GB2385934A

GB2385934A - Testing unit for fused electrical circuits

Info

Publication number: GB2385934A
Application number: GB0203623A
Authority: GB
Inventors: Richard Darling
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-02-15
Filing date: 2002-02-15
Publication date: 2003-09-03
Also published as: GB0203623D0

Abstract

A testing unit (10) for fused electrical circuits comprises a circuit breaker (see lever 12) arranged to be connected (over cable 20) with a circuit to be tested, and means (14) for selecting the value of the current at which the circuit breaker will trip. The cable (20) connects the unit (10) with a dummy fuse for insertion into the electrical circuit to be tested, in place of the usual fuse of that circuit. The circuit can therefore be tested without blowing a fuse, which may be particularly useful in testing circuits in vehicles.

Description

Testing Unit for Fused Electrical Circuits The present invention relates to a unit for testing electrical circuits which are protected by fuses.

When an electrical fuse blows, this is usually due to a short circuit or other fault on the circuit concerned. It is not always easy to make sure that the fault or faults are fully rectified before inserting a replacement fuse, which will blow again if there is still a fault on the circuit. The problem is common with electrical faults on vehicles, where the fuse box is often situated at some distance from the dashboard, where the control switches for the electrical circuits are positioned, and where it is often necessary to check lights etc at the front or rear of the vehicle.

I have now devised a testing unit which alleviates the difficulties described above.

In accordance with the present invention, there is provided a testing unit which comprises a circuit breaker arranged to be connected in series with a circuit to be tested, and means for selecting the value of current at which the circuit breaker will trip.

In using the testing unit, the circuit breaker is, in effect, connected into the electrical circuit under test, in place of the fuse which protects the electrical circuit. The selecting means is operated to select a current value, corresponding to the rate current of the fuse. The electrical circuit is then energised or switched on in the usual way : if the current flowing through the circuit exceeds the selected value, then the circuit breaker of the testing unit will trip, indicating that there is still a fault on the electrical circuit. If the current breaker does not trip, then this indicates that the current flowing is at a safe level and therefore there is no fault on the electrical circuit under test: a new fuse may be inserted.

The testing unit preferably comprises a hand-held device provided with a cable to connect the device to a dummy fuse for insertion into the electrical circuit to be tested, in place of the usual fuse. The dummy fuse and cable simply

provide an electrical path from one terminal in the fuse box to the other terminal, via the circuit breaker.

Preferably the cable is of substantial length, enabling the hand-held unit to be used at a distance from the fuse box, in particular at the vehicle dashboard or at the front or rear of the vehicle when checking its lights.

Preferably the cable includes a connector (e. g. a jack plug) for coupling to alternative types of dummy fuses.

Preferably the cable includes a connector (e. g. a jack plug) for coupling to a complementary connector of the testing unit.

Preferably the circuit breaker includes a projecting lever which moves from one position to another when the breaker trips, and which can be manually returned to its one position for resetting.

Preferably the selecting means comprises a rotary switch on the testing unit.

An embodiment of the present invention will now be described by way of example only and with reference to the accompanying drawings, in which: Figure 1 is an isometric view of a testing unit in accordance with the invention; Figure 2 is a similar view of the testing unit, on a reduced scale, shown with one end of a cable plugged into it ; Figure 3 is a view of the cable ; and Figure 4 is a view of two alternative forms of dummy fuses to which the other end of the cable is to be connected.

Referring to the drawings, there is shown a testing unit 10 which comprises a generally rectangular housing containing a circuit breaker having an operating lever 12 projecting from its front face. The unit 10 also contains a controller for the circuit breaker, the controller having a rotary switch 14 which is manually adjustable to set the level of current at which the circuit breaker will automatically trip.

The end of the test unit housing is provided with a socket 16 to receive the jack plug 18 at one end of a cable 20.

A similar jack plug 22 is provided at the other end of the cable 20 (Figure 3), for plugging into the connector socket 24 of a dummy fuse 26.

Figure 4 shows two different types of dummy fuse 26, at (a) of the type having projecting blades and at (b) of the inline type. Each of these dummy fuses has a projecting stalk 28 carrying the connector socket 24 to receive the jack plug 22 of the cable 20.

In use, in the event of a fuse of a vehicle blowing, the blown fuse is removed and replaced by the corresponding dummy fuse 26, either as shown at (a) or (b) in Figure 4 as appropriate. The cable 20 is used to connect the dummy fuse to the testing unit 10. The rotary switch 14 is turned to. set the trip current level of the circuit breaker to the same value as the current rating of the fuse which has blown. The relevant circuit of the vehicle is then energised : if there is still a fault in the circuit such that the current which flows exceeds the fuse rating, then the circuit breaker will trip and throw the lever 12 of the testing unit ; the fault in the circuit must be traced and rectified. If on the other hand the circuit breaker is not tripped, then it can be assumed that the circuit does not have a fault (or no longer has a fault) and a new fuse can be safely inserted.

It will be appreciated that the testing unit which has been described is of simple construction yet easy to use and, in particular, considerably simplifies the task of testing an electrical circuit for possible or remaining faults.

Whilst the device has been described as particularly useful for testing the electrical circuits of a vehicle, it may be made in heavier-duty form for domestic or industrial use.

Claims

CLAIMS 1) A testing unit which comprises a circuit breaker arranged to be connected in series with a circuit to be tested, and means for selecting the value of current at which the circuit breaker will trip.
2) A testing unit as claimed in claim 1, comprising a handheld device provided with a cable to connect said device to a dummy fuse for insertion into the electrical circuit to be tested, in place of the usual fuse.
3) A testing unit as claimed in claim 2, in which said cable is of sufficient length to enable the hand-held unit to be used at a vehicle dashboard or at the front or rear of the vehicle, when connected into the vehicle fuse box.
4) A testing unit as claimed in claim 2 or 3, in which said cable includes a connector arranged for coupling to alternative types of dummy fuses.
5) A testing unit as claimed in any one of claims 2 to 4, in which said cable includes a connector arranged for coupling to a complementary connector of said device.
6) A testing unit as claimed in any preceding claim, in which said circuit breaker includes a projecting lever which moves from one position to another when the breaker trips, and which can be returned manually to its said one position for resetting.
7) A testing unit as claimed in any preceding claim, in which said selecting means comprises a rotary switch.
8) A testing unit substantially as herein described with

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reference to the accompanying drawings.