Gas Insulated MV Switchgear (C-GIS) 12kV for provide reliable insulation and arc protection

Switchgear (C-GIS) 12kV

1. General Description

12kV Gas Insulated Medium Voltage Switchgear (C-GIS), also known as Compact Gas Insulated Switchgear, is a medium-voltage metal-enclosed switchgear system designed for distribution networks. It uses a gas-insulated compartment structure to provide reliable insulation and arc protection while maintaining a compact footprint.

Unlike conventional Air Insulated Switchgear (AIS), C-GIS encloses the primary electrical components in sealed gas compartments, making it highly resistant to environmental conditions such as humidity, dust, pollution, and salt contamination.

The 12kV C-GIS class is widely used in 10kV/11kV/12kV distribution systems, industrial power networks, renewable energy plants, commercial buildings, and urban substations.

2. Typical Technical Specifications
·Equipment Type: Compact Gas Insulated Switchgear (C-GIS)
·Rated Voltage: 12 kV
·System Voltage Class: 10 / 11 / 12 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: 28 kV
·Lightning Impulse Withstand Voltage (BIL): 75 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 circuit breaker is the main switching element.
Functions:
·Interrupts short-circuit currents
·Controls feeder switching
·Protects transformers and distribution equipment
Advantages:
·Long electrical life
·Low maintenance
·Environmentally friendly
·Fast interruption capability

2.) Gas Insulated Busbar Compartment
Features:
·Sealed metal enclosure
·Compact conductor arrangement
·High dielectric strength
Benefits:
·Prevents contamination
·Reduces insulation failures
·Improves operational reliability

3.) Disconnect Switch
Functions:
·Provides electrical isolation
·Enables safe maintenance
·Supports switching operations
Features:
·Compact mechanism
·High mechanical endurance

4.) Earthing Switch
Functions:
·Grounds isolated circuits
·Ensures operator safety
·Discharges residual voltage
·Interlocking systems prevent unsafe operations.

5.) Current Transformer (CT)
Used for:
·Overcurrent protection
·Metering
·Energy monitoring
·Fault detection

6.) Voltage Transformer (VT)
Provides voltage signals for:
·Protection relays
·Metering
·Power quality monitoring

7.) Cable Termination Compartment
Supports connection to:
·Underground cables
·Transformers
·Motors
·Ring main units

4. Advantages of 12kV C-GIS
* Compact Design
·Much smaller than conventional AIS panels
·Ideal for space-limited substations
* High Reliability
Protected against:
·Dust
·Moisture
·Pollution
·Condensation
* Low Maintenance
·Sealed insulation system
·Reduced cleaning requirements
·Stable dielectric performance
* Improved Safety
·Metal enclosure prevents accidental contact
·Internal arc protection available
* Flexible Installation
Suitable for:
·Indoor substations
·Underground substations
·Renewable energy projects

5. Typical Applications
12kV C-GIS is commonly installed in:
·Urban distribution substations
·Industrial plants
·Data centers
·Commercial buildings
·Solar PV plants
·Wind power collection systems
·Railway power systems
·Mining facilities
·Underground substations

6. Typical Panel Configurations
Incoming Feeder Panel
·Receives power from transformer or upstream grid
Outgoing Feeder Panel
·Supplies distribution circuits
Transformer Protection Panel
·Protects distribution transformers
Bus Section Panel
·Provides bus coupling and sectionalizing
Metering Panel
·Provides voltage/current measurement

7. Applicable Standards
·IEC 62271-1 — Common specifications for high-voltage switchgear
·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
12kV Gas Insulated MV Switchgear (C-GIS) is a compact 10/11/12kV-class medium-voltage switchgear system using sealed gas insulation and vacuum circuit breaker technology. It typically provides 630–2500A rated current and 20–31.5kA short-circuit capability, offering high reliability, small footprint, low maintenance, and excellent environmental resistance for modern distribution networks.