Electronics Technician Second Class (ET2) Advancement Practice Exam

The device that switches power from the normal source to an alternate source for nonvital users is the automatic bus transfer. An automatic bus transfer operates without human intervention, ensuring a seamless switch to a backup power source in case of failure in the primary power supply. This is particularly useful to ensure that essential systems remain powered without delay, which can be critical in maintaining operations.

In contrast, a manual bus transfer requires a technician or operator to physically initiate the switch from the normal source to the alternate source. This means that, during a power outage, there may be a delay before the backup power is supplied, which may not be acceptable for vital services that require an uninterrupted power supply.

The generator switch typically pertains to controlling the operation of generators specifically, while a remote power controller is used for managing power distribution from a distance but doesn't inherently perform the automatic transfer function. Therefore, for nonvital users needing an automatic switch, the automatic bus transfer is the most suitable device for ensuring continuity of service.