What Is a Static Transfer Switch?
A static transfer switch (STS) is a high-speed power switching device capable of ultra-fast transitions between two power systems.
It falls under the category of uninterruptible power switches, and there are various types available, including those using double-throw contactors and devices like thyristors (THY) or Gate Turn-Off Bipolar Transistors. Hybrid versions combining these technologies are also common. While all such switches are generally referred to as Automatic Transfer Switches (ATS), those employing thyristors are specifically known as Static Transfer Switches (STS).
In an STS, current continuously flows through the thyristor, resulting in some power loss. However, the key advantage of STS lies in its exceptionally fast switching time, typically within 5 milliseconds. STS can be seamlessly integrated into UPS systems on the secondary side, enabling the switching of power sources without the need to shut down Information and Communication Technology (ICT) equipment.