Primary switchgear ZF23-126

ACshort-circuithigh-voltage

• IEC 62271, ANSI/IEEE Std C37, NEMA
• ISO 9001, KEMA, CESI, CE, TUV, UL, ASTA
• Seismic design, ETGI-1.020, IEEE Std 693, NCh2369
• Structural design, ASTM A325, ANSI/AISC 360, AWS D1.1
• High altitude correction per IEC 62271 & IEEE C37, ~ 5000m
• High reliability, smart, compact and economic switchgear solutions
• Modular compact GIS offering outstanding flexibility for optimizing layouts

126kV Gas Insulated Switchgear (GIS) is a high-voltage switchgear system designed for 110kV class transmission networks. It uses SF6 gas or environmentally friendly alternative insulating gases as the insulation medium and integrates primary equipment such as circuit breakers, disconnectors, earthing switches, current transformers, voltage transformers, and busbars into a sealed metal enclosure.

Compared with conventional Air Insulated Switchgear (AIS), 126kV GIS provides a much more compact, reliable, and environmentally protected solution for transmission substations.

Main Functions
·Power Switching: Performs connection and disconnection of transmission circuits.
·Fault Interruption: Clears short-circuit faults through high-voltage circuit breakers.
·Electrical Isolation: Provides safe isolation for maintenance operations.
·Measurement and Protection: Integrates CTs and VTs for metering and protection systems.
·Substation Compactness: Reduces land requirements and improves installation flexibility.

Typical Applications
·110kV transmission substations
·Urban and underground substations
·Hydropower plants
·Wind and solar power grid connection substations
·Industrial transmission substations
·Railway traction substations
·Coastal and polluted environments
·Space-limited substations

Typical Technical Specifications
·Rated Voltage: 126 kV
·Highest System Voltage: 126 kV
·Rated Frequency: 50 Hz / 60 Hz
·Rated Current: 1250 A – 4000 A
·Short-Time Withstand Current: 31.5 kA – 50 kA (typical)
·Peak Withstand Current: 80 kA – 125 kA (typical)
·Insulation Medium: SF6 / alternative gas
·Installation: Indoor or outdoor enclosure
·Busbar Configuration: Single busbar, double busbar, ring bus, breaker-and-a-half
·Enclosure Type: Metal-enclosed grounded compartments

Main Components
1.) Gas Insulated Busbar
·Transfers power between GIS bays
·Enclosed in grounded aluminum or steel compartments
·Provides compact and reliable electrical connection
2.) High Voltage Circuit Breaker
·Interrupts rated and fault currents
·Typically uses SF6interruption technology or modern vacuum interruption solutions
·Controlled by protection and control systems
3.) Disconnector (DS)
·Provides electrical isolation
·Used for maintenance and switching operations
4.) Earthing Switch (ES)
·Grounds isolated sections
·Ensures safe maintenance procedures
5.) Current Transformer (CT)
·Provides signals for:
·Protection relays
·Revenue metering
·Monitoring systems
6.) Voltage Transformer (VT)
·Provides voltage signals for:
·Measurement
·Protection
·Synchronization
·Automation systems
7.) Gas Compartments
·Separate GIS sections into independent sealed units
·Allow localized maintenance
·Reduce outage impact

Operating Principle
Normal Operation
·High-voltage conductors are enclosed inside sealed metal chambers.
·Insulating gas maintains dielectric strength between energized parts and earth.
·Power flows through GIS busbars and switching devices.
Fault Operation
·Protection relay detects fault current.
·Circuit breaker receives trip command.
·Circuit breaker interrupts fault current.
·Disconnectors isolate the circuit section.
·Earthing switches ground the isolated equipment.

Advantages
·Very compact compared with AIS
·Excellent insulation reliability
·High resistance to pollution, humidity, and dust
·Suitable for indoor and underground installation
·High operational availability
·Reduced maintenance requirements
·Improved personnel safety
·Long service life
·Suitable for smart grid applications

Typical GIS Arrangements
Single Busbar GIS
·Simple design
·Economical solution
·Used for standard substations
Double Busbar GIS
·Allows flexible operation
·Improves system reliability
Ring Bus GIS
·Provides continuous power supply paths
·Used in important networks
Breaker-and-a-Half GIS
·Used for critical transmission substations
·Provides high operational flexibility

Applicable Standards
·IEC 62271-1 – High-voltage switchgear and controlgear common specifications
·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 C37.122 – Gas-Insulated Substations

Typical Applications by Industry
·Electric Utilities: 110kV transmission substations
·Renewable Energy: Wind and solar collector substations
·Hydropower: Generator step-up substations
·Industrial Plants: High-voltage receiving substations
·Railways: Traction power transmission systems
·Urban Infrastructure: Indoor and underground substations
·Oil & Gas: Reliable high-voltage supply systems

Key Features
·Rated voltage 126kV
·Designed for 110kV transmission systems
·Metal-enclosed gas-insulated construction
·Integrated CB, CT, VT, DS, and ES modules
·Compact installation footprint
·High dielectric strength
·Excellent environmental resistance
·Low maintenance requirements
·High reliability and operational safety
·Suitable for modern digital substations
·Compliant with IEC 62271 and IEEE C37.122 standards