12kV Withdrawable Switchgear | KYN28 Series | Sage Power

1. General Overview

The KYN28-12KV is an advanced indoor AC metal‑clad withdrawable switchgear developed according to IEC 62271‑200 and GB3906‑2006 standards. It is designed for three‑phase, 50/60Hz power systems with rated voltage up to 12kV. The switchgear adopts an armored, fully enclosed structure with four independent compartments: breaker compartment, busbar compartment, cable compartment, and low‑voltage instrument compartment. Each compartment is separated by grounded metal partitions, ensuring maximum operational safety.

This model is widely accepted in demanding environments – from utility substations and combined heat‑power plants to heavy industries (steel, cement, petrochemicals), data centers, airports, and high‑rise buildings. The withdrawable design allows quick replacement or maintenance of the circuit breaker without system shutdown, dramatically improving power continuity.

2. Advanced Mechanical Design & Compartmentalization

→ Metal‑clad construction with 2mm thickness cold‑rolled steel panels, welded or bolted to form a rigid structure. All compartments are independently earthed.

3. Withdrawable Circuit Breaker

• The main switching device is a spring‑operated or permanent‑magnet vacuum circuit breaker

• Three operating positions:

  • Service position – primary contacts engaged, secondary control circuit connected.

  • Test/isolated position – primary contacts separated, secondary circuit still connected for testing.

  • Disconnected/withdrawn position – complete isolation; truck can be rolled out of the panel.

• Mechanical interlocks prevent:

  • Moving the breaker into service position when the earthing switch is closed.

  • Closing the earthing switch when the breaker is in service position.

  • Racking the breaker with the main circuit closed (unless forced by override key, but safety first).

• The truck moves smoothly on ball bearing guides with a ratchet racking mechanism – low effort, clear position snap‑in feel.

4. Unmatched Safety Features – “Five‑Prevention” Interlock System

KYN28-12KV fully complies with the Chinese “five‑prevention” (and equivalent IEC safety) requirements:

1. Prevent closing of breaker or isolator under load – interlocks between breaker and earthing switch.

2. Prevent opening/closing of earthing switch with live main circuit – solenoid lock or mechanical cam interlock.

3. Prevent racking of breaker between service/test positions when main circuit closed – trip‑free mechanism.

4. Prevent access to live compartments without proper isolation – steel shutters automatically cover fixed contacts when breaker is withdrawn.

5. Prevent erroneous entry into high‑voltage areas – padlockable handles and shutter locks.

Optional arc‑resistant upgrade – Pressure relief channels on top of each compartment guide arc energy to the top/rear exhaust, meeting IAC AFLR 31.5kA/1s internal arc classification. Rear and front doors are reinforced.

5. Electrical & Technical Specifications (Detailed)

6. Key Features

• ✅ Fully metal‑clad & compartmentalized – each zone separated by earthed steel; no internal arc propagation across compartments.

• ✅ Withdrawable breaker truck – easy maintenance, reduced downtime (spare breaker can be inserted within minutes).

• ✅ Robust vacuum interrupter – 30,000+ mechanical operations, 20,000+ electrical operations (load‑dependent).

• ✅ High arc‑withstanding capability – pressure relief flaps and channels protect operator and adjacent panels.

• ✅ Anti‑condensation management – automatic space heaters with hygrostat prevent moisture damage (shipped standard for humid climates).

• ✅ Full front & rear access – modular cabling, easy busbar extension.

• ✅ Smart ready – space for digital relays (REF615, P127, Sepam 40/80), power quality meters, temperature sensors, and communication gateways.

• ✅ Environmentally friendly – no SF6 gas used in insulating medium (air‑insulated with solid insulation for busbars).

7. Typical Applications (Expanded)

8. Quality Assurance & Testing

Every KYN28-12KV panel is type‑tested according to IEC 62271‑200 in certified laboratories. The testing includes:

• Temperature rise test (1.1× rated current)

• Dielectric withstand test (power frequency & impulse)

• Short‑time withstand current and peak current test

• Mechanical endurance test (breaker + racking mechanism – 2000 cycles min.)

• Internal arc fault test (IAC AFLR classification)

• Protection class verification (IP4X)

• Partial discharge measurement (<10pC at 1.2Ur)

Routine tests performed on every unit: insulation resistance, contact resistance (micro‑ohm), main circuit withstand voltage, mechanical operation check, secondary wiring verification, and anti‑condensation heater test.

All components (circuit breakers, relays, CTs, VTs, insulators) are sourced from IEC‑certified partners with traceable serial numbers.

9. Optional Accessories & Upgrades

10. Ordering & Customization Information

When ordering, please specify:

• Rated current for main busbar (e.g. 1250A, 3150A)

• Short‑circuit withstand level (e.g. 31.5kA/4s)

• Number of panels and configuration (incoming, feeder, metering, PT, capacitor, coupling)

• Breaker type preference (VS1, VD4, VB2, or other)

• Protection relay model and communication protocol

• Dimension constraints (depth, height, cable entry direction)

• Accessories (spare truck, motorized racking, etc.)

• Optional certifications (IECEE, CB, GOST, or local standards)

We provide full GA drawings, bill of materials, wiring diagrams, and type test reports as part of documentation package.

11. Why Choose KYN28-12KV?

• Proven design – millions of units in operation worldwide for over 20 years.

• High part commonality – breakers, trucks, and shutters are interchangeable across the same series.

• Fast delivery – standard configurations in 15–25 days.

• Local after‑sales support – remote or on‑site commissioning, training, and spare parts supply.

• Cost‑effective without compromising safety – competitive pricing compared to fully imported brands while meeting all critical IEC requirements.

12. Case Study 1: 200MW Solar Power Plant — Northwest China

• Challenge: The plant needed 47 units of 12kV switchgear for power collection and grid interconnection, but the site had extreme temperature swings (−25°C to +45°C) and high-altitude conditions (2,800m). Traditional air-insulated switchgear was derating significantly at this altitude.

• Solution: Customized KYN28-12 units with altitude compensation and enhanced heating elements for cold-start reliability.

• Result: All 47 units passed factory acceptance and site commissioning on schedule. The switchgear has operated continuously for 18 months with zero unplanned outages. The withdrawable design has enabled three preventive maintenance cycles without taking the entire collector system offline.

• Key specs: 12kV, 1250A incoming, 630A feeder, 31.5kA breaking capacity.