CAST RESIN TRASFORMER

Efficient and Safe Solutions for Electrical Systems

Cast resin transformers are crucial electrical devices widely used in various applications, from industrial projects to high-rise buildings. With many outstanding advantages such as safety, high durability, and easy maintenance, cast resin transformers are gradually replacing traditional transformers. In this article, we will delve into the details of cast resin transformers, including their structure, operating principles, advantages, and practical applications.

1. What is a Cast Resin Transformer?

A cast resin transformer, also known as an oil-free transformer, uses air or epoxy resin as the insulating medium instead of oil. Its structure comprises coils wound around a magnetic core and insulated with heat-resistant materials. Cast resin transformers can be housed in either enclosed or open casings, depending on the specific requirements of each application.

2. Structure of a Cast resin Transformer

A cast resin transformer is a voltage conversion device designed to operate without the use of insulating oil. Its structure is specially designed to ensure high performance and safety during operation. Below are the main components of a cast resin transformer:

a. Magnetic Core

The magnetic core is the most critical component of a cast resin transformer, made from thin sheets of high-grade electrical steel with excellent magnetic properties. These sheets are arranged and tightly pressed together to minimize magnetic losses and eddy currents.

b. Windings

A cast resin transformer has two main windings:

• Primary Winding: This winding is connected to the input power source. When alternating voltage is applied, it creates a varying magnetic field in the core.
• Secondary Winding: This winding generates the output voltage from the varying magnetic field in the core. The output voltage depends on the ratio of the number of turns between the primary and secondary windings.

c. Insulating Material

Instead of using oil, cast resin transformers use air or insulating materials such as epoxy resin. The epoxy resin is molded around the windings to create a robust, high-temperature-resistant, and moisture-proof insulating layer.

d. Enclosure

Cast resin transformers are typically housed in protective enclosures made of metal or composite materials. This enclosure protects the internal components from environmental, dust, and mechanical impacts. Some enclosures are designed to be open to enhance cooling through natural or forced air.

e. Cooling System

Cast resin transformers are usually cooled by natural or forced air (using fans). This cooling system maintains a safe operating temperature for the transformer, ensuring its efficiency and longevity.

3. Operating Principle of Cast resin Transformers

The operating principle of cast resin transformers is similar to other transformers, based on the phenomenon of electromagnetic induction. When alternating voltage is applied to the primary winding, the varying magnetic field induces a current in the secondary winding, creating the output voltage. The main difference lies in the cooling and insulating methods. Cast resin transformers do not use oil for cooling but rely on air or epoxy resin for heat dissipation and insulation.

4. Advantages of Cast resin Transformers

Cast resin transformers offer numerous outstanding advantages, including:

• High Safety: Without the use of oil, the risk of fire and explosion is significantly reduced, making them suitable for densely populated and flammable areas.
• Easy Maintenance: No need for oil checks and replacements, reducing maintenance costs and time.
• High Durability: The protective casing and heat-resistant insulating materials extend the transformer’s lifespan.
• Environmentally Friendly: No oil emissions into the environment, reducing negative impacts on the ecosystem.

5. Applications of Cast resin Transformers

Cast resin transformers are widely used in various fields, including:

• Industrial: Factories, manufacturing plants, and industrial zones frequently use dry-type transformers to ensure safety and efficiency during operations.
• Construction: High-rise buildings, shopping centers, and hospitals use dry-type transformers to provide safe and stable electricity.
• Renewable Energy: In wind and solar power projects, dry-type transformers are preferred due to their sustainability and environmental friendliness.

6. Technical Specifications

Compliance with Quality Management Standards

•  Measurement of winding resistance
•  Measurement of voltage ratio and check of phase displacement
•  Measurement of short-circuit impedance and loss
•  Measurement of no-load loss and current
•  Dielectric routine tests
•  Tests on on-load tap-changers, where appropriate
•  Leak testing with pressure for liquid-immersed transformers(tightness test)
•  Tightness tests and pressure tests for tanks for gas-filled transformers
•  Check of the ratio and polarity of built-in current transformers
•  Check of core and frame insulation for liquid immersed transformers with core or frame insulation