Current sensing alarm arrangement for monitoring the presence of high voltage

• US 4,755,805 A
• Filed: 05/22/1986
• Issued: 07/05/1988
• Est. Priority Date: 05/22/1986
• Status: Expired due to Term

• Current Assignee: UtilX Corporation (Novinium, Inc.)
• Original Assignee: Flowmole Corporation
• Inventors: Chau, Albert W.
• Primary Examiner(s): Orsino, Joseph A.
• Assistant Examiner(s): Hofsass, Jeffery A.
• Application Number:
  US06/866,170
• Time in Patent Office: 775 Days
• Field of Search: 340/662, 340/679, 340/684, 340/685, 340/649, 340/660, 340/651, 361/91
• US Class Current: 340/662
• CPC Class Codes: E21B 17/003 with electrically conducting or insulating means E21B17/028 and E21B17/023 take precedence
• CPC Class Codes: E21B 47/09 Locating or determining the position of objects in boreholes or wells , e.g. the position of an extending arm; Identifying the free or blocked portions of pipes
• CPC Class Codes: G01R 15/144 Measuring arrangements for voltage not covered by other subgroups of G01R15/14
• CPC Class Codes: G01R 19/155 Indicating the presence of voltage
• CPC Class Codes: G01R 19/16576 comparing DC or AC voltage with one threshold G01R19/16514, G01R19/16519, G01R19/16528, G01R19/16533 and G01R19/1659 take precedence

Abstract

A system in which an electrically conductive boring device is caused to move through the ground to provide an underground tunnel, to install underground utilities, or for any other reason. A technique for detecting if the boring device electrically engages an underground source of high voltage such as an existing underground utility line. This arrangement, is also suitable for detecting if other electrically conductive apparatus, structural member, or like means engages a similar underground source of high voltage includes means defining an electrically conductive path leading from the boring device or other such member to a grounding point sufficient to reduce to a negligible level any high voltage to which the device or like member may be subjected. The present technique monitors the current through the grounding path and indicates if the current level through the path reaches a predetermined threshold level which is selected to correspond with the presence of high voltage.

Claims

1. An arrangement for detecting if an electrically conductive apparatus, structural member or the like may be inadvertently electrically connected to a source of high voltage, said arrangement comprising:

(a) means including a continuous electrically conductive ground cable defining an electrical ground path from said apparatus, structural member or the like to a grounding point, said ground path defining means being sufficiently conductive to reduce to at most a negligible level any high voltage to which the apparatus, structural member or the like may be subjected; and

(b) means for monitoring the current through said ground path and for indicating if the current level so monitored reaches a predetermined threshold level sufficiently high to indicate that the apparatus, structural member or the like is in electrical engagement with a source of high voltage, said monitoring means including means for directly sensing the current in said ground path and for producing a corresponding electrical signal, and means for comparing the magnitude of said signal to a reference signal serving as said threshold level, said current sensing means including transformer means which utilizes a section of said ground cable as a primary and which includes a secondary, whereby current carried by said ground cable is induced in and sensed by said secondary to produce said corresponding signal, said monitoring means including means for directly sensing the current in said ground path and for producing a corresponding electrical signal, means for comparing the magnitude of said corresponding signal to a reference signal serving as said threshold level, means for producing an alarm driving signal in the event that a current exceeding said threshold level is sensed, and an alarm responsive to said alarm signal for producing an audible and/or visual signal, said arrangement also including means for testing said monitoring means, said testing means including means for producing an oscillating signal, a transformer secondary forming part of said transformer means for simulating a fault current on said electrically conductive cable by means of induction through said transformer, whereby said simulated current is sensed by said first mentioned secondary forming part of said transformer means.

2. An arrangement according to claim 1 wherein said apparatus, structural member or the like includes an electrically conductive boring device which is caused to move through the ground to provide an underground tunnel, to install underground utilities and for any other reason, and an electrically conductive platform which is located above the ground for supporting controls for the boring device and an operator, and wherein said grounding path includes aid boring device, platform and electrically conductive cable means between the two.