CM of Electric Motors

It’s not monitoring the condition of the Motor because it’s not the motor that fails but the different parts of motor fails viz. Bearings, Windings, Shaft, Bearing Cartridge (Housing), Core. Hence, Monitoring the condition of the electric motor is monitoring condition of these parts & maintaining the healthy condition of these parts. The problems being told to the customer are either Misalignment or Unbalance in rotor but the parts of motor may fail due to Bent Shaft, Coupling Fault, Lubrication Problems, Transmitted Vibration, Vibration Resonance, Deformed Baserail, Weak Foundation, Faulty Fastening, Oversized Bearing Cartridge, Groove on Shaft, and even more, reasons. Although the CM Experts carry out Vibration Analysis for CM, has any of them reported any of these fault to you yet?

Many of these faults can be diagnosed after Root Cause Analysis (RCA) conducted in line with CM trend analysis.

Today, whatever experts in CM are doing while doing CM of Motor is pointless. That doesn’t serve the real purpose. The real CM of Electric Motor includes monitoring condition of Bearings, Windings, Core, Shaft, Coupling, Foundation/Base Rail/Fastening, etc. Condition Monitoring doesn’t conclude on root cause of the problem. Condition Monitoring tells us about the introduction of a fault in a part of the asset at a very early stage & hence, after knowing it we can conduct RCA & take necessary CAPA.

Condition Monitoring of different parts of LT electric motor includes, online monitoring as well offline monitoring.

Online Monitoring includes techniques like Thermography, Ultrasound Measurements & Vibration Measurements & Vibration Probing Study and Current – Voltage Measurement whereas Offline Monitoring includes Motor Current Signature Analysis (MCSA), Surge Comparison Test, Winding Resistance Test, Winding Insulation Test, Polarization Index Test, etc. Our CM of electric motor includes both, Online Condition Monitoring as well as Offline Condition Monitoring of different parts of the motor.

These are electric motors with operating voltages of 3300 volts, 6600 volts & 11000 volts. These motors are costly motors & operating at a critical position in the plant. The functional failure of these motors may lead to the stoppage of the complete plant & affects the productivity of the company. Hence, maintaining the healthy condition of different parts of these motors is an important function of the maintenance department.

Condition Monitoring of different parts of MV/HV motors includes online & offline testings same as in LT motors, but here the offline testings again are of two types, Non- destructive Testing & Destructive Testing.

Online Techniques of MV/HV Motors includes Thermography, Ultrasound Measurements, Vibration Measurements, Vibration Probing Study & Ultrasound Probing Study and Current/ Voltage monitoring.

Offline NDT Techniques includes, MCSA, Surge Comparison Testing, Winding Resistance Testing, Winding Insulation Resistance Testing, Polarization Index Test etc & Offline DT testings include, Tan δ & Capacitance Testing, Partial Discharge Testing and High Voltage Testing.

Under Comprehensive CM of MV/HV Electric Motor, We use all Online & Offline (NDT & DT) techniques to monitor condition of different parts of MV/HV motor & Maintain the healthy condition of Motors all the time. The Online Techniques includes Ultrasound Measurement, Thermography, Vibration Measurement. A point to note here that, the Ultrasound Measurement is done not only to monitor bearing conditions but it is done to find the condition of terminals/insulators in closed terminal box. The ultrasound measurements detects tracking, arcing & corona inside closed TB.