Gas Insulated Switchgear (GIS) 245kV offering compact, highly reliable, and low-maintenance solution for critical transmission substations

Switchgear (GIS) 245kV

245kV Gas Insulated Switchgear (GIS) is an extra-high-voltage switchgear system designed for 220kV class transmission networks. It uses SF6 gas or environmentally friendly alternative insulating gases as the insulation medium and integrates high-voltage primary equipment—including circuit breakers, disconnectors, earthing switches, current transformers, voltage transformers, surge arresters, and gas-insulated busbars—within sealed, grounded metal enclosures.

Compared with conventional Air Insulated Switchgear (AIS), 245kV GIS provides a compact, highly reliable, and low-maintenance solution for critical transmission substations.

Main Functions
·Transmission Circuit Switching: Controls connection and disconnection of 220kV-class transmission lines.
·Fault Current Interruption: Interrupts short-circuit currents through high-performance circuit breakers.
·Electrical Isolation: Provides safe isolation for maintenance and inspection.
·Protection & Measurement: Integrates CTs and VTs for relay protection, metering, and automation.
·Substation Space Optimization: Minimizes land requirements while maintaining high reliability.

Typical Applications
·220kV transmission substations
·Urban and underground substations
·Power generation plants
·Hydropower stations
·Large-scale wind and solar power plants
·Industrial high-voltage substations
·Railway traction power systems
·Coastal and heavily polluted environments
·Space-limited transmission facilities

Typical Technical Specifications
·Rated Voltage: 245 kV
·Highest System Voltage: 245 kV
·Rated Frequency: 50 Hz / 60 Hz
·Rated Current: 2000 A – 4000 A
·Short-Time Withstand Current: 40 kA – 63 kA
·Peak Withstand Current: 100 kA – 160 kA
·Lightning Impulse Withstand Voltage: Up to 1050 kV
·Power Frequency Withstand Voltage: Up to 460 kV
·Insulation Medium: SF6 / alternative gas
·Installation: Indoor or outdoor enclosure
·Enclosure Material: Aluminum alloy / stainless steel
·Protection Degree: Gas-tight sealed compartments

Main Components
1.) Gas Insulated Busbar
·Transfers power between GIS bays
·Completely enclosed by grounded metal housings
·Provides compact and reliable high-voltage connection
2.) High Voltage Circuit Breaker
·Interrupts normal and fault currents
·Uses SF6 or advanced interruption technology
·Provides fast and reliable fault clearing
3.) Disconnector (DS)
·Provides electrical isolation
·Enables safe maintenance operations
·Allows busbar and line switching arrangements
4.) Earthing Switch (ES)
·Grounds isolated equipment
·Ensures operator safety during maintenance
5.) Current Transformer (CT)
·Used for:
·Line protection
·Busbar differential protection
·Distance protection
·Energy metering
6.) Voltage Transformer (VT/CVT)
·Provides voltage signals for:
·Protection relays
·Synchronization systems
·Metering equipment
·SCADA monitoring
7.) Surge Arrester
·Protects GIS insulation from:
·Lightning surges
·Switching overvoltages
·Transient disturbances
8.) Gas Compartments
·Separate GIS sections into sealed modules
·Minimize gas loss during maintenance
·Improve availability and reliability

Operating Principle
Normal Operation
·High-voltage conductors operate inside sealed metal compartments.
·Insulating gas provides dielectric separation between live parts and earth.
·Electrical energy flows through enclosed busbars and switching equipment.
Fault Operation
·Protection relay detects a fault.
·Circuit breaker receives a trip command.
·Fault current is interrupted.
·Disconnectors isolate the affected circuit.
·Earthing switches ground isolated equipment for maintenance.

Advantages
·Extremely compact compared with AIS
·Excellent insulation performance
·High reliability and availability
·Resistant to pollution, dust, humidity, and salt contamination
·Suitable for urban and underground substations
·Reduced maintenance requirements
·Improved personnel safety
·Long service life
·Reliable operation under harsh environmental conditions

Typical GIS Configurations
Single Busbar GIS
·Simple and economical arrangement
·Used for standard transmission substations
Double Busbar GIS
·Provides operational flexibility
·Allows maintenance with reduced outages
Ring Bus GIS
·Improves supply reliability
·Used in important grid nodes
Breaker-and-a-Half GIS
·Provides high reliability
·Used for critical 220kV transmission substations

Applicable Standards
·IEC 62271-1 – High-voltage switchgear and controlgear common specifications
·IEC 62271-100 – High-voltage AC circuit breakers
·IEC 62271-102 – Disconnectors and earthing switches
·IEC 62271-203 – Gas-insulated metal-enclosed switchgear above 52 kV
·IEEE C37.122 – Gas-Insulated Substations

Typical Applications by Industry
·Electric Utilities: 220kV transmission substations
·Renewable Energy: Large renewable energy grid integration
·Power Generation: Generator step-up and transmission connection
·Industrial Plants: High-capacity receiving substations
·Railways: High-voltage traction supply systems
·Urban Infrastructure: Underground and compact substations
·Oil & Gas: Critical power transmission systems

Key Features
·Rated voltage 245kV
·Designed for 220kV transmission systems
·Metal-enclosed gas-insulated construction
·Integrated CB, CT, VT, DS, ES, and surge protection modules
·Compact installation footprint
·High dielectric strength and insulation reliability
·Excellent environmental resistance
·Low maintenance requirement
·High operational safety and availability
·Suitable for digital and smart grid substations
·Compliant with IEC 62271 and IEEE C37.122 standards