Gas Insulated MV Switchgear (C-GIS) 36kV offers the reliable solution for primary system

Switchgear (C-GIS) 36kV

1. General Description

36kV Gas Insulated Medium Voltage Switchgear (C-GIS), also known as Compact Gas Insulated Switchgear, is a medium-voltage metal-enclosed switchgear system designed for 30kV/33kV/36kV distribution and sub-transmission networks.

C-GIS uses a sealed gas-insulated enclosure to protect primary components such as the vacuum circuit breaker (VCB), busbars, disconnectors, earthing switches, current transformers (CT), and voltage transformers (VT). The compact design provides high reliability and excellent environmental resistance compared with conventional air-insulated switchgear (AIS).

The 36kV C-GIS class is commonly applied in 33kV distribution systems, renewable energy plants, industrial substations, and utility networks requiring compact and reliable medium-voltage equipment.

2. Typical Technical Specifications
·Equipment Type: Compact Gas Insulated Switchgear (C-GIS)
·Rated Voltage: 36 kV
·System Voltage Class: 30 / 33 / 36 kV
·Rated Frequency: 50 / 60 Hz
·Rated Current: 630 / 1250 / 2000 / 2500 / 3150 A
·Short-Time Withstand Current: 20 / 25 / 31.5 / 40 kA (3 s)
·Short-Circuit Breaking Current: 20–40 kA
·Peak Withstand Current: 50–100 kAp
·Power Frequency Withstand Voltage: 70 kV
·Lightning Impulse Withstand Voltage (BIL): 170 kVp
·Insulation Medium: SF6 / Dry Air / N₂ / Alternative Gas
·Circuit Breaker Type: Vacuum Circuit Breaker (VCB)
·Installation: Indoor / Outdoor enclosure
·Enclosure Type: Metal-enclosed sealed compartments

3. Main Components

1.) Vacuum Circuit Breaker (VCB)
·The vacuum interrupter is the main switching and protection component.
Functions:
·Interrupts short-circuit currents
·Performs feeder switching
·Protects transformers and cables
Features:
·High breaking performance
·Long mechanical life
·Low maintenance
·No arc products released into the enclosure

2.) Gas Insulated Busbar Compartment
·The main busbars are enclosed in a sealed gas compartment.
Advantages:
·High dielectric strength
·Compact conductor arrangement
·Protection from environmental contamination

3.) Disconnect Switch
Functions:
·Isolates electrical circuits
·Provides safe maintenance conditions
·Supports switching operations
Features:
·Compact mechanism
·High operational reliability
·Mechanical interlocking

4.) Earthing Switch
Functions:
·Grounds isolated circuits
·Discharges trapped electrical energy
·Improves operator safety
Types:
·Standard earthing switch
·High-speed earthing switch

5.) Current Transformer (CT)
Used for:
·Protection relays
·Metering
·Fault detection
·Load monitoring
·Typical protection applications:
·Overcurrent protection
·Earth fault protection
·Differential protection

6.) Voltage Transformer (VT)
Provides voltage signals for:
·Protection systems
·Metering equipment
·Synchronization
·Power monitoring

7.) Cable Termination Compartment
Supports connection to:
·Underground power cables
·Distribution transformers
·Motors
·Renewable energy equipment

4. Advantages of 36kV C-GIS
* Compact Structure
·Much smaller than conventional AIS
·Ideal for space-limited substations
* Excellent Environmental Resistance
The sealed gas system protects against:
·Dust
·Moisture
·Condensation
·Industrial pollution
·Salt contamination
* High Reliability
·Stable insulation performance
·Reduced external influence
·Suitable for continuous operation
* Low Maintenance
·No frequent cleaning of insulation surfaces
·Reduced inspection requirements
·Longer service intervals
* Improved Safety
·Metal-enclosed construction
·Reduced risk of accidental contact
·Internal arc-resistant options available

5. Typical Applications
36kV C-GIS is widely used in:
·33kV distribution substations
·Renewable energy collector substations
·Wind power plants
·Solar PV plants
·Industrial facilities
·Mining operations
·Railway power supply systems
·Urban distribution networks
·Commercial and infrastructure projects

6. Typical Panel Configurations
Incoming Feeder Panel
·Receives power from transformers or grid feeders
Outgoing Feeder Panel
·Supplies medium-voltage loads
Transformer Protection Panel
·Controls and protects distribution transformers
Bus Section Panel
·Provides bus splitting and coupling
Metering Panel
·Provides voltage/current measurement and monitoring
Capacitor Bank Panel
·Controls reactive power compensation equipment

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
36kV Gas Insulated Medium Voltage Switchgear (C-GIS) is a compact 33/36kV-class medium-voltage switchgear system using sealed gas insulation and vacuum circuit breaker technology. It typically provides 630–3150A rated current and 20–40kA short-circuit breaking capability, offering high reliability, small footprint, low maintenance, and strong environmental protection for renewable energy systems, industrial substations, and modern distribution networks.