KYN28-12 is currently the most widely used indoor armored withdrawable metal-enclosed switchgear for 12kV (10kV) distribution networks in China. It is mainly used in three-phase AC 50Hz power systems to achieve power reception, distribution, control and protection. It features high reliability, good interchangeability, convenient maintenance and high intelligence level, and is the mainstream choice for new substations, industrial and mining enterprises, municipal facilities, data centers and other scenarios.

I. Scope of Application
Rated Voltage: 12kV (applicable to 10kV systems)
Applicable Systems: Single busbar, single busbar sectionalized system
Typical Applications: Substations, power plant auxiliary power supply, industrial and mining enterprises, high-rise buildings, hospitals, data centers, rail transit, industrial parks, etc. for 10kV distribution systems
Compliance with Standards: GB/T 3906, GB/T 11022, DL/T 404, IEC 62271-200, etc.

II. Main Technical Parameters (General Type)
Rated Voltage: 12kV
Rated Current: 630A / 1250A / 1600A / 2000A / 2500A / 3150A
Rated Short-Circuit Breaking Current: 20kA / 25kA / 31.5kA / 40kA
Rated Thermal Stability Current (4s): 20kA / 25kA / 31.5kA / 40kA
Rated Dynamic Stability Current: 50kA / 63kA / 80kA / 100kA
1-minute Power Frequency Withstand Voltage: 42kV
Lightning Impulse Withstand Voltage: 75kV
Protection Grade: IP4X (Closed Door), IP2X (Open Door)
Mechanical Life: Circuit Breaker ≥ 10,000 Times, Disconnect Switch ≥ 3,000 Times

III. Structural Characteristics
1. Armored metal enclosure and compartmentalized design
The cabinet body is assembled from aluminized zinc sheet or cold-rolled steel plates, divided into four independent compartments: busbar compartment, circuit breaker drawer compartment, cable compartment, and relay and instrument compartment. These compartments are isolated by grounding metal partitions, making it difficult for arc faults to spread and ensuring high safety.
2. Removable drawer structure
The circuit breaker drawer is of the middle-mounted type, allowing for easy insertion / extraction. It has strong interchangeability.
The drawer has working position, test position, and open position, with accurate positioning and reliable interlocks.
3. Complete "five-prevention" interlocks
Prevent misoperation of circuit breaker
Prevent pulling the drawer while carrying load
Prevent closing the grounding switch while energized
Prevent closing the circuit breaker while the grounding switch is closed
Prevent entering energized compartments to achieve mandatory mechanical interlock, eliminating incorrect operations.
4. Pressure release and safety design
Pressure release channels are provided at the top of each compartment. The gas generated by internal faults of the arc can be directed to be discharged, ensuring the safety of personnel and the cabinet.
5. Wiring standard, flexible expansion
The cable compartment has ample space, facilitating the installation of cables, grounding switches, surge arresters, CTs, etc.
It can be flexibly configured as incoming line, outgoing line, tie line, PT, metering, isolation, and other functional cabinets.
IV. Performance Advantages
1. Strong versatility and good interchangeability
KYN28A-12 is an industry standard structure. Products from various manufacturers are basically interchangeable, and spare parts are easy to purchase.
2. Reliable operation, convenient maintenance
The drawer can be fully withdrawn for inspection without affecting the operation of other intervals, making it suitable for power-off maintenance.
3. Adapt to indoor conventional environments
It is suitable for an altitude of ≤1000m, with an environmental temperature range of -15℃ to +40℃. Customized high-altitude, low-temperature, and anti-condensation types are available.
4. Convenient for intelligent upgrades
The new KYN28 can integrate online temperature measurement, partial discharge monitoring, intelligent control device, integrated protection, IEC61850 communication interface, meeting the requirements of intelligent substations.
V. Typical Configuration
Circuit breaker: VS1 (ZN63) series vacuum circuit breaker
Operating mechanism: spring operating mechanism
Main busbar: copper busbar, insulated support
Grounding switch: JN15 series
Transformer: electromagnetic / electronic CT, PT
Secondary: microcomputer comprehensive protection, measurement and control, instruments, live display device
VI. Summary of Applicable Scenarios
KYN28-12 is the benchmark product of 10kV middle-mounted cabinets, balancing safety, economy, and practicality. It is suitable for the vast majority of indoor 10kV power distribution projects, especially for important load places with high requirements for power reliability and maintenance convenience.