Precision Power Transformer, Unwavering Performance.
01 General
1.1 Project Description
20/22 MVA power transformer was delivered to Canada in 2025. The rated power of the power distribution transformer is 20 kVA with ONAN cooling and 22 MVA with ONAF cooling. The high voltage is 132 kV with ±8*1.25% tapping range (NLTC), the low voltage is 11 kV, they formed a vector group of YNyn0.
Engineered for seamless integration into your existing infrastructure, a primary feature of this unit is its capability for parallel operation with the on-site existing transformer at the 132kV level. This ensures enhanced system reliability, operational flexibility, and increased capacity to meet growing load demands. The transformer is equipped with a side-mounted on-load tap changer (OLTC) for superior voltage regulation and minimal power disruption during adjustment. For critical protection against voltage surges and transient overvoltages, it comes complete with integrated lightning arresters (surge arresters).A key design aspect is the unified conservator tank system, where the main conservator and the tap changer conservator are combined into a single, integrated unit. This streamlined design simplifies maintenance, reduces external piping, and enhances overall reliability. Furthermore, to support long-term operational readiness and ease of maintenance, the transformer is supplied with 556 kg of reserved insulating oil as a backup.
Combining proven technology with practical design, this 22MVA power distribution transformer is built to deliver exceptional performance, durability, and ease of operation in a demanding utility environment.
1.2 Technical Specification
20/22 MVA power distribution transformer specifications type and data sheet
| Delivered to | South Africa |
| Year | 2025 |
| Type | Power transformer |
| Standard | IEC60076 |
| Rated Power | 20000/22000 kVA |
| Frequency | 50HZ |
| Phase | 3 |
| Cooling Type | ONAN/ONAF |
| Primary Voltage | 132 kV |
| Secondary Voltage | 11 kV |
| Winding Material | Copper |
| Angular displacement | YNyn0 |
| Impedance | % |
| Tap Changer | NLTC |
| Tapping Range | ±8*1.25% |
| No Load Loss | kW |
| On Load Loss | kW |
1.3 Drawings
20/22 MVA power distribution transformer diagram drawing and size.
02 Manufacturing
2.1 Core
| The core is constructed from high-grade cold-rolled grain-oriented silicon steel laminations. It features a three-phase, three-limb design with a multi-step cruciform cross-section and fully mitred joints, forming a low-reluctance magnetic path that minimizes no-load losses and operating noise. The entire core is securely clamped and has a single reliable grounding point to prevent discharge and overheating, ensuring efficient electromagnetic energy conversion and long-term reliable operation. |  |
2.2 Winding
 | This 22MVA, 132/11kV power distribution transformer utilizes a continuous disc winding design for both its high-voltage and low-voltage windings, constructed from flat copper conductors wound in a series of contiguous discs along the axial length of the core. This robust configuration provides high mechanical strength to withstand short-circuit forces, excellent heat dissipation properties, and superior reliability, making it a prevalent choice for transformers of this rating. |
2.3 Tank
| The tank for this power distribution transformer is constructed from high-quality steel plate, formed using CNC cutting and cold-bending processes. Its main seams are continuously welded with automated submerged arc or CO₂ gas-shielded welding to ensure structural integrity and a hermetic seal. The corrugated panels are stamped into shape, stress-relieved, and then welded to the main body to create an elastic expansion system. The entire structure undergoes shot blasting and is finished with multiple layers of anti-corrosion paint before finally being rigorously tested for leaks and strength via a vacuum pressure test. |  |
2.4 Final Assembly
 | The final assembly of this 22MVA power distribution transformer begins with carefully lowering the pre-dried and insulated core-coil assembly into the fabricated tank. All major components-including bushings, the on-load tap-changer, cooling radiators, conservator, and monitoring devices-are then methodically installed and aligned. The system is evacuated to a high vacuum before being filled with purified insulating oil to ensure complete impregnation and dielectric integrity. Finally, the assembled unit undergoes a comprehensive validation process to verify all mechanical connections, fluid sealing, and functional performance. |
03 Testing
04 Packing and Shipping
4.1 Packing
The power distribution transformer is packaged in a robust wooden crate, with the core-coil assembly secured to the base skid. Bushings and fragile components are individually cushioned and weather-proofed. The entire unit is covered with waterproof tarpaulins and securely strapped with steel bands to ensure maximum protection against impact, moisture, and handling hazards during transportation and storage.
4.2 Shipping
Under CIF (Cost, Insurance, and Freight) terms, the transformer will be transported via specialized heavy-haul trucks from the manufacturing facility to the designated port of loading. It will then be shipped using ocean freight services aboard a container vessel bound for the Port of Durban. All associated costs-including customs clearance, mandatory marine insurance coverage for the voyage, and freight charges-are borne by the supplier until the equipment is safely unloaded at the destination port.
05 Site And Summary
This 22MVA 132/11kV power transformer integrates rigorous craftsmanship with exceptional reliability, featuring a sturdy and durable tank design and robust continuous disc windings-all validated through international standard tests. Engineered for efficiency and durability, it delivers stable power transmission throughout its lifecycle, ensuring grid security and operational confidence. For detailed specifications or customized solutions, please contact our engineering team.
