Bridge circuit changing fault location method and device

Claim 1

Apparatus for locating a fault in a conductive loop having a faulted conductor comprising a bridge circuit having four branches and a pair of terminals to which the loop is connected, a plurality of resistance devices, switch means connected to said resistance devices for selectively inserting the loop and the resistance devices into the bridge circuit to establish different resistances in each of the branches corresponding to two operational modes, meter means connected to one of the resistance devices and the switch means for indicating balanced conditions in said operational modes of the bridge circuit, and means for adjusting said one of the resistance devices to establish said balance conditions in the two operational modes by resistance values in one of the branches respectively proportional to the total length of said loop and the percentage of said total length of a portion of the loop between the fault and one of the terminals.

Claim 11

A device for locating faults along a pair of electrical conductors extending between first and second locations and which have been shorted at the second location to define a conductive loop, said device comprising a resistance bridge circuit, means for indicating balance of said bridge circuit, first adjustable potentiometer means selectively connectible into said bridge circuit for balancing thereof in first and third modes of operation to respectively determine the total length of said loop and the ratio of a loop portion between a fault and said first of the locations to the entire loop, second adjustable potentiometer means selectively connectible into said bridge circuit in a second mode of operation to obtain a computed reading from the first adjustable potentiometer means in the third mode of operation, resistance means including a plurality of resistance values each corresponding to a conductor resistivity, switch means for selectively connecting the resistance means into said bridge circuit when operated in said first mode, and means for selectively connecting said conductive loop or portion thereof between said fault and said first location into said bridge circuit, said first potentiometer means including first selectively adjustable tap means for inserting a first value of resistance into said bridge circuit to achieve balance thereof in said first mode wherein said first value is directly proportional to the resistance of said conductive loop, said second potentiometer means being selectively adjustable in said second mode to achieve balance of said bridge circuit when a second value of resistance is inserted therein and equal to said first value of resistance, said first potentiometer means further including a second selectively adjustable tap means for inserting a third value of resistance into said bridge circuit to achieve balance in said third mode wherein said third value is directly proportional to the resistance of said portion of faulted conductor, said second tap means being coupled to a selector with associated indicia to provide a reading corresponding to the distance of the fault from said first location.

Claim 12

A device for locating faults along a pair of electrical conductors extending between first and second locations and which have been shorted at the second location to define a conductive loop, said device comprising a resistance bridge circuit, means for indicating balance of said bridge circuit, first adjustable potentiometer means selectively connectible into said bridge circuit for balancing thereof in first and third modes of operation to respectively determine the total length of said loop and the ratio of a loop portion between a fault and said first of the locations to the entire loop, second adjustable potentiometer means selectively connectible into said bridge circuit in a second mode of operation to obtain a computed reading from the first adjustable potentiometer means in the third mode of operation, resistance means including a plurality of resistance values each corresponding to a conductor resistivity, switch means for selectively connecting the resistance means into said bridge circuit when operated in said first mode, and means for selectively connecting said conductive loop or portion thereof between said fault and said first location into said bridge circuit, said first potentiometer means including first selectively adjustable tap means for inserting a first value of resistance into said bridge circuit to achieve balance thereof in said first mode wherein said first value is directly proportional to the resistance of said conductive loop, said second potentiometer means being selectively adjustable in said second mode to achieve balance of said bridge circuit when a second value of resistance is inserted therein and equal to said first value of resistance, said first potentiometer means further including a second selectively adjustable tap means for inserting a third value of resistance into said bridge circuit to achieve balance in said third mode wherein said third value is directly proportional to the resistance of said portion of faulted conductor, said second tap means being coupled to a selector with associated indicia to provide a reading corresponding to the distance of the fault from said first location.

Claim 13

A method for locating a fault in a conductive loop connected to a four branch bridge circuit formed by a plurality of resistance devices, at least one of which is adjustable in resistance value, comprising the steps of: interconnecting two of the resistance devices to form first and second branches of the bridge circuit in a first operational mode; interconnecting the loop and the adjustable resistance device to respectively form third and fourth branches of the bridge circuit in said first operational mode; varying the resistance of said adjustable resistance device in the fourth branch until a balanced condition is obtained in the bridge circuit corresponding to a resistance value in the fourth branch proportional to the length of the loop in the third branch of the bridge circuit in said first operational mode; reestablishing the bridge circuit in a second operational mode by: dividing the adjustable resistance device betWeen the first and fourth of said branches; isolating a portion of the loop between the fault and the adjustable resistance device in the third of the branches; inserting the remainder of the loop into the second of the branches; varying the resistance of the adjustable resistance device in the first and fourth branches until a balanced condition is obtained in the bridge circuit corresponding to a resistance value in the fourth branch proportional to the percentage of said portion of the loop in the third branch to the entire loop in the second and third branches of the bridge circuit in the second operational mode; and computing the product of the adjusted resistance values of the fourth branch of the bridge circuit in the two operational modes.

Claim 14

A method for locating a fault in a conductive loop connected to a four branch bridge circuit formed by a plurality of resistance devices, at least one of which is adjustable in resistance value, comprising the steps of: interconnecting two of the resistance devices to form first and second branches of the bridge circuit in a first operational mode; interconnecting the loop and the adjustable resistance device to respectively form third and fourth branches of the bridge circuit in said first operational mode; varying the resistance of said adjustable resistance device in the fourth branch until a balanced condition is obtained in the bridge circuit corresponding to a resistance value in the fourth branch proportional to the length of the loop in the third branch of the bridge circuit in said first operational mode; reestablishing the bridge circuit in a second operational mode by: dividing the adjustable resistance device betWeen the first and fourth of said branches; isolating a portion of the loop between the fault and the adjustable resistance device in the third of the branches; inserting the remainder of the loop into the second of the branches; varying the resistance of the adjustable resistance device in the first and fourth branches until a balanced condition is obtained in the bridge circuit corresponding to a resistance value in the fourth branch proportional to the percentage of said portion of the loop in the third branch to the entire loop in the second and third branches of the bridge circuit in the second operational mode; and computing the product of the adjusted resistance values of the fourth branch of the bridge circuit in the two operational modes.