KYN28-12 Metal-Clad Withdrawable Medium Voltage Switchgear – Complete Technical Guide, Features, Installation & Maintenance

1.Introduction

The KYN28-12 is an indoor, metal-clad, withdrawable (draw-out) type AC metal-enclosed switchgear. It is designed for 3.6kV – 12kV, 50/60Hz three-phase AC power systems (24kV variants also available).

As the industry standard for secondary power distribution, the KYN28-12 series is widely used in:

• Power plants (auxiliary power supply)

• Substations (primary/secondary distribution)

• Industrial facilities (steel, cement, chemical plants)

• Commercial complexes and high‑rise buildings

• Data centers and hospitals (reliable backup distribution)

• Renewable energy projects (solar farms, wind farms)

2. Core Features – Why KYN28-12?

2.1 “Five Anti” Safety Lockout System

The KYN28-12 incorporates a fully mechanical and electrical interlock system to prevent human error:

This system significantly reduces arc flash risks and ensures operator safety.

2.2 High Modularity & Breaker Compatibility

The KYN28-12 supports most mainstream vacuum circuit breakers without structural modification:

• VS1 (ZN63A) – most common

• VD4 (ABB compatible)

• VEP (Eaton compatible)

• VK (Toshiba compatible)

• Other ISO‑standard withdrawable circuit breakers

The draw‑out trolley runs on precision rails with three distinct positions:

• Working position (primary & secondary circuits connected)

• Test position (secondary connected, primary disconnected)

• Disconnected/withdrawn position

2.3 Robust Mechanical Construction

• Material: High‑grade aluminum‑zinc coated steel sheet (thickness ≥2mm)

• Process: CNC multi‑bending, seamless welding

• Corrosion resistance: Salt spray test >500 hours

• Mechanical endurance: >30,000 operations for moving parts

The modular design allows easy replacement of breakers, CTs, VTs, and other components.

2.4 Advanced Insulation System

• Busbars covered with flame‑retardant heat‑shrinkable tubing

• Insulated barriers between compartments (flame‑retardant SMC or DMC)

• Creepage distance meets IEC 62271‑200 standards

• Optional internal arc classification IAC (AFLR 31.5kA/1s)

2.5 Spacious Cable Compartment

• Sufficient space for multiple power cables per phase

• Non‑magnetic cable clamps prevent eddy current heating

• Easy front or rear cable entry

3. Technical Specifications Table

4. Internal Compartment Structure

The KYN28-12 is divided into four independent, grounded metal compartments:

This separated design ensures that a fault in one compartment does not cascade to others, improving overall safety and reliability

5. How the Withdrawable Mechanism Works

The trolley (circuit breaker carriage) moves between three positions:

1. Working position
   – Primary contacts engaged (busbar & cable sides)
   – Secondary control plug connected
   – Breaker can be closed/opened normally

2. Test position
   – Primary contacts fully separated (safe isolation)
   – Secondary control plug still connected
   – Allows control circuit testing without main circuit voltage

3. Disconnected / withdrawn position
   – Trolley completely removed from cubicle
   – Shutters automatically cover fixed contacts
   – Safe for maintenance or replacement

Operation note: A dedicated hand crank is used to move the trolley between positions. Mechanical interlocks prevent movement when the breaker is closed.

6. Five Anti Safety Interlock – Detailed Explanation

The “Five Anti” functions are mandatory for MV switchgear in most international markets:

✅ 1. Anti – Prevent moving trolley with breaker closed

When the breaker is closed, a mechanical latch blocks the hand crank insertion hole.

✅ 2. Anti – Prevent closing breaker while grounding switch is closed

• A linkage arm physically blocks the breaker closing mechanism if the grounding switch is engaged.

✅ 3. Anti – Prevent closing grounding switch when cables are live

• An electrical interlock (voltage sensing) or key interlock prevents operation.

✅ 4. Anti – Prevent accidental entry into live compartments

• Shutters automatically cover fixed contacts when the trolley is removed.

• Padlock provisions on shutters and doors.

✅ 5. Anti – Prevent closing/operating breaker outside designated position

• Position switches only allow closing in “Working” or “Test” positions.

This system complies with GB3906 and IEC 62271‑200 standards.

7. Installation Guide (Step‑by‑Step)

Proper installation is critical for safe and long‑term operation.

7.1 Pre‑installation inspection

• Check foundation level (≤2mm error over 1m)

• Verify anchoring points match the switchgear layout

• Ensure grounding network resistance ≤4Ω

7.2 Unpacking & handling

• Use a crane with lifting lugs (do not roll on sides)

• Keep unit upright at all times

7.3 Positioning & joining

• Start from the middle cubicle if multiple units

• Bolt adjacent cubicles together (torque M12 bolts to 50‑60 N·m)

• Align top and bottom front surfaces

7.4 Busbar installation

• Clean busbar surfaces with isopropyl alcohol

• Apply conductive grease on contact surfaces

• Tighten with torque wrench (check nameplate values)

7.5 Cable connection

• Strip cables according to termination instructions

• Use non‑magnetic cable clamps

• Torque cable lug bolts to specified values

7.6 Final checks before energization

• Perform insulation resistance test (≥1000MΩ at 2.5kV)

• Verify all mechanical interlocks function correctly

• Close doors and check protection rating

8. Maintenance & Common Troubleshooting

8.1 Routine maintenance (every 1‑2 years)

8.2 Troubleshooting table

8.3 Recommended spare parts

• One set of primary contacts (per phase)

• Shutter return springs

• Position switch micro‑switches

• Control fuses (various ratings)

• Auxiliary contact blocks for VS1/VD4
  

9. Application Scenarios

The KYN28-12 series is suitable for:

• Power generation – Auxiliary power distribution in thermal/hydro power plants

• Grid substations – Primary and secondary distribution up to 12kV/24kV

• Industrial plants – Steel mills, cement plants, petrochemical facilities

• Infrastructure – Airports, railway stations, metro systems

• Commercial buildings – Shopping malls, hospitals, data centers

• Renewable energy – Solar inverters outgoing, wind turbine step‑up stations

10. Ordering & Contact

We supply KYN28-12 switchgear with full technical support, including:

• Free preliminary GA drawings based on your SLD (Single Line Diagram)

• Customized panel layout and color (RAL codes)

• OEM breakers (VS1, VD4) or customer‑supplied breakers

• Complete shipping documentation and packing for sea/air freight

• Remote commissioning assistance available

Request a quote – please provide:

• System voltage (12kV or 24kV)

• Rated current per feeder

• Short‑circuit rating (25kA / 31.5kA / 40kA)

• Number of incoming/outgoing/PT/connection units

• Any specific relay or protection requirement (e.g., SEL, Areva, Schneider, or Chinese brands)

Contact us now for a fast response within 24 hours.

Phone/whatsapp：+86 15850515039

Email：RachLSY981125@gmail.com

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