How Does a Static Transfer Switch Work?

At Power Systems International, we tend to work with large loads and demanding systems that are sensitive to power interruption. If for whatever reason a power supply to one of these systems should fail, it’s imperative that backup power is quickly sourced, minimising the risk of any potential damage to its appliances or circuity.

Our PSI transfer switches ensure that your system is protected. But how do they do that? How do static transfer switches work? What are the advantages of using them, and what are the differences between automatic transfer switches and static transfer switches? In today’s article, we’ll tell you everything you need to know.

What is a Static Transfer Switch?

If the static transfer switch (STS) technology is new to you, then it makes sense to begin by explaining what the switch is and why its functionality is vital for large loads.

An STS is an electric device that rapidly switches between electrical power sources to ensure the highest availability of power supply to sensitive and critical applications. They perform instantaneous switching operations, supplying power to a load so quickly that the system doesn’t have time to register any interruption.

Super-fast transfer switches are becoming a standard feature of many large load assemblies. They protect large loads and their entire facility from short-term power disturbances. Uninterruptible Power Supply (UPS) Systems will almost always feature a static switch that initiates backup power to the system as soon as possible.

How Does a Static Transfer Switch Work?

The working principle of an automatic transfer switch is simple on paper. Essentially, this electrical device constantly monitors two different power sources and selects the better option based on a failure of either source.

It will typically be composed of three different components: controls and metering; rectifiers (usually silicon-controlled rectifiers); breaker and bus assembly.

The switches are very reliable. As soon as one power source shows even the slightest sign of degradation or failure to provide the required level of power, the switch instantaneously changes to the alternate, backup power source.

Unlike mechanical switches, static transfer switches have no moving parts. There are no frictional losses, wear and tear is minimal, and their value within any high-demand arrangement is well worthy of investment.

STS are used in IT arrangements, internet data centres, telecommunication centres, airport security systems, and many other essential electrical operations all over the world. These intelligent switches ensure that entire facilities will always have a reliable power source.

Are There Different Types?

There are generally two different types of static transfer switch available to the user, but they both operate in almost identical ways.

Automatic Transfer Switch

Automatic transfer switches, as the name suggests, operate without user input or action. A user-defined window of operation is assigned and should one of the available power sources fall below that level, the transfer switch will automatically make the changeover.

Static Transfer Switch

Static transfer switches, on the other hand, can involve more human interaction. With static transfer switches, an operator is able to force a switch between the two power sources if there is a requirement to do so. This is normally achieved from the mimic display panel or via a remote connection.

Importantly, both switches ensure that there is a transfer in less than four milliseconds, or one-quarter of an electrical cycle.

Static Transfer Switches with PSI

At Power Systems International, we fully understand the importance of an ultra-responsive backup power source capability. Our static transfer switches ensure the highest availability of power to your critical application, protecting it from interruptions or failures of distribution.

With our STS and UPS arrangement in place, your entire facility will be protected from power redundancy and power blackouts while simultaneously providing your operations team with remote management of the operations.

Contact our team today to find out more information about our static transfer switches and why you should be investing in these invaluable devices.