Static transfer switch is a semiconductor structure system that can switch between two phases, single-phase or three-phase, synchronous with each other, without any interruption to the load, automatically or manually. Power transmission in the device is done through thyristors.

Theory of operation: The primary function of the static transfer switch is to ensure that the load is supplied uninterruptedly from the other source, where there is a problem in any of the sources supplying it. One of the input sources of the static transfer switch is called "preferred source" and the other is called "alternative source". suppling the load from the preferred source is a priority. In other words, if both sources are within the limits, the load will be suppiled through the preferred source. If any problem is detected in the preferred source, the load will be transferred to the alternative source in less than 1/4 period. Which of the sources is the preferred source, which is the alternative source and the voltage limits can be adjusted.

Usage Areas: Static transfer switches are used as single system in almost every area where uninterrupted energy is very critical. Hospitals, medical centers, military systems, data processing centers, airports can be listed among these places.