The Stator, Rotor, and Air Gap fault zones can be evaluated in the AC Standard Test by evaluating the Phase-to-Phase Inductance measurements and the associated Inductive Imbalance. An increase in Inductive Imbalance above previous values may be associated with a developing fault in the Stator, Rotor, or Air Gap fault zone.
PdMA’s MCEGold software creates a default alert level of 8% Inductive Imbalance. While this value is based on a typical Inductive Imbalance value on a variety of motors, Inductive Imbalance may vary significantly between motors. On some motors, the normal inductive imbalance could be much lower than 8%. On other motors, the Inductive Imbalance may be significantly higher than 8% without indicating a fault. Comparing to a baseline test is the best way to determine whether the Inductive Imbalance is normal for any given machine.
In the next Tip of the Week, we will discuss how to use the MCEGold Rotor Influence Check to determine the correct Inductive Imbalance levels for each asset.
To see Inductive Imbalance used as an instrumental value in a case study go to