What type of electrical current do transmission circuit breakers NOT monitor?

Transmission circuit breakers are designed primarily for the protection and control of alternating current (AC) systems, which include both single-phase and multi-phase configurations. These breakers monitor AC because the majority of electrical transmission systems operate using alternating current due to its efficiency in long-distance transmission.

Direct current (DC), on the other hand, is not typically monitored by transmission circuit breakers because these systems are not structured for the handling of DC voltage in the same manner. DC circuits require different protective devices focused on their unique characteristics. Transmission circuit breakers are equipped with specific components to detect and respond to issues such as overcurrent and fault conditions that are prevalent in AC systems, leading to the conclusion that they do not account for direct current monitoring.

Additionally, all types of current are not part of their monitoring capabilities, as the focus remains on the alternating current, specifically due to the nature of most transmission lines. Thus, the identification of direct current as the type of current not monitored by these circuit breakers is accurate, highlighting the essential distinction in electrical transmission systems.