What does the white bushing of an instrument transformer indicate?

The white bushing of an instrument transformer serves a specific function in identifying the polarity of the transformer. In electrical systems, understanding polarity is crucial because it affects the accuracy of measurements and the functionality of protective devices. The polarity mark indicates how the transformer should be connected in relation to the primary circuit and ensures that the current and voltage measurements are consistent and correct. By using the white bushing, linemen and electricians can maintain proper phase relationships and ensure that the readings from the transformer align with the expected values, ultimately promoting safe and efficient operation of the electrical system.

In contrast, other options concern different attributes of transformers: the voltage rating refers to the operational limits of the transformer under certain conditions; the current type distinguishes between AC and DC applications, while the transformer size typically pertains to the physical dimensions or capacity of the transformer. These attributes are significant but do not directly relate to the marking conveyed by the white bushing.