APPARATUS AND METHOD FOR DETERMINING CONDUCTIVITY OF WIRING INSTALLATIONS

• US 3,651,399 A
• Filed: 11/24/1969
• Issued: 03/21/1972
• Est. Priority Date: 11/24/1969
• Status: Expired due to Term

• Current Assignee: Douglas A. Florance, Lloyd P. Nordholm
• Original Assignee: Douglas A. Florance, Lloyd P. Nordholm
• Inventors: Florance, Douglas A., Nordholm, Lloyd P.
• Primary Examiner(s): Strecker, Gerard R.
• Application Number:
  US04/879,108
• Time in Patent Office: 848 Days
• Field of Search: 324/51,54,55,73,62,66
• US Class Current: 324/541
• CPC Class Codes: G01R 27/02 Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant by measuring phase angle only G01R25/00

Abstract

An apparatus and method for determining the conductivity of wiring installations of power distribution circuits is described. Selected portions of the circuit are subjected to alternating and direct current potentials of predetermined magnitude from distinct sources. The resultant currents are alternately indicated on distinct meters at a rate higher than the mechanical inertia thereof, permitting substantially simultaneous visual observation of both indications.

Claims

1. Apparatus for determining the conductivity of the wiring installation of electric power circuits comprising a first current indicating meter and circuit therefor, a power source of alternating current supplying said circuit, a second current indicating meter and circuit therefor, a power source of direct current supplying said last mentioned circuit, a pair of test leads adapted to be clamped between desired points of said wiring installation, switching means for alternately and sequentially connecting said leads to said meter circuits, thereby indicating current flow between said test points in reference to alternating and direct current due to the applied potentials from said respective sources said switching means including a relay for transferring said test leads between said meter circuits, a power source for said relay, and a timer controlling the sequential energizing of said relay, and the duration of the time during which said relay is actuated, whereby the indications of said meters due to the switching rate of said switching means permit apparent simultaneous observation of both alternating and direct currents.

2. Apparatus in accordance with claim 1 wherein said direct current meter circuit includes a capacitance, said switching means being operable during connection of said test leads to said meter circuit for bridging said capacitance across a predetermined resistance carrying the test current from said direct current source and transferring said capacitance during disconnection of said test leads between the terminals of said indicating meter.

3. Apparatus in accordance with claim 1 wherein each of said meters has a face plate and a movement actuating a pointer, said switching means having a transfer rate higher than the inertia of said movements whereby the indications of said meters remain substantially stationary for alternate observation.

4. The method of testing the conductivity of the wiring installation of power circuits which comprises, alternately and sequentially applying to selected portions of said circuits an electrical potential of alternating current of predetermined magnitude, and an electrical potential of direct current of predetermined magnitude, indicating the resultant currents from said applied potentials in sequential order at a rate dependent upon the inertia of the indicating means and permitting apparent simultaneous observation of said currents.

5. The method of testing the conductivity of wiring installation of power circuits which comprises, subjecting in succession a selected test portion of said installation to an alternating current source for a first predetermined time duration, causing a current flow and indicating the magnitude of said current in terms of alternating current conductivity;

transferring said test portion to a direct current source for a second predetermined time duration, thereby causing a direct current flow in said portion charging a capacitance to a voltage proportional to said direct current flow during such time;

thereafter transferring said test portion back to said alternating current source for the duration of said first time and simultaneously indicating the voltage charge of said capacitance in terms of direct current conductivity during said first time duration.