HUARUI 
Model KYN28A-12 Armored Withdrawable AC Metal-Enclosed Switchgear
The KYN28A-12 metal-clad center-mounted enclosed switchgear (hereinafter referred to as the "switchgear") is an indoor complete set of power distribution equipment for three-phase AC 50Hz, 3.6~12kV power systems. It is mainly used for power transmission in power plants, power receiving and distribution in electric power systems and industrial and mining enterprise substations, as well as for controlling high-voltage motors that require frequent starting.
This switchgear complies with the requirements of standards such as GB 3906, DL/T 404, and IEC 62271-200 (formerly IEC 298). It is equipped with "five-prevention" functions, including:
➤Prevention of incorrect circuit breaker operation
➤Prevention of inserting or withdrawing the truck under load
➤Prevention of closing the earthing switch when the circuit is live
➤Prevention of energizing when the earthing switch is in the closed (earthing) position
➤Prevention of entry into live compartments
The switchgear consists of two main parts: a fixed enclosure and withdrawable components (referred to as the "truck"). The enclosure shell and partitions of each functional compartment are assembled using aluminum-zinc plated steel plates bolted together, with double crimping on the cabinet framework. The cabinet doors and side panels are manufactured from high-quality A3 cold-rolled 2.0mm steel plate, processed and welded using CNC equipment. The cabinet surface undergoes anti-corrosion treatment processes including degreasing, pickling, phosphating, and passivation, followed by high-pressure electrostatic spraying and high-temperature baking at 183°C to form an electrostatic spray coating layer. This protective layer can withstand impact forces of over 50Kg and has a service life of more than 10 years. The protection level of the switchgear enclosure is IP4X, and when the circuit breaker compartment door is opened, the protection level is IP2X.
This switchgear can be equipped with VD4, VEP, VS1, 3AE1, or other equivalent types of vacuum circuit breaker trucks. It can be installed in back-to-back or face-to-face double-row arrangements.
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Parameter name |
Unit |
Value |
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Model |
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KYN28A-12 (Customization Available) |
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Rated voltage |
kv |
10 |
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Maximum working voltage |
kv |
11.5 |
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Rated current |
A |
1250/2000/2500/3150 |
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insulation level |
1imi |
Alternate relativel |
kv |
42 |
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Between ports |
48 |
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LIWV |
Alternate relativel |
75 |
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Fracture surface |
85 |
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（4s）Rated short-circuit breaking current(4s) |
kv |
25 31.5 40 |
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Rated short-circuit making current |
KA |
63 80 100 |
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KA Rms |
25 31.5 40 |
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Rated peak withstand current |
60 80 100 |
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Rated voltage of control circuit |
DC110 220;AC110 220 |
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IP code |
Shell |
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IP4X |
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Compartment (when the cabinet door is open) |
IP2X |
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Enclosure/Cabinet
Made of high-quality aluminum-zinc plated steel plate assembled through multiple bending processes, featuring high strength and corrosion resistance. The cabinet is divided into four independent compartments: busbar compartment, circuit breaker compartment, cable compartment, and relay/instrument compartment. Metal barriers separate each compartment to ensure mutual isolation in the event of a fault.
Circuit Breaker Truck (Draw-out Unit)
Adopts a center-mounted draw-out structure equipped with a vacuum circuit breaker and associated operating mechanism. The truck has three positions: service, test/isolation, and removed. Clear positioning and mechanical interlocks are provided during position changes, facilitating easy maintenance and servicing.
Primary Conductive Circuit
Includes main busbars, branch busbars, fixed contact boxes, and contact arms. Main busbars run through and connect all cabinets. Branch busbars connect the contact boxes to the circuit breaker. All connection points are silver-plated to reduce contact resistance and ensure current-carrying capacity.
Instrument Transformers
Includes current transformers and voltage transformers. Current transformers are installed on the outlet side within the cable compartment for measurement and protection. Voltage transformers are installed in the busbar or cable compartment to provide voltage signals and operating power.
Earthing Switch
Installed in the cable compartment, equipped with a torque operating mechanism and rapid closing function. The earthing switch is mechanically interlocked with the circuit breaker, cabinet door, and cable compartment cover to prevent misoperation and ensure maintenance personnel safety.
Relay Protection and Instrumentation Devices
Installed in the relay/instrument compartment, including microcomputer-based protection devices, comprehensive measurement and control devices, smart instruments, selector switches, and indicating elements. These devices implement overcurrent, instantaneous overcurrent, and earth fault protection, as well as operational status monitoring.
Interlocking Mechanism
Includes inter-cabinet mechanical interlocks and internal forced interlocking devices, strictly implementing the "five-prevention" operating sequence: preventing incorrect circuit breaker operation; preventing opening or closing disconnectors under load; preventing closing the earthing switch when live; preventing energization when the earthing switch is closed; and preventing entry into live compartments.
Pressure Relief and Protection Devices
Each functional compartment is equipped with pressure relief channels at the top, allowing high-pressure gases to be directionally released in the event of an internal arcing fault, ensuring personnel safety. The enclosure protection level is IP4X, and when the circuit breaker compartment door is opened, the protection level is IP2X. Explosion-proof glass observation windows are provided.
1. Core Product Advantages
① Compact Structure, Space Saving: Adopts center-mounted draw-out truck structure with cabinet width of only 800mm (for 12kV standard cabinet). Supports back-to-back arrangement or wall-mounted installation, significantly saving floor space in the distribution room.
② Reliable "Five-Prevention" Interlocking: Equipped with a complete mechanical interlocking system that strictly implements the five-prevention functions, including preventing incorrect circuit breaker operation and preventing opening or closing disconnectors under load, effectively eliminating electrical misoperation accidents.
③ High Reliability Design: Cabinet made of aluminum-zinc plated steel plate with excellent corrosion resistance and impact resistance. Each compartment is independently separated, ensuring no mutual interference in the event of a fault.
④ Convenient Maintenance: Adopts center-mounted draw-out circuit breaker structure. During maintenance, the truck can be pulled out of the cabinet, facilitating easy maintenance and testing.
⑤ Comprehensive Safety Protection: Enclosure protection level IP4X, with protection level IP2X when the circuit breaker compartment door is opened. Each compartment is equipped with independent pressure relief channels, allowing high-pressure gases to be directionally released during internal arcing faults, ensuring personnel safety.
⑥ Strong Adaptability: Compatible with various domestic and international brands of vacuum circuit breakers such as VS1, VD4, and HVX. Main busbar rated current covers 630A ~ 4000A, short-circuit withstand current reaches 16kA ~ 50kA, meeting different capacity requirements.
⑦ High Intelligence Level: Can be equipped with microcomputer-based comprehensive protection devices, smart instruments, remote communication interfaces, etc., implementing overcurrent, instantaneous overcurrent, earth fault protection, and online operational status monitoring, adaptable to unattended smart substations.
⑧ Good Environmental Adaptability: Cabinet made of high-quality aluminum-zinc plated steel plate with excellent corrosion resistance, suitable for general industrial environments and coastal areas.
2. Service Life
Under standard operating conditions and proper usage, the overall design service life of the KYN28A-12 high voltage switchgear can reach 20 to 25 years. The aluminum-zinc plated steel plate enclosure, with its excellent corrosion resistance and stable structural strength, can achieve a service life of over 30 years. The vacuum circuit breaker has a mechanical life of 20,000 operations and an electrical life of 10,000 operations, while the vacuum interrupter can operate normally for up to 20 years under rated current. Current transformers and voltage transformers have a service life of 15 to 20 years. Microcomputer-based relay protection devices, due to aging of electronic components, have a service life of approximately 10 to 15 years.
Key factors affecting service life include operating frequency, short-circuit current impact, environmental conditions (humidity, dust, corrosive gases), and maintenance quality. Under standardized maintenance conditions (regular cleaning, tightening, preventive testing, and operating mechanism maintenance), along with timely replacement of critical components at the end of their service life, the overall equipment service life can be extended to over 25 years.
1. Daily Maintenance
① Check cabinet appearance, observation windows, and passageways for integrity and clearance.
② Monitor current, voltage, indicator lights, and listen for abnormal sounds.
③ Clean dust from insulators, contact boxes, and insulation parts annually.
④ Tighten busbar bolts and secondary terminal connections every six months.
⑤ Inspect truck contact burning and push-in mechanism flexibility annually.
⑥ Regularly test "five-prevention" interlocking functions for proper operation.
⑦ Check earthing switch opening/closing smoothness and contact closure.
⑧ Inspect protection device operation, indicators, and terminal blocks.
⑨ Perform insulation resistance and protection setting tests every 1-3 years.
2. Safety Regulations
1. Power-Off Operation: Maintenance must be carried out only after all isolating switches on both the high-voltage and low-voltage sides are completely disconnected. Strictly follow the procedures of power cut, voltage verification, discharge, and grounding wire installation.
2. Voltage Verification and Grounding: Only after performing three-level voltage verification and reliable grounding can work begin. Hang a "Do Not Close" warning sign.
3. Residual Charge Release: After the transformer is powered off, residual charge must be fully discharged before maintenance can be carried out. Special attention should be paid to the capacitive energy storage effect of the isolation transformer windings.
This product performs the functions of making and breaking, control, protection, and monitoring in power systems. It is mainly used in:
① Power Plants (auxiliary power distribution systems, main switches for small and medium-sized generators)
② Substations (power receiving and distribution)
③ Industrial and Mining Enterprise Power Distribution Systems
④ Large High-Voltage Motor Starting and other similar applications
1. Environmental Risks
1. Moisture and Condensation Risk: High humidity causes condensation on insulation parts inside the cabinet, reducing insulation resistance and easily leading to surface flashover or creepage discharge.
2. Dust Contamination Risk: Conductive dust accumulates on insulators and contact box surfaces, shortening creepage distance and possibly causing short circuits or partial discharge.
3. Corrosive Gas Risk: Corrosive gases in chemical plants and sewage treatment sites corrode metal parts, leading to poor contact due to oxidation of the cabinet and contacts.
4. High-Temperature Overheating Risk: Poor ventilation or excessive ambient temperature causes the temperature rise inside the cabinet to exceed limits, accelerating insulation aging and component damage.
5. Vibration Impact Risk: Proximity to large vibrating equipment may cause fasteners to loosen and the truck position to shift, affecting interlock reliability.
6. Altitude Risk: When altitude exceeds 1000m, the air insulation strength decreases, and insufficient external insulation distance may lead to phase-to-phase or phase-to-ground discharge.
2. Installation Restrictions
① Ambient Temperature: Maximum +45°C, Minimum -25°C
② Relative Humidity: Daily average not exceeding 95%, monthly average not exceeding 90%
③ Altitude: Not exceeding 1000m
④ Seismic Intensity: Not exceeding Grade 8
⑤ Saturated Vapor Pressure: Daily average not exceeding 2.2×10³ MPa, monthly average not exceeding 1.8×10³ MPa
⑥ Installation Site: The equipment shall be installed in locations free from fire, explosion hazards, severe pollution, chemical corrosion, and severe vibration.
The supply scope of the 10kV draw-out type switchgear shall be determined according to the configuration wiring diagram provided by the tendering party. All switchgears shall be equipped with relays, instruments, and secondary control devices in accordance with the secondary wiring drawings provided by the design institute. The switchgear shall include terminal blocks, disconnectors (isolating switches), and circuit breakers for external connections. The secondary wiring inside the switchgear shall be completely wired in accordance with the secondary wiring diagrams.
