Primary switchgear ZF23-72.5

insulatedhigh-voltageshort-circuit

• 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

72.5kV Gas Insulated Switchgear (GIS) is a compact high-voltage switchgear system that uses insulating gas (commonly SF6 or modern alternative gases) to provide electrical insulation and arc interruption in substations. It integrates major primary equipment such as circuit breakers, disconnectors, earthing switches, current transformers, voltage transformers, and busbars into sealed gas compartments.

GIS is widely used where high reliability, compact size, and environmental protection are required, especially in urban substations, industrial facilities, and renewable energy collection networks.

Main Functions
·Circuit Switching: Interrupts normal load currents and fault currents through high-voltage circuit breakers.
·Electrical Isolation: Provides reliable insulation between live conductors and grounded enclosures.
·Power Distribution Control: Enables safe connection, disconnection, and sectionalizing of power networks.
·Protection Integration: Works with protection relays to clear faults rapidly.
·Space Optimization: Reduces substation footprint compared with conventional AIS (Air Insulated Switchgear).

Typical Applications
·Urban substations
·Underground substations
·Utility transmission substations
·Industrial power plants
·Renewable energy substations
·Railway traction substations
·Hydropower and wind farm collector substations
·Coastal and polluted environments

Typical Technical Specifications
·Rated Voltage: 72.5 kV
·Highest System Voltage: 72.5 kV
·Rated Frequency: 50 Hz / 60 Hz
·Rated Current: 1250 A – 3150 A
·Short-Time Withstand Current: 25 kA – 40 kA (typical)
·Peak Withstand Current: 63 kA – 100 kA (typical)
·Insulation Medium: SF6 gas / alternative gas
·Installation: Indoor or outdoor enclosure
·Busbar Type: Single busbar / double busbar
·Protection Degree: Gas-tight metal enclosure

Main Components
1.) Gas Insulated Busbar
·Conducts power between GIS bays
·Encapsulated in grounded metal enclosures
·Provides compact and reliable connection
2.) Circuit Breaker (CB)
·Interrupts short-circuit currents
·Typically uses SF6 or vacuum interruption technology
·Provides fast fault clearing
3.) Disconnector (DS)
·Provides visible electrical isolation
·Used during maintenance operations
4.) Earthing Switch (ES)
·Safely grounds isolated sections
·Ensures personnel safety during maintenance
5.) Current Transformer (CT)
·Provides current signals for:
·Protection relays
·Metering systems
6.) Voltage Transformer (VT/CVT)
·Provides voltage measurement signals
·Used for protection and monitoring
7.) Gas Compartments
·Separate sections containing insulating gas
·Allow maintenance of individual sections without shutting down the entire GIS

Operating Principle
Normal Operation
·High-voltage conductors are enclosed inside grounded metal chambers.
·Insulating gas provides high dielectric strength between energized parts and earth.
·Power flows through busbars and switching devices.
During Fault Conditions
·Protection relay detects abnormal current.
·Circuit breaker receives trip command.
·Circuit breaker interrupts fault current.
·Disconnector isolates the affected section.
·Earthing switch grounds the isolated section for maintenance.

Advantages
·Very compact design
·High operational reliability
·Excellent insulation performance
·Suitable for limited-space substations
·Low sensitivity to pollution and weather
·Reduced maintenance requirements
·High personnel safety
·Long service life
·Suitable for indoor installation

Typical GIS Configurations
1.) Single Busbar GIS
·Simple arrangement
·Cost-effective
·Used for distribution substations
2.) Double Busbar GIS
·Provides operational flexibility
·Used in important substations
3.) Ring Bus GIS
·Improves supply reliability
·Used in transmission networks
4.) Breaker-and-a-Half GIS
·Used for critical transmission systems

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 for rated voltages above 52 kV
·IEEE C37.122 – Gas-Insulated Substations

Typical Applications by Industry
·Electric Utilities: 72.5kV transmission and distribution substations
·Renewable Energy: Wind and solar grid connection substations
·Industrial Plants: Compact high-voltage substations
·Railways: Traction power substations
·Oil & Gas: Reliable power supply systems
·Urban Infrastructure: Indoor and underground substations

Key Features
·Rated voltage 72.5kV
·Metal-enclosed gas-insulated construction
·Compact substation footprint
·Integrated circuit breaker, CT, VT, DS, and ES
·High dielectric strength
·Excellent reliability in harsh environments
·Low maintenance requirement
·Safe operation and high personnel protection
·Suitable for modern smart grid substations
·Designed according to IEC 62271 and IEEE C37.122 standards