Abstract: This invention provides an electromechanical transfer switch having a transfer time sufficiently fast, less than 20 milliseconds, as to allow computer based equipment to ride through a power interruption without shutdown. The transfer switch utilizes relatively slow acting, high amperage, electromechanical power relays that have been modified by replacing the relay armature spring with a higher tension substitute and applying overdrive voltage to the relays.

Abstract: A double-throw multi-pole power relay switch is modified to meet Underwriters Laboratories standards for a transfer switch that automatically switchs a load from a primary power source to a secondary power source upon interruption of the primary source and without cross connection of the primary and secondary sources in the event that one or more relay switch contacts become welded.

Abstract: The continuity of a series-wired, lamp circuit is restored after interruption caused by failure of a lamp filament by providing a control relay that is wired in parallel with each lamp. A power resistor having a resistive load substantially the same as that of a lamp filament is arranged in series with the relay contacts, which are normally open. The failure of a lamp filament causes a high voltage to be impressed across the coil of the relay, causing it to pick up and its contacts to close, thus substituting the resistor for the lamp filament and restoring continuity to the circuit.

Abstract: A power switching transfer relay is provided to automatically switch an electrical load, such as that drawn by a computer or other sensitive electrical or electronic equipment, from a primary power source to a secondary, or backup, power source upon interruption or loss of the primary source. The transfer relay includes a power relay and two control relays that are arranged to switch the electrical power input from the primary source to the backup source upon failure of the primary power source in the space of less than one cycle, and to actuate an alarm upon loss of the primary power source, loss of the backup power source, or the occurrence of a relay fault.

Abstract: A power switching transfer relay is provided to automatically switch an electrical load, such as that drawn by a computer or other sensitive electrical or electronic equipment, from a primary power source to a secondary, or backup, power source upon interruption or loss of the primary source. The transfer relay includes a power relay and two control relays that are arranged to switch the electrical power input from the primary source to the backup source upon failure of the primary power source in the space of less than one cycle, and to actuate an alarm upon loss of the primary power source, loss of the backup power source, or the occurrence of a relay fault.