In modern substations and industrial/mining distribution rooms, the MV Switchgear KYN28 series medium-voltage withdrawable metal-clad switchgear stands out as a star product in the medium-voltage distribution field, renowned for its reliable construction and excellent performance. It silently safeguards the safe operation of power systems, serving as an indispensable key component in power transmission and distribution.
The KYN28 series refers to indoor, metal-clad, withdrawable AC switchgear for three-phase systems with rated voltages from 3.6kV to 40.5kV and a frequency of 50Hz, strictly complying with national standards like GB3906. In the model designation: "K" stands for Metal-Clad, "Y" denotes Withdrawable (i.e., truck-mounted), "N" indicates Indoor use, and "28" is the design sequence number. Its core feature is that the withdrawable components (like the circuit breaker truck) are centrally mounted within the cabinet. This "center-mounted" design significantly optimizes operation and maintenance space.
The core functions of the MV Switchgear KYN28 switchgear are the safe reception, distribution, and protection of electrical energy. Its basic workflow is:
1.Power Reception & Isolation: Power is introduced via the busbars in the busbar compartment. The main circuit is connected through the disconnector (or via the mating of primary contacts when the truck is in the "service" position).
2.Circuit Control: The withdrawable circuit breaker truck performs the critical tasks of closing/opening the main circuit under load current and interrupting fault currents. An operating mechanism drives the breaker to execute commands.
3.Protection & Monitoring: Relay protection devices continuously monitor current and voltage. Upon detecting faults like short-circuits or overloads, they immediately trigger the circuit breaker to trip, rapidly isolating the faulty circuit.
4.Earthing Safety: The earthing switch allows reliable grounding of the outgoing cable side during maintenance, ensuring personnel safety.
5.Interlocking Security: A comprehensive mechanical "Five-Prevention" interlocking system strictly prevents misoperations (e.g., operating disconnectors under load, entering live compartments).
The MV Switchgear KYN28 employs a fully assembled, modular, metal-enclosed structure, with key functional zones segregated by high-quality steel plates:
1.Cabinet Enclosure: The main frame provides support and protection.
2.Truck Compartment (Central): Located centrally within the cabinet, housing the circuit breaker truck. The truck has three standard positions: Service/Test/Disconnected (Withdrawn). Movement is facilitated by a lead screw or chain mechanism, with self-locking contact systems to prevent accidental disengagement.
3.Busbar Compartment: Positioned at the upper rear or rear of the cabinet, housing the main and branch busbars.
4.Cable Compartment: Located at the lower rear of the cabinet, connecting incoming/outgoing cables. Typically houses current transformers (CTs), the earthing switch, surge arresters, etc.
5.Relay & Instrument Compartment: The space at the front upper section, accommodating secondary components like protection relays, meters, indicator lights, and control switches.
6.Pressure Relief Vent: Equipped on the cabinet top to ensure the safe, directional venting of high-pressure gases generated by an internal arc fault.
The KYN28 primarily covers the medium-voltage range, classified by rated voltage level:
1.12kV Class: The most widely used, suitable for the majority of 10kV distribution systems (e.g., factories, mines, residential areas, commercial buildings).
2.24kV Class: Meets specific requirements of certain industrial users or regional 20kV power grids.
3.35kV Class: Used for feeder circuits in 35kV substations and main distribution within factories/mines.
1.High Safety: Fully enclosed metal-clad structure with a reliable "Five-Prevention" mechanical interlock system ensures absolute operational safety.
2.High Reliability: Core components (circuit breakers, CTs, etc.) sourced from renowned domestic/international brands. Excellent insulation properties, low circuit resistance, and reliable conductivity.
3.Strong Withstand Capability: Superior dynamic and thermal stability performance, capable of withstanding and interrupting high short-circuit fault currents.
4.High Flexibility: Modular design allows flexible scheme combinations (incomer, feeder, metering, VT, bus coupler, isolator, etc.) and easy extension. Trucks offer good interchangeability.
5.Ease of Maintenance: The center-mounted truck design allows withdrawal for inspection or maintenance without specialized tools, minimizing outage time.
6.Long Service Life: Silver-plated main contacts and long mechanical life (circuit breaker typically rated for 10,000+ operations).
7.Smart Interface Compatibility: Easily integrates with intelligent monitoring terminals, supporting remote monitoring, control, and diagnostics (foundation for distribution automation).
The table below lists the key technical parameters for the KYN28 series switchgear:
|
Parameter |
12kV |
24kV |
35kV |
|
Rated Voltage (kV) |
12 |
24 |
35 (40.5) |
|
Rated Frequency (Hz) |
50 (or 60) |
50 (or 60) |
50 (or 60) |
|
Rated Current (A) |
630, 1250,1600, 2000, 2500, 3150, 4000 |
630, 1250, 1600, 2000, 2500 |
630, 1250, 1600, 2000 |
|
Rated Short-Time Withstand Current (kA/4s) |
20, 25, 31.5, 40 |
20, 25, 31.5 |
20, 25, 31.5 |
|
Rated Peak Withstand Current (kA) |
50, 63, 80, 100 |
50, 63, 80 |
50, 63, 80 |
|
Rated Short-Circuit Breaking Current (kA) |
20, 25, 31.5, 40 |
20, 25, 31.5 |
20, 25, 31.5 |
|
Rated Short-Circuit Making Current (kA) |
50, 63, 80, 100 |
50, 63, 80 |
50, 63, 80 |
|
Power Frequency Withstand Voltage (kV) (1 min) |
42 (phase/earth), 48 (isolating distance) |
65 (phase/earth), 79 (isolating distance) |
95 (phase/earth), 118 (isolating distance) |
|
Lightning Impulse Withstand Voltage (kV) |
75 (phase/earth), 85 (isolating distance) |
125 (phase/earth), 145 (isolating distance) |
185 (phase/earth), 215 (isolating distance) |
|
Protection Class |
Enclosure IP4X, Compartments IP2X |
Enclosure IP4X, Compartments IP2X |
Enclosure IP4X, Compartments IP2X |
Since its introduction and localization in the 1990s, the KYN28 series withdrawable metal-clad switchgear has evolved into one of the most widely used switchgear types in China's 3.6-40.5kV distribution systems, thanks to its outstanding safety, reliability, flexibility, and ease of maintenance. Its standardized design and mature manufacturing processes provide a solid guarantee for the safe and stable operation of power grids and reliable power supply for diverse users. In practical engineering selection and application, it is essential to choose certified products from qualified manufacturers that meet standard requirements based strictly on system parameters (voltage, current, short-circuit capacity, etc.) and specific environmental conditions. Furthermore, standardized installation, commissioning, operation, and maintenance are crucial to fully realizing its performance and ensuring the safe and smooth flow of power.
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