Full pressure direct start:
In the case of full-voltage direct start in both grid capacity and load, full-voltage direct start can be considered. It is mainly used for the starting of small power motors. From the perspective of saving electric energy, this method should not be used for motors larger than 11kw.
The advantage of direct start is that there are fewer devices required, the startup method is simple, and the cost is low. The current directly started by the motor is about 5 times that of normal operation. The motor that is often started, the line or transformer that supplies power should be more than 5 times the capacity of the motor.
For motors that do not start frequently, the line or transformer capacity that supplies power to the motor should be more than three times the capacity of the motor. This requirement is easy to implement for a small-capacity motor, so most of the small-capacity motors are directly activated and do not require a step-down start. For large-capacity motors, on the one hand, the line and transformer capacity of the power supply are difficult to meet the conditions for direct start of the motor. On the other hand, the strong starting current impacts the grid and the motor, affecting the service life of the motor, and is unfavorable for stable operation of the power grid. Therefore, a large-capacity motor and a motor that cannot be directly started must use a step-down start.
