In traditional power operations and maintenance (O&M) thinking, the notion that "the cleaner the switchgear, the safer it is" is a deeply ingrained operational principle. O&M personnel routinely blow out dust and perform deep cleaning inside switchgear enclosures, striving to keep the equipment spotless, under the belief that a dust-free environment can completely prevent insulation tracking, short circuits, and discharge faults. However, long-term frontline O&M data and insulation testing have proven that absolute cleanliness is not the optimal operating condition. Excessive dust removal can actually damage the insulation structures of some switchgear, while a moderate amount of dust accumulation offers unexpected protective benefits. Whether it's general-purpose 12 kV switchgear, three-phase switchgear commonly used in industrial power distribution, or high-precision enclosed GIS switchgear, blindly pursuing extreme cleanliness creates hidden risks. Mastering the proper balance in dust removal is the key to long-term insulation protection for the equipment.
Many operational incidents are not caused by excessive dust accumulation, but rather by wear on the insulation surface, coating damage, and electrostatic imbalance resulting from frequent and excessive dust removal. The insulation materials, structural designs, and operating environments of different types of switchgear vary greatly. 12 kV switchgear, three-phase switchgear, and GIS switchgear each have different tolerances and adaptability to dust accumulation. A one-size-fits-all "thorough dust removal" maintenance approach is quietly eroding the equipment's insulation margin.
I. Challenging Conventional Wisdom: Why Can a Moderate Amount of Dust Protect the Insulation Structure of Switchgear?
Most people equate dust with potential faults because they only see the conductivity and creepage issues caused by damp dust, while overlooking the physical protective value of a dry, uniform, thin layer of dust. In a dry power distribution environment, a uniform layer of fine dust forms a breathable protective film on the surface of insulating components, providing three unexpected protective benefits.
First, it prevents oxidation by air. Insulating materials such as epoxy resin, silicone rubber, and porcelain insulators, when exposed to air over long periods, are continuously eroded by oxygen, ultraviolet rays, and trace amounts of corrosive gases, causing their surface layers to gradually age and become powdery. A dry, moderate layer of dust can envelop the surface of the insulation, isolating it from direct contact with air, significantly slowing down the aging process of the insulating materials, and preserving the equipment's insulation margin. Second, it balances the surface electric field. A uniform, thin layer of dust can weaken localized electric field concentrations on the surface of insulating components, reducing the probability of corona discharge and partial discharge. Finally, it cushions temperature and humidity shocks. A thin layer of dust forms a microscopic insulating layer that mitigates the repeated impact on the insulating structure caused by diurnal temperature fluctuations within the cabinet and the alternating cycles of condensation and drying.
These protective effects are particularly evident in open-type switchgear. Conventional three-phase switchgear and 12 kV switchgear cabinets have numerous ventilation openings and frequent air exchange with the outside environment, making insulating components highly susceptible to oxidation and aging; in such cases, the protective effect of moderately dry dust accumulation is even more pronounced. In contrast, the internal environment of enclosed GIS switchgear is stable; while it does not rely on dust protection, excessive opening of the cabinet for dust removal can actually compromise the internal sealed environment, creating even greater safety hazards.
II. The Hidden Dangers of Excessive Dust Removal: Insulation Damage More Dangerous Than Accumulated Dust
In daily operations and maintenance, practices such as forceful blowing with high-pressure air guns, repeated wiping with cloths, and frequent deep dust removal may appear to ensure cleanliness and compliance with standards, but in reality, they cause irreversible, chronic damage to the insulation structure of switchgear. These practices are also the primary cause of sudden insulation degradation in many devices after several years of operation.
In 12 kV switchgear, insulating bushings, partitions, and insulators are primarily made of epoxy resin and feature a precision protective coating on their surfaces. Frequent vigorous wiping and high-pressure air jets gradually wear down the dense protective layer on the surface of the insulation, resulting in surface roughness and an increase in microscopic cracks. At this point, moist air inside the cabinet can easily penetrate the insulating matrix. After prolonged operation, this leads to the formation of tracking marks, making the equipment more prone to insulation failures than units with a moderate amount of dust accumulation.
For three-phase switchgear widely used in industrial power distribution-which is often deployed in workshops, factory buildings, and other environments with complex operating conditions-insulating components are constantly subjected to dynamic loads. Excessive dust removal can completely wipe away the protective layer of inert dust on the equipment's surface, exposing the newly bare insulating surface directly to corrosive workshop dust, oil fumes, and exhaust gases. Compared to a stable, thin layer of dust, a freshly exposed surface is more prone to adsorbing sticky contaminants, forming conductive deposits that accelerate equipment aging.
For precision GIS switchgear, the greatest hidden hazard is not internal dust accumulation, but rather the damage to seals caused by excessive dust removal. GIS equipment features a fully enclosed gas-insulated chamber structure. The interior is already maintained in a dust-free environment when the equipment leaves the factory, so frequent opening of the enclosure for dust removal is unnecessary during operation and maintenance. Blindly opening the enclosure for cleaning disrupts the internal pressure balance, shortens the service life of seals, and introduces trace amounts of moisture and impurities, leading to irreversible issues such as minor SF6 gas contamination and degraded insulation performance-problems far more dangerous than minor dust accumulation.
III. Defining Boundaries: Which Dust Deposits Should Be Removed, and Which Can Be Left Alone?
This article does not advocate "not removing dust," but rather aims to correct the operational misconception of excessive cleaning and blindly striving for a "zero-dust" environment. The core of switchgear maintenance is to remove harmful dust deposits while retaining harmless, thin layers of dry dust, thereby achieving the optimal balance for insulation protection. By considering the specific characteristics of 12 kV switchgear, 3-phase switchgear, and GIS switchgear, clear operational boundaries can be established.
Harmful dust that requires immediate removal: damp, clumped dust; conductive metal dust; dust adhering to oil fumes; and thick, unevenly distributed dust deposits. When exposed to moisture, this type of dust forms conductive pathways, leading to creepage, short circuits, and partial discharges. It poses a genuine risk of failure and must be thoroughly cleaned on a regular basis.
Harmless dust that can be retained: dry, uniform, and thin surface dust-free of clumps, oil residue, and metal impurities. This type of dust is non-conductive and actually provides ongoing protection to the insulation surface by preventing oxidation and wear; it does not require deliberate blowing or wiping.
For specific equipment scenarios: In open-type 12 kV switchgear and 3-phase switchgear, prioritize the removal of heavy dust deposits from live core components such as contacts, busbars, and terminal blocks; thin, dry dust on the surfaces of insulated enclosures and partitions may be left in place to a reasonable extent. Fully enclosed GIS switchgear does not require manual dust removal; its internal cleanliness is maintained solely by the equipment's sealed structure, eliminating the need for unnecessary opening of the enclosure.
IV. New Standards for Scientific Dust Removal and Maintenance: Cleaning Guidelines Tailored to Different Switchgear Types
To balance equipment cleanliness with long-term insulation protection, the industry has gradually established new maintenance standards centered on "moderate cleaning and precise dust removal," tailored to the operational requirements of three mainstream types of switchgear.
12 kV Switchgear Maintenance Guidelines: Conduct annual routine dust removal, focusing on removing heavy deposits from electrical connection points and hard-to-reach corners of insulating components; retain a uniform, thin layer of dry dust on the cabinet surfaces and the outer walls of insulating components. Do not use high-pressure air guns to blow directly at close range, and do not repeatedly scrub or wipe with dry cloths to protect the integrity of the insulating coating.
3-Phase Switchgear Maintenance Guidelines: Conduct quarterly inspections to remove contaminants, focusing on eliminating oil fumes, metal dust, and clumped dust deposits; Ordinary dry dust does not require frequent cleaning; the existing thin layer of dust acts as a barrier against corrosive workshop air, thereby delaying insulation aging.
GIS Switchgear Operation and Maintenance Guidelines: Adhere to the principle of "minimal enclosure opening and zero dust removal." Manual dust removal inside the enclosure is never required throughout its service life; only periodic checks of airtightness and gas purity are necessary to avoid human intervention that could compromise the equipment's sealed insulation system.
V. Industry Summary: The Essence of O&M Is Balance, Not Perfection
Switchgear O&M has never been about pursuing "spotless" cleanliness; rather, it involves finding the optimal balance between cleaning to prevent failures and protection against aging. Excessively meticulous cleaning may appear rigorous and standardized, but in reality, it continuously erodes the equipment's insulation margin, creating long-term safety hazards.
From commonly used 12 kV switchgear and three-phase switchgear at the heart of industrial operations to high-end integrated GIS switchgear, the O&M logic for all power switchgear follows the same principle: moderate fault tolerance and scientific maintenance are far safer than extreme perfectionism. By discarding the entrenched mindset that "the cleaner, the safer," distinguishing between harmful dust accumulation and protective dust accumulation, and establishing a differentiated, refined dust-removal maintenance system, we can truly extend the insulation life of equipment and ensure the long-term stable operation of power distribution systems.
About us
Since 2018, Zhejiang Lvma Electric Co., Ltd. has been providing world-class power distribution solutions backed by 17 years of transformer manufacturing experience. As an ISO 9001:2015-certified company, we supply oil-immersed and dry-type distribution transformers and switchgear to a broad international customer base spanning five continents. Our 40+ patents reflect a strong commitment to innovation, driving our transition from a traditional factory to a smart, green technology partner. Through digital production and intelligent monitoring systems, we deliver safe, efficient, and sustainable products for the global energy market.