بەشداری ئەو خراپییانەی پێکهاتە ڕەنگی بەستەرەکان بە پێی چەندین شێواز هەڵبژێرە
Pêşnûna Vê Rewşê
Di dema komîsyonkirina AC de ya yek substationê, çarşeyek şimendanên post insulator da pêşkeft. Rewşa xeta teqdimkirin diha:
Heke qapik 500 kV ya AC switchyard bi serbexiya busbarê bikriye, têne û hêviya dual - set busbar differential protection ya busbar ê amade kirin, û qapik çalak kir. Fasey xetayek fase B bo, û deravê xetayek 5,760 A bo. Analîz gas composition ya SF₆ gas da li ser gas chamber dibe, û SO₂ content 5.3 μL/L (standart 2 μL/L) bo.
Sazkirina Post Insulator
Gas chamber pirsa trê post insulators, particle traps, pull plates, jî binihêre. Wêgotin Figure 1, di dema montajê de, trê post insulators û particle traps bi bolts da ser metal pull plate fix kirin. Shielding cover bi bolts da ser metal insert di navbera insulator de saz kirin. Insert bi casting da li ser insulator bond kirin. Di dema montajê de, bi bolts da pull plate ser pipe busbar flange fix kirin. Malper material ya insulator epoxy resin bo, particle trap alloy material bo, û limit pad insulating material bo.
Malper farsa post insulator da ku malper conductor internal da support bikin û ji bervek isolating gas chamber nebe. Heke cihaz normal bikar bînin, post insulator di deravê gas constant da evenly stressed bikin, wêgotin Figure 2. Dilêrin, electric field distribution ya trê post insulator extremely uneven bo. Electric field strength di interface di navbera metal insert û epoxy resin de relatively high bo. Ev uneven distribution divê local charge accumulation relatively serious li ser trê post insulator bike. Heke foreign objects û serekî vêstîn, flashover discharge pêşkeft bibe.
Re - measurement Appearance Dimensions
Post insulator faulty li factory re - measurement dimensions û appearance inspection bika. Faulty busbar post insulators slightly wiped û marks polished bikan. Surface ya post insulator intact bo, û no visible cracks, bubbles, û other anomalies dibin.
Bi reference drawings, multiple key dimensions ya post insulator, particle traps, shielding covers, pull plates, jî re - measured bikan. Ev li ser re - measuring multiple dimensions center - to - center distance ya trê legs ya post insulator, circumferential diameter, û angle bêtir. Hemû dimensions qualified dibin.
Dye Penetrant Inspection
Dye penetrant inspection li ser post insulator bika. Di dema cleaning û grinding de, inspection bika. Cleaning agent spray bi ser paper, û then penetrant surface ya insulator clean bika. Li dema careful inspection, no penetrant seepage detected, û no anomalies dye penetrant inspection dibin.
X - ray and Industrial CT Inspection
X - ray inspection li ser post insulator bika. Post insulator rotated 360° li ser inspection, û no defects such as poor bonding, bubbles, û cracks dibin.
Industrial CT inspection tests li ser post insulator bikan. Internal insulation material generally uniform bo, û no air holes, cracks, impurities, û other defects dibin. No poor bonding between low - voltage end insert û epoxy resin, neither central cylinder û epoxy resin.
Mechanical Performance Test
Mechanical performance tests li ser post insulator bikan, including pressure test (12 kN, holding pressure for 30 min) û torsion test (15 kN, holding pressure for 30 min). Surface ya post insulator observed for any anomalies, cracks, û damage. No anomalies found through mechanical performance test.
Insulation Performance Test
Post insulators assembled into busbar test state with new particle traps û old particle traps (after grinding) returned from site respectively, û filled with 0.5 MPa SF₆ gas inside.
First, assessment carried out according in - factory withstand voltage test method: power - frequency withstand voltage (740 kV for 1 min - 381 kV for 5 min), û lightning impulse (±1675 kV, 3 times each); then, assessment carried out according on - site withstand voltage test method: power - frequency withstand voltage (318 kV for 5 min - 550 kV for 3 min - 740 kV for 1 min - 381 kV for 45 min). All test results normal, û no discharge or abnormal conditions.
Fault Reproduction Test
Based on above analysis post insulator, determined no fault problems found in design û manufacturing stages post insulator. Preliminarily judged foreign objects surface post insulator during installation stage might caused flashover discharge. To further confirm cause accident analyzed, considering possible hiding places foreign objects û situation non - application lubricating grease, reproduction tests under various working conditions carried out, including: applying 1/3 lubricating grease post insulator (no discharge), applying 1/2 lubricating grease post insulator (no discharge), applying 2/3 lubricating grease post insulator (no discharge), applying 1/3 lubricating grease post insulator û blowing dust (dust onto post insulator, no discharge), etc.
Based on reproduction test results under above - mentioned working conditions, can concluded single - source lubricating grease contamination û metallic foreign objects not likely cause surface flashover breakdown insulator; for insulators break down under power - frequency voltage, both central insert û ground - potential insert have obvious ablation marks; for insulators break down under lightning impulse voltage, central insert has ablation marks, similar phenomenon on - site fault.
