Automatic power transfer switch

Claim 2

An automatic transfer switching system comprising: a power source; sensing means connected to said power source for providing a first signal upon sensing a voltage loss from said power source; first switching means connected to receive said first signal for establishing a first current path upon receipt of said first signal having a plurality of relaxation oscillators connected to said sensing means for providing a plurality of second signals upon receipt of said first signal, and siliconcontrolled rectifier bridges to receive said second signals for providing said first current path upon receipt of said second signals; and second switching means connected to receive said first signal for subsequently establishing a second current path and interrupting said first current path upon receipt of said first signal.

Claim 3

An automatic transfer switching system according to claim 1 wherein said second switching means further comprises: an electromechanical switch connected in parallel with said silicon-controlled rectifier bridges for providing said second current path.

Claim 4

An automatic transfer switching system according to claim 2 wherein said second switching means further comprises: first relay means connected to said sensing means for closing a first plurality of normally open contacts on said electromechanical switch to provide a second current path and opening a normally closed contact on said electromechanical switch upon receipt of said first signal; and second relay means connected in series with said normally closed contact to interrupt said first current path upon opening of said normally closed contact.

Claim 5

In combination with a first power source for providing power to a load through a first electromechanical contactor and a second power source for automatically providing power to said load through a second electromechanical contactor upon failure of the first power source the improvement of which comprises: a plurality of silicon-controlled rectifier bridges connected in parallel with said second contactor; means for firing said bridges to establish a first current path from said second power source to said load upon failure of said first power source; and means for subsequently establishing a second current path from said second power source to said load through said second electromechanical contactor and for interrupting said first current path.

Claim 6

In combination with a first power source for providing power to a load through a first electromechanical contactor and a second power source for automatically providing power to said load through a second electromechanical contactor upon failure of the first power source the improvement of which comprises: a plurality of silicon-controlled rectifier bridges connected in parallel with said second contactor; means for firing said bridges to establish a first current path from said second power source to said load upon failure of said first power source; and means for subsequently establishing a second current path from said second power source to said load through said second electromechanical contactor and for interrupting said first current path.

Claim 7

A power system comprising: a first power supply; a second power supply; sensing means connected to said first power supply for providing a first signal upon sensing a failure of said first power supply having a plurality of diodes for rectifying said first power supply, a parallel combination of a capacitor and resistor connected to said plurality of diodes for receiving said rectifier signal, a transistor having its base connected to said diodes receiving said rectified signal, a DC power supply connected for providing a DC signal to the emitter of said transistor, a series combination of a diode and resistor connected between said emitter and said base of said transistor, a transformEr having its primary winding connected to the collector of said transformer, and a silicon-controlled rectifier having its gate and cathode connected across the secondary winding of said transformer, the anode of said SCR connected to said DC power supply.

Claim 8

A power system comprising: a first power supply; a second power supply; sensing means connected to said first power supply for providing a first signal upon sensing a failure of said first power supply having a plurality of diodes for rectifying said first power supply, a parallel combination of a capacitor and resistor connected to said plurality of diodes for receiving said rectifier signal, a transistor having its base connected to said diodes receiving said rectified signal, a DC power supply connected for providing a DC signal to the emitter of said transistor, a series combination of a diode and resistor connected between said emitter and said base of said transistor, a transformEr having its primary winding connected to the collector of said transformer, and a silicon-controlled rectifier having its gate and cathode connected across the secondary winding of said transformer, the anode of said SCR connected to said DC power supply.

Claim 9

A power system according to claim 5 wherein said first switching means further comprises: a plurality of relaxation oscillators connected to said sensing means for providing a plurality of second signals upon receipt of said first signal; and silicon-controlled rectifier bridges to receive said second signals for providing said first current path upon receipt of said second signals.

Claim 10

An automatic transfer switching system according to claim 6 wherein said second switching means further comprises: an electromechanical switch connected in parallel with said silicon-controlled rectifier bridges for providing said second current path.

Claim 11

An automatic transfer system according to claim 7 wherein said second switching means further comprises: first relay means connected to said sensing means for closing a first plurality of normally open contacts on said electromechanical switch to provide a second current path and opening a normally closed contact on said electromechanical switch upon receipt of said first signal; and second relay means connected in series with said normally closed contact to interrupt said first current path upon opening of said normally closed contact.