How to identify the capacity of the transformer?

There are several main ways to identify transformer capacity:

1. View transformer nameplate

- Location and Content : The transformer nameplate is usually installed on the shell of the transformer, which is more eye-catching. The nameplate will clearly mark the transformer model, rated capacity, rated voltage, rated current, winding connection group label and many other parameters. Among them, the unit of rated capacity is generally kilovolt-ampere (kVA), which is the most direct way to obtain transformer capacity. For example, the nameplate is marked with "rated capacity: 1000kVA", indicating that the capacity of the transformer is 1000kVA.

- Understand Model meaning : The transformer model may also contain capacity information. The model coding rules of different manufacturers vary slightly, but there are generally numbers to represent content related to capacity size. Taking the common oil-immersed transformer S11-M-1000/10 as an example, "1000" usually means that the capacity of the transformer is 1000kVA.

2. Estimates based on overall dimensions (not very accurate)

- Oil-immersed transformer : For oil-immersed transformers of the same type and series, to a certain extent, the larger the capacity, the larger the volume. Because the large capacity means that the size of the core and winding will increase accordingly. For example, the overall size of the general 100kVA oil-immersed transformer will be larger than that of the 50kVA. However, this method is only a rough estimate, affected by many factors such as transformer design and material, and can not be used as a basis for accurately judging the capacity.

- Dry-type transformer : dry-type transformer also has a similar rule, and the capacity is related to the overall size. Typically, a dry-type transformer cabinet with a large capacity is larger because it has to accommodate more components such as windings and iron cores.

3. Pass the test calculation

- Short-circuit test : short-circuit test can measure the short-circuit loss of the transformer and short-circuit voltage and other parameters, and then calculate the impedance of the transformer and other data, combined with other known rated voltage and other information, can calculate the capacity of the transformer. However, this method requires professional equipment and technical personnel to operate, and to be carried out in the case of transformer outage.

- No-load test: no-load test is mainly used to measure the no-load loss and no-load current of the transformer, through these data and the rated voltage of the transformer and other parameters, the use of the relevant electrical formula can also calculate the capacity of the transformer, but the same test environment and technical requirements are higher.