Hybrid Gas Insulated Switchgear (HGIS) 245kV offering the high-voltage switching system

Switchgear (HGIS) 245kV

1. General Description

245kV Hybrid Gas Insulated Switchgear (HGIS) is an extra-high-voltage switching system that combines the compactness and reliability of Gas Insulated Switchgear (GIS) with the flexibility and lower investment cost of Air Insulated Switchgear (AIS).

In a 245kV HGIS system, major primary equipment such as the circuit breaker, disconnectors, earthing switches, current transformers (CT), and voltage transformers (VT/CVT) are integrated into gas-insulated modules, while external connections such as busbars, overhead lines, and transformer connections can remain air-insulated.

The 245kV HGIS class is widely applied in 220kV transmission networks, large substations, power plants, and renewable energy transmission systems.

2. Typical Technical Specifications
·Equipment Type: Hybrid Gas Insulated Switchgear (HGIS)
·Rated Voltage: 245 kV
·System Voltage Class: 220 / 230 kV
·Rated Frequency: 50 / 60 Hz
·Rated Current: 2000 / 3150 / 4000 A
·Short-Time Withstand Current: 40 / 50 / 63 kA (3 s)
·Short-Circuit Breaking Current: 40–63 kA
·Peak Withstand Current: 100–160 kAp
·Power Frequency Withstand Voltage: Approx. 460 kV
·Lightning Impulse Withstand Voltage (BIL): 950 kVp
·Insulation Medium: SF6 / alternative insulating gas
·Circuit Breaker Type: SF6 or Vacuum Interrupter
·Installation: Outdoor / Indoor GIS hall
·Enclosure Type: Metal-enclosed gas compartments

3. Main Components

1.) 245kV Gas Insulated Circuit Breaker
·The circuit breaker is installed inside a sealed gas enclosure.
Functions:
·Interrupts short-circuit currents
·Controls transmission line switching
·Protects transformers and generators
Features:
·High breaking capacity
·Fast operation
·High mechanical durability
·Low maintenance requirements
Available technologies:
·SF6 circuit breaker
·SF6 free circuit breaker
·Vacuum interrupter circuit breaker (selected applications)

2.) Gas Insulated Disconnectors
Functions:
·Provide electrical isolation
·Enable safe maintenance
·Support bus transfer operations
Features:
·Compact design
·High dielectric strength
·Reliable mechanical operation

3.) Earthing Switches
Types:
·Maintenance earthing switch
·High-speed earthing switch
Functions:
·Ground isolated sections
·Discharge trapped charges
·Improve maintenance safety

4.) Current Transformer (CT)
Integrated CTs provide:
·Protection measurement
·Metering accuracy
·Fault detection
Applications:
·Differential protection
·Distance protection
·Overcurrent protection
·Energy measurement

5.) Voltage Transformer / Capacitor Voltage Transformer Interface
Provides voltage signals for:
·Protection relays
·Metering systems
·Synchronization
·Monitoring and control

6.) AIS Connection Section
The hybrid design allows connection to:
·Air-insulated busbars
·Overhead transmission lines
·Power transformers
·Cable systems

This provides excellent flexibility for new substations and retrofit projects.

4. Advantages of 245kV HGIS
* Compact Substation Layout
·Requires much less space than conventional AIS
·Suitable for land-limited transmission sites
* High Reliability
Gas-insulated components are protected from:
·Dust
·Humidity
·Pollution
·Salt contamination
* Lower Cost than Full GIS
·Reduced gas-insulated sections
·Lower installation complexity
·Reduced civil construction requirements
* Easy Retrofit and Expansion
Suitable for:
·Existing AIS upgrades
·Substation extension
·Replacement of aging equipment
* Reduced Maintenance
·Sealed high-voltage components
·Stable insulation performance
·Less exposure to environmental conditions

5. Typical Applications
245kV HGIS is commonly installed in:
·220kV transmission substations
·Large power plants
·Hydropower transmission systems
·Renewable energy export substations
·Industrial power networks
·Coastal and high-pollution areas
·Urban grid reinforcement projects
·Existing AIS modernization projects

6. Typical Configuration Schemes
Single Busbar
·Simple and economical
·Used for standard transmission substations
Double Busbar
·High operational flexibility
·Allows equipment maintenance without complete shutdown
Ring Bus
·Improves network reliability
Breaker-and-a-Half
·Used in important 220kV transmission nodes

7. Applicable Standards
·IEC 62271-1 — High-voltage switchgear common requirements
·IEC 62271-100 — High-voltage AC circuit breakers
·IEC 62271-102 — Disconnectors and earthing switches
·IEC 62271-203 — Gas-insulated metal-enclosed switchgear above 52kV
·IEEE C37 series — High-voltage switchgear standards

Summary
245kV Hybrid Gas Insulated Switchgear (HGIS) is a 220kV-class extra-high-voltage switching system combining GIS compactness with AIS flexibility. It typically provides 2000–4000A continuous current capacity and 40–63kA short-circuit breaking capability, making it suitable for large transmission substations, renewable energy integration, power plants, and high-reliability grid expansion projects.