What is a Metal-Clad Withdrawable Switchgear (KYN28 Type)?

Metal-clad withdrawable switchgear, commonly known as KYN28 medium-voltage switchgear, is a core component in modern power distribution systems. It is widely used in substations, power plants, and large industrial facilities, where it plays a critical role in power reception, distribution, and protection of electrical circuits and transformers.

1. Definition and Function

A metal-clad switchgear is a withdrawable circuit breaker cabinet designed for main power distribution and high-current applications. It provides reliable control and protection for electrical networks, ensuring safe and stable power operation in demanding environments.

Typical applications include:

• Power substations

• Power generation plants

• Large industrial factories

Its main functions are power reception, power distribution, and protection of transmission lines and transformers.

2. Structural Design

The switchgear adopts a three-compartment metal-clad structure, ensuring safety, reliability, and ease of maintenance:

• Upper compartment: Busbar and measuring instruments

• Middle compartment: Withdrawable circuit breaker (truck-type design)

• Lower compartment: Cable termination area

The withdrawable design allows the circuit breaker to be easily removed or inserted for maintenance without affecting the entire system.

3. Main Circuit Breaker

The core switching component is the vacuum circuit breaker (such as VS1 or VD4 type). It offers:

• Frequent switching operations

• Fast interruption of short-circuit currents

• High reliability and long service life

This makes it ideal for applications requiring frequent operation and high fault-breaking performance.

4. Electrical Ratings

Metal-clad switchgear is designed for medium-voltage, high-capacity power systems, with typical parameters as follows:

• Rated current: 630A – 5000A

• Short-circuit breaking capacity: 25kA – 50kA

The circuit breaker directly interrupts fault currents, ensuring system safety under extreme conditions.

5. Protection Functions

The system provides comprehensive protection capabilities, including:

• Overcurrent protection

• Short-circuit (instantaneous) protection

• Ground fault protection

• Auto-reclosing functions

• Intelligent control and monitoring options

These features significantly enhance operational safety and system reliability.

6. Insulation and Design Features

The switchgear uses air insulation technology and a robust metal-enclosed structure. Key characteristics include:

• High safety level

• Large physical size suitable for high-capacity systems

• Strong insulation performance

• Modular and maintainable design

7. Key Advantages

• High current capacity (up to 5000A)

• Strong breaking capability (up to 50kA)

• Excellent protection performance

• Withdrawable circuit breaker design for easy maintenance

• Suitable for frequent operation environments

However, compared with other switchgear types, it has a relatively higher cost due to its advanced design and performance.

8. Typical Applications

Metal-clad withdrawable switchgear is widely used in:

• Substation incoming and outgoing feeders

• Main transformer incoming circuits

• High-capacity industrial power systems

• Facilities requiring high reliability and continuous operation