Gas Insulated Switchgear (GIS) 170kV provide a compact substation solution

Switchgear (GIS) 170kV

170kV Gas Insulated Switchgear (GIS) is a high-voltage switchgear system designed for 150kV-class transmission networks. It uses SF6 gas or environmentally friendly alternative insulating gases as the primary insulation medium and integrates high-voltage switching and protection equipment into sealed, grounded metal compartments.

A 170kV GIS typically incorporates circuit breakers, disconnectors, earthing switches, current transformers, voltage transformers, surge arresters, and gas-insulated busbars into a compact substation solution.

Main Functions
·Power Switching: Controls connection and disconnection of high-voltage transmission circuits.
·Fault Current Interruption: Clears short-circuit currents using high-voltage circuit breakers.
·Electrical Isolation: Provides safe isolation for inspection and maintenance.
·Protection & Measurement: Supplies accurate current and voltage signals to protection relays and metering systems.
·Space Reduction: Provides a compact alternative to conventional AIS substations.

Typical Applications
·154/161kV transmission substations
·Utility grid substations
·Underground and indoor substations
·Hydropower plants
·Large renewable energy projects
·Industrial high-voltage receiving stations
·Railway traction substations
·Coastal and polluted-area substations

Typical Technical Specifications
·Rated Voltage: 170 kV
·Highest System Voltage: 170 kV
·Rated Frequency: 50 Hz / 60 Hz
·Rated Current: 1250 A – 4000 A
·Short-Time Withstand Current: 31.5 kA – 63 kA
·Peak Withstand Current: 80 kA – 160 kA
·Lightning Impulse Withstand Voltage: Up to 750 kV
·Power Frequency Withstand Voltage: Up to 325 kV
·Insulation Medium: SF6 / alternative gas
·Installation: Indoor or outdoor enclosure
·Enclosure Material: Aluminum alloy / stainless steel
·Protection Degree: Sealed gas compartments

Main Components
1.) Gas Insulated Busbar
·Transmits power between GIS bays
·Fully enclosed in grounded metallic housing
·Provides compact and reliable electrical connection
2.) High Voltage Circuit Breaker
·Interrupts normal and fault currents
·Uses SF6 or advanced interruption technology
·Controlled by protection and automation systems
3.) Disconnector (DS)
·Provides electrical isolation after circuit interruption
·Used for maintenance and operational switching
4.) Earthing Switch (ES)
·Grounds isolated circuits
·Ensures safe maintenance conditions
5.) Current Transformer (CT)
·Provides signals for:
·Differential protection
·Distance protection
·Overcurrent protection
·Revenue metering
6.) Voltage Transformer (VT)
·Provides voltage signals for:
·Protection relays
·Metering systems
·Synchronization
·Grid monitoring
7.) Surge Arrester
·Protects GIS equipment from lightning and switching surges
·Limits transient overvoltages
8.) Gas Compartments
·Divide GIS into independent sealed sections
·Allow maintenance without complete shutdown
·Improve system reliability

Operating Principle
Normal Operation
·High-voltage conductors are enclosed inside grounded metal chambers.
·Insulating gas provides high dielectric strength between energized parts and earth.
·Current flows through enclosed busbars and switching components.
During Fault Conditions
·Protection relay detects abnormal conditions.
·Circuit breaker receives a trip command.
·Fault current is interrupted.
·Disconnectors isolate the affected section.
·Earthing switches discharge and ground the isolated equipment.

Advantages
·Compact compared with AIS
·High insulation reliability
·Excellent performance in polluted and coastal environments
·Reduced substation footprint
·High operational availability
·Lower maintenance requirements
·Improved personnel safety
·Suitable for indoor, underground, and harsh environments
·Long service life

Typical GIS Configurations
Single Busbar GIS
·Simple arrangement
·Lower investment
·Suitable for standard substations
Double Busbar GIS
·Flexible operation
·Enables maintenance without major outages
Ring Bus GIS
·Improves power supply continuity
·Used in important grid locations
Breaker-and-a-Half GIS
·High reliability configuration
·Used in critical 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: 154/161kV transmission substations
·Renewable Energy: Large-scale wind and solar grid integration
·Hydropower: Generator step-up and transmission substations
·Industrial Plants: High-voltage power receiving stations
·Railways: High-voltage traction substations
·Urban Infrastructure: Compact indoor substations
·Oil & Gas: Reliable transmission-level power systems

Key Features
·Rated voltage 170kV
·Suitable for 150/154/161kV transmission systems
·Metal-enclosed gas-insulated construction
·Integrated CB, CT, VT, DS, ES, and surge protection
·Compact footprint compared with AIS
·High dielectric strength
·Excellent environmental resistance
·Low maintenance and high reliability
·Suitable for digital substations and smart grids
·Designed according to IEC 62271 and IEEE C37.122 standards