Huanghua Group Co., Ltd. 
KYN28A-24(Z) Metal-Clad Withdrawable AC Switchgear
KYN28A-24(Z) is an armoured, metal-clad withdrawable AC switchgear for 24 kV medium-voltage distribution, rated 630–3150 A with short-time withstand up to 31.5 kA / 4 s, fitted with the VS1-24 vacuum circuit breaker truck. It is used for power receiving and distribution in power plants, substations, industrial plants and renewable energy stations, providing control, protection, measurement and monitoring in compliance with IEC 62271-200.
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KYN28A-24(Z) serves power receiving and distribution in power plants, substations, industrial plants and renewable energy stations, providing control, protection, measurement and monitoring of lines and equipment. The armoured withdrawable (mid-mounted) design features four metal-segregated compartments, complies with IEC 62271-200 and GB 3906, and can be supplied as a package with transformers and LV switchgear under single-source responsibility.
Type Designation
Key Highlights
| Highlights | Value |
| Compact high-insulation design: outstanding insulation level without compound insulation or inter-phase barriers | Smaller footprint, lower civil work and substation cost |
| Full rating coverage: 24 kV, 630–3150 A, Icw 16/20/25/31.5 kA (4 s) | One platform from feeder to main incomer applications |
| VS1-24 vacuum circuit breaker truck with three-position (Connected–Test–Disconnected) mechanical interlock | Maintenance without de-energising the whole busbar section |
| Complete "Five-Prevention" interlocking plus IEC 62271-200 mandatory interlocks | Mis-operation proof, passes utility and EPC compliance audits |
| Four metal-clad segregated compartments: VCB / busbar / cable / instrument | Fault arc confined within compartment, protecting personnel and adjacent panels |
| IP4X protection (IP2X with compartment doors open); optional IAC A-FLR internal arc classification | Suitable for dusty and humid industrial environments |
| 100% interchangeable trucks of the same rating, modular assembly | Minimal spare parts stock and downtime |
| Compliant with IEC 62271-200 / GB 3906, full type-test documentation, single-source package supply | Transformer + MV + LV from one source, lower interface risk |
Product Features
| Features | Description |
| Compact Design | A compact layout delivers 24 kV insulation coordination within a 1000 mm panel width. Outstanding insulation is achieved without compound insulation or inter-phase barriers, maximising power density per square metre. |
| Four-Compartment Metal-Clad Segregation | VCB, busbar, cable and instrument compartments are independently segregated and earthed. An internal fault is confined to its compartment and cannot propagate to adjacent compartments or panels. |
| Robust Structure & Easy Installation | The cubicle is assembled from CNC-machined steel plate, giving high strength, dimensional accuracy and interchangeability. Front installation and front maintenance allow wall-mounted arrangement, saving trench and aisle space. |
| Excellent Lightning-Impulse Withstand | Rated lightning impulse withstand 125 kV (peak) and 1 min power-frequency withstand 65 kV, verified by lightning impulse tests — suitable for areas with high lightning activity and overhead line entry. |
| Withdrawable Trucks (Three Types) | Truck frames are made of CNC-processed steel sheet and co-ordinate insulatively with the cubicle for safe mechanical interlocking. Available as circuit-breaker, isolating and voltage-transformer trucks, fully interchangeable for the same rating. |
| Three-Position Locking & Interlocking | The truck can be locked in Disconnected, Test and Connected positions, with mandatory mechanical interlocks to the VCB, earthing switch and door, preventing load-breaking/closing and closing onto an earthed circuit. |
| Busbar Segregation & Fault Containment | Branch busbars connect directly to the fixed contact box and main busbar without extra supports. Adjacent panels are separated by wall bushings, confining arc faults to the faulty compartment. |
| Complete "Five-Prevention" Interlock | Prevents mis-operation of the circuit breaker, withdrawal under load, closing the earthing switch on a live circuit, energising with the earthing switch closed, and entry into live compartments — and satisfies IEC 62271-200 mandatory interlocks. |
| Secondary & Intelligent Interface | The instrument compartment accommodates numerical protection relays, metering and control devices, with optional Modbus / IEC 60870-5-103 / IEC 61850 communication for SCADA and energy management integration. |
| Environmental Adaptability & Options | Heater and lighting lamp are fitted as standard; options include anti-condensation controller, capacitive voltage indicator, surge arresters, earthing switch and core-balance CT. Customised -25 °C to +45 °C, high-altitude and enhanced-protection versions are available. |
| Maintenance-Friendly Design | Easy racking in/out, automatic shutter mechanism and aviation-plug secondary connections. Generous cabling space speeds up cable termination and CT replacement, shortening outage time. |
| Internal Arc Protection (Optional) | IAC A-FLR classification per IEC 62271-200 Annex AA can be provided, with pressure-relief ducts for the VCB and cable compartments — ideal for substations and overseas EPC projects with strict personnel-safety requirements. |
Technical Parameters
1.Basic Data
| Item | Data | Unit |
| Product Name | Metal-clad withdrawable AC switchgear | — |
| Model | KYN28A-24(Z) | — |
| Rated voltage (Ur) | 24 | kV |
| Rated frequency (fr) | 50（60） 50 (60) |
Hz |
| Rated current (Ir) | 630 / 1250 / 1600 / 2000 / 2500 / 3150 | A |
| Rated short-time withstand current (Icw) | 16 / 20 / 25 / 31.5 | kA |
| Rated peak withstand current (Ip) | 40 / 50 / 63 / 80 | kA |
| Rated short-circuit duration (tk) | 4 | s |
| Circuit breaker fitted | VS1-24 vacuum circuit breaker | — |
| Operating mechanism | Spring-stored, motor + manual emergency | — |
2.Insulation Level
| Item | Data | Unit |
| 1 min power-frequency withstand voltage | (50) 65 | kV |
| Rated lightning impulse withstand voltage (peak) | 125 | kV |
| Insulating medium | Air insulated (AIS) | — |
3. Construction & Dimensions
| Item | Data | Unit |
| Construction | Metal-clad, withdrawable, four compartments | — |
| Overall dimensions (W×D×H) | 1000×1820×2300 (cable outlet) 1000×2150×2300 (overhead in/out) |
mm |
| Depth D | 1820 (cable outgoing feeder) / 2150 (overhead incoming & outgoing feeder) | mm |
| Weight | 800; 1000 for rated current ≥1600 A | kg |
| Installation | Indoor, wall-mounted or free-standing | — |
| Cable / busbar entry | Bottom cable entry & exit / overhead entry & exit | — |
| Truck types | Circuit-breaker truck / isolating truck / voltage transformer truck | — |
4.Protection & Safety
| Item | Data | Unit |
| Degree of protection | Enclosure IP4X; IP2X with VCB or cable compartment door open | — |
| Interlocking | "Five-prevention" mechanical interlock + IEC 62271-200 mandatory interlocks | — |
| Internal arc classification | IAC A-FLR (optional, per IEC 62271-200 Annex AA) | — |
| Earthing system | Continuous earthing busbar bonded to the station earth grid; earthing switch optional | — |
| Standard fittings | Heater, lighting lamp, wall bushing, contact box, shutter mechanism, secondary interlock | — |
5.Service Conditions
| Item | Data | Unit |
| Ambient air temperature | -15 °C to +40 °C (customised -25 °C to +45 °C) | ℃ |
| Altitude | ≤1000 | m |
| Relative humidity | Daily average ≤95%, monthly average ≤90% | % |
| Water vapour pressure | Daily average ≤2.2, monthly average ≤1.8 | kPa |
| Earthquake intensity | ≤ magnitude 8 | — |
| Applicable places | Places free from steam, explosion hazard, corrosive and flammable gas | — |
6.Standards & Certification
| Item | Data | Unit |
| Main standard | IEC 62271-200 — High-voltage switchgear and controlgear: AC metal-enclosed switchgear | — |
| Circuit breaker standard | IEC 62271-100 (HV AC circuit breakers) | — |
| Earthing switch standard | IEC 62271-102 (AC disconnectors and earthing switches) | — |
| Common specifications | IEC 62271-1 (Common specifications for HV switchgear) | — |
| IP code standard | IEC 60529 (Degrees of protection provided by enclosures) | — |
| National standards | GB 3906, GB/T 11022, DL/T 404 (China national & power industry standards) | — |
