JPS5562757A - Method of cooling electric machine - Google Patents

Abstract

PURPOSE: To prevent dew condensation by detecting one of air temperature and vapor pressure and cooling medium temperature, controlling one of them to thereby retain the vapor pressure around the electric machine less than saturated vapor pressure at the temperature.

CONSTITUTION: When the surface of an electric machine 22 is cooled, the saturated vapor pressure at its temperature is less than the vapor pressure in the air resulting in dew condensation. At that time the temperature of the air 33 in the room of a building 21 and/or vapor pressure and water 27 temperature are detected to control it under the condition to eliminate dew condensation. The first method compares the water temperature detector 43 with the output of the indoor air vapor detector 41 to be thus controlled in such a manner that when the indoor vapor pressure is high, the humidity is dehumidified by a dehumidifier 34 lower than the saturated vapor pessure. The second method controls by the comparator output 40 or energization of the heater 36 by a controller 44 at the cooler 31 by the control output to heat water. The third method detects the water and room temperatures by detectors 43 and 42, respectively to compare the former with the latter by a comparator 40 to thereby drive a cooler 35 so as to lower the room temperature. The fourth method similarly drives the heater 36 to thereby raise the water temperature. Thus, it can prevent dew condensation on the surface of the electric machine.

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