| 摘要 |
PCT No. PCT/FI94/00137 Sec. 371 Date Sep. 19, 1995 Sec. 102(e) Date Sep. 19, 1995 PCT Filed Apr. 12, 1994 PCT Pub. No. WO94/24750 PCT Pub. Date Oct. 27, 1994The invention relates to a method of monitoring a temperature rise of a stator winding of a squirrel cage induction motor, in which method a stator current I of the motor is measured and the temperature rise of the motor at each moment is determined on the basis of this current I, when a rated temperature rise theta N of the motor at a rated current IN, the rated current IN and a temperature rise time constant tau of the motor are known. The method comprises steps of determining the stator current I of the motor as discrete moments separated by DELTA t long time periods, determining the temperature rise theta n(1) of the motor during one time period n from the equation <IMAGE> determining a cooling theta n(2) of the motor during the same time period n from the equation theta n(2)= theta n-1e- DELTA t/ tau ,where theta n-1 is the temperature rise of the motor at the end of the preceding time period, and summing the temperature rise theta n(1) and the cooling theta n(2) occurred during the same time period to obtain the temperature rise theta N of the motor at the end of the time period n.
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