Starting mode of soft starter

A soft starter is an electrical device used to reduce the impact and noise when the motor starts. In practical applications, soft starters have multiple starting modes. The following are several common starting modes:

1. Voltage reduction mode: In this mode, the soft starter will gradually reduce the voltage of the motor, thereby reducing the impact during starting. It is suitable for starting a single machine or a small unit.

2. Current Limitation Mode: In this mode, the soft starter can set the current limit to control the starting current of the motor while keeping the power supply voltage unchanged, thereby reducing the starting impact and noise. This mode is suitable for starting with higher power and heavier loads.

3. Time delay mode: In this mode, the soft starter will set a delay time before the machine starts, so that the motor will wait for a while until the power is reliable, thereby reducing the impact of starting. This mode is suitable for starting with lower power and light load.

4. Adaptive mode: In this mode, some special circuits are set in the starter to automatically adapt to the starting process under different load conditions. This mode is suitable for applications where the load conditions change greatly during the starting process.

Regardless of the starting mode, the soft starter can reduce the impact and noise during the starting process, thereby effectively protecting the machine and equipment components and extending the service life of the equipment. Therefore, when selecting a soft starter, the actual application conditions and needs should be considered, and the appropriate starting mode should be selected.

Starting mode of soft starter

1. Ramp boost soft start

The simplest starting method does not have current closed-loop control. It can only adjust the thyristor conduction angle to increase it in a certain functional relationship with time. Disadvantages: Due to the lack of current limiting, during the motor starting process, a large impact current is sometimes generated to damage the thyristor, which has a greater impact on the power grid and is rarely used in practice.

2. Step start

Start-up means making the starting current quickly reach the set value in the shortest time, which is called step start. By adjusting the starting current set value, a quick start effect can be achieved.

3. Ramp constant current soft start

This starting method is that the starting current gradually increases in the initial stage of the motor starting, and when the current reaches the preset value, it remains constant until the starting is completed. This starting method is the most widely used starting method, especially suitable for starting fans and pumps.

4. Pulse shock starting

At the beginning of starting, the thyristor is turned on with a large current for a very short time, then falls back, and then linearly increases according to the original setting value, and connected to constant current starting. This starting method is rarely used in general loads, and is suitable for starting occasions with heavy loads and need to overcome large static friction.

5. Voltage dual slope starting

During the starting process, the output torque of the motor increases with the voltage. An initial starting voltage Us is provided during starting. Us is adjustable according to the load. Us is adjusted to be greater than the static friction torque of the load. When the output voltage reaches the speed-reaching voltage Ur, the motor basically reaches the rated speed. The soft starter automatically detects the speed-reaching voltage during the starting process, and when the motor reaches the rated speed, the output voltage reaches the rated voltage.

6. Current-limited starting

Current-limited starting is a soft-start method that limits the starting current of the motor to a certain set value during its starting process. The output voltage increases rapidly from zero until the output current reaches the preset current limit Im, and then maintains the output current I. Advantages: The starting current is small and can be adjusted as needed.