Source Transfer Switches

Rack mount Source Transfer Switches (STS) are ideal for use within server cabinets and can provide power distribution and management functions. Renewable Energy Supplies supplies STS up 32A including single and three phase transfer switches. A source transfer switch connects one of two primary input power sources (A or B) to its output to power the connected loads. The two power sources can be two uninterruptible power supplies or mains power supplies or a combination of the two.

Rack mount source transfer switches generally provide several output sockets (outlet) to which server loads can be directly plugged into. Locking power cords may also be an available option. Using a source transfer switch can then reduce the need for additional power distribution units. Where power strips are plugged into an STS output socket care must be taken to ensure that the total loading does not exceed the rating of the connected socket.

Source transfer switches may also incorporate intelligent power management features. These are generally accessed via a front panel or software package from the STS manufacturer. Using software, individual and total STS power and energy metering may be possible including supply voltage (V) and frequency (Hz) as well as load in VA and Watts, power factor (pf) and energy uses (kWh). It may also be possible to remotely reboot the device or individual sockets and to configure the STS to load shed when there is a potential loss of one of the two power sources.

Source transfer switches below 32A tend to be designed for rack mount installation with a horizontal form factor, rack height from 1-2U more and a depth from 400mm or less. Wall mount and floor standing models are also available. The transfer mechanism may be based on relay technology rather than a static switch, meaning that there could be a slight delay in transfer, but this is far less than the capacitance (energy storage) characteristics of the switch mode power supplies used within file servers and computing devices.

Synchronised Power supplies a wide range of source transfer switches from leading manufacturers. Standard products are available from stock with custom design options manufactured to order.