
STANDARD TEST - Rotor Influence Check (RIC)
What does it tell you?
The rotor influence check (RIC) is a graphical representation of the rotor/stator relationship. By analyzing variations in the magnetic flux while rotating the rotor, eccentricity and rotor defects are identified. The RIC can also be used to confirm stator faults.
A motor acts similar to an electromagnet. The rotor acts like the "core" and the stator acts like the windings of the electromagnet. A RIC shows how the rotor's residual magnetism influences the stator inductance in different positions. As the magnetic field of the rotor interacts with more of the coils in each stator winding, the inductance of that winding changes. This influence causes repeatable patterns of change in the graph of the stator inductance, shown as sinusoidal waveforms.
Why is this important?
Broken rotor bars can cause extreme heat and vibration, which can result in winding failure, bearing failure, and loss of torque in a motor. Eccentricity, a non-uniformity of the air gap between the rotor and stator, can cause excessive vibration, which can result in winding and bearing failure.
