At the site of medium-voltage power distribution bidding and proposal coordination, there is an industry malpractice that causes the most headaches for chief engineers with years of experience: to save time and boost sales figures, many suppliers market KYN28 air-insulated switchgear as "universal cabinets" and recommend them indiscriminately, regardless of project operating conditions, environmental factors, or site constraints. While these cabinets may appear standardized and cost-effective, they actually plant long-term safety hazards in many projects. Either they are over-specified for the task, leading to wasted investment, or they are under-specified and unable to withstand operating conditions, resulting in frequent failures and constant maintenance and rework down the line. In reality, among the many types of switchgear, there is no one-size-fits-all formula for selecting power distribution equipment. The roles of the two most mainstream categories are extremely well-defined: AIS (air-insulated switchgear) is used for standard applications, while GIS (gas-insulated switchgear, specifically C-GIS) is mandatory for harsh or constrained environments. Accurately distinguishing the boundaries of their respective applications is the most critical strategy for avoiding pitfalls in electrical equipment selection.
Many clients and integrators are misled by the "KYN universal solution" myth, leading to two extreme errors: forcibly installing standard air-insulated switchgear in high-humidity, highly corrosive, or confined spaces-resulting in endless issues such as condensation discharge, insulation aging, and cabinet corrosion; or blindly investing in expensive gas-insulated switchgear for clean, standard indoor environments, causing massive waste of investment. Drawing on real-world engineering experience, this article clearly delineates the selection boundaries between AIS switchgear and GIS (Gas-Insulated Switchgear), clarifies the appropriate application scenarios for different types of switchgear, and puts an end to the "KYN28 is universal" misconception, helping the industry accurately avoid these pitfalls.
1. Why Is the "KYN28 Universal Switchgear" Considered the Biggest Myth in Product Selection?
KYN28 is the most widely used and technically mature medium-voltage air-insulated switchgear in China; it is a typical example of AIS switchgear. Thanks to its simple structure, low cost, ease of operation and maintenance, and universal compatibility of components, it dominates the vast majority of standard indoor power distribution applications. However, all of its advantages are based on the Prerequisite of "standard operating conditions, a dry environment, and ample space." Once these standard conditions are not met, its shortcomings are magnified infinitely.
As air-insulated equipment, it relies on air as an insulating medium. The cabinets are bulky and extremely sensitive to environmental cleanliness, temperature, and humidity; they lack the ability to provide sealed protection. Meanwhile, the various types of switchgear available on the market each have their own specific operational advantages; no single piece of equipment can handle every scenario. Suppliers deliberately downplay the equipment's shortcomings and exaggerate its versatility, portraying the KYN28 as a "universal" switchgear. Essentially, this sacrifices long-term project safety in exchange for easier sales, and it is also the root cause of countless operational and maintenance issues in distribution rooms later on.
2. When Is Air-Insulated (AIS) Switchgear Sufficient? Standard Scenarios That Are Cost-Effective and Adequate
AIS switchgear is suitable for all conventional, standardized, and clean indoor power distribution scenarios. It is also the most cost-effective option with the least maintenance requirements, making it completely unnecessary to blindly upgrade to gas-insulated switchgear. As long as the environment is dry, free of corrosive gases, low in dust, and the power distribution room has ample space, selecting air-insulated switchgear such as KYN28 is the optimal solution.
Specific suitable scenarios include: indoor power distribution rooms in conventional industrial facilities, municipal standard substations, power distribution for office buildings and commercial complexes, and industrial parks in arid regions. In these scenarios, the environment is stable, free from extreme weather disturbances and industrial corrosion sources; the insulation margin and operational stability of air-insulated switchgear fully meet standards, and equipment failure rates are extremely low. In these scenarios, any upgrade that replaces GIS (gas-insulated switchgear) constitutes overdesign and will only unnecessarily increase project procurement and O&M costs.
From the perspective of industry-standard switchgear selection logic, the core value of air-insulated equipment lies in "unbeatable cost-effectiveness for standardized scenarios." Provided that operating conditions are met, selecting AIS is always a more practical choice and better aligned with project budgets than gas-insulated switchgear.
3. When Is It Necessary to Use a C-GIS Gas-Insulated Switchgear? Harsh Environments Where Air-Insulated Switchgear Cannot Withstand the Conditions
The root cause of many project failures is the forced use of air-insulated switchgear in harsh operating conditions. When a project involves space constraints, harsh environments, outdoor or semi-outdoor installations, high humidity and condensation, salt fog corrosion, or high dust pollution, the open insulation structure of conventional air-insulated switchgear is completely unsuitable, and an upgrade to compact gas-insulated switchgear (GIS) is mandatory.
C-GIS switchgear completely seals core live components-such as busbars, circuit breakers, and isolating switches-within a pressurized gas-filled enclosure. The insulating medium does not rely on external air, providing complete protection against moisture, salt fog, dust, and corrosive gases, and offering exceptional environmental adaptability. At the same time, the compact cabinet design minimizes the footprint, perfectly addressing space constraints in cramped basements, utility tunnels, and compact substations.
Typical scenarios where gas-insulated switchgear is essential include: coastal areas with salt fog, chemical plants with corrosive environments, high-humidity and rainy regions in southern China, underground utility tunnels/distribution rooms, retrofit projects with extremely limited space, and unmanned remote substations. In these scenarios, the shortcomings of all air-insulated switchgear become glaringly apparent. Even with the addition of dehumidification systems or sealing modifications, they cannot match the stable performance of gas-insulated switchgear, which remains the only option among all types of switchgear capable of long-term, stable operation.
4. Chief Engineer's Practical Guide to Avoiding Pitfalls: A Simple Selection Mnemonic
Set aside supplier marketing hype; electrical equipment selection should be based solely on operating conditions. There's no need to blindly follow the "all-purpose cabinet" gimmick. The core selection logic is simple and clear:
Standard indoor environments, dry and clean, with ample space → Prioritize AIS switchgear-it's sufficient, cost-effective, and easy to maintain;
High humidity and corrosion, salt fog and dust, limited space, unattended operation → GIS (gas-insulated switchgear) is a must to eliminate potential future hazards;
All types of switchgear serve their specific purposes; there is no "one-size-fits-all" equipment-only precisely tailored solutions.
Conclusion
The KYN28 has never been a one-size-fits-all solution; it is simply the optimal choice for standardized indoor applications. The key to making wise electrical equipment selections lies in not wasting your budget, not overlooking risks, and precisely distinguishing the application boundaries between AIS switchgear and GIS (gas-insulated) switchgear. By understanding the logic behind matching different types of switchgear to specific operating conditions and rejecting one-size-fits-all marketing tactics, you can ensure that every investment in equipment is spent wisely-avoiding both blind overpricing and the temptation to cut corners-and eliminate long-term operational risks in the power distribution system from the outset.
About us
Zhejiang Lvma Electric Co., Ltd., founded in 2018, brings 17 years of consolidated industry experience. ISO 9001:2015 certified, we manufacture intelligent switchgear systems and oil-immersed and dry-type distribution transformers for clients across Europe, the Middle East, South America, Southeast Asia, and Africa.
With over 40 patents, our R&D team drives the transition from traditional manufacturing to smart energy solutions. Digital production and real-time monitoring ensure every product delivers reliable performance and uncompromising safety.