Is it normal for an AC induction motor to shake during startup?

I. Why does it "shake" when starting up? This "shake" is actually a manifestation of insufficient or uneven starting torque during the instant when the induction motor transitions from standstill to rotation. To understand this, we first need to understand its working principle: A single-phase AC induction motor (also called a single-phase asynchronous motor) has only two sets of windings on the stator. When single-phase AC power is applied, the stator generates only a "pulsating magnetic field" (the magnetic field strength alternates between strong and weak, but does not rotate). As a result, it cannot drive the rotor to turn on its own.