High-Efficiency Oil Immersed Power Transformers
Kokila Electricals is an ISO 9001:2015 certified manufacturer and global exporter of heavy-duty oil-filled power transformers. Backed by over 30 years of engineering excellence, our power transformers are designed to perform reliably in demanding power utility networks, high-voltage electrical substations, renewable energy plants, and heavy manufacturing facilities worldwide.
Utilizing high-grade raw materials and advanced thermal calculation models, our engineering team manufactures transformers that guarantee ultra-low power loss, minimal noise generation, high dielectric strength, and robust mechanical withstand capability against sudden short-circuit forces. All our designs conform strictly to global performance standards, including IEC 60076, IS 2026, ANSI/IEEE, and BS specifications.
Core Engineering & Design Excellence
Our industrial power transformers are manufactured using state-of-the-art machinery and stringent process controls at every stage of production:
Magnetic Circuit Construction
Built using high-permeability, low-loss Cold Rolled Grain Oriented (CRGO) silicon steel laminations (M3, M4, MOH, and ZDKH grades). Step-lap mitered core joints reduce no-load losses and magnetizing current.
Electric Circuit & Windings
Constructed with 99.9% pure electrolytic grade copper conductors. Continuous disc or helical winding structures with transposed conductors ensure uniform current distribution and superior short-circuit resistance.
Dielectric Insulation System
High-density pressboards, pre-compressed insulation blocks, and premium mineral insulating oil provide exceptional electrical clearance, high impulse withstand level, and long operational lifespan.
Effective Thermal Management
ONAN / ONAF cooling systems designed with natural or forced oil convection through axial and radial cooling ducts inside windings to prevent hotspot thermal concentration.
Technical Specifications & Parameters
We offer customized engineering to meet the exact voltage ratios, kVA/MVA capacity, cooling options, and vector group requirements of overseas procurement projects.
| Technical Parameter | Standard Specification / Range |
|---|---|
| Voltage Class | 11kV, 22kV, 33kV (Up to 66kV custom ratings on request) |
| Phase & Frequency | 3 Phase, 50 Hz / 60 Hz |
| Vector Group | Dyn11, Dyn1, Ynd11, or client-specified configuration |
| Winding Material | 99.9% Electrolytic Grade Copper Wire / Strip |
| Tap Changer | Off-Circuit Tap Changer (OCTC) / On-Load Tap Changer (OLTC) |
| Cooling Class | ONAN (Oil Natural Air Natural) / ONAF (Oil Natural Air Forced) |
| Insulation Class | Class A / Thermally Upgraded Insulation Paper |
| Duty Cycle | Continuous Heavy-Duty Operation |
| Applicable Standards | IEC 60076, IS 2026, IEEE C57, ISO 9001:2015 |
Comprehensive Protective & Monitoring Systems
To ensure operational safety, real-time diagnostic monitoring, and seamless integration into modern SCADA grid systems, our power transformers are equipped with premium protective accessories:
- Buchholz Relay: Double-float relay with alarm and trip contacts for early gas detection and internal fault protection.
- Oil Temperature Indicator (OTI): Fitted with micro-switches for multi-stage alarm and trip signaling.
- Winding Temperature Indicator (WTI): Simulates winding thermal profile for automated fan control and overload protection.
- Magnetic Oil Level Gauge (MOG): Provides clear visual oil level readout with low-level alarm contacts.
- Pressure Relief Valve (PRV): Instant mechanical pressure discharge device with alarm contacts.
- Weatherproof Marshalling Box: IP55 / IP65 rated enclosure housing indicator dials, wiring terminals, and control relays.
Factory Testing & Quality Assurance (FAT)
Every power transformer manufactured by Kokila Electricals undergoes comprehensive Factory Acceptance Testing (FAT) in our advanced, calibrated testing laboratory before export shipment. Routine, type, and special tests performed include:
- Measurement of Winding Resistance & Voltage Ratio Check
- Vector Group Verification & Phase Relationship Test
- Measurement of No-Load Loss and Magnetizing Current at Rated Voltage
- Measurement of Load Loss & Short-Circuit Impedance Voltage
- Separate Source AC Voltage Withstand Test & Induced Overvoltage Test
- Insulation Resistance (Megger) & Dielectric Oil Breakdown Test