Electrical conductor and short circuit locator

• US 4,129,825 A
• Filed: 05/02/1977
• Issued: 12/12/1978
• Est. Priority Date: 02/21/1975
• Status: Expired due to Term

• Current Assignee: Paul E. Brinegar
• Original Assignee: Paul E. Brinegar
• Inventors: Brinegar, Paul E.
• Primary Examiner(s): Strecker, Gerard R.
• Application Number:
  US05/792,923
• Time in Patent Office: 589 Days
• Field of Search: 324/51, 324/52, 324/66, 324/67
• US Class Current: 324/523
• CPC Class Codes: G01R 31/08 Locating faults in cables, transmission lines, or networks
• CPC Class Codes: G01R 31/085 in power transmission or distribution lines, e.g. overhead
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults

Abstract

An apparatus for locating electrical conductors and short circuits in AC and DC circuits is disclosed herein. The apparatus has leads for connecting across open circuit breaker or fuse box terminals. Current limiting resistors and transistors limit the current, if AC or converted to pulsated DC, to a value that is sufficiently high to be read on a clamp-on ammeter at any point in the circuit being tested. A first pulse generator intermittently interrupts the current through the current limiting means to create a momentary pulse of approximately 1/2 to 1 second duration at a frequency of approximately 3 to 5 seconds. A second pulse generator interrupts the current limiting means at approximately 225 cycles per second to provide a pulsating component in the momentary pulse for DC circuits. A clamp-on ammeter will indicate this pulse at all points in the circuit except at the short circuit, whether in a DC or AC circuit.

Claims

1. An apparatus for locating electrical conductors and short circuits comprising:

first and second test leads for connecting across open circuit breaker means in a circuit to be tested;

the open circuit breaker means having a voltage potential across its terminals due to a circuit power source;

current limiting means connected across the test leads for allowing current due to the circuit power source to flow through the current limiting means and the circuit, and for limiting the current in the circuit being tested to a predetermined value to prevent excessive short circuit current in the circuit being tested;

the predetermined value being sufficiently high such that pulsated and alternated currents are discernable at conducting points in the circuit by a clamp-on ammeter;

first pulse generating means, cooperating with the current limiting means, for intermittently interrupting the current in the circuit being tested;

the first pulse generating means providing an on duration of the current in the circuit being tested sufficient for a clamp-on ammeter in an AC circuit to indicate a momentary pulse with the off duration substantially greater than the on duration; and

second pulse generating means, cooperating with the current limiting means and connected in series with the first pulse generating means, for interrupting the momentary pulse created by the first pulse generating means to provide a pulsating component in the momentary pulse so that a current reading is visible on a clamp-on ammeter in a DC circuit at all points along the circuit except at the short circuit.

2. The apparatus according to claim 1 wherein the first pulse generating means provides a pulse of duration substantially in the range from 1/2 to 1 second occurring at a frequency substantially in the range from 3 to 5 seconds.

3. The apparatus according to claim 2 wherein the current limiting means limits the current to an amplitude substantially in the range from 0.25 amps to 5 amps.

4. The apparatus according to claim 3 wherein the second pulse generating means provides pulses of frequency substantially in the range from 100 to 500 cycles per second.

5. The apparatus according to claim 4 wherein the pulses generated by the second pulse generating means have a duty cycle of approximately 20 to 30 percent on-duration.

6. An apparatus for locating electrical conductors and short circuits, comprising:

power supply means for providing a DC voltage;

first pulse generating means connected to the power supply means for generating a momentary pulse of substantially 1/2 to 1 second duration substantially every 3 to 5 seconds;

second pulse generating means connected in series with the first pulse generating means for pulsating the momentary pulse at a frequency in the range from 100 to 500 cycles per second;

first and second test leads for connecting across open circuit breaker means in a circuit to be tested;

the open circuit breaker means having a voltage potential across its terminals due to a circuit power source;

current limiting means connected across the test leads for allowing current in the circuit due to the circuit power source to flow through the current limiting means and the circuit, and for limiting the current in the circuit being tested to a pulsating and alternating value substantially in the range from 0.25 to 5.0 amps;

switch means connected with the current limiting means for switching on and off the current flow; and

optical isolator means, including a light emitting diode and a photosensitive transistor, for actuating the switch means responsive to the pulsating output from the second pulse generator means, thereby causing an intermittent current pulse in the circuit being tested for detection by a clamp-on ammeter.

7. The apparatus according to claim 6 wherein the pulses generated by the second pulse generator have a duty cycle of 2 to 30 percent on duration to reduce the amount of time in which current is flowing through the circuit being tested.

8. An apparatus for locating electrical conductors and short circuits, comprising:

power supply means for providing a DC voltage;

first pulse generating means connected to the power supply means for generating a momentary pulse with an on duration sufficient for a clamp-on ammeter in an AC circuit to indicate a momentary pulse, with the off duration considerably greater than the on duration;

second pulse generating means connected in series with the first pulse generating means for pulsating the momentary pulse at a frequency sufficiently high so that a current reading is visible on a clamp-on ammeter in a DC circuit;

first and second test leads for connecting across open circuit breaker means in a circuit to be tested;

the open circuit breaker means having a voltage potential across its terminals due to a circuit power source;

current limiting means connected across the test leads for allowing current in the circuit due to the circuit power source to flow through the current limiting means and the circuit, and for limiting the current in the circuit being tested to a predetermined value to prevent excessive short circuit current;

the predetermined value being sufficiently high such that pulsated and alternated currents are discernable at conducting points in the circuit by a clamp-on ammeter;

switch means connected with the current limiting means for switching on and off the current flow; and

optical isolator means, including a light emitting diode and a photosensitive transistor, for actuating the switch means responsive to the pulsating output from the second pulse generator means, thereby causing an intermittent current pulse in the circuit being tested for detection by a clamp-on ammeter.