What determines the capacity of a transformer?

The capacity of a transformer is determined primarily by its kVA rating based on voltages and currents. This rating reflects the maximum amount of power that the transformer can handle without exceeding its thermal limits. The kVA rating is a function of the input and output voltages and the current it can safely carry, which collectively indicate how much electrical power can be transformed while maintaining safe operating conditions.

While the physical size and weight of a transformer may give a general indication of its power handling capabilities, it is the electrical parameters, specifically the voltages and currents associated with its kVA rating, that directly dictate its capacity. Similarly, the connection type and efficiency under load are relevant factors but do not directly measure the maximum power transformable by the device. Understanding the kVA rating is essential for ensuring proper sizing and application in electrical systems, preventing overloads, and ensuring reliability and safety in operation.