Motor Current Signature Analysis (MCSA)

Motor Current Signature Analysis detects faults in electric motors by analysing the frequency content of the supply current rather than by mounting sensors on the machine. Characteristic sidebands in the current spectrum reveal problems such as broken rotor bars, bearing wear and air-gap eccentricity.

A motor's stator current carries small modulations created by mechanical and electrical faults inside the machine and its driven load. MCSA captures the current, transforms it to the frequency domain, and looks for fault-specific frequency components — for example sidebands around the supply frequency that indicate broken rotor bars.

Because the measurement is taken at the motor control centre or terminals, MCSA is non-intrusive: there is no need to access the motor itself or stop it. This makes it attractive for motors that are hard to reach or run continuously, and it can detect electrical faults that vibration analysis sees only indirectly.

In practice MCSA complements vibration and thermography within a condition-monitoring programme, giving early warning of degrading motors so repairs can be planned before a winding or rotor failure causes unplanned downtime.

Related terms

Condition Monitoring · Vibration Analysis · Predictive Maintenance (PdM) · VFD (Variable Frequency Drive)