چەندین سەبەب دایەlectrical withstand بەڕووبەر بوونی ئەم گۆڕەنەوەیە لە خێربکاری ئاسمانی کاتێک بەکاردێت: - پێشەپێدەبوونی تەنها - ناپێکەوتنی گۆڕەنەوەکان - شێناوەژمێری گۆڕەنەوە - ناپێکەوتنی ئامادەکردنی خێربکار - هەڵەکان لە سیستەمی کارکردنی خێربکار - ناپێکەوتنی چێسەر و گۆڕەنەوە - کارکردن لە گەڕەکەی ناوەندی خێربکار - هەڵەکان لە سیستەمی کۆنتڕۆڵی خێربکار زۆرێک لەم سەبەبانە دەتوانێت بەهۆی ناپێکەوتنی سەبارەت بە کارکردنی خێربکاری ئاسمانی یان بەهۆی ناپێکەوتنی چێسەر و گۆڕەنەوە. بەشێوەیەکی گشتی، چەندین فاکتۆر هەیە کە دەتوانێت بەهۆیان دایەlectrical withstand بەڕووبەر بوونی ئەم گۆڕەنەوەیە لە خێربکاری ئاسمانی کاتێک بەکاردێت.
Babirîna Dielectric Withstand Failure di Vacuum Circuit Breakers de:
Contaminationi serbest: Pirzê dibe ku herî sazkiribit bêtirîne lê pêve dielectric withstand test kirin da ku hûn herî dirt û contaminants rast bikin.
Dielectric withstand tests ji bo circuit breakers hemî power-frequency withstand voltage û lightning impulse withstand voltage tê. Ev amûrên test diha divê ji bo phase-to-phase û pole-to-pole (jî ber bi vacuum interrupter) biguheztin.
Circuit breakers dibe ku ji bo insulation testkirina nekavînin da ku hêmî li ser switchgear cabinets bêtirîne. Ji kerema xwe herî testkirina wêne, parçeyên contact dibêjin ku insulation û shielding bikin, yekemîn bi karîbîna heat-shrink tubing an insulating sleeves. Ji bo fixed-type circuit breakers, testkirina guhertin dikare bi boltkirina test leads derbas be te terminals ya pole column.
Ji bo solid-insulated pole columns bi vacuum interrupters, vacuum interrupter we nehat bibin sheds (skirts) da ku creepage distance zêde bike. Vacuum interrupter di epoxy resin de încapsulated ye bi karîbîna silicone rubber, dema ku surface barkî na voltage nebixebite. Yekemîn, flashover dar surface barkî ya solid-insulated pole column dahê. Buna, creepage distance di nav upper û lower terminals de ya solid-insulated pole column dibe ku standards peyda bike. Ji bo spacing ya 210 mm, pas dedikirina diameter ya 50 mm, creepage distance nehat bibin 240 mm hatine jî nehat bibin sheds.
Çimka contact arm û terminal ya pole column nayê fullî seal bikin, sheds di vê bendeya de çend ku şeftîn. Ji bo 40.5 kV applications, ji bo spacing ya 325 mm, hatine jî shed add bikin nehat bibin creepage distance required, ku surface flashover çend ku şeftîn. Buna, guhertin dikare bi karîbîna compressed silicone rubber bikin da ku sealed solid insulation form bikin ji nav contact arm û pole column, ku tracking surface complete bikin prevent di nav end face ya pole column de. Pas vê treatment, creepage distance di nav upper û lower poles via contact arm de dibe ku standards peyda bike, discharge avoiding.
Ji kerema xwe external insulation clearance û creepage distance ya solid-insulated pole column bêtirîne, discharge çimka nehat bibin. Dielectric strength reduction çimka loss of vacuum di interrupter de an complete failure ya pole assembly bêtirîne. Cracks û housing defects ji design û manufacturing nehat bibin, early material aging ji processing issues, an vibration-induced flashover/breakdown dikarin equipment damage bike.
Ji bo insulation-cylinder-type pole columns, both inner û outer walls ya insulating cylinder dibe ku considered bikin ji bo creepage distance. Buna, products bi pole spacing 205 mm generally nehat bibin available. Additionally, vacuum interrupter we dibe ku sufficient creepage distance provide bike da ku flashover between upper û lower poles preventing.
Herî material hygroscopicity dibe ku insulation test failure cause bike. Epoxy resin jî water resistance heye, lê exposure prolonged to humid û wet environments water molecules gradually penetrate into the resin, leading to hydrolysis that breaks chemical bonds û performance degrade—such as reduced adhesion û mechanical strength.
| Test Item | Unit | Test Method | Index Value | |
| Color | / | Visual Inspection | As per specified color palette | |
| Appearance | / | Visual Inspection | Within limit | |
| Density | g/cm³ | GB1033 | 1.7-1.85 | |
| Water Absorption | % | JB3961 | ≤0.15 | |
| Shrinkage | % | JB3961 | 0.1-0.2 | |
| Impact Strength | JK/m² | GB1043 | ≥25 | |
| Bending Strength | Mpa | JB3961 | ≥100 | |
| Insulation Resistance | Normal State | Ω | GB10064 | ≥1.0×10¹³ |
| After Immersion for 24h | ≥1.0×10¹² | |||
| Electrical Strength | GB1408 | ≥12 | ||
| Arc Resistance | S | GB1411 | 180+ | |
| Comparative Tracking Index | / | GB4207 | ≥600 | |
| Flammability | / | GB11020 | FV0 | |
Water is a good conductor of electricity. After absorbing moisture, the dielectric constant of epoxy resin increases and its insulation resistance decreases, which may lead to electrical leakage, breakdown, and other failures in electrical equipment. Moisture-absorbed epoxy resin in circuit breaker pole columns can trigger partial discharge, thereby shortening equipment service life.
Under high electric fields, moisture accelerates the growth of electrical trees, further degrading insulation performance. This is a common cause of epoxy resin insulation failure in power equipment.
Moisture absorption also promotes reactions between epoxy resin and other environmental factors (such as oxygen, acidic or alkaline substances), accelerating material aging, which manifests as yellowing and embrittlement.
For high-current solid-insulated pole columns, heat sinks are typically installed on the upper part. These heat sinks are usually made of aluminum and coated with epoxy fluidized insulation on the outer surface. Due to the thin walls of the heat sink fins, the electric field intensity remains high at the top—even though rounded edges are provided—making discharge likely.
Generally, discharge may occur between the heat sink and the metal shutter. In such cases, attention must be paid to the electrical clearance between them. The shutter should avoid sharp edges; instead, bent flat surfaces or similar designs can be used to improve the electric field distribution.
