Buying Guide: How to calculate the transformer capacity?

Release time:

2023-08-29

Usually, if you find a transformer manufacturer to customize the transformer. There are two parameters that need to be provided to the transformer manufacturer, namely the capacity and number of phases of the transformer. Today we mainly introduce the capacity of the transformer. Only by choosing a transformer with a reasonable capacity can the efficiency of its power consumption be ensured. This article can give you a rough reference on how to calculate it.

Usually, if you find a transformer manufacturer to customize the transformer. There are two parameters that need to be provided to the transformer manufacturer, namely the capacity and number of phases of the transformer. Today we mainly introduce the capacity of the transformer. Only by choosing a transformer with a reasonable capacity can the efficiency of its power consumption be ensured. This article can give you a rough reference on how to calculate it.

Selection principle of transformer capacity: If the capacity is too large, the transformer will be in a no-load state for a long time, causing an increase in reactive power loss; if the capacity of the transformer is too small, the transformer will be in an overload state for a long time. It is easy to burn the transformer. Therefore, taking into account occasional peak fluctuations, choosing a transformer capacity that is 1.15 times the calculated load is the most appropriate capacity.

Of course, according to different industries and power consumption environments, there are different calculation methods for capacity selection and size calculation formulas. For example, distribution transformers can select transformer capacity according to economic capacity, that is, the load factor is between 0.5 and 0.6; only for drainage and irrigation For a special transformer that supplies power to other dynamic loads, the capacity of the transformer can generally be selected according to 1.2 times the nameplate power of the asynchronous motor; the transformer required for the motor needs to take into account the size of the current at startup. The capacity of the largest transformer should generally not exceed about 30% of the transformer capacity; for comprehensive power transformers such as power supply, lighting, agricultural and sideline product processing, etc., the capacity of the transformer should be selected based on 1.25 times the actual maximum possible load.

specific calculation method

For a single transformer that supplies power with a steady load, the load factor is generally about 85%, that is: β = S/Se. In the formula, S is the calculated load capacity (kVA), Se is the transformer capacity (kVA), and β is the load rate (usually 80% to 90%).

For a three-phase transformer, you need to take the maximum power of the three phases A, B, and C multiplied by 3, and then divided by the power factor. For example: the total power of the A-phase load is 10kW, the total power of the B-phase load is 9kW, and the total power of the C-phase load is 11kW. Multiply 11kw by 3, and then divide it by 0.8 (the power factor is calculated as 0.8) and 0.85 (the load is calculated as 0.85).

11x3÷0.8÷0.85=48.529, just take a 50KVA transformer.

Of course, the most reliable way is to communicate with the manufacturer in advance, and the manufacturer will provide a more scientific and reasonable power solution. If you have any needs, please come to Leilang Electrical Appliances to purchase.

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