power transfer switch

Transfer switches allow switching from a primary power source to a secondary or tertiary power source and are employed in some electrical power distribution systems. Most often transfer switches can be seen where emergency power generators are used to back up power from the utility source. The transfer switch allows switching from utility power to emergency generator power. The switch is either a manual switch, an automatic switch or a combination of manual and automatic. During a power outage, the transfer switches isolate the emergency circuits from the utility line allowing for efficient operation of the generator without back feeding onto the utility. All models with a power inlet on the front also include a cover for the power inlet installation of a power inlet for cord connection directly to the transfer switch.

Transfer switches continually monitor the incoming utility power. Any anomaly such as voltage sags, brownouts, spikes or surges will cause the internal circuitry to command a generator startup and then a transfer to the emergency generator when additional switch circuitry determines the generator has the proper voltage and frequency. When utility power returns, or no other anomalies have occured for a set time, the transfer switch will then transfer, back to utility power and command the generator to turn off after another specified amount of "cool down" time.

Break Before Make Transfer Switch

A Break Before Make transfer switch breaks contact with one source of power before it makes contact with another.