Air Insulated MV Switchgear (AIS) 36kV for 36kV distribution networks

Switchgear (AIS) 36kV

36kV Air Insulated Medium Voltage (MV) Switchgear (AIS) is a metal-enclosed switchgear system designed for 36kV distribution networks (maximum system voltage 40.5kV). It uses air insulation between energized components and grounded metal compartments, with vacuum circuit breakers (VCBs) typically used for switching and protection.

36kV AIS is commonly applied in utility substations, industrial plants, renewable energy facilities, mining, railway systems, and large infrastructure projects requiring reliable medium-voltage power distribution.

Main Features
·Rated voltage: 36 kV
·Highest system voltage: 40.5 kV
·Air-insulated metal-enclosed construction
·Vacuum circuit breaker switching technology
·Withdrawable or fixed-mounted breaker options
·Modular cubicle design
·High mechanical and electrical reliability
·Easy access for inspection and maintenance
·Protection and automation system integration
·Optional internal arc-resistant design

Typical Functional Panels
A 36kV AIS lineup may include:
·Incoming feeder panel
·Outgoing feeder panel
·Transformer feeder panel
·Bus coupler panel
·Bus sectionalizer panel
·Voltage Transformer (VT) panel
·Metering panel
·Motor feeder panel
·Capacitor bank feeder panel
·Earthing switch panel

Typical arrangements:
·Single busbar system
·Double busbar system
·Main and transfer bus system
·Sectionalized busbar configuration
·Ring distribution configuration

Typical Technical Specifications
·Rated Voltage: 36 kV
·Highest System Voltage: 40.5 kV
·Rated Frequency: 50/60 Hz
·Rated Current: 630–3150 A
·Short-Time Withstand Current: 20–31.5 kA, 3 s
·Peak Withstand Current: 50–80 kA
·Short-Circuit Breaking Current: 20–31.5 kA
·Lightning Impulse Withstand Voltage (BIL): 170 kV
·Power Frequency Withstand Voltage: 70 kV / 95 kV (1 min)
·Internal Arc Classification: AFL/AFLR 20–31.5 kA (optional)
·Protection Degree: IP4X / IP54 (application dependent)
·Circuit Breaker Type: Vacuum Circuit Breaker
·Mechanical Endurance: ≥10,000 operations
·Applicable Standards: IEC 62271-1, IEC 62271-100, IEC 62271-200

Main Components
1.) Vacuum Circuit Breaker (VCB)
Functions:
·Switching normal load currents
·Interrupting short-circuit currents
·Automatic fault isolation
·Frequent operation capability
2.) Main Busbar System
Features:
·Copper or aluminum conductors
·Air insulated or insulated busbar options
·High short-circuit withstand capability
·Modular extension capability
3.) Current Transformer (CT)
Applications:
·Overcurrent protection
·Earth fault protection
·Energy measurement
·Metering systems
4.) Voltage Transformer (VT)
Functions:
·Voltage measurement
·Protection input
·Synchronization
·Power quality monitoring
5.) Earthing Switch
Provides:
·Safe grounding during maintenance
·Operator protection
·Electrical interlocking
6.) Protection and Control Unit
Typical functions:
·Overcurrent protection
·Earth fault protection
·Transformer protection
·Distance protection (where applicable)
·Communication with SCADA systems

Working Principle
·The incoming 36kV feeder supplies power to the switchgear.
·The vacuum circuit breaker connects the feeder to the main busbar.
·The busbar distributes power to outgoing circuits.
·CTs and VTs continuously monitor electrical parameters.
·Protection relays detect abnormal conditions.
·The VCB trips automatically during faults.
·The affected feeder is isolated while the remaining network continues operation.

Advantages
Reliable Operation
·Proven AIS technology
·Strong mechanical structure
·Stable insulation performance
Easy Maintenance
·Clear compartment separation
·Simple inspection procedures
·No gas handling required
Environmental Friendly
·Uses natural air insulation
·No SF6 gas leakage risk
·Reduced environmental impact
Flexible Installation
·Expandable feeder arrangements
·Suitable for various distribution architectures
·Compatible with digital protection systems
Economical
·Lower initial cost than GIS
·Lower maintenance complexity
·Long service life

Typical Applications
·Utility substations
·Industrial substations
·Renewable energy collector systems
·Solar power plants
·Wind farms
·Mining operations
·Oil and gas facilities
·Railway traction substations
·Data centers
·Large commercial buildings
·Water treatment facilities

Applicable Standards
·IEC 62271-1 – Common specifications for high-voltage switchgear
·IEC 62271-100 – AC circuit breakers
·IEC 62271-200 – AC metal-enclosed switchgear and controlgear
·IEC 61869 – Instrument transformers
·IEC 60529 – Degrees of protection (IP Code)

Typical Ratings Summary
·Rated Voltage: 36 kV
·Maximum System Voltage: 40.5 kV
·Rated Current: 630–3150 A
·Short-Circuit Current: 20–31.5 kA
·Lightning Impulse Withstand: 170 kV
·Power Frequency Withstand: 70/95 kV
·Insulation Medium: Air
·Switching Device : Vacuum Circuit Breaker
·Installation: Indoor / Outdoor Enclosure
·Protection Degree: IP4X–IP54
·Service Life: ≥30 years

A 36kV Air Insulated MV Switchgear (AIS) provides a robust and economical solution for medium-voltage distribution systems. With air insulation, vacuum interruption technology, modular construction, and straightforward maintenance, it remains a widely used choice for utility and industrial networks requiring dependable operation at the 36kV voltage level.