Unit 1 Introduction to Power System Protection

• Role and objectives of power system protection
• Substation equipment overview
• Types of faults and abnormal system conditions
• Fault current calculation and fault clearing process
• Principles of protective relaying
• Neutral grounding methods and equipment grounding
• Switchgear terminology
• standards, and specifications
• static, and numerical relays
• HRC fuses – construction
• selection, and applications

Unit 2 High Voltage A.C. Circuit Breakers

4 lecture hours

• Circuit breaker fundamentals and interruption process
• Trip circuits
• control circuits, and auxiliary components
• constructional features, and operating mechanisms
• Interlocking schemes
• indication systems, and auxiliary switches
• Timing characteristics
• auto-reclosing, and trip‑free mechanisms
• Modern developments
• materials, and design considerations

Unit 3 Switching Phenomena and Circuit-Breaker Rating

8 lecture hours

• Transient phenomena in switching
• RLC representation of power system components
• Voltage and current behaviour under short‑circuit conditions
• transient, and steady‑state components
• Arc interruption theory for AC breakers
• Transient Recovery Voltage (TRV)
• its rate of rise
• damping, and control
• Resistance switching
• opening resistors, and current chopping
• Interruption of terminal faults
• short-line faults, and phase‑opposition switching

Unit 4 Circuit Breaker

8 lecture hours

• Air-Break Circuit Breakers: Arc extinction
• arc chute design
• operating mechanism
• Miniature circuit breakers (MCB): characteristics and ratings Air-Blast Circuit Breakers: Principle
• arc quenching
• resistance switching
• Generator circuit breakers
• compressed air system design SF₆ Circuit Breakers: Properties of SF₆ gas, Arc interruption mechanism
• puffer and self-blast designs
• environmental considerations Oil Circuit Breakers (Minimum & Bulk Oil): Types
• thermal and dielectric properties of oil, Pre-arcing
• TRV behaviour
• contact assembly Vacuum Circuit Breakers: Vacuum arc characteristics
• arc behaviour

Unit 5 Fault Analysis

4 lecture hours

• Introduction: Procedure of Fault calculation
• Representation of Power System
• Per Unit Method and its Advantages
• Selection of Bases
• Symmetrical Faults and Current Limiting Reactors: Fault MVA and fault current
• Reactors in Power Systems
• Principle Current limiting reactors: design features
• placement Impact on fault level reduction and system stability

Unit 6 Relays

8 lecture hours

• Fundamentals: Protective zones
• primary & backup protection
• Relaying terminology and desirable characteristics
• Protective CTs and PTs, actuating quantities
• numerical relays
• Carrier-aided protection
• programmable relays
• system security Relay Types: Auxiliary and sealing relays
• attracted armature
• balanced beam
• induction disc & cup relays
• rectifier, and frequency relays
• Directional relays (polarized
• DC relays
• Plug setting
• time setting
• testing methods

Unit 7 Protection

• Induction Motor Protection: Abnormal operating conditions and failure causes
• single-phasing protection
• Phase reversal
• phase-phase fault & earth-fault protection
• Rotor winding faults Transformer Protection: Protection requirements
• safety devices
• Buchholz relay
• oil & 10 Program Name: Bachelor of Engineering Level: UG Branch: Power Electronics Subject Code: BE05024051 Subject Name: Switch Gear & Protection Sr.No Content Total Hrs winding temperature protection
• Percentage and biased differential protection
• Restricted earth fault
• protection of parallel transformers
• Thermal overload protection Generator Protection: Stator & rotor faults
• differential protection
• Negative sequence
• loss of excitation
• Reverse power
• field suppression Bus-Zone Protection: Busbar protection philosophy
• High impedance and biased differential protection
• CT location & secondary monitoring
• Interlocked over-current protection
• Bus transfer schemes for industrial and auxiliary switchgear