Fault indicator having electrostatically-actuated indicator flag
First Claim
1. A fault indicator for indicating the occurrence of a fault current in an electrical conductor, comprising, in combination:
- a housing;
an indicator flag mounted in said housing for movement between a fault-indicating position and a reset-indicating position;
electrostatic actuator means including at least an actuator electrode positioned for exerting an electrostatic force on said indicator flag;
circuit means electrically connected to said actuator electrode for establishing an electric field between said actuator electrode and said indicator flag to exert an electrostatic force on said indicator flag to position said indicator flag to a selected one of said indicating positions;
biasing means comprising a permanent magnet for positioning said indicator flag to the other of said indicating positions in the absence of said electric field; and
said circuit means being responsive to the occurrence of a fault current in the electrical conductor to position said indicator flag to said fault-indicating position.
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Accused Products
Abstract
A fault indicator for indicating the occurrence of a fault current in a monitored conductor includes an electrostatically-actuated indicator assembly. During normal operation a lightweight indicator flag rotatably mounted in and viewable from the exterior of the indicator housing is held in a reset-indicating position by electrostatic force resulting from an electric field existing between the flag and adjacent electrodes. Upon occurrence of a fault current in the monitored conductor the electric field is removed and the indicator flag, under the influence of a permanent magnet, is caused to rotate to a fault-indicating position. By avoiding the use of magnetic actuator windings and associated pole pieces the indicator assembly is easier and more economical to construct.
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Citations
23 Claims
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1. A fault indicator for indicating the occurrence of a fault current in an electrical conductor, comprising, in combination:
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a housing; an indicator flag mounted in said housing for movement between a fault-indicating position and a reset-indicating position; electrostatic actuator means including at least an actuator electrode positioned for exerting an electrostatic force on said indicator flag; circuit means electrically connected to said actuator electrode for establishing an electric field between said actuator electrode and said indicator flag to exert an electrostatic force on said indicator flag to position said indicator flag to a selected one of said indicating positions; biasing means comprising a permanent magnet for positioning said indicator flag to the other of said indicating positions in the absence of said electric field; and said circuit means being responsive to the occurrence of a fault current in the electrical conductor to position said indicator flag to said fault-indicating position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An electrostatically-actuated indicator for indicating one of two alternative conditions in response to an applied control effect, comprising, in combination:
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a housing; an indicator flag mounted in said housing for movement between a first indicating position and a second indicating position; electrostatic actuator means including at least one actuator electrode positioned for exerting an electrostatic force on said indicator flag; circuit means electrically connected to said actuator electrode for establishing an electric field between said actuator electrode and said indicator flag to exert an electrostatic force on said indicator flag to position said indicator flag to a selected one of said indicating positions; biasing means comprising a permanent magnet for positioning said indicator flag to the other of said indicating positions in the absence of said electric field; and said circuit means being responsive to the applied control effect in positioning said indicator flag to said first indicating position. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification