What does phase sequence indicate in an electrical system?

Phase sequence in an electrical system refers to the order in which the phases of an alternating current (AC) system reach their peak values. This is crucial in three-phase systems because it determines the direction of rotation in electric motors and the proper operation of three-phase equipment.

The correct answer emphasizes that phase sequence directly indicates how shore power is connected. In the context of shore power, particularly in marine applications or during maintenance of electrical systems, ensuring that the phase sequence is correct is essential to prevent equipment damage and to ensure that motors and other three-phase devices function correctly. An incorrect phase sequence could lead to motors running in the wrong direction, which might cause mechanical failures or safety risks.

The other options do not accurately reflect what phase sequence indicates. For instance, while the type of power source, load capacity, and voltage levels are important parameters in electrical systems, they are not directly related to the sequence or order of phases in a three-phase supply. Understanding phase sequence is vital for safe and efficient operation in electrical engineering and maintenance.