Inventory of international standards for small and medium-sized motors

International Standards for Rated Current of Small and Medium-sized Motors

Refers to the line current passing through the three-phase stator winding when the three-phase asynchronous motor is running at rated voltage, rated frequency and rated load, the unit is A. Due to different connection methods of the stator winding and different rated voltages, the rated current of the motor is also different. For example, for a three-phase asynchronous motor with a rated power of 10kW, when its winding is connected in a triangle, the rated voltage is 220V and the rated current is 68A; when its winding is connected in a star, the rated voltage is 380V and the rated current is 39A. In other words, the nameplate indicates: connection method - triangle/star; rated voltage - 220/380V; rated current - 68/39A.

International standard for working quota of small and medium-sized motors

Refers to the working mode of the motor, that is, the duration or working cycle of the motor under specified working conditions. The operation of the motor can be divided into three basic operating modes according to the heating conditions: continuous operation, short-time operation and intermittent operation;

Continuous operation - long-term operation at the power specified on the nameplate. For example, the use of motors on water pumps, ventilators and machine tools is continuous operation.

Short-time operation: operation at rated power is only allowed for a specified time each time, and there should be sufficient shutdown cooling time as required before restarting.

Intermittent operation - the motor runs in an intermittent manner. For example, the motors used in equipment such as cranes and hoists are in intermittent operation.

International standards for temperature rise of small and medium-sized motors

Refers to the value of the motor's operating temperature being higher than the ambient temperature when it is running continuously for a long time. my country stipulates that the maximum ambient temperature is 40°C. For example, if the allowable temperature rise of the motor is 65°C, then its allowable operating temperature is 65+40=105°C. The allowable temperature rise of the motor is related to the grade of the insulation material used. The temperature rise during motor operation has a great influence on the service life of the insulation material. Theoretical analysis shows that when the temperature of the insulation material during motor operation rises by 8°C above the rated temperature, its service life will be shortened by half.