Protective grounding jumper cable testing method

• US 5,684,408 A
• Filed: 12/18/1996
• Issued: 11/04/1997
• Est. Priority Date: 05/09/1995
• Status: Expired due to Term

• Current Assignee: Hubbell, Inc.
• Original Assignee: Hubbell, Inc.
• Inventors: King, Clayton C.
• Primary Examiner(s): Karlsen, Ernest F.
• Assistant Examiner(s): DO, DIEP N
• Application Number:
  US08/769,167
• Time in Patent Office: 321 Days
• Field of Search: 324/522, 324/523, 324/525, 324/527, 324/539, 324/543, 324/691, 324/713, 324/714, 324/718, 324/722, 324/723, 324/133, 379/21, 379/22, 379/26, 379/30
• US Class Current: 324/718
• CPC Class Codes: G01R 1/04 Housings; Supporting members; Arrangements of terminals
• CPC Class Codes: G01R 27/205 Measuring contact resistance of connections, e.g. of earth connections
• CPC Class Codes: G01R 31/14 Circuits therefor , e.g. for generating test voltages, sensing circuits G01R31/1209 - G01R31/1227 take precedence; for testing switches G01R31/327

Abstract

A protective grounding jumper cable tester basically includes a housing, a direct current power supply, a pair of jumper attachment terminals, a pair of test probe terminals, a current applying circuit connected between the direct current power supply and the pair of jumper attachment terminals for applying a direct current through a jumper cable attached between the jumper attachment terminals, and a resistance sensing circuit connected to the test probe terminals for sensing resistance to the flow of the direct current through the jumper cable by using a pair of test probes connected to the test probe terminals. A protective grounding jumper cable testing method includes connecting a jumper cable that is to be tested between a pair of terminals, applying a direct current to the cable, observing a current sensing meter while adjusting the direct current flowing through the jumper cable, either continuing with testing of the jumper cable if the direct current can be adjusted to a first preselected quantity, retest the jumper cable after inspecting and maintaining it or reject the jumper cable, setting a resistance sensing meter to sense resistance within a first preselected test range, contacting a pair of test probes to the terminals to indicate the resistance of the jumper cable to the direct current, comparing the resistance indicated by the resistance sensing meter with the first preselected test range, and, based on the comparison, either accept the jumper cable, retest the jumper cable after inspecting and maintaining it or reject the jumper cable.

Claims

1. A method of testing resistance of a protective grounding jumper cable, said testing method comprising the steps of:

(a) connecting a jumper cable to be tested between a pair of terminals;

(b) applying a direct current to said pair of terminals so as to cause flow of said direct current through the jumper cable;

(c) observing a current sensing meter in a circuit connected across said terminals for sensing and indicating the quantity of said direct current flowing through the jumper cable while adjusting said direct current flowing through the jumper cable;

(d) deciding in response to said observing of said current sensing meter to either

(i) continue with testing of the jumper cable in accordance with subsequent steps (e) through (h) only if said direct current can be adjusted to a first preselected quantity,

(ii) retest the jumper cable in accordance with previous and subsequent steps (a) through (h) after inspecting and maintaining the jumper cable, or

(iii) reject the jumper cable;

(e) setting a resistance sensing meter to sense resistance within a first preselected test range;

(f) contacting a pair of test probes connected to said resistance sensing meter with said terminals to sense and indicate on said resistance sensing meter the resistance to the flow of said direct current through the jumper cable;

(g) comparing the resistance indicated by said resistance sensing meter with said first preselected test range; and

(h) deciding in response to said comparison of the resistance indicated by said resistance sensing meter with said first preselected test range to either

(i) accept the jumper cable,

(ii) retest the jumper cable in accordance with said steps (a) through (h) after inspecting and maintaining the jumper cable, or

(iii) reject the jumper cable.

2. The method of claim 1, wherein in response to said observation of said current sensing meter, the jumper cable is retested in accordance with said steps (a) through (h) after inspecting and maintaining the jumper cable only if:

(i) said direct current cannot be adjusted to said first preselected quantity; and

(ii) the jumper cable has not yet been retested.

3. The method of claim 1, wherein in response to said observation of said current sensing meter, the jumper cable is rejected only if:

(i) said direct current cannot be adjusted to said first preselected quantity; and

(ii) the jumper cable has already been inspected and maintained and is presently being retested in accordance with said steps (a) through (h).

4. The method of claim 1, wherein in response to said comparison of the resistance indicated by said resistance sensing meter with said first preselected test range, the jumper cable is accepted only if the resistance is within said first preselected test range and below a predetermined safe resistance level.

5. The method of claim 1, wherein in response to said comparison of the resistance indicated by said resistance sensing meter with said first preselected test range, the jumper cable is retested only if:

(i) the resistance exceeds a predetermined safe resistance level; and

(ii) the jumper cable has not yet been inspected, maintained and retested in accordance with said steps (a) through (h).

6. The method of claim 1, wherein in response to said comparison of the resistance indicated by said resistance sensing meter with said first preselected test range, the jumper cable is rejected only if:

(i) the resistance exceeds a predetermined safe resistance level; and

(ii) the jumper cable has already been inspected and maintained and is presently being retested in accordance with said steps (a) through (h).

7. The method of claim 1, further comprising the steps of:

(i) deciding in response to said comparison of the resistance indicated by said resistance sensing meter with said first preselected range to retest the jumper cable in accordance with subsequent steps (j) through (n) because the resistance is below said first preselected test range;

(j) adjusting said direct current flowing through the jumper cable to a second preselected quantity, said second preselected quantity being greater than said first preselected quantity;

(k) setting said resistance sensing meter to sense resistance within a second preselected test range, said second preselected test range being lower than said first preselected test range;

(l) contacting said pair of test probes with said terminals to sense and indicate on said resistance sensing meter the resistance to the flow of said direct current through the jumper cable;

(m) comparing the resistance indicated by said resistance sensing meter with said second preselected test range; and

(n) deciding in response to said comparison of the resistance indicated by said resistance sensing meter with said second preselected test range to

(i) accept the jumper cable,

(ii) retest the jumper cable in accordance with said steps (a) through (h) after inspecting and maintaining the jumper cable, or

(iii) reject the jumper cable.

8. The method of claim 7, wherein in response to said comparison of the resistance indicated by said resistance sensing meter with said second preselected test range, the jumper cable is accepted only if the resistance is within said second preselected test range and below said predetermined safe resistance level.

9. The method of claim 7, wherein in response to said comparison of the resistance indicated by said resistance sensing meter with said second preselected test range, the jumper cable is retested only if:

(i) the resistance exceeds said predetermined safe resistance level; and

(ii) the jumper cable has not yet been inspected, maintained and retested in accordance with said steps (i) through (n).

10. The method of claim 7, wherein in response to said comparison of the resistance indicated by said resistance sensing meter with said second preselected test range, the jumper cable is rejected only if:

(i) the resistance exceeds said predetermined safe resistance level; and

(ii) the jumper cable has already been inspected and maintained and is presently being retested in accordance with said steps (i) through (n).

11. The method of claim 7, further comprising the steps of:

(o) deciding in response to said comparison of the resistance indicated by said resistance sensing meter with said second preselected range to retest the jumper cable in accordance with subsequent steps (p) through (s) because the resistance is below said second preselected test range;

(p) setting said resistance sensing meter to sense resistance within a third preselected test range, said third preselected test range being lower than said second preselected test range;

(q) contacting said pair of test probes with said terminals to sense and indicate on said resistance sensing meter the resistance to the flow of said direct current through the jumper cable;

(r) comparing the resistance indicated by said resistance sensing meter with said third preselected test range; and

(s) deciding in response to said comparison of the resistance indicated by said resistance sensing meter with said third preselected test range to

(i) accept the jumper cable,

(ii) retest the jumper cable in accordance with said steps (a) through (h) after inspecting and maintaining the jumper cable, or

(iii) reject the jumper cable.

12. The method of claim 11, wherein in response to said comparison of the resistance indicated by said resistance sensing meter with said third preselected test range, the jumper cable is accepted only if the resistance is below said predetermined safe level.

13. The method of claim 11, wherein in response to said comparison of the resistance indicated by said resistance sensing meter with said third preselected test range, the jumper cable is retested only if:

(i) the resistance exceeds said predetermined safe resistance level; and

(ii) the jumper cable has not yet been inspected, maintained and retested in accordance with said steps (o) through (s).

14. The method of claim 11, wherein in response to said comparison of the resistance indicated by said resistance sensing meter with said third preselected test range, the jumper cable is rejected only if:

(i) the resistance exceeds said predetermined safe resistance level; and

(ii) the jumper cable has already been inspected and maintained and is presently being retested in accordance with said steps (o) through (s).

15. The method of claim 11, wherein prior to said step of retesting the jumper cable, inspection of the jumper cable includes identifying portions of the jumper cable having relatively high resistance to the flow of said direct current therethrough by contacting said pair of test probes at various locations on the jumper cable to sense and indicate on said resistance sensing meter the resistance to the flow of said direct current through different portions of the jumper cable.