The Perils of 2-Phase Operation
2. What Actually Happens Inside the Motor?
When a 3-phase motor runs in 2-phase, several things start to go wrong. First, the balanced rotating magnetic field collapses. Instead of a smooth, consistent pull, you get a pulsating, uneven force. This causes the motor to vibrate and produce a characteristic humming sound, which is your first clue that something is amiss. Think of it like your washing machine when it's unbalanced — that shuddering, rattling noise is not a good sign!
This uneven pull also means the motor loses a significant amount of torque, or rotational force. It's like trying to start your car in fifth gear — the engine will struggle, and might not even be able to get going. If the motor is already running under load when it loses a phase, it will likely slow down considerably. If it's starting, it might not start at all.
Perhaps the most dangerous consequence is the increased current flow in the remaining phases. Because the motor is trying to do the same amount of work with fewer power sources, those sources have to work harder. This leads to overheating of the motor windings, which is a major threat to the motor's lifespan. Imagine running a marathon while only breathing through one nostril — you're going to overheat pretty quickly! The excessive heat deteriorates the winding insulation, leading to short circuits and, eventually, motor failure.
The increased current also puts a strain on other components in the system, such as wiring, breakers, and contactors. Over time, this can cause these components to fail as well, leading to a cascading series of problems. It is definitely not a desired outcome, and should be avoided in all situations.
