6 MVA Railway Transformers-22/1.22 kV | South Africa 2023

Powering the future of rail transport-traction transformers for efficient energy transfer!

01 General

1.1 Project Description

This 6MVA traction transformer is exported to South Africa in August 2024. The vector group of this transformer is Y/d11y0y0n. The primary voltage is 22 kV, the secondary voltage is 2*1.22＋1.22 kV, the transformer is equipped with no load tap changer, the tapping range is ±2*2.5% at primary side, the cooling is ONAN.

The railway transformers are designed to minimize the effects of harmonic interference. When the transformer is continuously full load, the temperature rise of the transformer winding after thermal balance and stable temperature does not exceed 65 ° C, does not exceed 70 ° C under 3 times the load in one minute, does not exceed 70 ° C under 10 seconds 3.5 times the load, and does not exceed 100 ° C under 2 times the load in 30 minutes. The transformer is equipped with an overload thermal relay to protect the overload of the transformer with ambient temperature compensation and tripping contacts. The transformer is equipped with a detachable radiator. The radiator adopts a special hot-dip galvanizing process and the radiator surface is painted and insulated. The transformer can withstand 3.5 times the load.

1.2 Technical Specification

6 MVA railway transformers specification and data sheet

1.3 Drawings

167 kVA railway transformers diagram drawing and size.

02 Manufacturing

2.1 Core

Structure: Composed of three vertical legs and upper and lower yokes, forming a closed magnetic circuit. Each leg carries one phase winding, ensuring symmetrical three-phase magnetic paths. Material: Made of high-permeability silicon steel laminations coated with insulating varnish to reduce eddy current and hysteresis losses. Performance: Magnetic flux distribution is uniform, with minimal leakage flux and high efficiency. Cooling methods typically include oil cooling or air cooling, with a stable mechanical structure and excellent vibration resistance.

2.2 Winding

Connection: Y/d11y0y0n(low voltage third winding capacity 150kVA) High voltage winding: star connection Low voltage primary winding: Angle connection Low voltage secondary winding: star connection Low-voltage tertiary winding: The secondary side of the transformer provides a three-phase third winding to supply power to the auxiliary transformer, and the third winding can be tapped directly from the secondary winding or a third winding can be made separately. The third winding should have a separate sleeve, which can supply power to the auxiliary transformer. The auxiliary transformer is 150kVA. Temperature rise limit: At continuous full load, the temperature rise of the transformer winding shall not exceed 65 ° C after thermal equilibrium and stable temperature 1 minute 3 times the load does not exceed 70℃ 10 seconds 3.5 times the load does not exceed 70 ° C 30 minutes 2 times the load does not exceed 100 ° C Low voltage third winding voltage 1.22kV, capacity 150kVA, with neutral point The high voltage winding adopts continuous disc winding and the low voltage winding adopts spiral winding All windings are fully insulated The transformer is used in the area of severe lightning strikes, and the lightning arrester is installed between the high voltage bus and the ground of the substation Transformer windings have sufficient mechanical strength to resist fault currents effectively

2.3 Tank

The tank is made of steel plate ≥6mm Tank bottom plate thickness 16mm Transformer tank grey, oil pillow white, paint thickness of at least 125 microns On the main fuel tank, there is a pipe with a faucet on the pillow side and on the opposite side for connecting the oil filter, the height is suitable for ground operation, one side is located at a high place and the other side is located at a low place (if necessary, this side can be combined with the oil drain valve) the faucet has 50mm internal thread

2.4 Final Assembly

03 Testing

1. Measurement of dissolved gasses in dielectric liquid from each separate oil compartment except diverter switch compartment

2. Measurement of Voltage Ratio and Check of Phase Displacement

3. Measurement of Winding Resistance oil temp:33.0℃ relative humidity:63% Unit：Ω

4. Check Of Core And Frame Insulation For Liquid Immersed Transformers With Core Or Frame Insulation oil temp:33.0℃ relative humidity: 63%

5. Measurement Of D.C Insulation Resistance Between Each Winding To Earth And Between Windings oil temp:33.0℃ relative humidity: 63 %

6. Determination of capacitances windings to earth and between windings

7. Applied Voltage Test

8. Measurement of No-Load Loss and Current

9. Induced Voltage Test

10. Measurement of Short-circuit Impedance and Load Loss

11. Temperature Rise type test

12. Leak Testing With Pressure For Liquid-Immersed Transformers

04 Packing and Shipping

05 Site And Summary

As the core equipment of the railway electrification power supply system, railway transformers deliver high efficiency, stability, and reliability, driving the development of modern railway transportation. Whether facing complex load variations or demanding operating environments, railway transformers consistently ensure safe and stable power supply with exceptional quality. We are dedicated to providing customers with technologically advanced, energy-efficient, and environmentally friendly traction transformer solutions, contributing to the sustainable development of railway transportation. Choosing SCOTECH railway transformers means choosing efficiency, stability, and trust!