CA2112215C - Cable test set - Google Patents

Cable test set Download PDF

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Publication number
CA2112215C
CA2112215C CA 2112215 CA2112215A CA2112215C CA 2112215 C CA2112215 C CA 2112215C CA 2112215 CA2112215 CA 2112215 CA 2112215 A CA2112215 A CA 2112215A CA 2112215 C CA2112215 C CA 2112215C
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CA
Canada
Prior art keywords
conductors
indicating
voltage
test
test voltage
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
CA 2112215
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French (fr)
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CA2112215A1 (en
Inventor
Paul Eugene Large, Jr.
Phillip Stuart Robinson
Walter Kenneth Jiles
Kenneth E. Heifner
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Southwire Co LLC
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Southwire Co LLC
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Publication date
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Publication of CA2112215A1 publication Critical patent/CA2112215A1/en
Application granted granted Critical
Publication of CA2112215C publication Critical patent/CA2112215C/en
Anticipated expiration legal-status Critical
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  • Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)

Abstract

Apparatus for product quality and safety testing of circuit size electrical cable having plural conductors is disclosed. The disclosed embodiments of the invention include simplified apparatus and method for testing both the conductivity and insulation leakage integrity of such cable.

Description

2 :l '~ ~ ~ ~.' CABLE TEST SET
TECHNICAL FIELD
The present invention relates to product quality and safety testing of circuit size electrical cable having plural conductors. More particularly, the present invention relates to an apparatus and method for testing the continuity and insulation leakage integrity of such cable.
BACKGROUND ART
Various local and governmental standards authorities have established standards that require certain electrical cables to be subjected to continuity and insulation leakage integrity testing before sale to the public. When each marketable length of cable must be tested, the process is labor-intensive and adds significantly to the product cost. Previously, the cable was tested manually by first connecting the respective ends of the cable to a voltage source and a lamp or meter for indicating electrical continuity through the individual wires comprising the cable. Thereafter, any electrical insulation leakage integrity between electrical wires was tasted by means of a megohmmeter or the like to indicate electrical insulation leakage integrity faults or failure.
Only a limited number of lengths of cable could be tested per hour by any one person with such an apparatus.
MoreoverP if high voltages were involved, the testing personxiel would be subjected to safety hazards if the cables were mishandled.
Since the operating and test voltage standards may vary in different areas, the test voltage level must be adjusted to the desired values.
The present invention organizes and regiments the testing equipment and test procedures to ensure rapid and efficient compliance with the best standards and with maximum test personnel safety.

DISCLOSURr ON INVENTION
In view of the foregoing limitations and shortcomings of the prior art testing methods and procedures, as well as other_ disadvantages not specifica:Lly mentioned above, it should be apparent that there exists a need in the art for an improved apparatus and method for testing circuit size electrical cables having multip:Le conductors.
More particularly, the present invention organizes the apparatus and the steps of the standards testing in a form which ensures efficient and safe testing of the object cables.
It is, therefore, a primary object of this invention to fulfill that need by providing a first apparatus for testing circuit size electrical cable having plural conductors, which includes: a voltage source of a first level; apparatus for adjusting said voltage to test voltage levels; a device for indicating the presence of said test voltage levels; apparatus for selectively connecting said test voltage levels to the individual conductors of said cable; and a device for selectively switching said voltage levels to said connecting device at different switching device positions; wherein said indicating device is adapted for connection through said switching device, said indicating device, and said individual ones of said conductors of said cable to said voltage levels to indicate continuity in respective ones of said conductors in a first switch position and an electrical leakage integrity path between two or more conductors in another switch position. ~ voltage meter or other indicator may be included to indicate specific test voltage levels.
The objective of the invention may also be accomplished by providing an apparatus for testing circuit size electrical cable having plural conductors, including:
a first voltage source; a test voltage source; first device for indicating the presence of said test voltage;
second device for indicating the presence of said first voltage; a relay device for selectively connecting said second indicating device and said first voltage source;
apparatus for selectively connecting said test voltage to separate conductors of said cable; and a device for.
selectively switching said test voltage to said connecting apparatus at different switching device positions; wherein said first indicating device is adapted for connection through said switching device and said first indicating device to individual conductors of said cable to said test voltage to indicate electrical leakage integrity between said individual conductors in a first switch position, and , wherein said second indicating device is adapted for connection to said first voltage through respective ones of said conductors via said relay device under control of said switching device to indicate continuity of individual conductors in another switch position.
Tn apparatus for testing circuit size electrical cable having plural conductors, the objective of the invention can be achieved by the test method which includes the steps of providing d first voltage;
selectively connecting ends of individual ones of the conductors to the fixst voltage thraugh the contacts of a relay and an indicator in series therewit~i via a switch controlling said relay in a first switch position to indicate electrical continuity of each conductor; noting the-indicator response for each conductor; providing a test voltage; selectively connecting separate conductors in a second switch position to said test voltage via an indicator and said switch in a second position to indicate an electrical leakage integrity path among said conductors; and noting the indicator response for each combination of two conductors.
With the foregoing and other advantages and features of the invention that will become hereinafter apparent, the nature of the invention may be more clearly understood by reference to the following detailed description of the invention, the appended claims, and the view illustrated in the attached drawing.

~~.~.~~a.
BRIEF DESCRIfZ'ION OF DRAWING
FIG. 1 is a schematic diagram i_l.lustrating an example of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
There is shown in FIG. 1 an embodiment of the present invention suitable for testing circuit size electr.i.cal cable 12 having plural conductors, or wires. Such cables are also known in 'the art as building wire or non-metallic sheathed cable. Each cable is composed of at least two circuit conductors 16, 18, which are conventionally longitudinally encased within plastic electrical insulation 30, and at least one ground wire 14, which is often uninsulated. A third circuit conductor 20 may be included; when such is supplied, it is also usually insulated. Occasionally, a cable may be encountered which does not include the ground wire 14. At least a portion of the ground wire may be wrapped with a paper wrapping (not shownj. A longitudinal reinforcing material may also be included.
The two specific electrical tests for which this apparatus and method are intended include continuity, here defined as the substantial electrical conductivity of the wire, and electrical insulation leakage, defined here to refer 'to an unacceptable electrical current path between pairs of wire conductors.
A source of voltage 22 is provided to the test apparatus 10. The present invewtion contemplates use of ordinary electrical AC mains voltage as source 22. DC
voltages may be used with. appropriate circuit equivalents and substitutes for AC specific elements described in the exemplary embodiment.
Often, the test voltage level desired is other than that conveniently available from the AC mains. Tn such situations, a means for adjusting the voltage to the required test levels must be provided to accommodate this voltage difference. In the present.embodiment, an adjustable transformer may be used, shown here schematically as autotransformer 24. A Powerstat Model ~klOC autotrans.former may be used with AC mains voltage levels in the range of from about 9U to a-t least about 150 volts to produce a test voltage level of from about 0 to at least about 150 volts.
A meter 50 may be convenient to indicate the voltage level available from the autotransformer 24. Safety precautions commensurate with good engineering practice should be followed. A power ON/OFF switch 32 and a fuse 34 or.other circuit overload protection device may therefore be incorporated into the primary circuit of the autotransformer, as shown. Appropriate grounding of exposed metal cabinet parts should be arranged to minimize personnel injury hazards. It may also be convenient to include a POWER ON indicator such as lamp 36 to indicate when the test apparatus is energized, as potentially lethal voltage levels are anticipated.
The present embodiment includes separate indicators for the continuity test and for the electrical leakage integrity test; however, a single indicator could be used as explained hereinafter. For the purposes of this illustrative example, individual red incandescent lamps are used to indicate failure of a cable to pass the respective continuity or electrical leakage integrity test. Other indicators and other lamp colors may also be used.
A first lamp 26 for indicating electrical leakage integrity failure is connected between the autotransformer 24 secondary winding and a pair of test leads 28, which are to be connected to the cable conductors under test, via switch 42 in.the "LEAKAGE" test position 46.
When internally set to test electrical leakage integrity, each of the test leads 28 is connected to different conductor at ane end thereof, ixsually the beginning or the end of the cable 12. Then, when switch 42 is placed in the "LEAKAGE" position, a complete electrical path is formed only when a low resistance path is provided between the two conductors, such as occurs with defective insulation 16 on the conductors. Such a defect results in a short circuit, connecting the indicator lamp 26 to the test voltage source 24 and lighting the indicator 26. Two of the conductors 14, 16, 18, 20 are connected at a time and 'tested in pairs. Thus, each of the conductors 14, 16, 18, and 20 in a given cable 12 is tested in this way in combination with each of the other conductors in the cable to ensure absence of electrical leakage between the wires.
A second lamp 38 for indicating continuity failure is connected across 'the AC mains via normally-open contacts 48 of a relay 40. The relay coil (not shown) is operated via.a pair of test leads 28, which are to be connected to the ends of a conductor (14, 16, 18, or 20) in the cable 12 under test, via switch 42 in the "CONTINUITY" test position 44.
Switch 42 is shown as a double-pole, double-throw switch, with each of the test leads (28) connected to one of the respective common poles of the switch. One switched pair of poles is connected to the autotransformer 24 output. The remaining pair of switched poles is connected to a relay, as will be discussed subsequently.
Those of ordinary skill in the art will recognize that a double-pole, double-throw relay and appropriate control circuit may be substituted for the switch, the switch version being shown here for simplicity.
When internally set to test continuity, each of the test leads 28 is connected to wn opposite end of a given wire conductor 14, 16, 18, 20, placing the conductor in series with the internal operating coil (not shown) of relay 40 and completing thereby a circuit path across -the source voltage. Relay 40 may be, for example, a MEK Model 54 transistorized relay with at least one set of normally open contacts 48. When switch 42 is placed in the "CONTINUITY'° position 44, a complete path is formed which includes the relay coil to activate the relay 40 and close contacts 48, connecting the indicator lamp 38 to the AC
mains voltage source and lighting 'the indicator. Each of the conductors in a given cable is tested in this way to ensure full continuity of the wires.
Each of the two switch 42 positions corresponds to one of the cable tests. When switch 42 is in the position labeled "CONTINUITY" 44, the cable conductor continuity is tested. When switch 42 is in the po:oition labeled "LEAKAGE" 46, the cable conductor electrical leakage integrity is tested. Though not sho~m, a center-off switch could be substituted, having a third position which could be labelled "OFF" or the like.
One of ordinary skill in the art will recognize that a variation of the switching circuit, especially suitable when a relay is used in place of switch 42, would be to substitute a four-pole, double-throw contact arrangement in which the common poles of the extra double-pole, double-throw contacts are connected to a single indicator to signal a failure. In this configuration, the switched extra pairs of. poles.are connected, respectively, to points 52, 54 and 56, 58 in place of the separate indicator lamps 26, 38. In this manner, a single indicator or lamp can be alternately connected to indicate failure.of the cable for both of the functions being tested.
A cable may be tested for continuity by a method which includes both continuity tests and leakage integrity tests. This is accomplished by first supplying a voltage such as AC mains voltage from a source at 22, connecting the test leads 28 to the ends of individual conductors and then placing the switch 42 in the "CONTINUITY" position 44 with the source voltage applied, noting the response of indicator lamp 38, and subsequently repeating this process for each conductor of the cable. The cable may then be tested for electrical leakage integrity by supplying a test voltage, such as 100 volts AC or such other voltage level as may be required, from a source at 24 (the voltage level from which may be adjusted as required), connecting the test leads 28 to an end of each of two individual conductors in pairs of conductors and then placing the ~~~~~~M~9 fl switch 42 in the "L>;AKAGK" position 46 with the source voltage applied, noting the response of indicator lamp 26, and subsequently repeating -this process for each combination of two conductors in the cable.
Although certain presently preferred embodiments of the invention have been described herein, it will be apparent to those skilled in the art to whidh the invention pertains that variations and modifications of the described embodiment may be made without departing from -the spirit and scope of the invention. Accordingly, it is intended that the invention be limited only to the extent required by the appended claims and the applicable rules of law.

Claims (12)

1. Apparatus for testing circuit size electrical cable having plural conductors, comprising:
(a) an AC voltage source of a first voltage level;
(b) voltage variable transformer means for adjusting said first AC voltage to a predetermined minimum AC test voltage level;
(c) first means connected to said AC test voltage level for indicating the AC
test voltage level, comprising an AC voltmeter;
(d) second indicating means for indicating electrical continuity;
(e) means for selectively connecting said AC test voltage level to the individual conductors of said cable; and (f) means for selectively switching said first AC voltage level and said AC
test voltage level to said connecting means at different switching means positions;
wherein said second indicating means is adapted for connection in a series circuit through said switching means and said individual ones of said conductors of said cable to said first AC voltage level to indicate continuity in respective ones of said conductors in a first switching means position and said first indicating means is connected in a series circuit to said AC test voltage level and to an electrical leakage path among at least two conductors in another switching means position.
2. The testing apparatus of claim 1, wherein said means for connecting includes cable conductor connectors for leakage testing and further includes a relay having a pair of contact means connectable for communicating a voltage for the continuity test.
3. The testing apparatus of claim 1, wherein said second indicating means is a lamp.
4. The testing apparatus of claim 1, wherein said first indicating means is a lamp for indicating an electrical leakage failure and said second indicating means is a lamp for indicating continuity.
5. Apparatus for testing circuit size electrical cable having plural conductors, comprising:
(a) a first AC voltage source;
(b) adjustable means for providing an AC test voltage of a predetermined minimum AC voltage level;
(c) first means for indicating the presence of said AC test voltage;
(d) AC voltmeter means for indicating that said AC test voltage exceeds said predetermined minimum AC voltage level;
(e) second means for indicating the presence of said first AC voltage;
(f) first means for selectively connecting said second indicating means and said first AC voltage;
(g) second means for selectively connecting said AC test voltage to separate conductors of said cable; and (h) means for selectively switching said AC test voltage and said first AC
voltage to said connecting means at different switching means position;
wherein said first indicating means is adapted for connection in a series circuit through said switching means to individual conductors of said cable to said AC test voltage to indicate electrical leakage between said individual conductors in a first switching means position and said second indicating means is adapted for connection in a series circuit to said first AC
voltage through respective ones of said conductors via said first connecting means under control of said switching means to indicate continuity of said conductors in another switching means position.
6. The testing apparatus of claim 5, wherein said AC test voltage source is provided by a transformer.
7. The testing apparatus of claim 6, wherein said transformer is an adjustable voltage transformer.
8. The testing apparatus of claim 5, wherein said means for connecting includes cable conductor connectors for leakage testing and further includes a relay having a pair of contacts for the continuity test.
9. The testing apparatus of claim 5, wherein said first means for indicating is a lamp.
10. The testing apparatus of claim 5, wherein said first and second means for indicating are lamps and said AC voltmeter are connected to said AC test voltage level for indicating the AC test voltage level.
11. A method for testing circuit size electrical cable having plural conductors, comprising the steps of:
(a) providing a first AC voltage;
(b) selectively connecting ends of individual ones of the conductors to the first AC voltage through the contacts of a relay and a continuity indicator in series therewith via a switch to indicate electrical continuity of each conductor;
(c) noting the continuity indicator response for each conductor;
(d) providing an AC test voltage of at least a predetermined minimum level;
(e) measuring said AC test voltage to ensure that it exceeds the predetermined minimum AC voltage level;
(f) selectively connecting separate conductors to said AC test voltage via a leakage indicator to indicate an electrical leakage path among said conductors; and (g) noting the leakage indicator response for each combination of conductors.
12. The test method of claim 11, further including means for providing an adjustable AC
test voltage level, and further including the step of adjusting the AC test voltage level.
CA 2112215 1992-12-14 1993-12-15 Cable test set Expired - Fee Related CA2112215C (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US99031392A 1992-12-14 1992-12-14
US07/990,313 1992-12-14

Publications (2)

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CA2112215A1 CA2112215A1 (en) 1994-06-15
CA2112215C true CA2112215C (en) 2002-06-18

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CA 2112215 Expired - Fee Related CA2112215C (en) 1992-12-14 1993-12-15 Cable test set

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MX (1) MX9306431A (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2452906A (en) * 2007-06-25 2009-03-25 Simon Oliver Capon Two part diagnostic test lead

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MX9306431A (en) 1994-06-30
CA2112215A1 (en) 1994-06-15

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