There are many ways to start an air compressor, including variable frequency start, soft start, and star-delta reduced pressure start. These starting methods are all designed to reduce the impact on the power grid during startup and protect the normal operation of the motor and other equipment. The differences and connections between these three startup methods will be introduced below:

1. Frequency conversion start:

Variable frequency starting is to control the speed and current of the motor through the frequency converter so that the motor gradually accelerates to the rated speed when starting. Variable frequency starting can achieve smooth starting of the motor by adjusting the voltage and frequency, avoiding current impact and mechanical impact during the starting process. Variable frequency starting is suitable for high-power motors and occasions that require frequent starts and stops. It can save energy and extend the service life of the equipment.

2. Soft start:

Soft start is to gradually increase the starting current of the motor through the electronic control device so that the current and torque of the motor during the starting stage increase linearly. Soft start can reduce the current impact during starting and protect the motor and other equipment from excessive starting current. Soft start is suitable for large-capacity motors and situations that require a smooth start, such as compressors, fans, etc.

3. Star-delta voltage reduction start:

Star-delta step-down starting is to control the circuit connection method of the motor and switch the motor winding from star connection to delta connection during the starting stage to reduce the current and torque during starting. During the switching process, the rated voltage of the motor will be reduced to 3 times the square root of the delta connection, thereby achieving a lower starting current. Star-delta step-down starting is suitable for small to medium-power motors, which can reduce the current impact during starting and reduce the impact on the power grid.

The differences and connections between these three startup methods are as follows:

1. Differences in startup methods:

Variable frequency start realizes the smooth start of the motor by adjusting the voltage and frequency and is suitable for high-power motors and occasions with frequent starts and stops. Soft start realizes the smooth start of the motor by gradually increasing the starting current and is suitable for large-capacity motors and situations where a smooth start is required. Star-delta step-down starting reduces the current during starting by switching the connection method of the motor and is suitable for small to medium-power motors.

2. How to start contact:

These three starting methods are all designed to reduce the current impact during starting and protect the normal operation of the motor and other equipment. They all use the method of gradually increasing the current or adjusting the voltage to achieve a smooth starting of the motor. During the startup phase, it can reduce the impact on the power grid and equipment and improve the reliability and service life of the equipment.

However, these three startup methods also have some differences in application. Variable frequency starting is suitable for high-power motors and occasions that require frequent starts and stops. It can achieve precise control of motor speed and current and save energy. Soft start is suitable for large-capacity motors and situations that require a smooth start, such as compressors and fans. Star-delta step-down starting is suitable for small to medium-power motors. It can reduce current and torque during starting and reduce the impact on the power grid.

To sum up, variable frequency start, soft start, and star-delta step-down start are different motor starting methods. They are different in their starting principles and applications, but they are all designed to reduce the current impact during starting and protect the motor and normal operation of other equipment. Depending on the specific application requirements, choosing the appropriate startup method can improve the performance and reliability of the device.