Dl/t 626-2024 Compliance Guide: Managing Chalking In Composite Insulators
The release of the updated DL/T 626-2024 standard introduces stringent assessment protocols for overhead line maintenance. Power grid operators frequently encounter surface degradation, specifically chalking, on organic housing materials. Determining whether to replace a compromised insulator depends heavily on quantitative evaluation rather than visual inspection alone.
Evaluating Surface Chalking on High-Voltage Lines
Should chalked composite insulators be replaced under DL/T 626-2024? Replacement is mandatory if chalking penetrates the core fiberglass rod, reduces hydrophobicity to class HC6 or HC7, or lowers the wet flashover voltage by more than twenty percent. Superficial chalking without mechanical or severe hydrophobic loss only requires scheduled monitoring.
Severe environmental exposure accelerates the aging of silicone rubber components. When field testing dead end suspension insulators, technicians must measure the remaining hydrophobic properties. If the material fails to shed water effectively, localized dry bands form, leading to tracking, erosion, or eventual flashover under wet conditions.
Standardized Testing and Field Decisions
Adhering to the updated regulatory framework ensures grid reliability while optimizing maintenance budgets. The inspection workflow demands specific diagnostics to prevent premature asset disposal while eliminating high-risk components from active circuits.
Three-Step Inspection
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Perform visual assessment and manual chalk wipe analysis to classify surface powdering.
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Measure hydrophobicity classification using the water spray method to check recovery tracking.
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Execute ultrasonic internal testing on any suspect polymer deadend insulator to detect core degradation.
Maintenance Action Thresholds
| Chalking Severity Level | Hydrophobicity Class | Required Action Plan |
|---|---|---|
| Light (Surface powder only) | HC1 - HC3 | Retain in service; re-test during next cycle. |
| Moderate (Deep discoloration) | HC4 - HC5 | Increase inspection frequency; apply coatings if needed. |
| Severe (Material erosion) | HC6 - HC7 | Immediate replacement of the affected unit. |
Operational safety relies on the structural integrity of tension assemblies. Utilizing qualified dead end insulators that meet the mechanical load mandates of DL/T 626-2024 prevents catastrophic line drops during extreme weather events.
