| 摘要 |
PURPOSE:To prevent seizing and reduce damage by storing a current value corrected by the voltage value of an electric motor in a memory circuit which is renewed at every defined time and operating a bearing seizing preventing circuit when the corrected current value becomes above a stored current value. CONSTITUTION:An ammeter 3 and a voltmeter 4 are provided in the power circuit 2 of an electric motor 1 and input signals from converters 5, 6 for carrying out the digital convertion of a current value and a voltage value into a correction operating device 7, respectively, to correct fluctuation in the current value due to fluctuation in voltage, and this corrected value is outputted into a sampling device 8. A sampling signal oscillator 12 is connected to the sampling device 8 to output a sampling current value to a comparator 9 as a memory comparison value via a memory device 13. And, when the current value of the correction operation device 7 is larger than the memory comparison value, a seizing preventing circuit is operated via an AND circuit 14 and a transistor 15. Thereby the seizing of bearing can be prevented reducing damage.
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