JP2005038801A - Fuse saving test device for circuit with fuse - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric circuit tester which identifies the electrical trouble position by promptly responding to the existence of short circuit without flowing a large current for a long time to the electrical system of various types of rated current. <P>SOLUTION: The tester is provided with a pair of contacts capable of connecting electrically to the fuse holder for fuse of a prescribed rated current of a testing electrical system as the both ends and a switch which is connected to the above contacts and is capable of connecting to the power supply source and can close instantaneously in order to supply a current pulse to the fuse holder. The above switch closes instantaneously and repeatedly and generates a current pulse which flows from the power supply source through the system. By comparing the size of the current pulse with a prescribed reference current value, when it is the prescribed reference value or more, a recognizable signal showing existence of electrical troubles is generated. This can be designed as a tester which can be used for a circuit of various types of rated current as a format in which a plug having a plurality of breaker modules capable of exchange is inserted in a fuse terminal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a tester, and particularly to a tester such as a short circuit or ground circuit detector and display device for testing a circuit with a fuse.

  Many electrical systems include circuits with fuses, and the fuses of those circuits are located in a central fuse panel or fuse box. It is often convenient to test a circuit with a fuse board if the fuse board is in a relatively easily accessible location. When testing a circuit with a fuse panel, a tester is often connected in parallel with the fuse of the circuit to be tested. However, when testing short circuits, this approach can blow the fuse.

  In order to test a circuit with a fuse, it is known to install a built-in circuit breaker in a circuit tester that can be connected to a fuse board instead of a fuse. One such device is a short circuit locator sold by Snap-on Tools, Inc. under the name YA809. Since the YA809 has only one circuit breaker with a large rated current, when connected to a circuit with a low rated current, a circuit that tests “potentially damaging current” It becomes possible to flow. In addition, the YA809 requires an operator to be at the fuse board location to see a given visual indicator. This is inconvenient and requires a worker somewhere in the circuit to be tested while the test is running. Another diagnostic technique for identifying the location of a current flow path or short circuit through which a current excess is passed is to repeatedly replace a blown fuse until a fault location is identified. This method can waste a large number of fuses before a successful test. A more practical test method is to try to determine the short-circuit location by passing an instantaneous current through a resettable breaker.

  One model of such a tester is a 30-A self-resettable thermal breaker that is installed in parallel with a blown fuse and repeatedly causes a current flow in the form of a current pulse to the short circuit. is there. This circuit breaker opens after a short thermal delay and automatically resets upon cooling. As a result of the repetitive operation of the circuit breaker, a magnetic field is generated around the shorted wiring during the moment of the instantaneous high current pulse. The tester includes a needle magnetic detector that detects in response to a magnetic field. By moving the magnetic detector along the wiring harness, the user can identify the location of the short circuit when meter deflection stops.

  This tester is difficult to use. This is because it is necessary for this detector to be in close proximity to the wiring in order to function. In addition, the repetition rate of the thermal circuit breaker is on the order of a few ten seconds (tens of seconds), so the position of the thermal circuit breaker that closes the circuit to see if a short circuit exists at that position. Makes the worker wait for a long time. Such a waiting time creates difficulties when it is difficult to approach the position of the short circuit. If the duration of the current pulse is long, the electrical system is exposed to a high level of “current that can destroy the circuit” for a long time while applying each pulse. Thermal breakers are susceptible to initial failures and are unstable because the breaking current depends on temperature, duration of use and other external factors.

  Other circuit testers use high-frequency AC signals that are sent to a short circuit and a receiver that moves along the wiring instead of passing a large current. The tester functions when the electrical system power is either on or off. When the signal drops to zero, the location of the short is determined. Therefore, it takes time to ensure a proper connection, which slows down the location of the short circuit. The cost of such a system is relatively high and this method is not the desired tool.

  Thus, there is a need for an electrical system tester that quickly responds to the presence of a short circuit and locates electrical faults more quickly without letting the electrical system flow destructive large currents for extended periods of time. Yes. There is also a need for a tester that can test an electrical system independently of multiple contacts in the circuit under test. There is also a need for a tester that operates by setting the current limit of the breaker to quickly find the level of current flowing through the circuit.

The present application discloses an improved electrical circuit tester that allows additional structural and operational advantages while avoiding the disadvantages of prior art testers.

  A tester is disclosed that can be inserted directly into a fuse board when replacing fuses in a fused circuit.

  Further disclosed is a tester that can be used to test circuits of different rated currents without risking exceeding the rated current of any circuit.

Further disclosed is a tester for acoustically and visually displaying test results.

  Further disclosed are testers of simple, compact and economical construction.

  Further disclosed is a method of testing a fused circuit without risking blowing the fuse.

  When a switch is attached to both ends of the fuse terminal of the circuit under test and this switch is closed instantaneously and repeatedly, a short-duration current pulse is generated in the circuit. Compared with current pulse of current.

  A method for testing an electrical system for a current flow exceeding a predetermined value is to connect a pair of contacts with a fuse holder for a fuse of a predetermined rating at both ends, and instantaneously close the circuit between both contacts to flow through the electrical system. Generating a current pulse, comparing the magnitude of the current pulse with a predetermined reference current value, and generating a recognizable signal if the current pulse magnitude is greater than the predetermined reference current value. Including.

  A diagnostic tester for an electrical system includes a pair of contacts that connect a fuse holder for a predetermined rated fuse at both ends. The switch momentarily closes both contacts and generates a current pulse through the electrical system. The comparator compares the current pulse magnitude with a predetermined reference current value. The output device is connected to generate a recognizable signal that indicates when the current pulse magnitude is greater than or equal to the current pulse magnitude at a predetermined reference current value.

  In one form, the current pulse is repeated until the operator identifies the fault location of the circuit. The duration of the pulse is short enough not to destroy the system during the time of the current pulse. A pair of contacts are connected by mounting a test contact in the receptacle of the fuse. The tester input voltage is independent of the connections to the pair of contacts. The potentiometer displays and adjusts the predetermined current setting to a threshold that is directly proportional to the rated current of the corresponding fuse.

  A tester that tests an electrical system for excessive current flow includes a pair of contacts connecting a fuse holder for a predetermined rated fuse at both ends. The switch is provided to momentarily close both contacts and generate a current pulse through the electrical system. The microprocessor closes the switch momentarily to generate a current pulse that flows through the circuit under test, compares the magnitude of the current pulse with a predetermined reference current value, and the magnitude of the current pulse is equal to the predetermined reference current. If it is greater than or equal to the value of the current pulse, a recognizable signal is generated.

  Closing the circuit between the pair of terminals momentarily generates a current pulse through the system. Subsequently, the electrical system is tested for current flow above a predetermined value by comparing the predetermined value with the magnitude of the current pulse.

  In one form, the current pulse is controlled to have a width in the range of 10-20 ms. The pulse repetition rate is on the order of one pulse per second.

  In order to facilitate understanding of the subject matter requiring protection, an embodiment of the subject matter is described in the accompanying drawings. When considered in connection with the following description, the subject matter that needs to be protected, its structure and operation, and its many advantages should be readily understood and appreciated from a review of these examples. is there.

  Referring to FIG. 1, circuit breaker 12 (see FIG. 5), generally designated by the numeral 10, may be a specific rated load current, eg, a 20-amp self-resettable thermal breaker. An electrical system tester 10 containing a housing 11 containing is shown. The housing 11 is attached with a pair of spade terminals 14 extending from one end of the housing 11 and the same as the terminals of the fuse normally mounted on the fuse board, such as a fuse board of an automobile. There is a reduced-width and thickness projection 13 that is designed to be inserted directly into the mating terminal. The housing 11 includes an opening 15 for viewing a suitable visual indicator such as an LED flasher and an opening 16 for an audible annunciator device such as a suitable beeper. There is. The tester 10 is designed to be inserted directly into a fuse board instead of a fuse of the same rated current to test for a short circuit, and the circuit breaker in the tester 10 does not waste the fuse. Is designed to prevent overload current. When used, it will be appreciated that the tester assembly may include a plurality of tester units 10 that are each of a different rated current and sufficient to cover all the fuse ratings of a given fuse panel. Let's go.

  Referring to FIG. 2, a tester 10A is shown. In the tester 10A, instead of having a spade-type terminal mounted directly on the protrusion 13, the internal circuit of the system 10A is directly connected to an associated fuse board to which a spade-type terminal 19 is attached by a cable 17 including a conductor. It is almost the same as the tester 10 of FIG. 1 except that it is connected to a fuse adapter 18 that is to be inserted. Due to such a structure, when the fuse board is placed at a position where inspection is difficult, the housing of the tester 10A can be arranged at a slight distance from the fuse board.

  Referring to FIG. 3, a tester assembly 20 including a housing 21 having a projection 23 having a socket 22 attached to one end thereof and a pair of spade terminals 24 attached to the other end with a reduced thickness and width. It is shown. The housing 21 has windows 25 and 26 for visible and audible indicators. The tester assembly 20 also includes a circuit breaker module 27 that includes the same circuit breaker 12 as the circuit breaker of the tester 10. The circuit breaker module 27 has a pair of terminals 28 that are adapted to be connected to corresponding terminals 29 of the housing 21 when inserted into the socket 22. The circuit breaker module 27 has a predetermined rated current of, for example, 20 amps, corresponding to the rated current of the fuse exchanged by the tester assembly 20. The shape of the circuit breaker module 27 is a male coupling that fits inside the socket 22 in the form of a female coupling.

  In use, the housing 21 is inserted directly into the associated fuse board in place of the fuse of the circuit under test, in the same manner as described above for the tester 10 of FIG. It will be appreciated that the tester assembly 20 can include a plurality of circuit breaker modules 27 each having various rated currents corresponding to various rated currents of various fuses, such as a particular fuse panel. Thus, for example, if the tester assembly 20 is used to test a 10 amp fused circuit, a 10 amp circuit breaker module 27 is inserted into the socket 22. This device requires only one test and indicator circuit, but has the advantage that it can test circuits of various different current ratings.

  Referring to FIG. 4, a tester assembly 20A is shown. The tester assembly 20A is similar to the tester 10A of FIG. 2 in that the internal circuit of the housing 21 is replaced by the cable 17 as in the tester 10A of FIG. 3 except that a spade-type terminal 19 is attached and connected to a plug 18 inserted into the fuse board, and the housing 21 is slightly spaced from the fuse board. Allows to place and place.

  Referring to FIG. 5, there is shown a type of circuit that is disposed in the tester 10, the tester 10A, the tester assembly 20, and the housing 21 of the tester assembly 20A as described above. The terminal 31 of this circuit is connected directly to the spade terminals 14 and 24 or to the conductors of the cable 17, respectively. Each terminal 31 is connected to a terminal of a diode bridge 32, and an output terminal of the diode bridge 32 is connected to a terminal of an audible signal device or a beeper 33. Connected in series to both ends of the beeper 33 are a resistor 34 and an LED 35. The beeper 33 is arranged in the housing 11 or 21 directly below the audible indicator window 16 or 26, and the LED 35 is arranged so that it can be seen through the window 15 or 25 of the visual indicator. The circuit 30 includes the circuit breaker 12, and in the case of the tester 10 or 10A, the circuit breaker 12 is fixed by wiring as both ends of the terminal 31, and is inserted into the socket 22 in the case of the tester assembly 20 or 20A. It is arranged in the circuit breaker module 27 so that it can.

  With reference to FIGS. 6-10, a tester assembly 40 is shown. The tester assembly 40 includes a main housing 41 that can include two model members 42 and 43 that are coupled together by suitable means. The housing 41 has a neck 44 with a reduced thickness protruding from one end thereof. Arranged in the housing 41 is a circuit that may be essentially the same as the circuit shown in FIG. 5 and includes an audible signal or beeper 46 and a visible signal such as an LED 47, and a neck 44. A circuit board 45 having a pair of contact terminals 48 extending into the neck and defining a socket in cooperation with the neck 44. The terminals 48 are respectively connected to adjacent ends of a conducting wire 49 that forms a cable and whose other end is connected to the socket 50.

  The tester assembly 40 includes a plurality of plug adapters. Three of them are shown and are labeled 51A, 51B and 51C, respectively. These adapters 51A to 51C are provided with different-sized spade terminals 53A, 53B and 53C respectively inserted into different-sized fuse sockets of the fuse board. Three adapters 51A-51C are shown, but it will be understood that any number can be provided, depending on the number of connector terminals on the heterogeneous fuseboard where the tester assembly 40 is to be used. Each of the plug adapters 51 </ b> A to 51 </ b> C is provided with a pair of terminals 54 that are adapted to be inserted into the socket 50 at the opposite ends.

  Tester assembly 40 is similar to circuit breaker module 27 described above in connection with FIG. 3 and includes a plurality of circuit breaker modules 60 (one shown) each having a different rated current. The circuit breaker module 60 has a body or housing 61 that can include two molded body members 62 and 63 that are secured together by any suitable means. The body 61 has a neck 64 protruding at one end thereof and accommodates a suitable circuit board 65 to which a circuit breaker 66 of a specified current capacity is attached. The circuit breaker module 60 is disposed in the neck 64, and when the neck 64 of the circuit breaker module 60 is inserted into the neck 44 of the main housing 41, a pair of terminals are coupled to the terminals 48 of the main housing 41. 68. Tester assembly 40 is becoming more flexible and can provide not only multiple circuit breaker modules with different current capacities, but also multiple different plug adapters, so that instead of any one of a variety of different types of fuses. It will be appreciated that the tester assembly 40 can be inserted into the circuit.

  The electrical system tester shown in FIGS. 13 to 17 provides a pulse with a fast repetition rate and a short duration for generating a load current pulse flowing through the electrical system when applied to the electrical system. If a pulse with a fast repetition rate and a short duration is generated, the on-time of the pulse is shortened and the current flow through the system is reduced. The operator connects a pair of terminals with the fuse holder as both ends, and sets the rated amperage of the blown or removed fuse with a potentiometer dial or other reference level indicator. Thus, instantaneously and repeatedly closing the circuit to generate a load current is a series of current pulses that flow throughout the system by momentarily and repeatedly closing the switch between the terminals, as described below. Will be sent.

  When it is turned on at or above the selected current level, an adjustable and recognizable alarm occurs, indicating that excess current is flowing in the circuit. If the alarm does not turn on, the fuse may have blown early or the short circuit may be intermittent or non-recurrent. If a short circuit exists, the alarm pulse turns on and off, indicating that there is more current in the circuit than can be delivered by the fuse. A magnetic field is generated around the short-circuited wiring during the moment of the instantaneous high current pulse. The operator scans the short circuit by moving the magnetic sensor along the wiring and identifies the position of the short circuit where the sensor stops displaying the current flow. Alternatively, the operator may “jiggle” the wiring rapidly until the alarm stops pulsing.

  Manually manipulate the potentiometer or other reference adjustment device to adjust the amplitude of the current pulse according to the rated current of the blown or removed fuse. By adjusting the potentiometer upward until the alarm stops, the amount of current drawn by the circuit is displayed.

  FIG. 11 shows a diagram of the electrical system in the vehicle. The system 110 has a plurality of circuits powered by a battery 112 that provides DC power to various electrical loads, such as lights illustrated as loads 114, motorized components, and other DC components. . A set of fuses 116 is contained in a fuse box 118, placed in a fuse holder, and has a removable structure. Each fuse is in series with its corresponding circuit and has an amperage that matches the current that can flow in that circuit. The rated current of the fuse is such that when a short circuit occurs or a large current flows through a part of the circuit, the fuse operates or blows out before the main component is destroyed due to excess current .

  FIG. 12 shows a typical fuse used in an automobile electrical circuit. The fuse 130 includes a resistance element 132 that is protected inside an insulating case such as a tube 138. The electrical resistance of the element 132 determines the rated current of the fuse, such that a high resistance corresponds to a high rating and a low resistance reduces the rated current of the fuse. Conductive heads 134 and 136 connected to both ends of the fuse are in contact with the conductive receptacle by being placed in the fuse holder 120 as shown in FIG.

  Referring to FIG. 13, the external configuration of the electrical tester is illustrated with an example of the housing and external functions of the tester. The housing 181 provides various terminals for display and connection to other devices on the outer surface of the electrical tester, and protects the circuit of the electrical tester. The LED window 182 and the alarm sound output 186 become a recognizable diagnostic display. A partition 184 is located on one of the surfaces of the housing 181 and provides a removable battery location to allow the tester to be portable. As an alternative, an AC adapter may be connected to an AC outlet 185 to provide power when the battery is not in use. The connector outlet 188 is a terminal into which a tester cord 154 is inserted, and the cord 154 is connected to a power receiving plug 150 of the tester having plug inserts 152. A pair of detachable terminals such as a hook clip or other suitable connector is mounted, and the plug for receiving power of the tester is connected to a fuse circuit having both ends of the fuse holder 120 shown in FIG. The housing 181 further includes a dial 190 that sweeps a current scale 192 that is marked to display the scale of the rated current used for the test. This dial selects the rated current from the current scale and sets the tester to a current representative of the automobile circuit.

  An example of a circuit diagram of an electrical system tester is shown in FIG. This tester includes a pair of input terminals 220 that use the fuse holder shown in FIG. 11 as both ends. Resistor R1 is wired in series with the contacts of the normally open electromagnetic relay 200. When this contact is closed momentarily and repeatedly, a short duration current pulse is generated which flows from the power source through the input terminal of the electrical circuit and the fuse holder. According to Ohm's law, an input voltage determined by the current flow through the resistor occurs across R1.

  The input voltage is applied to the tester circuit via a full wave rectifier 202 that consists of diodes D1-D4 and provides a positive voltage signal through the current limiting resistor R2. This input voltage is independent of the connection direction of the pair of contacts at both ends of the input terminal. In other words, if a full-wave rectifier is used, the contacts at both ends of the fuse holder are connected without having to follow the polarity, so that the test processing speed can be increased. In a full wave rectifier, current flows through two diodes in either direction. For example, for a germanium diode, the total voltage drop is approximately 0.6 volts, which is twice the voltage drop of 0.3 volts across each diode.

  Capacitor C1 is connected across the rectifier and is charged by the input voltage pulse through resistor R1. The C1-R1 network acts as a low pass filter and stores the input voltage instantaneously. The stored voltage across capacitor C1 is applied to a differential amplifier circuit including a first operational amplifier and resistors R3-R6. The values of these resistors are selected such that the stage gain is “−1”. The operational amplifier may be a discrete component or part of an integrated circuit with several amplifiers IC1 on one chip, such as the LM324. The output of this amplifier is pulsed with respect to the negative power supply rail "-V" which is taken as a reference to a common bus in the circuit and is synchronized with the voltage across C1.

  The output from the differential amplifier is connected to a voltage comparator circuit comprising a second operational amplifier 206 through a resistor R7. A trip point reference indicating the rated amperage of a blown or removed fuse is given by a voltage divider consisting of resistors R8-R10, and the common point of the circuit and the negative power rail “-V” Connected between. Resistor R9 is an adjustable resistor or potentiometer that is mounted on the front panel of the housing and selects the trip point of the comparator. The dial 190 shown in FIG. 13 is coupled to the shaft of resistor R9 on the negative input of operational amplifier 204 to select various amperage settings on scale 192. Changing the resistance value makes it easy for the operator to adjust the tester according to the rated amperage of the blown or removed fuse. A resistor R11 connected across the operational amplifier 206 as a feedback resistor provides hysteresis to the comparator for stability. Capacitor C5 is connected between the negative input of operational amplifier 206 and a negative power supply to minimize the reference noise of the comparator.

  The output from the comparator is used to switch the alarm 208 when the computer output is high. This switching is accomplished by coupling the output of the comparator to the driving transistor Q1 via resistor R12 and energizing the alarm 208. The alarm device generates an audible alarm sound output from the audible alarm device 186, as shown in FIG. The alarm may be a display that lights up or a device that generates some signal that can be perceived by humans. As an example, an audible alarm sound may be generated using an alarm sound generator MSR-320. The alarm is on while the voltage across capacitor C1 continues to be greater than the voltage at the comparator set point. This time is much longer than the time the relay contacts are closed to allow the operator to recognize the voice. A typical on-time as an alarm is approximately 100 milliseconds.

  Still referring to FIG. 14, a pulsating astable oscillator generates control pulses across the relay 200. The relay 200 closes the circuit between the contacts 220 instantaneously and repeatedly. Thus, current pulses from the power source are generated through the electrical system under test. This oscillator incorporates an operational amplifier 210 and resistors R13 to R16, among which R14 is connected to both ends of the operational amplifier as a feedback resistor. Resistors R15 and R16 are in series with one of the stabilizing diodes D5 and D6 connected across the operational amplifier 210, respectively. Resistor R15 and diode D5 set the duration of the output current pulse, and resistor R16 and diode D6 set the repetition rate of the pulse train. Capacitor C2 is connected between the negative input of operational amplifier 210 and a negative power supply.

  As shown in FIG. 14, the output of the oscillator drives transistor Q2 through resistor R17. This transistor is on when the output of the oscillator is low for approximately 10 milliseconds. As described above for the electrical system tester, the on-state transistor Q2 energizes the winding of the relay 200, thus closing the contacts located with the fuse holder at both ends. Resistor R18, shunt transistor Q2, ensures that transistor Q2 switches off when the high output of the operational amplifier drops to approximately 1.5 volts below the positive supply rail “+ V”. Therefore, when the transistor Q2 is switched on and off and the winding of the relay 200 is energized during the on state, the contact 220 is closed instantaneously and repeatedly. In addition, if the diode D7 is placed across the relay 200, it will shunt the inductive noise spikes that occur across the relay winding 200 when a current pulse is generated.

  The output of operational amplifier 210 further drives the display device and sends a signal to inform the tester operator of the time during which the current pulse is on. The indicator device may be a light emitting diode (LED), an audible alarm or some perceptible signal. For example, as shown in FIG. 14, the LED 212 is connected between the output of the operational amplifier 210 and a negative power source via a resistor R19. The LED 212 emits light when the output of the oscillator is approximately 1 second high, and indicates that a current pulse is generated. The LED 212 is mounted under one of the LED windows 182 of the tester housing box 181.

  A microprocessor can be used in place of discrete components to momentarily close the contacts at both ends of the fuse holder and control the generation of current pulses flowing from the power source through the electrical system. An example of such a system is illustrated in FIG. 15, which shows a system 300 that uses a microprocessor. System 300 includes a microprocessor 302, a memory device 304, and an I / O port 306 for communication of information and instructions. As shown in FIG. 11, the microprocessor 302 is programmed to generate control pulses of a predetermined frequency and pulse width that are used to instantaneously and repeatedly close the circuits at both ends of the fuse holder. In addition, the processor is programmed to compare the reference current value set by the rated current of the blown or removed fuse with the magnitude of the current pulse of the electrical circuit under test. The analog / digital (A / D) converter 308 is a gateway that receives a current set from the dial 190 shown in FIG. 13 and sets a digital threshold value of the current to the microprocessor 302. In addition, the A / D converter 308 receives the current level of the circuit under test and converts it to a digital measurement of the current pulse corresponding to the excess current of the circuit. Current pulse measurements are sent to the microprocessor 302 via the I / O port 306.

  The microprocessor compares the current pulse readings from the circuit under test to the fuse's rated threshold. If the electrical system is drawing a current greater than the threshold level, a signal 320 is generated to switch on the alarm and indicate that a current greater than the rating of the fuse corresponding to that electrical system is flowing. The microprocessor is programmed to keep the alarm on for a time long enough for the operator to recognize the signal. This signal may be an audible signal, a visible signal, an LED or both. Another display similar to the display described with reference to FIG. 14 is activated by the output of the microprocessor. FIG. 15 further shows a display device 310 and an input device 312 that are connected to the microprocessor via the I / O port 306 to perform the tests and program the system using the microprocessor.

  Referring to FIG. 16A, the control pulse 400 displays a pattern of closing the contacts instantaneously and repeatedly at both ends of the fuse holder for the fuse that has been blown or removed. The pulse repetition rate is on the order of once per second. The pulse is controlled to have a width of 10 to 20 ms. Both the microprocessor of FIG. 15 and the circuit of FIG. 14 are programmed or designed to provide control pulses within a specified frequency and pulse width.

  FIG. 16B shows a current pulse 450 having the same frequency as the control pulse 400 and representing the current of the electrical circuit under test obtained from the power source. The current level 470 represents a predetermined reference current value or threshold value set by the dial 190 on the front of the housing 180 shown in FIG. 13 and representing the rated current of the blown or removed fuse. Current pulse 460 shows the electrical circuit current obtained from the power source, but this current may exceed the threshold level 470 when a short circuit is present or excessive current is flowing through a portion of the circuit. There can be. A system using a comparator circuit or programmed microprocessor compares the amplitude of pulse 460 with a current threshold level 470. When the tester detects that the electrical circuit current exceeds a predetermined reference current, it generates a recognizable alarm.

  The magnetic detector is used to locate the short circuit when an excess current in the electrical circuit is detected. This detector displays the magnetic field surrounding the shorted wire during the moment of the high current pulse that occurs as a result of repeating the switching operation. An example of such a magnetic detector is illustrated in FIG. 17, which shows a sensor 500 having a housing 508 with a conductive loop coupled to the top. Ports 510 and 512 each provide a connection to ground and power. The presence of a magnetic field is indicated by a shake of a needle 504, or other type of indicator, such as a digital display, placed in a strip gauge or display window 502, for example. By moving the sensor along the wiring of the circuit under test, the location of the short circuit is identified when the sensor stops displaying current flow. The magnetic sensor may be a separate unit or an integral part of the disclosed electrical system tester. Other modifications can be made to the tester housing to provide a magnetic sensor integrated with the tester or a removable magnetic sensor coupled to the tester.

  The electrical system tester of FIGS. 13-15 took power from a 9 volt battery, and the voltage regulator stabilized between the negative power rail “-V” and the circuit common. Supply 5 volts. Obviously, alternative power supplies may be included. Depending on the particular design or configuration, removable battery cells, AC adapters and other power sources may be added to the tester. The power source may be a detachable unit that is inserted into the battery receptacle with or without an AC adapter connection port.

  The described power supply unit of the electrical system tester may have various configurations depending on the particular application. For example, the power source may be in the form of various types of batteries that can supply the necessary power source. The battery may be a conventional alkaline battery, a high quality lithium ion battery, or a custom battery cell. The battery may be rechargeable for convenience and repeated use. Such a rechargeable battery may be a nickel cadmium (MiCd) battery or a nickel metal hydride (NiMH) battery. However, it should be noted that any other type of rechargeable battery that can output the required power can be used in the electrical system tester.

  It will be apparent that the electrical system tester structure disclosed can provide a device that is small, handheld and simple. These testers may be made of metal that prevents impact so that they can withstand repeated drops from various heights.

  The embodiments described herein include any suitable power source, such as a battery, an AC power source, etc., and can provide any suitable voltage, such as about 13 volts, about 43 volts.

  The embodiments described herein can be used with any desired system or engine. These systems or engines can include items that utilize fossil fuels such as gasoline, natural gas, propane, and electricity generated by wind, or a combination thereof, such as batteries, generators, solar cells, and the like. These systems or engines may be incorporated into other systems such as passenger cars, trucks, boats and ships, motorcycles, generators, aircraft, and the like.

  The described tester of FIGS. 13-15 allows the operator to test the electrical system for current flows that exceed a predetermined reference current value by generating high frequency current pulses through the system. The display device outputs a signal indicating the presence of a current level equal to or higher than the reference current value. The operator then determines the fault location of the circuit in a short time without exposing the electrical system to dangerous high levels of current that are sent to the system during the time of each pulse.

  From the foregoing, it can be seen that an improved test apparatus is provided for testing shorted or grounded circuits. That is, the tester provides both visual and audible indicators and can be inserted directly into various types of fuse panels in place of the fuses of the fused circuit being tested, while Overload can be effectively prevented during the time.

While specific embodiments have been shown and described, it will be apparent to those skilled in the art that changes and modifications can be made without departing from the principles of the testing methods of the broad aspects of the invention. The matter defined in the foregoing description and accompanying drawings is offered by way of example only and not as a limitation.
(Related patent application)

This application claims the right to the filing date of two co-pending US provisional applications filed on May 24, 2002 and September 20, 2001 as shown below, and by referring to these applications: The disclosures of which are incorporated herein by reference.
US Provisional Patent Application No. 60 / 382,934 US Provisional Patent Application No. 60 / 323,384

It is a front elevation view of a tester. FIG. 2 is a view similar to FIG. 1 of a modified tester. FIG. 2 is a view similar to FIG. 1 of the tester assembly. FIG. 4 is a view similar to FIG. 3 of a modified tester assembly. It is a schematic diagram of the circuit of the tester of FIGS. FIG. 6 is a plan view of another tester assembly. FIG. 6 is a perspective view of the tester assembly of FIG. 5 with a circuit breaker module and one of the plug adapters connected to the main unit. FIG. 8 is an exploded perspective view of the tester assembly of FIG. 7. FIG. 7 is an enlarged, exploded perspective view of a portion of the tester assembly of FIG. 6. FIG. 9 is another perspective view of an enlarged and further exploded view of a portion of the tester assembly of FIG. 8. FIG. 2 depicts a vehicle electrical system according to an illustrated embodiment. 1 is a diagram showing one type of fuse used in a vehicle electrical system. FIG. It is a figure which shows an example of the housing of the other type of electric system tester described. It is a figure which shows the circuit diagram used with the electrical tester of FIG. It is a figure which shows the general structure of the other electrical tester using the microprocessor used with the electrical tester of FIG. It is a figure which shows the response which generate | occur | produces with the waveform of the pulse generate | occur | produced with a fuse holder as both ends, and the circuit under test. It is a figure which shows the structure of the magnetic current tracer used with the electrical tester of FIG.

Explanation of symbols

10, 10A Tester 11, 21, 61, 180, 181, 508 Housing 12 Circuit breaker 20, 20A, 40 Tester assembly 30 Circuit 110, 300 System 116, 130 Fuse 120 Fuse holder 200 Electromagnetic relay 202 Full wave rectifier 204 , 206, 210 Operational amplifier 208 Alarm 302 Microprocessor 304 Memory device 306 I / O port 308 Analog to digital converter 310 Display 312 Input device 316 Input current 318 Potentiometer

Claims (34)

A tester for testing an electrical system including a fuse holder for a fuse energized by a power source and having a predetermined rating for excess current flow, comprising:
A pair of contacts that can be electrically coupled with the fuse holder as both ends; and
A switch coupled to the contact, coupleable to the power source, and can be momentarily closed to send a current pulse to the fuse holder;
A controller coupled to the switch for controlling the switch to close instantaneously and repeatedly;
A comparator that compares a predetermined reference current value with the magnitude of the current pulse;
An indicator for generating a recognizable signal when the magnitude of the current pulse exceeds the predetermined reference current value;
Including the tester.   The tester of claim 1, further comprising a rectifier having a pair of contacts in a circuit, wherein the rectifier generates an input voltage signal independent of a plurality of connections to the pair of contacts. Tester.   2. The tester according to claim 1, wherein the controller includes an oscillator that generates a control pulse having a predetermined width and frequency.   4. The tester of claim 3, wherein the pulse width of the control pulse is in the range of about 10-20 milliseconds and the pulse repetition rate is about 1 cycle per second.   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 to detect a voltage drop across the resistor.   The tester according to claim 1, wherein the comparator includes an operational amplifier. The tester according to claim 1, wherein
a) momentarily closing the switch to generate a current pulse flowing from the power source through the electrical system;
b) comparing the magnitude of the current pulse with a predetermined reference current value;
c) generating a recognizable signal if the magnitude of the current pulse is greater than the magnitude of the predetermined reference current value;
Said tester comprising:   The apparatus for testing an electrical system according to claim 7, wherein the steps (a) to (c) are repeated to generate a current pulse of a predetermined width and frequency.   9. The apparatus for testing an electrical system according to claim 8, wherein the current pulse width is in the range of about 10-20 milliseconds and the pulse repetition rate is about 1 cycle per second. Equipment to be tested. A method of testing an electrical system including a fuse holder for a fuse energized by a power source and having a predetermined rating for excess current flow comprising:
Connecting a pair of contacts with the fuse holder as both ends;
Momentarily closing a circuit between the contacts to generate a current pulse flowing from the power source through the electrical system;
Comparing the magnitude of the current pulse with a predetermined reference current value;
Generating a recognizable signal if the magnitude of the current pulse is greater than the magnitude of the predetermined reference current signal;
Including methods. A method for testing an electrical system according to claim 10, comprising:
The method further comprising the step of instantaneously closing a circuit between the contacts to generate a repetitive current pulse flowing through the electrical system.   12. The method of testing an electrical system according to claim 11, wherein each of the current pulses occurs at a rate of once per second.   The method of testing an electrical system according to claim 12, wherein the duration of each of the current pulses is in the range of 10 to 20 milliseconds.   11. The method for testing an electrical system according to claim 10, further comprising the step of setting the predetermined reference current value according to a rated current of a fuse designated to be connected to the fuse holder.   15. The method for testing an electrical system according to claim 14, wherein the predetermined reference current value is set by adjusting a variable resistor.   11. The method of testing an electrical system according to claim 10, further comprising the step of generating a positive voltage signal that flows through the system regardless of the polarity of the pair of contacts.   11. A method for testing an electrical system according to claim 10, further comprising the step of determining a position of a short circuit when the perceptible signal is generated. A tester for testing an electrical system, comprising a fuse holder for a fuse having a predetermined rated load current,
A pair of contacts electrically connectable to the fuse holder;
A circuit breaker electrically coupled to the pair of contacts and having the same predetermined rated load current as the fuse;
An indicator that generates a recognizable signal if an overcurrent condition exists in the circuit breaker;
Including the tester.   19. The tester of claim 18, further comprising a housing that houses the circuit breaker, wherein the pair of contacts are rigidly and rigidly coupled to the housing.   19. The tester according to claim 18, further comprising a housing and wiring for coupling the pair of contacts to the housing.   19. The tester according to claim 18, further comprising a housing having a protruding portion with a reduced width and thickness coupled to the pair of contacts.   23. The tester according to claim 21, wherein the pair of contacts is the same as another pair of contacts, and the other pair of contacts is a pair of contacts of the fuse.   23. The tester according to claim 22, wherein the circuit breaker is a self-resetting thermal circuit breaker. A plurality of testers for testing an electrical system comprising a fuse holder for a fuse having one of a plurality of predetermined rated loads,
Each tester
A pair of contacts electrically connectable to the fuse holder;
A circuit breaker electrically coupled to the pair of contacts and having one of a plurality of predetermined rated load currents;
An indicator that generates a recognizable signal if an overcurrent condition exists in the circuit breaker;
The plurality of testers including:   25. The plurality of testers according to claim 24, wherein the circuit breaker of one tester has a predetermined rated load current different from that of another tester.   25. The plurality of testers of claim 24, wherein one of the testers further includes a housing that houses the circuit breaker, and the pair of contacts are tightly and securely coupled to the housing. Tester.   25. The plurality of testers of claim 24, wherein one of the testers further includes a housing and wiring that couples the pair of contacts to the housing.   25. The plurality of test devices according to claim 24, wherein one of the test devices further includes a housing having a protrusion portion with a reduced width and thickness coupled to the pair of contacts. A method for testing an electrical system including a fuse holder for a fuse having a predetermined rating, comprising:
Providing a plurality of testers each having a circuit breaker each having a predetermined rated load current;
Selecting a tester comprising a circuit breaker having a predetermined rated load current that matches the predetermined rating of the fuse for the fuse holder from the plurality of testers;
Connecting the contacts of the selected tester with the fuse holder as both ends,
Providing a recognizable indication of an overcurrent condition via the circuit breaker;
Said method comprising: A tester for testing an electrical system including a fuse holder for a fuse having a plurality of possible predetermined ratings,
A display unit comprising a first pair of contacts electrically connectable to the fuse holder and a second pair of contacts electrically coupled to the first pair of contacts; An indicator coupled to a pair of contacts;
A circuit breaker module having a third pair of contacts detachably coupled to the second pair of contacts and having a predetermined rated load current;
In a tester including
The indicator generates a recognizable signal if an overcurrent condition exists in the circuit breaker module;
The tester.   31. The tester of claim 30, further comprising a housing that houses the indicator, wherein one of the male and female joints includes the second pair of contacts and the housing. And the other one of the male and female joints includes a third pair of contacts and is received by the first circuit breaker module, and the male joint is connected to the second and third pairs. Said tester being removably insertable into a female joint for electrically coupling the contacts of   32. The tester according to claim 31, wherein any one of the male joint and the female joint includes a socket in the housing, and the first circuit breaker module includes the second and third pairs. The tester is removably insertable into the socket to electrically couple the contacts.   31. The tester of claim 30, comprising a further circuit breaker having a fourth pair of contacts removably coupled to said second pair of contacts and having a further predetermined rated load current. The tester further comprising a further circuit breaker module.   34. The tester according to claim 33, wherein the predetermined rated load current is different from the further predetermined rated load current.