On-Line/Off-Line condition monitoring and preventive maintenance of three-phase induction motors – The State-of-the-Art

In this paper, efforts have been made to bring out State-of-the-art status of On-line/Off-line condition monitoring and prevention maintenance of three-phase induction motors. The various techniques available for this purpose in India and abroad have been discussed briefly to highlight their principle of operation, their benefits and limitations. The on-line condition monitoring techniques are based on continuous monitoring and analysis of one or more of the motor operational parameters like stator current, axial flux, vibrations, speed fluctuations, shaft voltage, shaft grounding current etc. While some of these techniques are new, others are already in practice since long. In Off-line condition monitoring, the motor need not be disassembled, while in Preventive Maintenance, the motor has to be disassembled for doing the necessary maintenance.