SoftStartVerfahren

The SoftStartVerfahren, often translated as soft-start procedure or soft-start method, refers to a technique used in electrical engineering to control the ramp-up of electrical equipment, particularly AC motors. Its primary purpose is to reduce the high inrush current that occurs when a motor is directly connected to the power supply. This inrush current can be several times the motor's normal operating current and can cause several problems.

Direct on-line starting of large motors can lead to significant voltage dips on the power supply network, affecting other connected equipment. It can also cause mechanical stress on the motor, the driven load, and the power transmission components due to the sudden application of torque. The SoftStartVerfahren mitigates these issues by gradually increasing the voltage applied to the motor over a short period.

There are several implementations of soft-start technology. One common method utilizes thyristors (also known as silicon-controlled rectifiers or SCRs) to control the voltage. By phase-controlling the firing angle of the thyristors, the effective voltage delivered to the motor is gradually increased, allowing the motor to accelerate smoothly. Other methods may involve electronic starters that use semiconductor devices to achieve similar voltage ramp-up effects.

The benefits of employing a SoftStartVerfahren include reduced electrical stress on the power supply system, minimized mechanical wear and tear on equipment, improved safety, and potentially energy savings by avoiding peak demand charges. Once the motor reaches its desired speed, the soft-starter is typically bypassed, and the motor operates at full voltage.