Engineering Quality Beyond Expectations
At Kokila Electricals, our Quality Assurance Plan (QAP) is engineered to guarantee flawless mechanical, electrical, and thermal integrity across every transformer unit. Established under an ISO 9001:2015 Quality Management System, our zero-defect strategy encompasses stringent raw material testing, bought-out item verification, stage-by-stage process controls, and rigorous Factory Acceptance Testing (FAT) compliant with international standards including IEC 60076, IEEE C57, and IS 2026.
1. Material Traceability
100% incoming inspection of prime-grade CRGO laminations, high-purity electrolytic copper, and mineral transformer oils with Mill Test Certificates (MTC).
2. In-Process Surveillance
Multi-stage quality hold points during core stacking, precision coil winding, active part assembly, and controlled vacuum drying processes.
3. FAT & Compliance
Comprehensive electrical routine, type, and special diagnostic testing witnessed by leading international third-party inspection agencies (TPI).
Raw Material Inspection Standards
| Component & Operation | Characteristics to Check | Method of Verification | Inspection Frequency | Reference Standards |
|---|---|---|---|---|
| Tank Steel Structure | Physical properties, dimensional accuracy, surface coating, and structural integrity | Mill TC verification, caliper measurement, visual audit | 100% Inspection | IS 226 / IS 2062 & Purchase Specifications |
| CRGO Core Steel | Surface insulation condition, dimensions, edge burr levels, specific core loss (Watt/kg), inter-lamination resistance | Visual inspection, precision micrometers, loss tester, TC validation | Sample testing per heat/coil | IS 3024, IEC 60404 & Engineering Approved Drawings |
| Paper Insulated Copper / Aluminium Conductor | Surface finish, bare & covered dimensions, corner radius, electrical conductivity, tensile strength | Visual audit, digital micrometer, conductivity meter, TC verification | Sample testing per reel | IS 7404, IS 12444 & Purchase Specifications |
| Insulating Pressboard & Components | Surface condition, thickness tolerance, moisture content, mechanical/chemical/electrical oil compatibility | Visual check, micrometer measurement, dielectric strength test, TC verification | 100% Batch Inspection | IS 1576 - 1992 / IEC 60641 |
| Transformer Mineral Oil | Breakdown voltage (BDV), moisture content (PPM), dielectric dissipation factor (Tan Delta), interfacial tension, neutralisation value | High-voltage dielectric testing, Karl Fischer titration, tan delta bridge test | Sample testing per tanker delivery | IS 335 - 2018 / IEC 60296 |
Bought-Out Component Acceptance Standards
| Component & Operation | Characteristics to Check | Method of Verification | Inspection Frequency | Reference Standards |
|---|---|---|---|---|
| Temperature Indicators (OTI / WTI) | Outer housing finish, thermal calibration accuracy, electrical contact operational test | Visual audit, temperature bath calibration, continuity test | 100% Routine / Sample Calibration | Approved Supplier Data & PO Requirements |
| Off-Load / On-Load Tap Switch | Overall dimensions, contact resistance, mechanical switching withstand strength, alignment | Dimensional measurement, milliohm meter test, mechanical endurance check | 100% Inspection | IS 8468 / IEC 60214 & Supplier Drawings |
| Porcelain Insulators & Bushings | Surface finish, creepage distance, dimensions, electrical high-voltage insulation withstand, porosity | Visual inspection, TC verification, dye penetration test | 100% Visual & TC Audit | IS 2099 / IS 3347 / IEC 60137 |
| Sealing Gaskets & O-Rings | Dimension, surface defect check, Shore A hardness, oil absorption & thermal degradation index | Visual check, durometer measurement, oil immersion test TC | 100% Dimension / Sample Physical | IS 4253 & Engineering Specifications |
| Cooling Radiators | Pressure withstand capability, welding seams, internal cleanliness, paint thickness | Hydrostatic leak testing under pressure, visual check | 100% Pressure Tested | IEEMA Specifications & Approved Drawings |
Core Assembly & Coil Winding Quality Controls
| Component & Operation | Characteristics to Check | Method of Verification | Inspection Frequency | Reference Standards |
|---|---|---|---|---|
| Core Stacking & Assembly | Stacking dimensions, clamping bolt tightness, core losses, insulation resistance at 112% excitation voltage | Precision scale measurement, torque wrench, electrical no-load loss measurement | 100% of Core Units | Manufacturing Design Standards & IS 2026 |
| Coil Winding | Inner/Outer diameter, axial length, turn count verification, crossover insulation placement, transposition, turn-to-turn insulation | Dimensional check, optical turn counter, inter-turn impulse test, visual audit | 100% of Windings | Approved Winding Schedule & Kokila Standards |
| Coil Thermal Drying | Axial shrinkage stabilization to final design dimensions, moisture removal index | Precision height measurement post-drying press | 100% of Coils | Manufacturing Process Control Directives |
Active Part Assembly & Insulating Oil Testing
| Component & Operation | Characteristics to Check | Method of Verification | Inspection Frequency | Reference Standards |
|---|---|---|---|---|
| Core & Coil Active Assembly | Physical clearance check, lead wire routing, internal connection joint soldering/crimping, insulation resistance (IR value), voltage transformation ratio | Visual inspection, dimensional measurement, megohmmeter, turns-ratio meter | 100% Inspection | Kokila Assembly Engineering Drawings |
| Insulating Oil Preparation | Breakdown voltage (BDV), density, volume resistivity at 90°C, oxidation stability, moisture content | HV oil breakdown kit, density meter, insulation resistance tester, Karl Fischer apparatus | 100% Oil Filling Batch Tests | IS 6792 / IS 1448 / IS 12422 / IS 2362 |
Final Factory Acceptance Testing (FAT) & Dispatch Audit
| Component & Operation | Characteristics to Check | Method of Verification | Inspection Frequency | Reference Standards |
|---|---|---|---|---|
| Final Transformer Testing (FAT) | Routine tests (winding resistance, voltage ratio, vector group, load/no-load losses, short-circuit impedance, applied/induced voltage test), type tests & special tests | Calibrated computerized electrical testing lab equipment | 100% Routine Test on Every Unit / Type Test per Design | IEC 60076 / IS 2026 / Customer Specifications |
| Final Dispatch Verification | General paint finish thickness, surface aesthetics, complete assembly of all accessories as per packing list, nitrogen pressure sealing (if applicable) | Visual inspection, magnetic paint gauge, accessory check-sheet audit | 100% Final Pre-Shipment Audit | Quality Inspection Record & Shipping Drawings |
Global Third-Party Inspection Support
To ensure complete transparency and peace of mind for our international clients, our factory acceptance testing (FAT) protocol fully supports witness inspections by recognized third-party agencies including SGS, Bureau Veritas (BV), TÜV, DNV, Intertek, and Lloyd's Register. Complete Material Test Certificates (MTC), routine test certificates, and operation manuals are provided with every shipment.
Require Custom Quality Specifications or Test Reports?
Our engineering quality team is ready to provide customized Quality Assurance Plans (QAP), technical datasheets, and factory inspection protocols tailored to your project requirements.
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