The technical specifications for a 400 kV switchyard outline the requirements and parameters necessary for the design, construction, and operation of the switchyard, which is a crucial component of an electrical power transmission system. Here are some key aspects typically included in the technical specifications:

1. Voltage Level: The switchyard is designed to handle high voltage, typically at 400 kV, which is necessary for the transmission of bulk power over long distances.

2. Layout and Configuration: The technical specifications detail the layout and configuration of the switchyard, including the arrangement of equipment such as circuit breakers, disconnect switches, transformers, busbars, and surge arresters. This ensures efficient operation and maintenance of the switchyard.

3. Clearances and Spacings: Clearances and spacings between conductors, equipment, and structures are specified to comply with safety standards and to prevent electrical arcing and flashovers, especially under high voltage conditions.

4. Equipment Ratings: Specifications for the ratings and capacities of various equipment such as circuit breakers, transformers, and busbars are provided to ensure they can handle the expected electrical loads and fault conditions.

5. Protection and Control Systems: Detailed requirements for protection and control systems are included, such as relay protection schemes, supervisory control and data acquisition (SCADA) systems, and communication interfaces. These systems are crucial for monitoring and safeguarding the switchyard against faults and abnormal operating conditions.

6. Earthing System: Specifications for the earthing system design and installation are provided to ensure proper grounding of equipment and structures, which is essential for safety and to mitigate the effects of lightning and fault currents.

7. Civil Works and Foundations: Requirements for civil works and foundations are outlined, including specifications for the design and construction of foundations for equipment, support structures, and fencing to withstand environmental loads and provide structural stability.

8. Environmental Considerations: Environmental considerations such as protection against corrosion, seismic design criteria, and measures to mitigate electromagnetic interference (EMI) and radio frequency interference (RFI) are addressed to ensure the longevity and reliability of the switchyard.

9. Testing and Commissioning: Procedures for testing, commissioning, and acceptance testing of the switchyard equipment and systems are specified to verify compliance with design requirements and to ensure safe and reliable operation.

10. Documentation and Drawings: Detailed documentation including drawings, technical specifications, operation and maintenance manuals, as-built drawings, and test reports are required to provide comprehensive guidance for installation, operation, and maintenance of the switchyard.

These technical specifications serve as a guideline for contractors, engineers, and operators involved in the design, construction, and operation of a 400 kV switchyard, ensuring that it meets performance, safety, and reliability requirements for transmitting electricity efficiently and securely.

 

Technical Specification for 400 kV Switchyard Package

1. General Requirements

1.1 Scope

• Complete design, engineering, and installation of 400 kV switchyard
• Supply of all equipment and materials
• Testing and commissioning
• Integration with existing systems
• Documentation and training

1.2 Standards Compliance

• IEC 62271: High-voltage switchgear and controlgear
• IEC 60044: Instrument transformers
• IEC 60071: Insulation coordination
• IEEE C37: Power switchgear standards
• National electrical safety codes and regulations

2. Major Equipment Specifications

2.1 Circuit Breakers

• Type: SF6 gas insulated
• Rated voltage: 420 kV
• Rated normal current: 3150 A
• Short circuit breaking current: 50 kA
• Operating mechanism: Spring-charged motor
• Operating cycle: O-0.3s-CO-3min-CO
• Auxiliary voltage: 220V DC

2.2 Disconnectors

• Type: Center break/Pantograph
• Rated voltage: 420 kV
• Rated normal current: 3150 A
• Short-time withstand current: 50 kA for 1 second
• Operating mechanism: Motor operated with manual override
• Earthing switches: Integrated where specified

2.3 Current Transformers

• Type: Oil-filled/SF6
• Ratio: 2000-1000/1-1-1-1 A
• Accuracy class:
  • Protection core: 5P20
  • Metering core: 0.2S
• Rated burden: 30 VA
• Short-time current rating: 50 kA for 1 second

2.4 Voltage Transformers

• Type: Electromagnetic/Capacitive
• Ratio: 400kV/√3 : 110V/√3
• Accuracy class:
  • Protection: 3P
  • Metering: 0.2
• Rated burden: 50 VA
• Voltage factor: 1.2 continuous, 1.5 for 30 seconds

3. Insulation Requirements

3.1 Insulation Levels

• Rated lightning impulse withstand voltage: 1425 kV peak
• Rated switching impulse withstand voltage: 1050 kV peak
• Rated power frequency withstand voltage: 630 kV rms
• Minimum creepage distance: 25 mm/kV

3.2 Clearances

• Phase to phase (minimum): 4000 mm
• Phase to ground (minimum): 3500 mm
• Section clearance: 4500 mm
• Safety clearance (ground level): 8400 mm

4. Control and Protection

4.1 Protection Systems

• Main-1 protection: Numerical distance protection
• Main-2 protection: Line differential protection
• Backup protection: Directional overcurrent and earth fault
• Breaker failure protection
• Auto-reclose functionality
• Synchro-check functionality

4.2 Control Systems

• Bay control units with IEC 61850 compliance
• Station HMI system
• SCADA integration capability
• Sequence of events recording
• Fault recording and analysis

5. Support Systems

5.1 Auxiliary Power Supply

• AC supply: 415V ±10%, 50Hz ±5%
• DC supply: 220V ±10%
• Emergency power backup
• Automatic transfer scheme

5.2 Lightning Protection

• Lightning masts or shield wires
• Earth grid design as per IEEE 80
• Surge arresters:
  • Rated voltage: 336 kV
  • Energy handling capability: Class 5

6. Civil and Structural Requirements

6.1 Foundations

• Equipment foundations with design load factors
• Cable trenches and ducts
• Oil collection pits for transformers
• Surface treatment and finishing

6.2 Structures

• Galvanized steel structures
• Wind load consideration: As per site conditions
• Seismic considerations: Zone specific
• Anti-climbing devices

7. Testing and Commissioning

7.1 Factory Tests

• Routine tests as per IEC standards
• Type tests certificates
• Special tests as specified
• Witness testing requirements

7.2 Site Tests

• Installation checks
• Pre-commissioning tests
• System integration tests
• Protection coordination tests
• Performance guarantee tests

8. Documentation Requirements

8.1 Design Documents

• Single line diagrams
• Layout drawings
• Equipment drawings
• Cable schedules
• Protection coordination studies

8.2 Operation and Maintenance

• Operation manuals
• Maintenance schedules
• Spare parts list
• Test reports
• As-built drawings

9. Quality Assurance

9.1 Quality Control

• ISO 9001 certification requirement
• Manufacturing quality plan
• Field quality plan
• Inspection hold points
• Test certificates

9.2 Warranty

• Equipment warranty: 24 months from commissioning
• Performance guarantee parameters
• Defect liability period
• Service support requirements

10. Environmental Requirements

10.1 Operating Conditions

• Ambient temperature: -5°C to +50°C
• Relative humidity: Up to 95%
• Altitude: Site specific
• Pollution level: Heavy/Very Heavy

10.2 Environmental Protection

• Oil spill prevention measures
• SF6 gas handling procedures
• Noise level restrictions
• EMC compliance

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