How to select the type of power transformer

Power transformer is an indispensable and important equipment in power system, which is mainly used for voltage conversion and power transmission, and is widely used in substation, factory and building distribution system. Correct selection of the model and parameters of power transformer is not only related to the stable operation of the system, but also directly affects the economy and safety. This paper will discuss the selection method and matters needing attention of power transformer from many angles.

First, clear the use environment and load requirements

Before selecting the type, the operating environment and load requirements of the transformer should be defined first. The use environment includes installation location (indoor or outdoor), altitude, temperature range, humidity and whether it is in corrosive or flammable and explosive environment. These factors will directly affect the choice of transformer cooling mode and protection grade.

In terms of load demand, load capacity and load type need to be calculated in detail. For example, continuous operation of industrial load, periodic fluctuation of commercial load or seasonal change of agricultural electricity consumption all have different effects on the working state and life of transformers. Generally, the rated capacity of transformer should be slightly larger than the maximum load to ensure the safety margin of operation.

Second, determine the type of transformer and cooling mode.

According to the use and installation conditions, power transformers can be divided into two main types: oil-immersed type and dry type. Among them, the oil-immersed transformer has good heat dissipation performance and is suitable for large-capacity outdoor installation; Dry-type transformer is oil-free and has good fireproof performance, which is suitable for use in buildings or places with high fireproof requirements.

The cooling mode is also AN important factor in the selection, such as natural cooling (AN), air cooling (AF) and forced oil circulation (OD). Different cooling methods correspond to different load capacity and installation environment requirements.

Third, pay attention to technical parameters and energy efficiency grades

Attention should be paid to the main technical parameters of the transformer, including rated voltage, rated capacity, short-circuit impedance, wiring group, frequency, etc. In addition, with the popularization of the concept of energy conservation and environmental protection, the energy efficiency grade of transformers has also become an important reference standard for type selection. Although the initial investment of high-efficiency and energy-saving transformers is high, the long-term operation cost is lower, which is in line with the trend of green development.

Fourth, consider economy and maintenance convenience

In addition to performance parameters, the selection of transformer should also take into account economy and maintenance convenience. The purchase cost, operation loss, maintenance cost and service life of the equipment should be comprehensively considered, and the products with high cost performance should be selected. At the same time, giving priority to manufacturers' products with reasonable structure, easy maintenance and sufficient spare parts supply will help reduce the later operation and maintenance costs.

Five, follow the relevant standards and norms

The selection of power transformer should strictly follow the technical standards of the state and related industries, such as GB 1094.1-2013 Power Transformer Part 1: General Provisions, GB/T 6451-2015 Technical Parameters and Requirements of Oil-immersed Power Transformer, etc., to ensure that the selected equipment meets the requirements of safety, reliability and environmental protection.

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To sum up, the selection of power transformer is a systematic project, which needs to be comprehensively considered from the aspects of service environment, load characteristics, technical indicators, economy and standards. Only by selecting the transformer model and parameters scientifically and reasonably can it play a stable and efficient role in the power system and provide a strong guarantee for the safe operation of the power grid.