Which information is not required to be marked on a transformer nameplate?

The nameplate of a transformer provides essential specifications that ensure safe and efficient operation. Information such as primary voltage, secondary voltage, and the manufacturer's name are critical for anyone working with or installing the transformer.

Primary voltage indicates the input voltage that the transformer is designed to accept, while secondary voltage shows the output voltage that is intended to be delivered to the load. The manufacturer's name is important for warranty, support, and safety recall information as it identifies the origin of the equipment.

While the primary current calculation is essential for understanding the load characteristics and for proper circuit protection, it is not always explicitly marked on the nameplate. This is because primary current can vary depending on the load connected to the secondary side. Therefore, while knowing the primary current is important for electrical design and safety, it is not a standard requirement for it to be displayed on the transformer's nameplate. This distinction underscores why primary current is the correct choice as the information not required to be marked.