Fault powered fault indicator having timed reset
First Claim
1. A fault indicator for indicating an occurrence of a fault current in a monitored electrical conductor, comprising:
- a housing;
status indicating means within said housing for indicating a status of said fault indicator, said status indicating means having a reset-indicating state and a fault-indicating state;
first circuit means for deriving operating power only from said fault current in said conductor;
second circuit means operable from the operating power derived by said first circuit means for conditioning said status indicating means to said fault-indicating state in response to said occurrence of said fault current in said conductor; and
third circuit means for conditioning said status indicating means to said reset-indicating state upon expiration of a predetermined period of time after said occurrence of said fault current in said conductor.
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Accused Products
Abstract
A fault indicator is described having a winding disposed on a magnetic pole assembly. The winding delivers energy from a monitored conductor to circuitry of the fault indicator. A series-connected threshold device, such as a four layer bilateral diode or a zener diode, precludes a capacitor from charging during normal current flow in the monitored conductor. The series-connected threshold device, however, breaks down when a fault current flows in the monitored conductor. After break down, the fault current charges the capacitor. A shunt-connected threshold device, such as a zener diode, limits the voltage developed across the capacitor. After its charging phase, the capacitor drives a multivibrator which actuates an LCD, displaying the occurrence of the fault current to an operator. A series-connected threshold device shuts the LCD off when the voltage across the capacitor drops to a sufficiently low level. The arrangement of these electrical components allows the operator to accurately define the duration of time in which the LCD displays the occurrence of the fault current in the monitored conductor.
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Citations
16 Claims
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1. A fault indicator for indicating an occurrence of a fault current in a monitored electrical conductor, comprising:
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a housing; status indicating means within said housing for indicating a status of said fault indicator, said status indicating means having a reset-indicating state and a fault-indicating state; first circuit means for deriving operating power only from said fault current in said conductor; second circuit means operable from the operating power derived by said first circuit means for conditioning said status indicating means to said fault-indicating state in response to said occurrence of said fault current in said conductor; and third circuit means for conditioning said status indicating means to said reset-indicating state upon expiration of a predetermined period of time after said occurrence of said fault current in said conductor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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Specification