors: Tailored based on requirements, voltage rating, and available space.
  • Mechanically gang-operated type: All poles linked together mechanically (difficult above 245kV).
  • Electric gang-operated type: Each phase uses separate mechanisms linked by electric cables.

Earth Switches

• Purpose: Ground any trapped charges in transmission lines.

Practical Demonstrations

• Dedicated videos available for practical understanding.
  • Link in the video description or comment section.
  • Includes scenarios like what happens when disconnectors are opened improperly.

Conclusion

• Proper isolation techniques are fundamental for safe and effective electrical maintenance.
• Understanding the difference and proper usage of circuit breakers and disconnectors is crucial.
• Practical knowledge and correct operational sequences are essential for technical proficiency.