KYN Middle-Placed Switchgear Explained – Structure, Features, Standards & Applications

Outline

Introduction to KYN Middle-Placed Switchgear

KYN middle-placed switchgear is one of the most widely used medium voltage switchgear types in modern power distribution systems. Known for its withdrawable design, high safety level, and standardized structure, this switchgear has become a benchmark solution for indoor medium voltage applications.

With the rapid development of urban infrastructure, industrial facilities, and utility substations, the demand for reliable, compact, and safe switchgear has increased significantly. KYN middle-placed switchgear meets these requirements by combining robust mechanical design with advanced electrical performance.

Definition and Concept

KYN middle-placed switchgear refers to a metal-clad, air-insulated, withdrawable switchgear where the circuit breaker is installed in the middle position of the cabinet. The switchgear typically integrates a vacuum circuit breaker mounted on a withdrawable truck, allowing easy insertion and removal.

The “middle-placed” concept ensures optimal electrical clearance, balanced compartment arrangement, and enhanced safety for operation and maintenance.

Development Background

The KYN series switchgear was developed to meet the growing need for standardized, modular medium voltage equipment. Inspired by international IEC standards, the design emphasizes compartmentalization, interlocking, and withdrawable structures.

Over time, KYN middle-placed switchgear has evolved into a mature product platform used extensively across Asia, Europe, and emerging markets.

Typical Model and Voltage Range

KYN middle-placed switchgear is commonly applied in voltage levels such as:

• 3.6 kV

• 7.2 kV

• 12 kV

• 24 kV

• 40.5 kV

Rated current typically ranges from 630 A to 3150 A, with short-circuit withstand capability up to 40 kA.

Overall Structural Layout

The switchgear cabinet is a metal-enclosed structure, usually made of galvanized steel sheets. It is divided into independent compartments separated by metal partitions, ensuring fault containment and operational safety.

The enclosure provides high mechanical strength and reliable grounding continuity.

Compartment Arrangement

A standard KYN middle-placed switchgear consists of four main compartments:

• Circuit breaker compartment

• Busbar compartment

• Cable compartment

• Low voltage control compartment

This compartmentalized design minimizes fault propagation and simplifies maintenance.

Circuit Breaker Compartment

The circuit breaker compartment is located in the center of the cabinet. It houses a withdrawable vacuum circuit breaker mounted on a truck mechanism.

The breaker can be positioned in:

• Service position

• Test position

• Isolated position

This flexibility allows safe testing and maintenance without disconnecting power cables.

Busbar Compartment

The busbar compartment is located at the top rear of the cabinet. It contains the main busbars and branch busbars, fully enclosed and insulated.

Busbars are typically made of copper or aluminum and insulated with heat-shrink tubing or epoxy coating.

KYN middle-placed switchgear

Cable Compartment

The cable compartment is located at the lower rear section of the cabinet. It accommodates:

• Power cables

• Current transformers

• Earthing switches

Sufficient space is provided for cable termination and inspection.

Low Voltage Control Compartment

The low voltage compartment is positioned at the front top of the cabinet. It houses:

• Protection relays

• Control circuits

• Measurement devices

• Communication interfaces

This compartment is isolated from high-voltage sections for operator safety.

Withdrawable Design Concept

The withdrawable design is a key feature of KYN middle-placed switchgear. It allows the circuit breaker to be removed or inserted without disturbing primary connections.

Advantages include:

• Enhanced safety

• Easy maintenance

• Reduced downtime

• Clear isolation

Vacuum Circuit Breaker Integration

KYN switchgear is commonly equipped with vacuum circuit breakers such as VS1 type. Vacuum interruption provides:

• Long electrical life

• Minimal maintenance

• High breaking capacity

• Environmentally friendly operation

This makes vacuum breakers ideal for medium voltage applications.

Insulation and Dielectric Design

Air is used as the primary insulation medium, supported by solid insulation components. Insulation design considers:

• Rated voltage

• Overvoltage conditions

• Pollution degree

Clearance and creepage distances comply with IEC standards.

Interlocking and Safety System

Comprehensive interlocking systems prevent incorrect operations, including:

• Preventing breaker movement when closed

• Blocking earthing switch operation under voltage

• Restricting access to live compartments

Both mechanical and electrical interlocks are applied.

Electrical Performance Characteristics

KYN middle-placed switchgear offers stable electrical performance, including:

• High short-circuit withstand strength

• Reliable insulation coordination

• Low partial discharge level

These characteristics ensure long-term reliability.

Mechanical Performance and Endurance

The switchgear cabinet and operating mechanisms are designed to withstand:

• Frequent switching operations

• Mechanical vibration

• Short-circuit forces

Mechanical endurance meets or exceeds standard requirements.

Standards and Certifications

KYN middle-placed switchgear is manufactured according to:

• IEC 62271-200

• GB/T 3906

• Relevant utility specifications

Compliance ensures safety, compatibility, and global acceptance.

Application in Power Distribution

KYN switchgear is widely used in medium voltage distribution networks, providing feeder control, transformer protection, and sectionalizing functions.

Application in Industrial Systems

In industrial plants, KYN middle-placed switchgear supports stable power supply for production lines, motors, and critical loads.

Substation and Utility Applications

Utility substations rely on KYN switchgear for its reliability, safety, and ease of maintenance. It is suitable for both new installations and retrofit projects.

Installation Requirements

Proper installation includes:

• Level foundation

• Secure grounding

• Accurate alignment

• Correct cable termination

Professional installation ensures optimal performance.

Operation and Switching Procedures

Clear operating procedures must be followed to ensure safety. Operators can visually confirm breaker position and isolation status.

Maintenance and Inspection

Routine maintenance includes:

• Visual inspection

• Contact resistance measurement

• Mechanical operation checks

The withdrawable design simplifies inspection and reduces downtime.

Common Faults and Solutions

Common issues may include:

• Control circuit faults

• Mechanical misalignment

• Cable termination issues

Most problems can be resolved through preventive maintenance.

Advantages of KYN Middle-Placed Switchgear

Key advantages include:

• High safety level

• Flexible operation

• Standardized structure

• Long service life

These benefits make it a preferred solution worldwide.

Comparison with Other Switchgear Types

Compared with fixed-type switchgear, KYN middle-placed switchgear offers superior safety and maintainability. Compared with GIS, it provides lower cost and easier servicing.

Development Trends

Future trends include:

• Digital protection integration

• Smart monitoring

• Eco-friendly materials

• Higher compactness

These developments align with smart grid evolution.

Frequently Asked Questions

What is KYN middle-placed switchgear?
A withdrawable, metal-clad medium voltage switchgear with centrally mounted circuit breaker.

What voltage levels does it support?
Typically from 3.6 kV to 40.5 kV.

Is it suitable for indoor installation?
Yes, it is designed primarily for indoor use.

What are its main advantages?
Safety, reliability, easy maintenance, and standardization.

Conclusion

KYN middle-placed switchgear represents a mature and reliable solution for medium voltage power distribution. Its compartmentalized structure, withdrawable circuit breaker design, and comprehensive safety features make it ideal for substations, industrial facilities, and utility networks. As power systems continue to evolve, KYN middle-placed switchgear will remain a core component of modern electrical infrastructure.