What is the standard output voltage of a potential transformer when connected phase-to-phase?

The correct output voltage of a potential transformer when connected phase-to-phase depends on the system voltage in which it operates. In many three-phase systems, particularly those prevalent in commercial and industrial applications, potential transformers are often used to step down voltages for measurement and protection purposes.

In a typical three-phase system, if you consider a standard service voltage of 240V phase-to-ground, the phase-to-phase voltage would typically be 240V multiplied by the square root of 3 (approximately 1.732), resulting in a voltage around 416V. However, many systems standardize their outputs for utility measurements, so a potential transformer designed for a 480V system would output 480V when connected phase-to-phase.

Choosing 240V as the output voltage phase-to-phase assumes the transformer is stepping down from a grid system where phase-to-phase voltage reflects the output service level. Thus, it is reasonable to select 240V as the standard output voltage of that potential transformer when connected phase-to-phase based on typical system designs and standards.