In extremely cold mining regions in the north, such as Mohe, where winter temperatures routinely drop to -40°C, electrical equipment deployed outdoors faces extreme challenges year-round, including icing, freezing, low-temperature embrittlement, and mechanical jamming. In ultra-low-temperature environments, standard switchgear is highly prone to failures such as mechanical jamming, insulation failure, seal hardening, and lubricant solidification, preventing normal closing and startup. This directly leads to downtime for open-pit mining equipment and the paralysis of power distribution systems. Many engineers assume that low-temperature tripping and startup failures are the norm in the industry, when in reality, the equipment simply lacks specialized design adaptations for extreme cold. This specialized switchgear, custom-designed for the extreme operating conditions of the Mohe open-pit mine, overcomes the low-temperature limitations of conventional equipment and achieves reliable, single-attempt closing even under extreme sub-zero freezing conditions. Among the various types of switchgear adapted for industrial and mining scenarios, this custom-designed equipment for extreme cold has redefined the operational standards for open-pit power distribution in northern regions. Both the 24 kV switchgear for the mine's main power supply and the air-insulated switchgear (AIS) commonly used outdoors have undergone specialized low-temperature upgrades, making them the preferred choice for power distribution in extremely cold mining areas.
The vast majority of general-purpose switchgear is designed to withstand temperatures ranging only from -20°C to +40°C, making them completely unsuitable for Mohe's extreme outdoor conditions. Extreme cold can compromise the protection of conventional equipment across multiple dimensions-including mechanical structure, insulation performance, electrical circuits, and sealing materials-leading to startup failures. Drawing on a real-world project at an open-pit mine in Mohe, this article will dissect the core technical logic behind the successful first-time closing of extreme-cold switchgear, compare the differences in low-temperature adaptation among various types of switchgear, and detail the key modification solutions for 24 kV switchgear and air-insulated switchgear (AIS) in extreme cold conditions.
1. -40°C Extreme Cold Conditions: Four Core Causes of Failure in Conventional Switchgear Closing
The Mohe open-pit mine represents an unsheltered outdoor environment with extreme cold, where nighttime low temperatures combined with wind, snow, and frost cause thin ice and frost layers to form easily on both the exterior and interior surfaces of switchgear cabinets. Under these conditions, conventional switchgear frequently malfunctions and is unable to close properly. The root causes are concentrated in four key aspects-common weaknesses shared by all standard types of switchgear under low-temperature environments.
First, mechanical components freeze and jam. At -40°C, lubricants used in typical mechanical springs, transmission rods, and operating mechanisms completely solidify, losing their lubricating function. This dramatically increases mechanical resistance and reduces the torque required for opening and closing operations, directly resulting in stuck closing mechanisms and operational failure.
Second, sealing materials become brittle at low temperatures. Ordinary rubber seals harden and crack in extreme cold, allowing wind, snow, and moisture to penetrate into the cabinet and form internal ice buildup, which interferes with switch operation.
Third, insulation performance deteriorates. Standard insulating materials become more brittle and less resilient at ultra-low temperatures, making them prone to micro-cracks and significantly reducing insulation margins.
Fourth, electrical drift occurs in secondary circuits. Low temperatures cause parameter shifts in relays and protective devices, leading to incorrect closing logic and triggering lockout mechanisms.
These issues collectively result in a sharp increase in failure rates for standard air-insulated switchgear (AIS) in extreme cold, open-pit mining environments. Even conventional 24 kV switchgear, if not specially designed for low-temperature operation, will frequently suffer from closing failures and equipment refusal to operate, failing entirely to meet the power supply demands of continuous open-pit mining production.
2. Equipment Selection and Adaptation for Extreme Cold: Variations in Low-Temperature Tolerance Among Different Switchgear Types
Among the various types of switchgear commonly used in industrial and mining power distribution, equipment with different structures and insulation methods exhibit significant differences in cold-weather adaptability. These differences make universal selection impractical; instead, precise customization according to open-pit mine operating conditions is essential.
Air-insulated switchgear (AIS), which relies on air insulation and an open ventilation design, features a simple structure and excellent heat dissipation. However, it has poor resistance to freezing temperatures. Conventional AIS units lack sealed thermal insulation and active de-icing mechanisms, making them highly susceptible to internal ice formation under extreme cold. Frost and ice accumulation on insulating surfaces can lead to surface tracking, discharges, and mechanical jamming. As a result, standard AIS equipment can only operate reliably in indoor, ambient-temperature environments. To function effectively in the harsh cold conditions of Mohe's open-pit mines, specialized modifications are required.
As the core of the mining area's main power distribution system, 24kV switchgear supplies electricity to all equipment involved in mining, transportation, and drainage operations in open-pit mines, demanding extremely high reliability in closing operations and operational stability. Standard 24kV switchgear typically features complex mechanical designs and numerous precision components, which are prone to insufficient torque and parameter drift in low-temperature environments. This makes such equipment a key focus for cold-weather adaptation and also the primary customized model in this Mohe project.
3. Core Technical Solution: Five Customized Designs for Achieving a Single-Pole Closing at -40°C in Icy Conditions
In response to the extreme operating conditions at the Mohe open-pit mine-including temperatures as low as -40°C, ice-covered surfaces, and severe wind and snow-the project team carried out comprehensive low-temperature customization and upgrades to the core power distribution equipment. By addressing five key dimensions-structure, materials, temperature control, logic, and protection-the team completely resolved the challenges of low-temperature closing, enabling the custom-designed 24 kV switchgear and the retrofitted air-insulated switchgear (AIS) to achieve precise, single-attempt closing even under ice-covered conditions.
1. Specialized Low-Temperature Mechanical System to Prevent Freezing and Seizure of Operating Mechanisms
All operating mechanisms were replaced with specialized damping lubricants resistant to ultra-low temperatures, enabling operation across a wide temperature range from -45°C to +55°C and completely eliminating the risk of low-temperature solidification; Torque parameters of the spring-energy-storage mechanisms have been optimized with built-in low-temperature resistance redundancy to offset increased mechanical resistance in extremely cold environments, ensuring sufficient power for closing and opening operations and eliminating closing jamming and failure-to-operate faults at their source. This solution is simultaneously compatible with the mechanical structures of all types of switchgear in the project.
2. Active Constant-Temperature De-icing System: Eliminating Ice-Related Hazards Inside the Cabinet
The cabinet is equipped with a built-in intelligent constant-temperature heating and dehumidification system that monitors internal temperature and humidity in real time. It automatically activates heating at low temperatures and dehumidification at high humidity levels, preventing condensation, ice formation, and frost buildup inside the cabinet. To address the design limitations of the open structure in air-insulated switchgear (AIS), controllable, enclosed thermal insulation and dust-proof components are installed. These components balance ventilation and heat dissipation with freeze protection at low temperatures, preventing wind and snow from entering and causing equipment to freeze.
3. Upgraded Low-Temperature, Brittle-Resistant Materials to Ensure Stable Insulation and Sealing
All cabinet seals have been replaced with low-temperature-resistant silicone rubber, maintaining flexible sealing even at -40°C without cracking or air leakage. Insulation components are made of modified low-temperature epoxy resin, eliminating issues such as low-temperature brittleness and insulation degradation. This ensures stable insulation performance for 24 kV switchgear under extreme low-temperature conditions, with no risk of creepage or breakdown.
4. Low-Temperature Anti-Vibration Design for Secondary Circuits, Ensuring Stable Closing Logic
Protection devices, relays, and secondary components are all industrial-grade equipment rated for a wide temperature range, suitable for operation at ultra-low temperatures of -40°C, thereby avoiding issues such as parameter drift and signal misinterpretation at low temperatures; the closing interlock logic has been optimized, and a self-test program for low-temperature conditions has been added-closing commands are executed only after the equipment status meets the required standards, eliminating the risk of misoperation or failure to operate.
5. Optimized Outdoor Freeze-Proof Cabinet Structure
A double-walled insulated cabinet structure is adopted, with the interlayer filled with insulating and flame-retardant material to enhance the cabinet's freeze resistance and thermal insulation capabilities. Snow- and ice-prevention structures are installed on the top and sides of the cabinet to prevent snow and ice accumulation from weighing down on the equipment, ensuring comprehensive adaptation to the extreme cold conditions of open-pit mines with no shelter.
4. On-Site Field Testing: Practical Test of Single-Cycle Closing Under Icy Conditions
In an extreme low-temperature field test scenario in Mohe during winter, the equipment was left stationary for 72 consecutive hours at -40°C in freezing conditions. Frost formed on the exterior of the switchgear cabinet, and thin ice covered certain areas, simulating the most severe shutdown conditions in a mining area. After the specially customized 24 kV switchgear and the modified air-insulated switchgear (AIS) initiated their self-test procedures, the temperature-controlled system rapidly melted the minimal frost buildup. The operating torque, insulation parameters, and circuit signals all met the required standards, and the closing operation was successfully completed on the first attempt-without any jamming, failure to operate, or alarms. The equipment's operating parameters fully complied with industrial and mining power distribution standards.
Field tests prove that the start-up reliability of switchgear in extreme cold is never a matter of luck, but rather the result of systematic, low-temperature custom design. Low-temperature failures in standard equipment can be completely avoided through technical modifications, enabling all types of switchgear to adapt to the extreme cold of northern outdoor environments.
Conclusion
From the frequent failure of conventional equipment to operate at low temperatures to the successful first-time closing of extreme-cold-customized equipment at -40°C in icy conditions, technological upgrades have completely overcome the power distribution challenges in northern mining areas with extreme cold. Whether it is 24 kV switchgear for main power distribution or general-purpose outdoor air-insulated switchgear (AIS), the stable operation of all types of switchgear under extreme conditions relies on targeted design adaptations to specific operating conditions. The core logic of power distribution in extreme cold is not merely to force equipment to adapt to low temperatures, but to comprehensively reconstruct equipment performance across all dimensions-including materials, structure, temperature control, and operational logic-to build a reliable power supply defense line for safe production in extremely cold outdoor mining areas such as Mohe.
About us
Since 2018, Zhejiang Lvma Electric Co., Ltd. has drawn on 17 years of hands-on experience in the electrical sector. As an ISO 9001:2015-certified enterprise, we excel in manufacturing intelligent switchgear systems and reliable oil-immersed and dry-type distribution transformers, exporting to Europe, the Middle East, South America, Southeast Asia, and Africa.
Backed by over 40 patents, our R&D strength drives our evolution toward intelligent and environmentally friendly power distribution. Through digitalized operations and smart monitoring, we consistently deliver products that combine innovation, safety, and long-term durability.