How is the size of a transformer usually indicated in blueprints?

The size of a transformer is typically indicated in blueprints by its rating in kilovolt-amperes (kVA) or kilowatts (kW). This rating provides a measure of the transformer's capacity to handle electrical power. It is essential for understanding how much load the transformer can support safely and efficiently.

Knowing the kVA or kW rating helps in selecting the appropriate transformer for specific applications, ensuring it can handle the electrical demands placed upon it without overheating or performing inefficiently. This clear indication of capacity is crucial for engineers and technicians when planning electrical systems to avoid potential failures due to overload.

Other options, such as physical dimensions or the ampacity of its wiring, do not convey the transformer's capacity or functionality as effectively as its power rating. While the number of circuits connected can offer some insight into usage, it does not provide a direct indication of the transformer's size or capacity.