Measuring thermal losses of water cooled motors using oscillating ultrasonic temperature sensors

Abstract – simulations have shown that the evaluation of thermal losses of water cooled electric motors using inexpensive conventional temperature sensors is complicated by the relatively low accuracy of the latter. This accuracy must be below 0.05 K to evaluate motor efficiency with an accuracy of 1%. By experiment, it was shown that oscillating ultrasonic temperature sensors can potentially achieve the required accuracy. It was observed that the output frequency of the oscillating ultrasonic sensor featured substantial hysteresis that would complicate the development of accurate ultrasonic instrumentation.