Motor Rotor Eccentricity

👉 Why 2X Line Frequency (100 Hz or 120 Hz) is Dominant in Eccentric Rotor of Motor? 👈
In some countries like Egypt and KSA, electrical line frequency is 50 Hz (3000 CPM) and 60 Hz (3600 CPM), respectively and the fault of eccentric rotor causes high vibrations due to 2X Line Frequency (100 Hz or 120 Hz). The physical analysis of this pattern displayed that every motor revolution in a two-pole motor causes a magnetic pull toward the closest pole two times per revolution (i.e., the magnetic pull goes from zero to maximum twice per revolution). This rotation causes the electrical signal to fluctuate from 0 to 100 Hz or 0 to 120 Hz based on the feeding source. Therefore, when a rotor is not centered within the stator, it causes a variable air gap between the rotor and the stator, which affects the 2x line frequency.