Fuse saving tester for fused circuit

• US 20040017203A1
• Filed: 09/20/2002
• Published: 01/29/2004
• Est. Priority Date: 09/20/2001
• Status: Active Grant

• Current Assignee: Snap-On Incorporated
• Original Assignee: Snap-On Incorporated
• Inventors: Lionberg, Daniel D., Bruno, William G., Becker, Thomas P., Crass, Matthew D.
• Granted Patent: US 7,148,698 B2
• Time in Patent Office: Days
• US Class Current: 324/507
• CPC Class Codes: G01R 31/006 on road vehicles, e.g. automobiles or trucks testing of ignition installations peculiar to internal combustion engines F02P17/00
• CPC Class Codes: G01R 31/083 in cables, e.g. underground
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults
• CPC Class Codes: G01R 31/74 Testing of fuses

Abstract

In one form, tester for an electrical system, such as for a vehicle, develops repetitively applied, short duration, control current pulses for reducing load current pulses through the electrical system. An operator connects a pair of input contacts across a fuse holder. A circuit between the input contacts is closed momentarily and repetitively to produce repetitive current pulses from the electricity source through the system. A perceptible alert is produced when the magnitude of the current pulse exceeds that of a prescribed reference current value. In another form, a tester for an electrical system is designed to plug into the fuse terminals in a fuse box. The tester can include a plurality of interchangeable circuit breaker modules to allow the tester to be used on circuits having differing current ratings.

Claims

1. A tester for testing an electrical system for excessive current flow, which system is powered by an electricity source and includes a fuse holder for a fuse having a predetermined rating, the tester comprising:

a pair of contacts electrically coupleable across the fuse holder;

a switch coupled with the contacts and coupleable with the electricity source, the switch being momentarily closeable to pass a current pulse to the fuse holder;

a controller, coupled to the switch that controls the switch to momentarily close repeatedly;

a comparator that compares the magnitude of the current pulse with a prescribed reference current value; and

an indicator that produces a perceptible signal when the magnitude of the current pulse exceeds that of the prescribed reference current value.

2. The tester according to claim 1, further comprising a rectifier in circuit with the pair of contacts, wherein the rectifier produces an input voltage signal that is independent of the polarity of the connection to the pair of contacts.

3. The tester according to claim 1, wherein the controller comprises an oscillator that generates control pulses of a predetermined width and frequency.

4. The tester according to claim 3, wherein the pulse width of the control pulses is within the range of about 10-20 milliseconds and the pulse repetition rate is at about one cycle per second.

5. The tester according to claim 1, further comprising a resistor in series with the pair of contacts and a differential amplifier coupled to the resistor, wherein the differential amplifier detects a voltage drop across the resistor.

6. The tester according to claim 1, wherein the comparator includes an operational amplifier.

7. The tester according to claim 1, further comprising a microprocessor programmed for

a) momentarily closing the switch to produce a current pulse from the electricity source through the electrical system;

b) comparing the magnitude of the current pulse with a prescribed reference current value; and

c) producing a perceptible signal when the magnitude of the current pulse exceeds that of the prescribed reference current value.

8. A device for testing an electrical system according to claim 7, wherein the steps (a) through (c) are repeated to generate current pulses having a predetermined width and frequency.

9. A device for testing an electrical system according to claim 8, wherein the current pulse width is about 10-20 milliseconds and the pulse repetition rate is about one cycle per second.

10. A method of testing an electrical system for current flow exceeding a prescribed value, which system is powered by an electricity source and includes a fuse holder for a fuse having a predetermined rating, the method comprising the steps of:

connecting a pair of contacts across the fuse holder;

momentarily closing a circuit between the contacts to produce a current pulse from the electricity source through the electrical system;

comparing the magnitude of the current pulse with a prescribed reference current value; and

producing a perceptible signal when the magnitude of the current pulse exceeds that of the prescribed reference current signal.

11. A method of testing an electrical system as in claim 10, further comprising:

repeating the step of momentarily closing the circuit between the contacts to produce repeating current pulses through the electrical system.

12. The method of testing an electrical system as in claim 11, wherein the current pulses are produced at a rate of one pulse per second.

13. The method of testing an electrical system as in claim 12, wherein each of the current pulses has a duration within the range of 10-20 milliseconds.

14. A method of testing an electrical system as in claim 10, further comprising the step of setting the prescribed reference current value according to the current rating of a fuse specified for connection to the fuse holder.

15. A method of testing an electrical system according to claim 14, wherein the prescribed reference current value is set by adjusting a variable resistor.

16. A method of testing an electrical system according to claim 10, further comprising the step of generating a positive voltage signal through the system independent of a polarity of the pair of contacts.

17. A method of testing an electrical system according to claim 10, further comprising the step of establishing a location of a short circuit when the perceptible signal is produced.

18. A tester for testing an electrical system, which includes a fuse holder for a fuse having a predetermined current load rating, the device comprising:

a pair of contacts electrically coupleable to the fuse holder;

a circuit breaker electrically coupled to the pair of contacts and having the same predetermined current load rating as the fuse; and

an indicator which produces a perceptible signal when an overcurrent situation exists in the circuit breaker.

19. The tester of claim 18, further comprising a housing carrying the circuit breaker, wherein the pair of contacts are rigidly coupled to the housing.

20. The tester of claim 18, further comprising a housing and a wire coupling the pair of contacts to the housing.

21. The tester of claim 18, further comprising a housing having a reduced-width and thickness projection coupled to the pair of contacts.

22. The tester of claim 21, wherein the pair of contacts are identical to another pair of contacts, wherein the other pair of contacts are those of the fuse.

23. The tester of claim 22, wherein the circuit breaker is a self-resetting thermal breaker.

24. A plurality of testers for testing an electrical system, which includes a fuse holder for a fuse having one of a plurality of predetermined load ratings, each tester comprising:

a pair of contacts electrically coupleable to the fuse holder;

a circuit breaker electrically coupled to the pair of contacts, the circuit breaker having one of a plurality predetermined current load ratings; and

an indicator which produces a perceptible signal when an overcurrent situation exists in the circuit breaker.

25. The plurality of testers of claim 24, wherein the circuit breaker of one tester has a different predetermined current load rating from the circuit breaker of another tester.

26. The plurality of testers of claim 24, wherein one of the testers further comprises a housing carrying the circuit breaker, wherein the pair of contacts are rigidly coupled to the housing.

27. The plurality of testers of claim 24, wherein one of the testers further comprises a housing and a wire coupling the pair of contacts to the housing.

28. The plurality of testers of claim 24, wherein one of the testers further comprises a housing having a reduced-width and thickness projection coupled to the pair of contacts.

29. A method of testing an electrical system, which system includes a fuse holder for a fuse having a predetermined rating, comprising:

providing a plurality of testers respectively having circuit breakers respectively with predetermined current load ratings,

selecting from the plurality of testers, a tester having a circuit breaker with a predetermined current load rating that matches the predetermined rating of the fuse for the fuse holder;

connecting the contacts of the selected tester across the fuse holder; and

providing a perceptible indication of an overcurrent situation through the circuit breaker.

30. A tester for testing an electrical system, which system includes a fuse holder for a fuse having one of plurality of possible predetermined ratings, the tester comprising:

an indicator unit including a first pair of contacts electrically coupleable to the fuse holder and a second pair of contacts electrically coupled to the first pair of contacts and an indicator coupled to the second pair contacts; and

a circuit breaking module having a third pair of contacts for removably coupling to the second pair of contacts, the circuit breaking module including a circuit breaker having a predetermined current load rating;

wherein the indicator produces a perceptible signal when an overcurrent situation exists in the circuit breaking module.

31. The tester of claim 30, further comprising a housing carrying the indicator, wherein one of a male coupling and a female coupling includes the second pair of contacts and is carried by the housing, the other of the male coupling and the female coupling includes the third pair of contacts and is carried by the first circuit breaking module;

and the male coupling is removably insertable in the female coupling for electrically coupling the second and third pairs of contacts.

32. The tester of claim 31, wherein the one of the male coupling and the female coupling comprises a socket in the housing and the first circuit breaking module is removably insertable in the socket for electrically coupling the second and third pairs of contacts.

33. The tester of claim 30, further comprising a further circuit breaking module having a fourth pair of contacts for removably coupling to the second pair of contacts, the further circuit breaking module including a further circuit breaker having a further predetermined current load rating.

34. The tester of claim 33, wherein the predetermined current load rating is different from the further predetermined current load rating.