What factors should be considered when selecting a transformer?

1. Voltage level: Determined according to the input and output voltage requirements of the actual application scenario, it needs to match the grid voltage and the rated voltage of the electrical equipment, including the voltage values of the primary and secondary sides, such as the common 10kV/400V, etc.
2. Capacity: Select according to the power demand of the load, considering the active power and reactive power of the load, generally in kilovolt-amperes (kVA), and need to meet the maximum power demand of the load, and appropriately reserve a certain margin to cope with possible load growth.
3. Winding form: Commonly used are single-phase and three-phase windings. Single-phase is suitable for occasions with low power and single-phase loads, and three-phase is used for three-phase power supply and high power loads. In addition, there are special multi-winding transformers that can meet systems with multiple voltage output requirements.
4. Core material: Mainly silicon steel sheet and amorphous alloy materials. Silicon steel sheet core is widely used and has good magnetic conductivity and cost performance; amorphous alloy core has lower iron loss, can effectively reduce energy consumption, and is suitable for occasions with high energy saving requirements.
5. Cooling method: including oil-immersed self-cooling, oil-immersed air cooling, dry self-cooling, dry air cooling, etc. The oil-immersed type has good heat dissipation effect and large capacity, but the maintenance is relatively complicated; the dry type is more environmentally friendly, safe, and simple to maintain. It is often used in places with high requirements for fire prevention and explosion prevention.
6. Short-circuit impedance: Short-circuit impedance affects the short-circuit current and voltage fluctuation of the transformer. Generally speaking, the short-circuit impedance is large and the short-circuit current is small, but the voltage change rate may be large. It is necessary to select a suitable short-circuit impedance value according to the stability of the system and the short-circuit capacity requirements.
7. Insulation level: Determined according to the use environment and voltage level, it must be able to withstand the influence of factors such as overvoltage and insulation aging in the system to ensure the safe operation of the transformer, including the selection of insulation materials and the design of insulation structure.
8. Overload capacity: Consider the possible short-term overload of the load, and select a transformer with appropriate overload capacity to ensure that it will not be quickly damaged when overloaded. Transformers of different types and designs have different overload capacities.
9. Volume and weight: Due to the limitations of installation space and transportation conditions, in places with limited space, such as box-type substations, small distribution rooms, etc., it is necessary to choose transformers with small size and light weight, such as dry-type transformers or some specially designed compact transformers.
10. Price and maintenance cost: Considering the purchase cost and the long-term maintenance cost, the prices of transformers of different brands, specifications and technical parameters vary greatly. At the same time, the maintenance costs of oil-immersed transformers and dry-type transformers are also different, and a comprehensive economic evaluation is required.