Importance

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Abstract

A high speed load transfer system for use with critical loads, e.g. computers, includes a high speed transfer logic circuit which has rapid sensing and rapid contactor energizing means; so that in the event of power failure, power to the critical load can be switched instantaneously to an alternative power supply. A solid state sensor, responsive to a step change, detects instantaneous power failure and operates an output to a contactor. A voltage doubler circuit using an AC input capacitor and a DC output capacitor is provided at the contactor, with the DC capacitor connected across the contactor; so that when a transfer signal is received at the contactor, the DC capacitor is discharged across the contactor, so as to provide a surge of power through the switch means when the switch means closes and to minimize contactor response time--as well as to ensure connection to the critical load. The power supply can be a commercial AC line, or a hot standby inverter. In one embodiment, a differential voltage sensor is provided in parallel with the step sensor to sense voltage failure such as brown-outs, or failures within a set time interval e.g., 2-4 msec after the event. In another embodiment, an inverter voltage sensing circuit is provided for switching power from the inverter to a bypass AC line in the event of overload.

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First Claim