A new approach to motor condition monitoring in induction motor drives

A new method for condition monitoring of an electrical machine is proposed. The method uses the power leads to the machine itself as the communication link between the sending station located within the machine and the receiving station located remotely outside the machine. The required communication circuit to realize data transmission in both the cases of the ordinary 60 Hz power line and the special PWM inverter-fed power line is then constructed. The communication circuit uses an asynchronous serial communication protocol and an FSK modulation for realizing frequency multiplexing in the power line. An on-line winding temperature monitoring system for an inverter-fed induction machine is constructed using this power line communication link. Experimental results demonstrate satisfactory operation of the system