Due to the existence of various losses during the use of the motor, the temperature continues to rise. If it cannot be cooled well, it will affect the service life of the motor. The power of high-voltage motors is generally large, and the absolute value of the power loss is also large. For normal use, cooling is particularly important.
For open-type motors, ambient air is generally used to directly enter the motor for cooling, and the cold air directly takes away the heat of the motor and discharges it to the surrounding environment. There are three main routes of air inside the motor. One is the axial direction, where cold air enters from one end of the motor and exits from the other end. Since only one end needs to be equipped with a fan, a fan with a larger diameter can be installed, the cooling effect is better, and the iron core structure is more compact. The disadvantage is that the ventilation loss is large, and the temperature distribution along the axis of the motor is uneven, and it is generally used for motors with small capacity. The other is radial, where cold air enters from both ends and exits from the core's radial ventilation channels. The disadvantage is that the fan must be installed at both ends, so the outer diameter of the fan can only be smaller than the diameter of the rotor.
The capacity of the fan is limited, and radial ventilation slots are required to make the size of the motor slightly larger. The advantage is that due to the use of axial fans, the ventilation efficiency is higher, the heat dissipation area is larger, and the temperature along the motor axis is more uniform. There is also a combination of axial and radial ventilation. It is designed to combine the advantages of both axial and radial ventilation. It has better ventilation and cooling effects, and the temperature is more uniform, but the structure is more complicated.
For closed motors, the air flow in the casing is similar to the open type. The biggest difference between the closed motor and the open motor cooling method is that when the closed motor is cooled, the hot air in the casing needs to be exchanged with the external cold medium. The most common medium is air, followed by water. When air is used as the cooling medium, an external fan coaxial with the motor is usually used to generate wind pressure to drive the outside air; if water cooling is used, a special water pump is required to drive the circulating refrigerant water to circulate the hot air in the cabinet in the cooling water tank Allow to cool. Usually motors below 1000kW use air cooling, while motors above 1000kW mostly use water-cooled cooling.
1) Cooling: When the motor performs energy conversion, there is always a small part of the loss that is converted into heat. It must continuously radiate heat through the motor housing and surrounding medium. This process of dissipating heat is called cooling.
2) Cooling medium: a gas or liquid medium that transfers heat.
3) Primary cooling medium: a gas or liquid medium whose temperature is lower than a certain part of the motor, which contacts the part of the motor and takes away the heat it emits.
4) Secondary cooling medium: the gas or liquid medium whose temperature is lower than the primary cooling medium, the heat released from the primary cooling medium is taken away through the outer surface of the motor or the cooler.
5) Final cooling medium: heat is transferred to the final cooling medium.
6) Surrounding cooling medium: the gas or liquid medium surrounding the motor.
7) Remote medium: a medium far from the motor, through the inlet and outlet pipes or channels to absorb the heat of the motor and discharge the cooling medium to the remote.
8) Cooler: a device that transfers the heat of one cooling medium to another cooling medium and keeps the two cooling mediums separate.
2. The content of the cooling method code
1. The motor cooling method code is mainly composed of the cooling method mark (IC), the cooling medium circuit layout code, the cooling medium code, and the cooling medium movement promotion method code. IC + circuit layout code + cooling medium code + promotion method code
2. The code name of the cooling method is the abbreviation of International Cooling in English, which is expressed by IC.
3. The code of the circuit layout of the cooling medium is represented by characteristic numbers. The main ones are 0, 4, 6, 8 and so on. The meaning of them is described below.