Air Insulated MV Switchgear (AIS) 12kV solution for primary insulation in power distribution systems

Switchgear (AIS) 12kV

12kV Air Insulated Medium Voltage (MV) Switchgear (AIS) is a metal-enclosed switchgear assembly used in medium-voltage power distribution systems. It utilizes air as the primary insulation medium between energized conductors and grounded metal enclosures, while vacuum circuit breakers (VCBs) are commonly used for switching and fault interruption. The equipment provides safe, reliable, and efficient control, protection, isolation, and monitoring of electrical distribution networks.

12kV AIS switchgear is widely installed in utility substations, industrial facilities, commercial buildings, renewable energy plants, and infrastructure projects.

Main Features
·Rated voltage: 12 kV
·Air-insulated, metal-enclosed construction
·Vacuum Circuit Breaker (VCB) for switching and protection
·Withdrawable or fixed-mounted breaker design
·Modular cubicle configuration
·High operational reliability
·Mechanical and electrical interlocking
·Easy maintenance and inspection
·SCADA and automation compatible
·Arc-resistant construction available

Typical Functional Panels
A 12kV AIS lineup may include:
·Incoming feeder panel
·Outgoing feeder panel
·Bus coupler panel
·Bus riser panel
·Transformer feeder panel
·Motor feeder panel
·Capacitor bank feeder panel
·Voltage Transformer (VT) panel
·Metering panel
·Bus sectionalizer panel

Typical Technical Specifications
·Rated Voltage: 12 kV
·Highest System Voltage: 12/17.5 kV
·Rated Frequency: 50/60 Hz
·Rated Current: 630–4000 A
·Rated Short-Time Withstand Current: 20–40 kA, 3 s
·Rated Peak Withstand Current : 50–100 kA
·Rated Short-Circuit Breaking Current: 20–40 kA
·Lightning Impulse Withstand Voltage (BIL): 75 kV
·Power Frequency Withstand Voltage: 28 kV (1 min)
·Internal Arc Classification: AFLR 20–40 kA (optional)
·Degree of Protection: IP4X (higher options available)
·Mechanical Endurance (VCB): 10,000–30,000 operations
·Applicable Standards: IEC 62271-1, IEC 62271-200, IEC 62271-100

Main Components
·Metal-clad switchgear enclosure
·Vacuum Circuit Breaker (VCB)
·Main busbars
·Busbar insulation
·Current Transformers (CTs)
·Voltage Transformers (VTs)
·Protection relays
·Earthing switch
·Cable termination compartment
·Low-voltage control compartment
·Mechanical and electrical interlocks
·Instrument and metering devices

Working Principle
·The incoming feeder supplies power to the main busbar through the vacuum circuit breaker.
·Power is distributed to outgoing feeders via individual breaker panels.
·Protection relays continuously monitor current and voltage conditions.
·During overloads or short circuits, the relay commands the vacuum circuit breaker to trip.
·The faulty circuit is isolated while healthy feeders continue operating.

Advantages
·Simple air insulation system
·No insulating gas required
·Environmentally friendly
·Easy inspection and maintenance
·Modular and expandable design
·High operational safety
·Excellent reliability
·Lower life-cycle maintenance cost
·Suitable for indoor substations

Typical Applications
·Utility distribution substations
·Industrial manufacturing plants
·Commercial buildings
·Hospitals
·Data centers
·Airports
·Universities
·Mining facilities
·Water and wastewater treatment plants
·Renewable energy plants
·Oil and gas facilities

Applicable Standards
·IEC 62271-1 – High-voltage switchgear and controlgear – Common specifications
·IEC 62271-100 – High-voltage alternating-current 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: 12 kV
·Highest System Voltage: 17.5 kV
·Rated Current: 630–4000 A
·Short-Circuit Current: 20–40 kA
·BIL: 75 kV
·Power Frequency Withstand: 28 kV
·Circuit Breaker: Vacuum Circuit Breaker (VCB)
·Insulation Medium: Air
·Protection Degree: IP4X or higher
·Installation: Indoor
·Service Life: ≥30 years

Key Benefits
A 12kV Air Insulated Medium Voltage (AIS) Switchgear provides a cost-effective, reliable, and environmentally friendly solution for medium-voltage power distribution. By combining air insulation with vacuum circuit breaker technology, it delivers dependable switching, fault protection, and operational safety while allowing straightforward maintenance and future system expansion. It is a preferred choice for indoor substations where installation space is sufficient and long-term operational reliability is required.