{"id":18886,"date":"2026-08-01T09:34:00","date_gmt":"2026-08-01T01:34:00","guid":{"rendered":"https:\/\/www.cnbcsd.com\/?p=18886"},"modified":"2026-08-01T09:34:00","modified_gmt":"2026-08-01T01:34:00","slug":"comprehensive-quality-control-for-oil-immersed-and-dry-type-distribution-transformers","status":"publish","type":"post","link":"https:\/\/www.cnbcsd.com\/de\/comprehensive-quality-control-for-oil-immersed-and-dry-type-distribution-transformers\/","title":{"rendered":"Qualit\u00e4tspr\u00fcfungsverfahren f\u00fcr Transformatoren von Shendian Electric"},"content":{"rendered":"

Comprehensive Quality Control for Oil-Immersed and Dry-Type Distribution Transformers<\/p>\n

1. Overview
\nTransformers are critical assets in power distribution systems, and their quality directly impacts grid stability and operational safety. This document outlines a comprehensive quality inspection framework based on international standards including IEC 60076, IEEE C57, and GB\/T standards, tailored for both oil-immersed and dry-type distribution transformers.
\n2. Incoming Raw Material Inspection
\n2.1 Silicon Steel Sheet Inspection
\nSilicon steel is the core material for transformer magnetic circuits. Its quality directly impacts no-load losses and noise levels.
\n\uf0b7Thickness tolerance: \u00b10.02mm
\n\uf0b7Core loss test: P1.7\/50 \u2264 1.10 W\/kg (Grade 30Q130)
\n\uf0b7Magnetic induction: B8000 \u2265 1.88T
\n\uf0b7Coating insulation resistance: \u2265 50 \u03a9\u00b7cm\u00b2\/sheet
\n\uf0b7Visual inspection: No rust, burrs, or cracks
\n\"\"<\/p>\n

2.2 Magnet Wire (Copper\/Aluminum) Inspection
\n\uf0b7Conductor resistivity: \u03c120 \u2264 0.017241 \u03a9\u00b7mm\u00b2\/m (copper)
\n\uf0b7Insulation thickness: 0.12-0.20mm (depends on voltage class)
\n\uf0b7Film continuity: Pinholes \u2264 6 per 5m
\n\uf0b7Flexibility: No cracks at 1x diameter bend
\n\uf0b7Dielectric test: 2kV\/1min without breakdown
\n2.3 Insulating Oil Inspection (Oil-Immersed Transformers)
\n\uf0b7Breakdown voltage: \u2265 35kV (new oil)
\n\uf0b7Dissipation factor: tan\u03b4 \u2264 0.5% (at 90\u00b0C)
\n\uf0b7Moisture content: \u2264 20mg\/L
\n\uf0b7Acid value: \u2264 0.03 mg KOH\/g
\n\uf0b7Interfacial tension: \u2265 40 mN\/m
\n2.4 Epoxy Resin Inspection (Dry-Type Transformers)
\n\uf0b7Gel time: 150-300 seconds (at 180\u00b0C)
\n\uf0b7Glass transition temperature: \u2265 110\u00b0C
\n\uf0b7Dielectric strength: \u2265 20kV\/mm
\n\uf0b7Flame resistance: Class F1 (IEC 60705)
\n\uf0b7Moisture resistance: Stable at \u2265 95% RH<\/p>\n

3. In-Process Quality Control
\n3.1 Core Assembly Inspection
\nThe core assembly is the magnetic circuit of the transformer. Its manufacturing quality directly impacts no-load performance and acoustic noise.
\n1.Stacking factor: \u2265 96%
\n2.Joint gap: \u2264 1.0mm
\n3.Core clamping force: 15-20 N\/cm\u00b2
\n4.Core grounding: Single-point reliable grounding
\n5.Core loss test: Deviation \u2264 5% from calculated value
\n3.2 Winding Manufacturing Inspection
\n6.Winding dimensional accuracy: \u00b12mm
\n7.Turn-to-turn insulation: No damage or wrinkles
\n8.Welding quality: Resistance deviation \u2264 1%
\n9.Winding compression: Per process specification
\n10.Layer voltage test: 1.5x rated voltage\/1min
\n3.3 Active Part Assembly Inspection
\n\uf0b7Insulation clearance: Compliant with GB\/T 1094.3
\n\uf0b7Lead connections: Secure, contact resistance qualified
\n\uf0b7Insulation assembly: Clean, accurate positioning
\n\uf0b7Clamping system: Uniform pressure, no looseness<\/p>\n

4. Final Inspection and Type Testing
\n4.1 Routine Tests (Performed on Every Unit)
\nPer IEC 60076-1 and GB\/T 1094.1, every transformer must undergo the following tests before delivery:
\n11.Winding resistance measurement: Three-phase unbalance \u2264 2%
\n12.Voltage ratio measurement: Deviation \u2264 0.5%
\n13.Vector group verification: Dyn11, Yyn0, etc.
\n14.No-load loss and no-load current measurement
\n15.Load loss and impedance voltage measurement
\n16.Power frequency withstand test: 35kV class – 85kV\/1min
\n17.Induced voltage test: 1.5x rated voltage
\n18.Insulating oil test (oil-immersed): Breakdown voltage, dissipation factor<\/p>\n

4.2 Type Tests (Sampling or Special Requirements)
\n\uf0b7Temperature rise test: Top oil \u2264 55K (oil-immersed)
\n\uf0b7Lightning impulse test: Full\/Chopped wave 75kV\/170kV
\n\uf0b7Short-circuit withstand test: 2-second short-circuit current
\n\uf0b7Sound level: \u2264 55dB (10kV\/400kVA)
\n\uf0b7Partial discharge: \u2264 10pC (dry-type transformers)
\n4.3 Special Tests (Per Customer Requirements)
\n\uf0b7Zero-sequence impedance measurement
\n\uf0b7Harmonic analysis test
\n\uf0b7Environmental adaptability test (high altitude, low temperature)
\n\uf0b7Seismic performance test
\n\uf0b7Noise spectrum analysis
\n5. Quality Documentation and Traceability
\nWe maintain a comprehensive quality traceability system. Each transformer is assigned a unique serial number, and all inspection data is recorded in the quality file, including: material certificates, process inspection records, test reports, non-conformance handling records, and customer acceptance records. Best practices in quality management ensure product traceability and continuous improvement.
\n6. Inspection Differences: Oil-Immersed vs. Dry-Type
\nReference: IEC 60076 Series, IEEE C57 Series, GB\/T 1094 Series
\nInspection Item\tOil-Immersed Transformer\tDry-Type Transformer
\nInsulating Medium\tInsulating oil: Breakdown voltage, dissipation factor, moisture\tEpoxy resin: Curing degree, partial discharge level
\nSealing Test\tTank sealing test: 0.05MPa\/24h without leakage\tN\/A; check casting integrity instead
\nTemperature Rise Test\tMeasure top oil and winding temperature rise\tMeasure winding temperature rise (no oil medium)
\nFire Safety\tOil chromatography, oil drainage\/nitrogen injection\tFlame class F1, fire resistance time evaluation
\nEnvironmental\tOil biodegradability, leak prevention\tMaterial recyclability, halogen-free requirements
\nReference: IEC 60076 Series, IEEE C57 Series, GB\/T 1094 Series<\/p>","protected":false},"excerpt":{"rendered":"

Comprehensive Quality Control for Oil-Immersed and Dry-Type Distribution Transformers 1. Overview Transformers are critical assets in power distribution systems, and their quality directly impacts grid stability and operational safety. This document outlines a comprehensive quality inspection framework based on international standards including IEC 60076, IEEE C57, and GB\/T standards, tailored for both oil-immersed and dry-type […]<\/p>\n","protected":false},"author":1,"featured_media":18789,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[133,138],"tags":[],"class_list":["post-18886","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog","category-company-news"],"_links":{"self":[{"href":"https:\/\/www.cnbcsd.com\/de\/wp-json\/wp\/v2\/posts\/18886","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.cnbcsd.com\/de\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.cnbcsd.com\/de\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.cnbcsd.com\/de\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.cnbcsd.com\/de\/wp-json\/wp\/v2\/comments?post=18886"}],"version-history":[{"count":2,"href":"https:\/\/www.cnbcsd.com\/de\/wp-json\/wp\/v2\/posts\/18886\/revisions"}],"predecessor-version":[{"id":18889,"href":"https:\/\/www.cnbcsd.com\/de\/wp-json\/wp\/v2\/posts\/18886\/revisions\/18889"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.cnbcsd.com\/de\/wp-json\/wp\/v2\/media\/18789"}],"wp:attachment":[{"href":"https:\/\/www.cnbcsd.com\/de\/wp-json\/wp\/v2\/media?parent=18886"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.cnbcsd.com\/de\/wp-json\/wp\/v2\/categories?post=18886"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.cnbcsd.com\/de\/wp-json\/wp\/v2\/tags?post=18886"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}