Performance characteristics and operating conditions of three-phase oil-immersed transformer

Time：2024-10-16    Auther：ZTelec-www.ztelectransformer.com

What is a three-phase oil-immersed transformer?

A three-phase oil-immersed transformer is a commonly used power device that features a fully oil-filled sealed design. The corrugated structure of the oil tank utilizes elasticity to absorb changes in oil expansion, achieving permanent sealing and is widely used in various distribution applications.

What are the basic components of a three-phase oil-immersed transformer?

1. Core: Made of silicon steel sheets with a thickness of 0.35mm to 0.5mm, stacked with insulating layers between the sheets, primarily constituting the magnetic circuit.

Core post: Used to support the windings.

Yoke: The horizontal part that forms a closed magnetic circuit.

2. Windings: Made of copper or aluminum wire,  divided into primary winding (high voltage side) and secondary winding (low voltage side), with the low voltage winding close to the core and the high voltage winding on the outside.
3. Oil tank: Contains transformer oil for insulation and heat dissipation; large-capacity transformers often have additional heat sinks or heat pipes externally.
4. Transformer oil: Functions in insulation and heat dissipation, with oil types (10, 25, or 45) chosen based on the ambient temperature.

What are the performance characteristics of a three-phase oil-immersed transformer?

1. Excellent winding design

The low voltage winding typically uses a copper foil wrapped cylindrical structure, ensuring uniform current distribution and reducing winding losses.

The high voltage winding adopts a multi-layer cylindrical structure, balancing the amp-turn distribution, enhancing short-circuit resistance.

2. Reliable fastening structure

The core and windings are secured with self-locking nuts, making the transformer strong against transport vibrations, able to withstand even 5G acceleration impacts.

There is no need for a center hanger design, further improving equipment stability.

3. Superior drying and oil filtration processes

Adopting vacuum drying technology reduces internal moisture and improves insulation performance.

Vacuum oil filtration and filling processes ensure that the oil is free from impurities and moisture, enhancing the oil’s insulation strength.

4. Corrugated oil tank design

The corrugated plates offer both oil storage and breathing functions, eliminating the need for a separate oil storage cabinet, reducing floor space, and effectively isolating air from oil to prevent oxidation and moisture ingress.

5. Low maintenance cost and long lifespan

There is no need to replace the oil during normal operation, significantly reducing maintenance costs.

The service life often reaches over 30 years, extending about 10 years more than traditional transformers.

Operating conditions for a three-phase oil-immersed transformer

1. Altitude and temperature requirements for three-phase oil-immersed transformers

Elevation should not exceed 1000 meters, with operating temperature ranging from -25°C to +40°C.

In high-temperature environments, good heat dissipation must be ensured to prevent oil oxidation; in low-temperature environments, transformer oil with a low pour point should be selected.

2. Relative humidity and environmental requirements for three-phase oil-immersed transformers

Suitable for environments with relative humidity not exceeding 95%, with sealing measures taken to prevent moisture ingress.

Use in flammable, chemically corrosive, or high-vibration environments should be avoided, with appropriate fire prevention and vibration reduction measures implemented.

Future market development trends for three-phase oil-immersed transformers

1. Increasing market demand

With global electricity demand rising, emerging markets such as China and India are driving continuous growth in the demand for power equipment due to urbanization and industrialization processes.

2. Technological innovation and environmental transformation

New insulating materials and optimized cooling systems can enhance transformer performance and extend service life.

The development of smart monitoring technology enables remote monitoring and fault diagnosis, improving the stability of power systems.

As environmental regulations become stricter, the market share for eco-friendly products, such as fire-resistant oil-immersed transformers, will gradually expand.

With their efficiency, stability, and low maintenance characteristics, three-phase oil-immersed transformers hold an irreplaceable position in the power industry. In the future, companies should grasp market demand, continuously innovate technologies, and focus on environmental trends to enhance competitiveness and expand market share.