Air Insulated MV Switchgear (AIS) 24kV of 24kV distribution systems

Switchgear (AIS) 24kV

24kV Air Insulated Medium Voltage (MV) Switchgear (AIS) is a metal-enclosed switchgear assembly designed for 24kV distribution systems. It uses air as the insulation medium between live conductors and grounded metal compartments. Vacuum circuit breakers (VCBs) are commonly used for switching and protection, providing reliable interruption of load and short-circuit currents.

24kV AIS is widely applied in utility distribution substations, industrial plants, renewable energy systems, commercial facilities, and infrastructure projects where reliable medium-voltage power control and protection are required.

Main Features
·Rated voltage: 24 kV
·Highest system voltage: 24/25.8 kV
·Air-insulated metal-enclosed construction
·Vacuum circuit breaker technology
·Withdrawable or fixed breaker design
·Modular cubicle arrangement
·High operational safety
·Easy maintenance and inspection
·Protection and automation compatible
·Optional internal arc-resistant design

Typical Functional Panels
A 24kV AIS lineup normally includes:
·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 configurations:
·Single busbar system
·Double busbar system
·Main and transfer bus arrangement
·Ring distribution arrangement

Typical Technical Specifications
·Rated Voltage: 24 kV
·Highest System Voltage: 24/25.8 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): 125 kV
·Power Frequency Withstand Voltage: 50 kV (1 min)
·Internal Arc Rating: AFL/AFLR 20–31.5 kA (optional)
·Protection Degree: IP4X / IP54 (application dependent)
·Circuit Breaker Type: Vacuum Circuit Breaker
·Mechanical Endurance: 10,000–30,000 operations
·Applicable Standards: IEC 62271-1, IEC 62271-100, IEC 62271-200

Main Components
1.) Vacuum Circuit Breaker (VCB)
·Fault current interruption
·Load switching
·High mechanical endurance
·Low maintenance requirement
2.) Main Busbar System
·Copper or aluminum conductors
·Supports feeder interconnection
·Available with insulated busbar options
3.) Current Transformer (CT)
Used for:
·Protection measurement
·Metering
·Fault detection
4.) Voltage Transformer (VT)
Used for:
·Voltage measurement
·Protection functions
·Synchronization
5.) Earthing Switch
Provides:
·Safe maintenance grounding
·Operator protection
·Interlocked operation
6.) Protection Relay Compartment
Includes:
·Overcurrent protection
·Earth fault protection
·Differential protection
·Communication modules

Working Principle
·Incoming 24kV power enters the switchgear through the incoming feeder panel.
·The vacuum circuit breaker controls connection to the main busbar.
·Busbars distribute power to outgoing feeders.
·Protection relays monitor electrical parameters continuously.
·When abnormal conditions occur, the relay sends a trip command to the VCB.
·The faulty feeder is disconnected while healthy feeders remain energized.

Advantages
High Reliability
·Proven medium-voltage technology
·Robust mechanical structure
·Stable insulation performance
Easy Maintenance
·Accessible compartments
·Simple inspection procedures
·No insulating gas handling required
Environmental Benefits
·No SF6 gas required
·No greenhouse gas leakage risk
Flexible Design
·Expandable switchgear lineup
·Multiple feeder arrangements
·Compatible with automation systems
Cost Effective
·Lower initial investment compared with GIS
·Reduced maintenance complexity

Typical Applications
·Utility substations
·Industrial power distribution
·Manufacturing plants
·Solar PV substations
·Wind farms
·Commercial buildings
·Data centers
·Transportation systems
·Mining facilities
·Oil & gas installations
·Water treatment plants

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 – Enclosure protection ratings

Typical Ratings Summary
·Rated Voltage: 24 kV
·Maximum System Voltage: 25.8 kV
·Rated Current: 630–3150 A
·Short Circuit Current: 20–31.5 kA
·BIL: 125 kV
·Power Frequency Withstand: 50 kV
·Insulation Medium: Air
·Switching Device : Vacuum Circuit Breaker
·Installation: Indoor / Outdoor Enclosure
·Protection: IP4X–IP54
·Service Life: ≥30 years

A 24kV Air Insulated MV Switchgear (AIS) is a reliable and economical solution for medium-voltage distribution networks. It combines air insulation, vacuum switching technology, modular construction, and easy maintenance to provide safe power distribution for utilities, industries, renewable energy projects, and large commercial installations.