(1) Temperature measurement of cooling medium of grain cleaning sieve. The so-called cooling medium refers to substances that can directly or indirectly take away the heat of the stator and rotor windings, iron cores and bearings; such as air, water and oil. For motors that are cooled by surrounding air, the temperature of the cooling air (generally referred to as the ambient temperature) can be measured with several expansion thermometers (not less than 2) placed in the path of the cooling air entering the discharge machine. The position of the bulb of the thermometer is 1~2m away from the motor, and is not affected by external radiant heat and airflow. It is appropriate to select a thermometer with a division of 0.2°C or 0.5°C and a range of 0-50°C.
(2) Measurement of winding temperature of grain cleaning sieve. The resistance method is a recognized standard method for measuring the temperature rise of windings. Almost all AC motors below 1000kW are measured by the resistance method. The resistance method uses the change in resistance of the windings of the motor when heating to measure the temperature of the windings. The specific method is to use the DC resistance of the windings to determine the temperature of the windings by the corresponding increase in the resistance value after the temperature rises. Is the average value of the winding temperature. The resistance in the cold state (the resistance measured before the motor is running) and the resistance in the hot state (the resistance measured after the operation) must be measured at the same terminal of the motor. The temperature of the winding in the cold state can generally be considered equal to the ambient temperature around the motor. In this way, the temperature of the winding in the hot state can be calculated.
(3) Measurement of core temperature of grain cleaning sieve. The temperature of the stator core can be measured with several thermometers attached to the core yoke along the axis of the motor to obtain the highest temperature. For enclosed motors, the thermometer is allowed to be inserted into the eye of the machine base. The core temperature can also be measured with a copper-constantan thermocouple or resistance thermometer placed at the lower part of the tooth.