Gas Insulated MV Switchgear (C-GIS) 24kV the robust solution for Compact Gas Insulated Switchgear

Switchgear (C-GIS) 24kV

1. General Description

24kV Gas Insulated Medium Voltage Switchgear (C-GIS), also known as Compact Gas Insulated Switchgear, is a medium-voltage metal-enclosed switchgear system designed for 20kV/22kV/24kV distribution networks.

C-GIS combines gas insulation technology with vacuum circuit breaker (VCB) interruption technology to provide a compact, reliable, and environmentally resistant switching solution. All major primary components, including busbars, circuit breakers, disconnectors, and earthing switches, are enclosed inside sealed compartments.

Compared with conventional AIS, 24kV C-GIS requires less installation space and provides improved protection against humidity, dust, pollution, and harsh operating environments.

2. Typical Technical Specifications
·Equipment Type: Compact Gas Insulated Switchgear (C-GIS)
·Rated Voltage: 24 kV
·System Voltage Class: 20 / 22 / 24 kV
·Rated Frequency: 50 / 60 Hz
·Rated Current: 630 / 1250 / 2000 / 2500 A
·Short-Time Withstand Current: 20 / 25 / 31.5 kA (3 s)
·Short-Circuit Breaking Current: 20–31.5 kA
·Peak Withstand Current: 50–80 kAp
·Power Frequency Withstand Voltage: 50 kV
·Lightning Impulse Withstand Voltage (BIL): 125 kVp
·Insulation Medium: SF6 / Dry Air / N₂ / Alternative Gas
·Circuit Breaker Type: Vacuum Circuit Breaker (VCB)
·Installation: Indoor / Outdoor enclosure
·Protection Degree: IP4X–IP65 (depending on design)

3. Main Components

1.) Vacuum Circuit Breaker (VCB)
·The vacuum interrupter provides arc extinction during switching operations.
Functions:
·Interrupts short-circuit faults
·Switches feeders and transformers
·Controls distribution circuits
Advantages:
·Long operating life
·Low contact erosion
·Minimal maintenance
·Environmentally friendly operation

2.) Gas Insulated Busbar System
·The busbar is installed inside a sealed gas compartment.
Features:
·Compact arrangement
·High insulation strength
·Protected from external contamination
Benefits:
·Reduced insulation failures
·Improved reliability
·Smaller switchgear dimensions

3.) Disconnect Switch
Functions:
·Provides electrical isolation
·Enables safe maintenance
·Supports operational switching
Features:
·Gas-insulated design
·Mechanical interlocking system
·High reliability

4.) Earthing Switch
Functions:
·Grounds isolated circuits
·Removes residual voltage
·Ensures maintenance safety
Safety features:
·Electrical and mechanical interlocks
·Fault withstand capability

5.) Current Transformer (CT)
Provides measurement signals for:
·Overcurrent protection
·Transformer protection
·Metering
·Energy monitoring

6.) Voltage Transformer (VT)
Used for:
·Voltage measurement
·Protection relay inputs
·Synchronization
·Power quality monitoring

7.) Cable Connection Compartment
Designed for connection to:
·Underground cables
·Transformers
·Motors
·Ring main units
·Renewable energy systems

4. Advantages of 24kV C-GIS
* Compact Footprint
·Requires less space than AIS
·Suitable for urban and indoor substations
* High Environmental Protection
The sealed enclosure protects against:
·Dust
·Moisture
·Salt contamination
·Industrial pollution
* High Reliability
·Stable insulation performance
·Reduced external influences
·Suitable for continuous operation
* Low Maintenance
·No frequent cleaning required
·Long service intervals
·Reduced operating costs
* Enhanced Safety
·Metal enclosure prevents accidental contact
·Internal arc-resistant designs available

5. Typical Applications
24kV C-GIS is commonly used in:
·20kV/22kV distribution substations
·Industrial power systems
·Commercial buildings
·Data centers
·Renewable energy plants
·Solar PV collector systems
·Wind power substations
·Railway electrification
·Urban underground substations
·Mining and heavy industry

6. Typical Panel Configurations
Incoming Feeder Panel
·Receives power from upstream transformer or grid
Outgoing Feeder Panel
·Supplies distribution loads
Transformer Feeder Panel
·Provides transformer switching and protection
Bus Coupler Panel
·Connects and separates bus sections
Metering Panel
·Provides voltage and current measurement

7. Applicable Standards
·IEC 62271-1 — High-voltage switchgear common requirements
·IEC 62271-100 — AC circuit breakers
·IEC 62271-102 — Disconnectors and earthing switches
·IEC 62271-200 — AC metal-enclosed switchgear and controlgear up to 52kV
·IEEE C37 series — Medium-voltage switchgear standards

Summary
24kV Gas Insulated Medium Voltage Switchgear (C-GIS) is a compact 20/22/24kV-class distribution switchgear system using sealed gas insulation and vacuum circuit breaker technology. It typically supports 630–2500A rated current and 20–31.5kA short-circuit breaking capability, providing a reliable, space-saving, low-maintenance solution for urban distribution networks, industrial facilities, renewable energy systems, and modern substations.