Why is phase sequence critical in three-phase systems?

Phase sequence is critical in three-phase systems primarily because it determines the direction of rotation of motors. In a three-phase system, the electrical power supply consists of three alternating currents that are out of phase with each other. The order in which these phases reach their peak voltage (their sequence) influences how motors will rotate.

When the phase sequence is altered, it can cause motors to rotate in the opposite direction. This is particularly important in applications where the direction of rotation is crucial for the operation of machinery, such as in fans, pumps, or conveyors. If a motor is designed to rotate in a specific direction, an incorrect phase sequence can lead to operational issues, equipment damage, or unexpected performance that can compromise safety.

Understanding phase sequence is vital for installation, maintenance, and troubleshooting in systems that rely on three-phase power, ensuring that motors and generators operate as intended.