Electrical load protection device
First Claim
1. Electrical circuitry for protecting an electrical load energized by a source of alternating current supply voltage comprising, in combination, switch means for disconnecting the energization supply voltage source from the electrical load, a first means controlled by a predetermined increase in the supply voltage source for actuating said switch means to disconnect said energization supply voltage source from the electrical load, a second means controlled by a predetermined decrease in the supply voltage for actuating said switch means to disconnect said energization supply voltage source from the electrical load, said second means further being controlled by a temporary interruption of said energization supply voltage source to actuate said switch means for disconnecting said energization supply voltage source from the electrical load for a predetermined minimum interval of time, said first and second means comprising a window comparator circuit, the input voltage to said window comparator circuit being derived as a direct current analog of said energization supply voltage source, voltage divider means for adjusting said analog input voltage to correspond with a predetermined "normal" energization supply voltage, a regenerative delay circuit controlled by the output of said window comparator circuit, said regenerative delay circuit including a capacitor discharge circuit for establishing said predetermined interval of time for the disconnection of said energization supply voltage source from the electrical load.
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Accused Products
Abstract
Electronic circuitry senses over-voltage and under-voltage within narrow threshold limits, and voltage interruption, in the energization circuit of a sensitive load, such as a refrigeration compressor motor load, to protect against overheating damage and burn-out. Setting to a nominal operating line voltage is provided for to obviate readjustment to the threshold voltages of a window comparator utilized to sense over-voltage and under-voltage.
54 Citations
7 Claims
- 1. Electrical circuitry for protecting an electrical load energized by a source of alternating current supply voltage comprising, in combination, switch means for disconnecting the energization supply voltage source from the electrical load, a first means controlled by a predetermined increase in the supply voltage source for actuating said switch means to disconnect said energization supply voltage source from the electrical load, a second means controlled by a predetermined decrease in the supply voltage for actuating said switch means to disconnect said energization supply voltage source from the electrical load, said second means further being controlled by a temporary interruption of said energization supply voltage source to actuate said switch means for disconnecting said energization supply voltage source from the electrical load for a predetermined minimum interval of time, said first and second means comprising a window comparator circuit, the input voltage to said window comparator circuit being derived as a direct current analog of said energization supply voltage source, voltage divider means for adjusting said analog input voltage to correspond with a predetermined "normal" energization supply voltage, a regenerative delay circuit controlled by the output of said window comparator circuit, said regenerative delay circuit including a capacitor discharge circuit for establishing said predetermined interval of time for the disconnection of said energization supply voltage source from the electrical load.
Specification