The thesis investigates the development of a soft-start electronic unit suitable for different devices, which are known by significant inrush currents. Different devices, such as a transformer, a universal motor, AC rectifier with a capacitive load, etc., which in the case of direct switching on the network cause a short-term high current flow, are presented in the first part. Further, some of the known solutions for limiting the inrush current are examined. In the central part, a development of soft-start electronic unit, which is based on the phase control of triac or two anti-parallel coupled thyristors by means of PIC18F4520 microcontroller is highlighted. Some software solutions for the implementation of a soft-start electronic unit for different types of loads are explained. Due to additional circuit for detecting the switch-on and switch-off on the load side, a soft-start of devices, which are otherwise characterised by high inrush current, can be carried out. This can be achieved without any changes or modification of the device itself. Soft-start unit can be without any difficulties inserted between the device and the network.
An important advantage of a proposed soft-start electronic units is the possibility of adjusting the activation procedure with respect to the specific requirements of the device.
At the end, practical examples of use of a soft-start electronic unit and its effectiveness are presented.