Hybrid Gas Insulated Switchgear (HGIS) 362kV for extra-high-voltage switching system

Switchgear (HGIS) 362kV

1. General Description

362kV Hybrid Gas Insulated Switchgear (HGIS) is an extra-high-voltage switching system that combines the advantages of Gas Insulated Switchgear (GIS) and Air Insulated Switchgear (AIS) for high-capacity transmission networks.

The HGIS design integrates major primary equipment—including the circuit breaker, disconnectors, earthing switches, current transformers (CT), and voltage transformers (VT/CVT)—into compact gas-insulated modules, while maintaining AIS-style connections for busbars, overhead lines, and transformers. This provides a balance between GIS compactness and AIS flexibility.

The 362kV class is mainly applied in 345kV/362kV transmission systems and large-scale grid substations.

2. Typical Technical Specifications
·Equipment Type: Hybrid Gas Insulated Switchgear (HGIS)
·Rated Voltage: 362 kV
·System Voltage Class: 345 kV
·Rated Frequency: 50 / 60 Hz
·Rated Current: 3150 / 4000 / 5000 A
·Short-Time Withstand Current: 50 / 63 kA (3 s)
·Short-Circuit Breaking Current: 50 / 63 kA
·Peak Withstand Current: 125 / 160 kAp
·Power Frequency Withstand Voltage: 510 / 650 kV (typical)
·Switching Impulse Withstand: Up to 950 / 1050 kVp
·Lightning Impulse Withstand (BIL): Up to 1175 / 1425 kVp
·Insulation Medium: SF6 or alternative insulating gas
·Circuit Breaker Type: SF6 interrupter (typical)
·Installation: Indoor / Outdoor
·Mechanical Endurance: M2 class

Typical 362kV HGIS ratings include 3150–5000A continuous current and 50–63kA short-circuit interruption capability.

3. Main Components

1.) 362kV Gas Insulated Circuit Breaker
·The circuit breaker is the main fault-clearing device.
Functions:
·Interrupts high short-circuit currents
·Performs line and transformer switching
·Protects transmission equipment
Features:
·High breaking capacity
·Fast operating mechanism
·High mechanical reliability
·Reduced maintenance requirements

2.) Gas Insulated Disconnectors
Functions:
·Isolate equipment sections
·Provide maintenance safety
·Enable bus transfer operations
Advantages:
·Compact construction
·High dielectric strength
·Reliable switching performance

3.) Earthing Switches
Types:
·Maintenance earthing switch
·High-speed earthing switch
Functions:
·Ground isolated sections
·Discharge trapped electrical energy
·Ensure safe maintenance operations

4.) Current Transformers (CT)
Integrated CTs provide:
·Protection signals
·Metering measurement
·Fault detection
Applications:
·Line protection
·Transformer differential protection
·Distance protection
·Revenue metering

5.) Voltage Transformer / CVT Interface
Provides voltage measurement for:
·Protection relays
·Synchronization systems
·Monitoring equipment
·Control systems

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

This makes HGIS suitable for both new substations and expansion of existing AIS yards.

4. Advantages of 362kV HGIS
* Reduced Footprint
·Requires significantly less space than conventional AIS
·Suitable for large transmission substations with limited land availability
* High Reliability
Gas-insulated modules protect critical equipment from:
·Dust
·Humidity
·Pollution
·Salt contamination
* Lower Cost Compared with Full GIS
·Fewer fully enclosed GIS sections
·Reduced installation complexity
·Lower civil construction requirements
* Faster Installation
·Factory-assembled modules
·Reduced site assembly work
·Shorter commissioning period
* Flexible Substation Integration
Suitable for:
·New EHV substations
·AIS replacement projects
·Grid expansion projects

5. Typical Applications
362kV HGIS is commonly used in:
·345kV transmission substations
·Large power generation plants
·Hydroelectric transmission systems
·Renewable energy export substations
·Interconnection substations
·Urban EHV substations
·Coastal/high-pollution environments
·Existing AIS modernization projects

6. Typical Configuration Schemes
Single Busbar
·Simple arrangement
·Lower investment
·Used for standard transmission stations
Double Busbar
·Improved operational flexibility
·Allows maintenance during operation
Ring Bus
·Increased supply reliability
Breaker-and-a-Half Scheme
·Used for critical 345kV transmission networks

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 requirements

Summary
362kV Hybrid Gas Insulated Switchgear (HGIS) is an 345kV-class extra-high-voltage switching solution combining GIS reliability with AIS flexibility. It typically supports 3150–5000A continuous current ratings and 50–63kA short-circuit breaking capacity, providing a compact, reliable, and economical solution for large transmission substations, renewable energy integration, and EHV grid expansion projects.