Power Transformer: Channeling Energy, Powering Progress.
01 General
1.1 Project Description
10 MVA power transformer was delivered to South Africa in 2025. Designed for outdoor installation at altitudes up to 1000 meters, it delivers stable voltage conversion and power transfer for industrial facilities, regional power grids, and large commercial projects.
Boasting a rated power of 10,000 KVA, this transformer steps down 33 kV primary voltage to 11 kV secondary voltage, adopting a YNd1 vector group and 50 Hz rated frequency to align with standard power system requirements. Equipped with a Shanghai Huaming Brand On-Load Tap Changer (OLTC), it offers a ±8×1.25% tapping range on the primary side, enabling uninterrupted voltage regulation to adapt to fluctuating loads. The ONAN (Oil Natural Air Natural) cooling system, paired with PCB-free transformer mineral oil, ensures efficient heat dissipation-controlling oil temperature rise at 60 K and winding temperature rise at 65 K to protect internal components.
Constructed with high-quality materials, the transformer features copper windings and grain-oriented silicon steel sheet cores, minimizing energy loss (7.8 KW no-load loss and 60 KW on-load loss) for enhanced efficiency. Its insulation performance meets strict safety criteria: the primary side withstands 170 kV basic impulse lighting voltage and 70 kV power frequency voltage, while the secondary side handles 75 kV and 28 kV respectively, safeguarding against electrical surges and faults.
All HV, LV, and neutral bushings are porcelain-made and mounted on the tank top cover for easy maintenance. Complemented by essential accessories-including a plate-type radiator, oil temperature indicator with alarm/trip functions, Buchholz relay, oil conservator, and stainless steel terminal box-it ensures real-time monitoring, safe operation, and convenient handling via four lifting lugs.
Combining rugged design, energy-saving performance, and compliance with international standards, this transformer is a cost-effective, low-maintenance solution for voltage transformation needs, reflecting Jiangshan Scotech’s commitment to quality in electrical equipment manufacturing.
1.2 Technical Specification
10 MVA power transformer specifications type and data sheet
| Delivered to | South Africa |
| Year | 2025 |
| Type | Power transformer |
| Standard | IEC60076 |
| Rated Power | 10 MVA |
| Frequency | 50HZ |
| Phase | 3 |
| Cooling Type | ONAN |
| Primary Voltage | 33 kV |
| Secondary Voltage | 11 kV |
| Winding Material | Copper |
| Vector Group | YNd1 |
| Impedance | 8% |
| Tap Changer | OLTC |
| Tapping Range | ±8*1.25% |
| No Load Loss | 7.8 kW |
| On Load Loss | 60 kW |
1.3 Drawings
5000 kVA traction transformer diagram drawing and size.
02 Manufacturing
2.1 OLTC
| OLTC (On-Load Tap Changer) is a key device for power transformers (rated voltage ≤110kV, current ≤500A, frequency 50-60Hz). It enables tap switching under load to stabilize output voltage within a specified range or adjust line voltage per load demands. Available in CV/SV series (3-phase/single-phase, Y/D connections), it features up to 27 operating positions, mechanical life ≥800,000 operations, and electrical life ≥200,000 operations. Designed for oil immersion (-25℃ to 100℃ oil temp), it ensures reliable voltage regulation with compact structure and robust performance. |  |
2.2 Capsule Oil Conservator
 | The capsule oil conservator is a critical component of power transformers, designed to store transformer oil and compensate for volume variations caused by temperature fluctuations during operation. Its hermetically sealed capsule isolates oil from air, effectively preventing moisture ingress and oil oxidation, thereby safeguarding transformer insulation integrity and extending service life with reliable performance. |
2.3 Terminal Box
| The terminal box of a power transformer is an essential component that houses and protects wiring terminals, providing a safe, enclosed space to shield terminals from external elements such as dust and moisture. It enables convenient cable connection, inspection, and maintenance, ensuring reliable and stable electrical connectivity between the transformer and external devices. |  |
2.4 Gas Relay
 | The gas relay (e.g., model QJ4-80) is a key protective component for power transformers, constructed with die-cast aluminum ADC12 and nitrile rubber gaskets. It monitors internal faults by detecting gas accumulation or abnormal oil flow, operating within a flow velocity range of 0.7-1.5 m/s to trigger alarm signals or trip the transformer for protection; models with an air intake box are designated by adding “A” to the model number (e.g., QJ4-80A). |
2.5 continuous Winding
| The continuous winding of a power transformer is a typical winding structure, made by continuously winding flat conductors; insulating spacers are placed between its segments to form axial oil ducts that boost heat dissipation. It has a compact structure and high mechanical strength, so it’s widely used in high-voltage, large-capacity transformers to ensure stable operation and reliable insulation. |  |
2.6 Oil Temperature Indicator
 | The Oil Temperature Indicator of our best power transformers is a key monitoring component, typically mounted on the transformer tank or conservator. It displays the real-time temperature of the insulating oil (a core parameter reflecting the device’s operational state); when the temperature exceeds the safe threshold, it can trigger alarm signals or linked protective devices, avoiding insulation damage caused by overheating and safeguarding the transformer’s stable, safe operation. |
2.7 Bushing
| The bushing of our best power transformers is a key insulated component linking the device’s internal windings to external circuits. It provides electrical insulation between high-voltage windings and the transformer tank, safely leads out winding terminals for current transmission, and resists external elements (e.g., dust, moisture), enabling stable, safe operation under high-voltage conditions. |  |
2.8 Oil Draining And Sample Valve
 | The Oil Draining and Sample Valve of our best power transformers is usually installed at the bottom of the transformer tank, serving dual functions: it drains transformer oil during maintenance or overhauls, and enables convenient extraction of oil samples for quality inspections (e.g., checking impurities, moisture, or oil aging). It ensures tight sealing during normal operation to avoid oil leakage, thus protecting the transformer’s operational safety and the integrity of the insulating oil. |
03 Testing
best power transformers testing encompasses key items such as dissolved gas analysis in insulating oil, voltage ratio and phase displacement check, winding/insulation resistance measurement, applied voltage test, no-load/load loss detection, and leak testing, conducted in line with standards like the IEC 60076 series to verify electrical performance, insulation reliability, and operational safety, ensuring the product meets design requirements and is qualified for factory delivery.
04 Packing and Shipping
05 Site And Summary
At SCOTECH, our power transformers embody precision engineering, uncompromising reliability, and industry-leading efficiency-designed to deliver stable, efficient power distribution for utility grids, industrial complexes, and critical infrastructure worldwide. Backed by rigorous quality control, advanced materials, and customizable configurations, we empower your operations with durable, future-ready solutions that adapt to evolving energy demands. Choose SCOTECH for a trusted partnership in powering progress-where performance meets peace of mind.
