Motors are susceptible to various faults in industrial applications. A motor failure cannot be identified in an initial stage but may become disastrous and the motor may suffer severe damage if not identified earlier. Therefore, undetected motor faults may cause motor failure which may lead to production shutdown. Nobody wants to keep the motors humming as this is a warning to a potential threat. Diagnostics can let you know when a motor is having problems. If a motor fails, it could shut your process down for days causing a great financial loss to your industry.
Motor failure includes inter turn short circuits in stator windings, bearing failures and broken end ring and rotor bars. It has been noticed that approximately 60% of motor failures are caused because of bearing failure and 30% because of inter turn short circuit in stator windings.
Significant efforts have been made to develop techniques for motor fault diagnosis during the last two decades. Many fault detection techniques have been developed these days. In the old days, diagnosis of motor was quite expensive but things have changed today and availability of microprocessors in starters, motor control centers and variable motor drives have given tons of data which was unavailable previously. Now, you can bring several key parameters to different systems at a quite little cost with digital serial communications.
Some of the techniques used for motor diagnosis include torque profile analysis, acoustic noise measurement, vibration analysis, magnetic field analysis and temperature analysis. These techniques require expensive sensors, additional mechanical and electrical installations and regular maintenance. In addition, the use of a sensor in a motor fault diagnosis system results in lesser system reliability as compared to other fault identification systems that do not need any other extra instrumentation.
There are two new methods used for motor diagnosis which can determine the arrival of a potential threat. This is important to ensure seamless working of the industrial processes and also to ensure a constantly growing profitability graph.
The first method is known as induction motor fault diagnostic technique. This method classifies two types of motor faults:
- Broken rotor bars
- Inter turn short circuits
Moreover, this method also identifies the severity of motor fault.
The second method is motor fault monitoring techniques which identifies whether the operating condition of a motor is healthy or faulty. This method is quite robust because it provides high level of motor fault monitoring accuracy.