摘要 |
A method for determining the efficiency and loading of an electric motor (10) comprises affixing a strain gauge (30) to the drive shaft (14), calibrating the strain gauge (30), measuring the input power of the motor (10), measuring the rotational speed of the drive shaft (14), transmitting an RF signal from the strain gauge (30) through a rotary antenna (34) to a stationary antenna (40) and calculating the torque in the drive shaft (14) under load. An apparatus for carrying out said method comprises means for determining the input power of the motor (10), means for determining the rotational speed of the drive shaft (14), a strain gauge (30) affixed to the draft shaft (14) coupled to an RF transmitter (32) transmitting a signal through a rotary antenna (34) affixed to the drive shaft (14), and transmitting means (38) coupled to the stationary antenna (40) for transmitting an RF signal to the rotary antenna (34) and receiving an RF signal from the rotary antenna (34) proportional to the amount of strain experienced by the strain gauge (30). The output power of the motor (10) can thus be determined under load conditions without decoupling the motor (10) from the load, and related to the input power to determine the efficiency of the motor (10). <IMAGE>
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