Industrial transformers: dry and oil-complex, efficiency and harmonic effects

Introduction

Transformers are the main element of electric power systems that ensure the stable functioning of industrial installations. Choosing the right type of transformer—dry or oil-type—has a significant impact on the efficiency, safety, and longevity of the installation. This article examines the fundamental principles of transformer operation, the standards governing their use, and practical recommendations for selection, installation, and inspection.

Fundamental principles

Transformers work on the basis of alternating magnetic flux that occurs in iron cores, and also use the principle of induction to transfer energy between windings. The magnetic flux that occurs when a current passes through the primary winding, inducing a current in the secondary winding, provides a change in the output voltage.

Dry-type transformers use air as a dielectric, while oil-composite transformers have oil-composite oil, which performs the functions of cooling, dielectric insulation and humidity equalization. The choice of transformer type should take into account the working environment, load level, temperature conditions and operational requirements.

Technical specifications and standards

Dry transformers comply with standards ISO 281, EN 60076-1, IEC 60076-5, as well as DSTU 3060-95. They have high reliability, reduce the risk of oil leaks and are more environmentally friendly. The ISO 281 standard establishes requirements for the stability and efficiency of transformers.

Oil-complex transformers comply with standards IEC 60076-7, EN 60076-2, as well as DSTU 3061-95. They are used for high loads, but have a higher level of operating costs, including costs for cooling and oil recovery. Efficiency requirements are set by the IEC 60076-1. standard

Selection and calculation

The choice of transformer depends on the load level, temperature conditions, efficiency level and safety requirements. Here is an example of calculating the power of a transformer:

To select a transformer, use the following table:

Practical recommendations for installation and commissioning

When installing the transformer, it is important to ensure compliance with the requirements for ventilation, distance to other elements and electrical insulation. For dry transformers, adequate ventilation is required, and for oil-complex ones, the installation of a cooling system.

During start-up, it is necessary to check the voltage level, temperature, compliance with the requirements of the standards and the absence of deviations. After start-up, it is necessary to perform an initial inspection and install a control system.

Failure causes and root cause analysis

The most common causes of transformer failure are overheating, increased losses, moisture, reduced efficiency, and electrical faults. Failures can be detected due to higher temperatures on the windings, increased noise levels, changes in electrical state parameters, and changes in insulation properties.

Use data collection, temperature measurement, power measurement, and electrical parameter techniques for root cause analysis. If a failure is detected, it is necessary to repair or replace the components.

Predictive protection and condition monitoring

Monitoring methods such as thermography, power measurement, analysis of harmonic effects and current measurement are used for predictive protection of transformers. Thermography allows you to detect overheating, power measurement — to detect an increase in losses, analysis of harmonic effects — to detect deviations from nominal values.

For effective monitoring, it is recommended to use automatic data collection systems that perform real-time measurements and send results to a central server.

Comparison table

Conclusion

Choosing the right type of transformer—dry or oil-type—has a significant impact on the efficiency, safety, and longevity of the installation. Application of relevant standards, consideration of technical parameters and implementation of installation and inspection recommendations will ensure stable operation of industrial systems. Contact UNITEC-D GmbH for components that meet the requirements as well as for any technical questions.

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Sources

1. ISO 281:2005 - Transformers - Test methods
2. IEC 60076-1:2006 - Transformers - Design requirements
3. DSTU 3060-95 — Electric power transformers
4. EN 60076-7:1998 - Transformers - Thermal tests
5. IEC 60076-2:2006 - Transformers - Performance requirements