How Does A Static Transfer Switch Work?

To shift power from one source to another, all systems require the use of a switch. The two most common types of switches are automatic transfer switches and static transfer switches.

The static transfer switch is considered the optimal choice as it provides a faster transfer to one of two redundant power sources when there is a power failure. While automatic transfer switches are fast, the use of a static transfer switch means instantaneous transfer to the most stable power source. In some cases, the static transfer switch or STS can transfer to the more stable power source before the system has to access the USP.

The Switch Speed

There are differences in the speed of the switch to a stable power source. Typically, with a static transfer switch, this is about three to five-thousandths of a second, which means that most electronic equipment and devices will not register the millisecond loss of power. While extreme temperatures and operating conditions can extend the time for the switch, it is still much faster than an automatic transfer switch in the same working conditions.

The static transfer switch is able to accomplish this through the use of silicon-controlled transfer rectifiers. These are non-mechanical, semi-conductor components that are able to detect power issues and complete the switch.
There are both low voltage and medium voltage static transfer switches used on both small and large types of systems.

For assistance in selecting the ideal static transfer switch for your service, give us a call at 800-399-7414.