Multi-phase voltage sensing switching device
AssigneeWestinghouse Electric Corp.
InventorJoseph J. Matsko
Life of this patent
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Abstract
The disclosure describes a device for detecting undervoltage conditions on multi-phase alternating current circuits which senses the voltage on the phase having the highest instantaneous positive voltage. A differential between pickup and dropout voltage is provided. Also provided is a delayed pickup following a return to normal voltage on the circuit being monitored.
Claims12
A voltage sensitive switching device for monitoring conditions on multi-phase alternating current circuits, said device comprising:
- a. switch means having two operation states,
- b. switch operating means, activation or deactivation of said switch operating means changing said switch means from one operational state to another operational state,
- c. rectifier means having an input and an output, said input connectable to each phase of a multi-phase alternating current circuit,
- d. sensing means connected to said output of said rectifier means for activating said switch operating means when the local minima of the rectified voltage of the phase having the highest instantaneous voltage passes through a first level corresponding to a first predetermined percentage of single phase normal voltage, said sensing means deactivating said switch operating means when the local minima of the rectified voltage of the phase having the highest instantaneous voltage passes through a second level corresponding to a second predetermined percentage of single phase normal voltage.
A voltage sensitive switching device for monitoring conditions on multi-phase alternating current circuits, said device comprising:
- a. switch means having two operational states,
- b. switch operating means, activation or deactivation of said switch operating means changing said switch means from one operational state to another operational state,
- c. rectifier means having an input and an output, said input connectable to each phase of a multi-phase alternating current circuit,
- d. sensing means connected to said output of said rectifier means for activating said switch operating means when the rectified voltage of the phase having the highest instantaneous voltage passes through a first level corresponding to a first predetermined percentage of single phase normal voltage, said sensing means deactivating said switch operating means when the rectified voltage of the phase having the highest instantaneous voltage passes through a second level corresponding to a second predetermined percentage of single phase normal voltage, and
- e. means for providing a differential between said first level and said second level, said differential means comprising a single voltage divider and means controlled by said switch operating means for changing the resistance of a portion of said voltage divider.
Dependencies are inferred from the claim text.