How to Optimize Insulation Performance in Medium Voltage Switchgear

As power systems continue to develop and modernize, medium voltage switchgear is becoming increasingly widespread and critical for grid operation. However, ensuring the long-term reliable operation of this equipment faces significant challenges. Recent statistical analyses reveal that insulation-related issues account for as much as 30% of medium voltage switchgear malfunctions. These issues predominantly include insulation defects, surface creepage, flashover events, and insulation degradation stemming from small animal ingress.

A considerable number of older medium voltage switchgear installations currently fall short of fully adhering to the latest national or industrial standards concerning insulation clearances. This deficiency markedly elevates the potential for insulation breakdown, particularly when operating in demanding environments characterized by high humidity, severe pollution, or elevated altitudes. Upon equipment failure, the prevailing industry tendency is to prioritize scrutinizing manufacturing quality or technical specifications, with concerted efforts directed towards enhancing these parameters. Yet, from the intrinsic perspective of power system functionality, the insulation integrity of equipment constitutes the fundamental safeguard for its enduring stability and operational safety. Overlooking the ongoing degradation of insulation performance will directly impact power supply reliability.

Therefore, this article will systematically explore key technologies and strategies for enhancing medium voltage switchgear insulation, including the role of advanced switchgear insulation products. The goal is to effectively prevent and resolve equipment failures caused by insulation issues, thereby comprehensively boosting the reliability and safety of power systems.

Optimizing Air Insulation Clearance

Historically, certain medium voltage switchgear manufacturers have failed to rigorously comply with pertinent international/national technical standards. This has led to many in-service switchgear units having smaller-than-ideal air insulation clearances between live conductors (phase-to-phase and phase-to-ground), typically ranging from 100 mm to 125 mm. For example, relevant international/national standards explicitly mandate a minimum air clearance of 125 mm for 10kV pure air-insulated electrical equipment. Repeated AC withstand voltage tests and comprehensive accident analyses demonstrate that an air insulation clearance below 125 mm in 10kV medium voltage switchgear significantly increases the likelihood of insulation breakdown. This can subsequently trigger short circuits, equipment damage, and potentially lead to widespread grid outages. Thus, strict adherence to standards, ensuring the sufficiency and optimized design of air insulation clearance, represents the foremost priority for elevating overall insulation performance.

Strengthening Composite Insulation Design and Air Clearance Control

In some 10kV medium voltage switchgear designs, manufacturers often overlook the crucial role of air gaps within composite insulation structures, despite using insulating material partitions between live components and grounded parts. Practical experience shows that even with composite insulation, the internal air gap should be no less than 30 mm. Failing to meet this requirement significantly lowers the switchgear’s overall insulation level, potentially leading to uneven interface electric field distribution and partial discharge accumulation, ultimately causing insulation failures. Effectively strengthening composite insulation structures and meticulously managing internal air gaps are vital for ensuring long-term insulation reliability.

Ensuring Contact Integrity and Managing Thermal Hotspots

Insufficient contact capacity or substandard contact quality within medium voltage switchgear can lead to abnormal localized temperature escalation as current flows through. In extreme cases, this may result in the burnout of current-carrying components, subsequently initiating phase-to-ground or phase-to-phase arc flashovers, thereby compromising insulation integrity. Prolonged local overheating not only shortens equipment lifespan but also increases fire risk and can even lead to cascading trips. For example, a substation once experienced a switch panel fire and explosion due to an overheated and burnt-out disconnector blade, clearly illustrating the severe consequences and potential risks of poor contacts. Therefore, selecting high-quality contact materials, optimizing contact pressure and structural design, and implementing effective hotspot monitoring are crucial methods to prevent insulation degradation.

Optimizing Operational Conditions and Enhancing Maintenance Protocols

The operating environments for 10kV medium voltage switchgear are generally intricate and rigorous, often subjecting the equipment to degradation from airborne contaminants such as dust, smoke, and steam. These pollutants progressively corrode the surface of the insulation, thereby creating conductive pathways that ultimately manifest as insulation defects.

Additionally, some switchgear operators don’t prioritize routine medium voltage switchgear maintenance and inspection, failing to promptly identify and eliminate potential insulation hazards. This is also a significant reason for insulation accidents. By improving the equipment’s operating environment—for example, by enhancing cleanliness and controlling humidity—and establishing robust regular maintenance and testing mechanisms, we can effectively slow down insulation aging and prevent insulation accidents.

Rigorous Control Over Accessory Insulation Quality

A common practice among some medium voltage switchgear manufacturers, driven by cost-saving imperatives, involves selecting accompanying accessories—such as insulators, insulating panels, and epoxy resin bushing—that possess inferior insulation properties. These substandard components frequently exhibit deficiencies like low dielectric strength, reduced partial discharge inception voltage, and poor resistance to aging. Consequently, their inherent insulation strength often fails to conform to stipulated nominal standards, leading to a diminished pollution flashover voltage for the entire switchgear assembly. Based on relevant industry standards and practical operating experience, the creepage distance ratio for accessory surface insulation should meet the following: ceramic insulators no less than 18 mm/kV, and organic insulators no less than 20 mm/kV. Accessories that do not meet these specifications are highly susceptible to breakdown due to inadequate insulation strength during their extended operational lifespan. Hence, the stringent selection and exclusive use of high-standard, comprehensively tested insulation accessories are paramount to guaranteeing the sustained overall insulation integrity of the switchgear.

Liyond’s Solution: Unrivaled Insulation for Power System Safety

Addressing the pervasive insulation challenges inherent in medium voltage switchgear, Liyond as a professional custom switchgear manufacturer, is steadfast in its commitment to stringent engineering principles and the relentless pursuit of product excellence. We deeply understand that equipment insulation performance directly impacts the reliable operation of power systems and personnel safety. That’s why, in every stage—from product design and material selection to manufacturing processes and quality control—Liyond strictly adheres to and surpasses industry standards. We utilize high-quality insulating materials and advanced insulation structures to ensure that Liyond medium voltage switchgear delivers exceptional insulation performance and long-term stable operation in diverse and complex conditions. We are dedicated to providing solutions that not only meet standards but also effectively address real-world operational challenges, safeguarding your power assets.