Fault locating system for electric cables and the like
Patent 4291204 Issued on September 22, 1981. Estimated Expiration Date: 
August 13, 1999. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
August 13, 1999. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References3488580 InventorApplicationNo. 06/066077 filed on 08/13/1979US Classes:324/456, For flaw detection324/529, Using a magnetic field sensor324/534, By reflection technique324/536, By spark or arc discharge73/570VIBRATIONExaminersPrimary: Robinson, Mark A.Attorney, Agent or FirmInternational ClassesG01R 31/10 (20060101)G01R 31/08 (20060101) G01R 31/11 (20060101) AbstractA system for locating faults in an electric cable including a flyback transformer or inductor and control circuitry therefor for developing an arc through a high resistance short circuit between two conductors or one conductor and ground. The control circuitry limits the current flow in the arc to avoid burning or welding of the conductors but maintains the current so that the high resistance short appears temporarily as a low resistance short which can be detected. A low level DC bias current stabilizes the system, particularly in the presence of large line capacitance when the distance between the apparatus and the cable fault is large. The circuitry includes an audible tone generator which can be sensed by induction with known inductive pickup equipment. The circuit also allows use of a time domain reflectometer to determine the location of high resistance shorts from a remote location on the cable to which connections can be made.Other References
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