Introduction to basic knowledge of air compressor motor

 

In industrial production, electric motors, especially three-phase squirrel-cage asynchronous motors, are widely used, including compressors. An electric motor is mainly composed of two parts: the stator and the rotor. The respective magnetic fields of the stator and rotor interact to produce torque, causing the rotor shaft to begin to rotate. This article will provide you with some basic knowledge about air compressor motors, namely motor speed, motor insulation level and motor protection level.

1. Motor speed

 

Regarding the speed of the motor, theoretically, if the shaft rotation speed of an asynchronous motor is synchronized with the magnetic field, the induced current in the rotor will be zero. However, in actual operation, the rotation speed of the motor shaft is always slightly slower than the magnetic field speed by 1-5%. This phenomenon is called slip. Therefore, the efficiency of the motor is not lossless. It always produces losses when converting energy, mainly including resistance losses, ventilation losses, magnetization losses, and friction losses.

2. Motor insulation level

 

The insulation level of electric motors is classified according to the IEC60085 standard, which is a standard proposed by the International Electrotechnical Commission. Different dielectric materials are graded according to temperature, using letters to indicate the grade. This temperature value is the highest temperature that the dielectric material can withstand. If the temperature is 10°C above this limit for a period of time, the life of the dielectric material may be halved.

 

3. Motor protection level

The protection level, specified by the International Electrotechnical Commission (IEC) in IEC60034-5, mainly describes the motor’s protection ability against contact and waterproofing. The motor protection capability is generally represented by the two letters “IP” plus two digits. For example, the protection level of SOLLANT oil-free air compressors is generally IP23. The number “2” here means that the motor can prevent the intrusion of solids with a diameter greater than 12mm, and “3” means that the motor can prevent the direct injection of water tilted upward to 60°. IP54 and IP55 respectively indicate that the motor has the ability to protect against dust and water spray from any direction, and the ability to protect against dust and low-pressure water spray from any direction.