| 摘要 |
The winding temperature of an asynchronous motor is determined for control as regards overheating, in that a value representing the prevailing motor resistance is calculated on the basis of the amplitude of the voltage (2) impressed on the motor, the amplitude of the motor current (1), the phase angle (8) between the voltage and the current, as well as the slip (3), derived from overtones in the current flowing in the input lines to the motor. The resistance value is converted (15) to a corresponding temperature value which is used for updating a winding temperature value produced in parallel on the basis of the difference between the dissipated power and the cooling loss power, when the slip lies within predetermined limits. |
