As autumn sets in, the temperature difference between day and night widens across most regions nationwide, accompanied by more showers and dewyhumid weather. After operating at fullload under high temperatures throughout summer, power distribution systems enter a highrisk period for seasonal faults. Loose connections caused by thermal expansion and contraction, reduced insulation performance due to temperaturedifference condensation, as well as corrosion and poor contact triggered by moisture ingress constitute the most common power distribution hazards in autumn.

Drawing on operationandmaintenance experience from industrial, commercial, data center and other scenarios, we have sorted out six special inspection and maintenance tasks that must be completed before autumn arrives to identify hidden risks in advance and ensure stable equipment operation through the seasonal transition.

I. Torque Reverification of Fasteners: Counteract Stress from Thermal Expansion and Contraction under Temperature Fluctuations

Core Risks 

Following fullload operation under high summer temperatures, growing daynight temperature swings in autumn increase repeated thermal expansion and contraction of conductors and metal connectors. Bolt pretension gradually relaxes, contact resistance rises accordingly, which may easily lead to joint overheating and poor contact, or even ablation failures in severe cases. Such latent hazards are hard to detect under steadyload conditions and often develop into serious issues by the time an overtemperature alarm is triggered.

Inspection & Maintenance 

Key scope: straight busway joints, plugin units, maincircuit terminals of power distribution cabinets, highcurrent outgoing terminals, copper bar lap joints, and circuits running continuously at full load in summer;

Operation standard: Retighten fasteners onebyone strictly in accordance with manufacturerspecified torque values under poweroff conditions. Tightening by feel is prohibited. Mark highcurrent circuits for priority verification;

Disposal requirements: Polish oxidized or slightly ablated contact surfaces, apply conductive grease, then tighten to standard torque. Promptly replace severely damaged components.

II. Special Insulation Performance Test: Guard against Insulation Degradation Caused by Condensation

Core Risks 

Large morningevening temperature differences in autumn readily produce condensation inside power distribution rooms, cable shafts and enclosed cable trays. Combined with dust accumulated over summer operation, insulation resistance may drop sharply and give rise to creepage, earth faults and shortcircuits. Conventional wrappedtype busways and aging distribution cabinets see significantly higher insulationfailure rates during this period than in other seasons.

Inspection & Maintenance

 Key scope: phasetophase and phasetoground insulation of busway trunking, insulation for main and secondary circuits in distribution cabinets, wallpenetrating /floorpenetrating busway sections, and powerdistribution equipment in humid areas;

Operation standard: Test with a 1000 V megohmmeter. Insulation resistance of lowvoltage powerdistribution systems shall be no lower than 0.5 MΩ. Compare readings with historical summer test data. Prioritize investigation for causes including moisture ingress, dust accumulation and insulation aging when resistance drops by more than 30%;

Compatibility note: Mega Technology epoxy resin fluidizedinsulation busways adopt an integrated compact insulation structure without air gaps or splicing seams. Insulation performance remains stable under condensation conditions, effectively lowering insulationfailure risks during seasonal transitions.

III. Inspection of Sealing & Protection Structures: Block Moisture and Rainwater Ingress

Core Risks 

Autumn brings frequent showers and heavier morningevening humidity. Failed busway sealing or poorly sealed distributionroom barriers allow rainwater and moisture to penetrate equipment, resulting in conductor corrosion, dampened insulation and caked dust. Wallpenetrating sections, floorpenetrating sections and outdoor incomingline points represent highrisk leakage locations.

Inspection & Maintenance 

Key scope: sealing gaskets for busway covers, expansionjoint sealing structures, wallpenetrating /floorpenetrating sealing points, doorwindow gaps in distribution rooms, as well as waterproof sealing and drainage facilities for cable trenches;

Operation standard: Sealing gaskets shall be free of aging and cracking; covers shall fit tightly without warped edges. Wallpenetrating openings shall be fully sealed with no gaps. Cable trenches shall hold no standing water and drainage passages shall remain unobstructed;

Disposal requirements: Replace aged and failed sealing components; reseal damaged wallpenetrating points. Add drainage and dehumidification measures at cabletrench locations prone to water accumulation.

IV. Remeasurement of Temperature Rise at Key Points: Detect Latent ContactDegradation Hazards

Core Risks 

After fullload hightemperature operation through summer, latent contact degradation may occur at certain connection points. Load adjustments in autumn produce inconspicuous surface temperature rises, making hazards easy to overlook. Over time, poor contact worsens progressively and may cause overtemperature tripping or even equipment burnout.

Inspection & Maintenance 

Key scope: busway joints, plugin units, circuitbreaker incomingoutgoing terminals, busway lap joints, and highload branch circuits;

Operation standard: Carry out tests with an infrared thermal imager under steadyload conditions. Conductor temperature rise shall comply with limit values specified in GB 7251.1. Mark locations where temperature difference between adjacent points on the same circuit exceeds 10 K for continuous monitoring;

Disposal requirements: Power off, disassemble and inspect points with abnormal temperature rise to eliminate poorcontact risks. Resume operation only after satisfactory retesting.

V. Verification of Earthing & Protection Circuits: Ensure Reliable Fault Protection

Core Risks 

High summer temperatures and humidity may corrode earthing connectors and age protectivedevice components. Changes in load profiles in autumn reduce the suitability of original protection settings and weaken faultprotection capacity. Failed earthing or nontripping protection devices may significantly expand accident consequences upon faults.

Inspection & Maintenance 

Key scope: main earthing conductors of powerdistribution systems, equipmentenclosure earthing jumpers, circuitbreaker protection settings, residualcurrent protective devices, and secondary control circuits;

Operation standard: Earthing resistance of lowvoltage systems shall be no greater than 4 Ω. Earthing connectors shall be free of corrosion and looseness. Protection settings shall match actual presentday loads with reliable operating characteristics. Residualcurrent protective devices shall pass standardized functional tests;

Disposal requirements: Remove rust and tighten all earthing connectors, adjust protection settings according to currentload characteristics, and replace malfunctioning or aged protective components.

VI. Rectification of Environment & Auxiliary Facilities: Optimize Equipment Operating Conditions

Core Risks 

Dust and debris accumulated during summer operation may block equipment heatdissipation passages. Rodents and insects tend to migrate into powerdistribution rooms in autumn, gnawing cables and building nests that cause shortcircuits, poor contact and inadequate heat dissipation. These seemingly minor environmental hazards underlie many unexplained equipment failures.

Inspection & Maintenance 

Key scope: equipment heatdissipation air ducts, ventilation and dehumidification equipment in distribution rooms, rodentandinsectproof sealing measures, emergency lighting and firefighting equipment;

Operation standard: Heatdissipation passages shall be free of dust blockages; ventilationdehumidification equipment shall operate normally. Cable entryexit points and doorwindow gaps shall maintain intact rodentandinsectproof sealing. Emergencylighting and firefighting supplies shall be complete and functional;

Disposal requirements: Thoroughly clean dust inside equipment and air ducts, service ventilationdehumidification units, reinforce rodentandinsectproof measures, and verify emergencyfireprotection installations.

Preemptive Intervention Is the Core of Seasonal Operation & Maintenance

Seasonal faults in powerdistribution systems commonly stem from latent risks gradually accumulating under changing environmental conditions until breaking out collectively. Preemptive inspection and proactive intervention incur lower costs and produce less disruption compared with emergency repairs after faults occur. The six tasks above cover six dimensions: connections, insulation, protection, performance, faultprotection and operating environment. They effectively mitigate common autumnseason fault risks and support smooth seasonal transition for powerdistribution systems.

All powerdistribution product series from Mega Technology feature structural and performance optimizations for seasonal operatingcondition variations. We also provide seasonalmaintenance technical guidance, hiddenrisk investigation and equipmentupgrade services to support safe and stable operation of powerdistribution systems across diverse application scenarios.

Should you require consultation on seasonal powerdistributionsystem maintenance, hiddenrisk surveys or equipment upgrading & retrofitting, please send us a backstage message to connect with our professional technicalsupport team.