Basic technical requirements for small and medium-sized motors
About small and medium-sized low-voltage motors
An electric motor is a device that converts electrical energy into mechanical energy. As the power source of the transmission system, it plays a decisive role in the industrialization process of world development. Like electricity, electric motors are increasingly integrated into our daily lives and environment, such as household appliances such as air conditioners, refrigerators, and washing machines; mechanical equipment such as fans, water pumps, compressors, and machine tools; such as construction, automobiles, aviation, In fields such as new energy, electric motors have been widely used in all walks of life in modern society. In China, the electricity consumption of electric motors accounts for about 60 to 70% of the total power generation! Entering the 21st century, developing a low-carbon economy, saving energy and reducing emissions, and improving the efficiency of electric motors have attracted more and more attention from around the world.
Usually we define motors with a rated voltage lower than 1140V as low-voltage motors; motors with a shaft center height (frame size) of 65-560mm are defined as small and medium-sized motors.
1. Structure and installation form
Comply with the requirements of GB/T 997 and IEC 60034-7. The diagram and code are shown in the figure below.
2. Shell protection level
Shell protection is mainly to prevent the human body from getting an electric shock or coming close to the live parts or rotating parts in the shell, to prevent the entry of solid foreign matter, and to prevent accidents caused by water, oil, etc. Harmful effects, in compliance with GB/T 4942.1 and IEC60034-5. The codes and meanings of protection forms are as follows.
3. Common working systems of motors
S1 (continuous working system): The motor runs under a constant load until it reaches a thermally stable state.
S2 (short-time working system): When running under a constant load for a given time, the motor is not enough to reach thermal stability within this time, and then stops and loses energy. The time is enough for the motor to operate again. Cool until the difference between the temperature of the cooling medium and the temperature of the cooling medium is within 2K. This work system is referred to as S2 and shall be subsequently marked with the duration of the work system. Such as: S260min.
S3 (intermittent cycle working system): It is a series of identical working cycles. Each cycle includes a period of constant load operation and a period of stop and power failure. In this type, the starting current of each cycle should have no obvious effect on the temperature rise of the motor; every 10 minutes is a working cycle, that is, six starts per hour. This working system is referred to as S3, and shall be subsequently marked with load duration. Such as: S325.
4. Conditions of use
The altitude does not exceed 1000m. The ambient temperature changes with the seasons, but the highest does not exceed 40℃ and the lowest does not fall below -15℃.
5. Commonly used electrical data calculations
6. International standards for motor energy efficiency
7. Performance tolerance range
8. Insulation Level and temperature rise limit
In order to operate the motor reliably, insulating materials need to be used to isolate the live parts and the casing. The service life of the insulating material is greatly affected by the insulation level and operating temperature of the material itself. relationship. As an energy conversion or signal conversion component, the motor itself has energy loss during operation, and some of the energy loss causes its own temperature to rise. Under normal conditions, the insulation material grade, withstand the highest service limit temperature, and the resistance method is used to measure the motor. The temperature rise limit values ??meet the requirements of Table 4. The motor should be able to operate normally within this temperature rise limit value. Comply with the regulations of GB/T755 and IEC 60034-1.
9. Ordering instructions (please pay attention to the contents when ordering)
1. Motor model
2. Rated frequency
3 . Rated power
4. Rated voltage
5. Efficiency
6. Number of poles
7. Protection level
8. Cooling method
9. Installation form
10. Rotation direction
11. Outlet box location
12. Usage environment
13. Noise, vibration
14. Thermal protector
15. Altitude 16 others