Leakage current detector

Abstract

The utility model relates to a leakage current detector, which belongs to the technical field of electric leakage detection and comprises a first detection pen, a second detection pen, a rectifying circuit, a gear selection circuit, a current limiting resistor, a shunt resistor, an alternating current and direct current selection switch, a current display unit, a power management circuit, a power switch and a power supply. A proper working gear can be selected through the gear selection switch according to the rated working voltage of the to-be-detected equipment, so that the leakage current detector is prevented from being damaged, and the test safety is effectively ensured. In addition, a proper working mode of the leakage current detector can be selected through the alternating current and direct current selection switch according to the working mode of the equipment to be detected, so that the leakage current detector can adapt to various testing environments.

Description

Technical Field

[0001] The utility model belongs to the technical field of leakage detection, and in particular relates to a leakage current detector. Background Art

[0002] Although the use of electricity provides convenience for human beings, at the same time, if it is not properly managed and used, it can be very dangerous and there is a great possibility of inducing major accidents such as electrical fires or electric shocks.

[0003] For example, one of the causes of the major accident is leakage current, which is closely related to the poor insulation of circuits and equipment. Here, leakage current includes leakage current caused by electrostatic capacitance to the ground and leakage current caused by insulation resistance to the ground which is directly related to insulation resistance. In the distribution network, leakage current problem has always been a hidden danger affecting personal and equipment safety. When leakage occurs in equipment or lines, electric shock is likely to occur, and even electrical fires may occur in severe cases. At the same time, leakage current will cause power loss and economic losses.

[0004] The existing leakage current detector discloses a leakage current detection device (publication number CN207150534U), including: a resistor, a millivoltmeter and a switch; the resistor is connected in series with the switch; the millivoltmeter is connected in parallel to both ends of the resistor and is suitable for measuring the voltage generated on the resistor; the leakage current detection device also includes a first power connection terminal, a second power connection terminal, a first detection connection terminal and a second detection connection terminal; the end of the resistor away from the switch is electrically connected to the first power connection terminal; the end of the switch away from the resistor is electrically connected to the first detection connection terminal; and the switch is also electrically connected to the first power connection terminal and the second detection connection terminal respectively. The leakage current detector can only be used in one detection environment, and the detection environment cannot be selected, which has limitations. Summary of the invention

[0005] The purpose of the utility model is to provide a leakage current detector designed to solve the problems existing in the prior art in view of the defects existing in the prior art.

[0006] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0007] A leakage current detector comprises a first detection pen, a second detection pen, a rectifier circuit, a gear selection circuit, a current limiting resistor, a shunt resistor, an AC / DC selection switch, a current display unit, a power management circuit, a power switch and a power supply, wherein the first end of the first detection pen is connected to the first end of a device to be detected, the second end of the first detection pen is connected to the first end of the rectifier circuit, the second end of the rectifier circuit is connected to the second end of the device to be detected through the second detection pen, the third end of the rectifier circuit is connected to the first end of the current limiting resistor and the first end of the current display unit through the gear selection circuit, the second end of the current limiting resistor is connected to the first static contact of the AC / DC selection switch and the first end of the shunt resistor, the moving contact of the AC / DC selection switch, the second end of the shunt resistor and the fourth end of the rectifier circuit are all connected to the second end of the current display unit, the positive pole of the power supply is connected to the input end of the power management circuit through the power switch, the output end of the power management circuit is connected to the first power supply end of the current display unit, and the negative pole of the power supply, the ground end of the power management circuit and the second power supply end of the current display unit are all grounded.

[0008] A further improvement of the technical solution is that the rectifier circuit includes a fuse FU1 and a rectifier bridge U1, the first end of the fuse FU1 is connected to the second end of the first detection pen, the second end of the fuse FU1 is connected to the first end of the rectifier bridge U1, the second end of the rectifier bridge U1 is connected to the second end of the device to be detected through the second detection pen, the third end of the rectifier bridge U1 is connected to the first end of the current limiting resistor and the first end of the current display unit through the gear selection circuit, and the fourth end of the rectifier bridge U1 is connected to the second end of the current display unit.

[0009] A further improvement of the technical solution is that the rectifier bridge U1 adopts the Yinglingfei KBPC2510 rectifier bridge.

[0010] A further improvement of the present technical solution is that the gear selection circuit includes a gear resistor R1, a gear resistor R2 and a gear selection switch S1, the first end of the gear resistor R1 and the first end of the gear resistor R2 are both connected to the third end of the rectifier bridge U1, the second end of the gear resistor R1 is connected to the first static contact of the gear selection switch S1, the second end of the gear resistor R2 is connected to the second static contact of the gear selection switch S1, and the moving contact of the gear selection switch S1 is connected to the first end of the shunt resistor and the first end of the current display unit.

[0011] A further improvement of the technical solution is that the current display unit includes a voltage collection element, a controller and a digital tube, the first end of the voltage collection element is connected to the first end of the shunt resistor, the second end of the voltage collection element is connected to the moving contact of the AC / DC selection switch, the third end of the voltage collection element is connected to the input end of the controller, and the output end of the controller is connected to the digital tube.

[0012] A further improvement of the technical solution is that the power management circuit includes capacitor C1, capacitor C2, capacitor C3, power management chip U2, rectifier diode D1, inductor L1, capacitor C4, capacitor C5, capacitor C6, resistor R3, MOS tube Q1, resistor R4, resistor R5, capacitor C7, resistor R6, diode D2, resistor R7, transistor Q2, resistor R8, resistor R9 and diode D3;

[0013] The first end of capacitor C1, the first end of capacitor C2 and the first end of capacitor C3 are all connected to the power input pin of power management chip U2, the second end of capacitor C1 and the second end of capacitor C2 are both grounded, the second end of capacitor C3 is connected to the voltage adjustment pin of power management chip U2, the voltage output pin of power management chip U2 is connected to the cathode of rectification diode D1 and the first end of inductor L1, the cathode of rectification diode D1 is grounded, the second end of inductor L1 is connected to the first end of capacitor C4, the first end of capacitor C5, the first end of capacitor C6, the first end of resistor R3 and the drain of MOS tube Q1, the second end of capacitor C4 and the second end of capacitor C5 are both grounded, the second end of capacitor C6 is connected to the feedback pin of power management chip U2, resistor R3 The second end of the resistor R4 is connected to the first end of the resistor R5, the output current detection pin of the power management chip U2, the first end of the capacitor C7, the first end of the resistor R6 and the emitter of the transistor Q2, the second end of the resistor R5 is grounded, the second end of the capacitor C7 is connected to the anode of the diode D2, the second end of the resistor R6 and the first end of the resistor R7, the cathode of the diode D2 is connected to the power input pin of the power management chip U2, the second end of the resistor R7 is connected to the base of the transistor Q2, the collector of the transistor Q2 is connected to the gate of the MOS tube Q1, the first end of the resistor R9 and the anode of the diode D3 through the resistor R8, and the second end of the resistor R9 and the cathode of the diode D3 are both connected to the source of the MOS tube Q1.

[0014] The beneficial effect of the utility model is that the utility model can select a suitable working gear through the gear selection switch according to the rated working voltage of the device to be tested, thereby preventing damage to the leakage current detector and effectively ensuring the safety of the test. In addition, the utility model can also select a suitable working mode of the leakage current detector through the AC / DC selection switch according to the working mode of the device to be tested, so that the leakage current detector can adapt to a variety of test environments.

[0015] In addition, the utility model has a reliable design principle, a simple structure and a very broad application prospect.

[0016] It can be seen that compared with the prior art, the present invention has outstanding substantive features and significant progress, and the beneficial effects of its implementation are also obvious. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the circuit schematic diagram of the leakage current detector.

[0018] Figure 2 This is the schematic diagram of the power management circuit.

[0019] 110 is a detection connector, R10 is a current limiting resistor, R11 is a shunt resistor, S2 is an AC / DC selection switch, 120 is a current display unit, 130 is a power management circuit, S3 is a power switch, and 140 is a power supply. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0022] The key terms appearing in the present invention are explained below.

[0023] MOS tube is a metal-oxide-semiconductor field effect transistor, or metal-insulator-semiconductor. The common ones on the market are generally N-channel and P-channel. Regardless of N-type or P-type MOS tubes, their working principles are essentially the same. MOS tubes control the current at the output drain by the voltage applied to the input gate. MOS tubes are voltage-controlled devices. They control the characteristics of the device by the voltage applied to the gate. There will be no charge storage effect caused by the base current when the triode is used as a switch. Therefore, in switching applications, the switching speed of MOS tubes should be faster than that of triodes.

[0024] like Figure 1As shown, the utility model provides a leakage current detector, including a first detection pen, a second detection pen, a rectifier circuit, a gear selection circuit, a current limiting resistor, a shunt resistor, an AC / DC selection switch, a current display unit, a power management circuit, a power switch and a power supply, wherein the first end of the first detection pen is connected to the first end of the device to be detected, the second end of the first detection pen is connected to the first end of the rectifier circuit, the second end of the rectifier circuit is connected to the second end of the device to be detected through the second detection pen, the third end of the rectifier circuit is connected to the first end of the current limiting resistor and the first end of the current display unit through the gear selection circuit, the second end of the current limiting resistor is connected to the first static contact of the AC / DC selection switch and the first end of the shunt resistor, the moving contact of the AC / DC selection switch, the second end of the shunt resistor and the fourth end of the rectifier circuit are all connected to the second end of the current display unit, the positive pole of the power supply is connected to the input end of the power management circuit through the power switch, the output end of the power management circuit is connected to the first power supply end of the current display unit, and the negative pole of the power supply, the ground end of the power management circuit and the second power supply end of the current display unit are all grounded.

[0025] The leakage current detector also includes a shell, in which a rectifier circuit, a gear selection circuit, a current limiting resistor, a shunt resistor, a power management circuit and a power supply are all arranged, and an AC / DC selection switch, a current display unit and a power switch are arranged on the shell. Two detection connectors are also arranged on the shell, and the first ends of the detection connectors are respectively connected to appropriate positions of the rectifier circuit, and the second ends of the detection connectors are respectively connected to a first detection pen and a second detection pen, and the first detection pen and the second detection pen are both detachably connected to the detection connectors.

[0026] Specifically, the rectifier circuit includes a fuse FU1 and a rectifier bridge U1, the first end of the fuse FU1 is connected to the second end of the first detection pen, the second end of the fuse FU1 is connected to the first end of the rectifier bridge U1, the second end of the rectifier bridge U1 is connected to the second end of the device to be detected through the second detection pen, the third end of the rectifier bridge U1 is connected to the first end of the current limiting resistor and the first end of the current display unit through the gear selection circuit, and the fourth end of the rectifier bridge U1 is connected to the second end of the current display unit. Among them, the rectifier bridge U1 adopts the Yinglingfei KBPC2510 rectifier bridge.

[0027] In addition, the gear selection circuit includes a gear resistor R1, a gear resistor R2 and a gear selection switch S1, the first end of the gear resistor R1 and the first end of the gear resistor R2 are both connected to the third end of the rectifier bridge U1, the second end of the gear resistor R1 is connected to the first static contact of the gear selection switch S1, the second end of the gear resistor R2 is connected to the second static contact of the gear selection switch S1, and the moving contact of the gear selection switch S1 is connected to the first end of the shunt resistor and the first end of the current display unit. The resistor R1 is a 500 ohm resistor, and the resistor R2 is a 60 ohm resistor.

[0028] In addition, the current display unit includes a voltage collection element, a controller and a digital tube, the first end of the voltage collection element is connected to the first end of the shunt resistor, the second end of the voltage collection element is connected to the moving contact of the AC / DC selection switch, the third end of the voltage collection element is connected to the input end of the controller, and the output end of the controller is connected to the digital tube.

[0029] In order to improve the reliability of power supply, the leakage current detector is equipped with a power management circuit, such as Figure 2 As shown, the power management circuit includes capacitor C1, capacitor C2, capacitor C3, power management chip U2, rectifier diode D1, inductor L1, capacitor C4, capacitor C5, capacitor C6, resistor R3, MOS tube Q1, resistor R4, resistor R5, capacitor C7, resistor R6, diode D2, resistor R7, transistor Q2, resistor R8, resistor R9 and diode D3; the first end of capacitor C1, the first end of capacitor C2 and the first end of capacitor C3 are all connected to the power input pin of the power management chip U2, the second end of capacitor C1 and the second end of capacitor C2 are both grounded, the second end of capacitor C3 is connected to the voltage adjustment pin of the power management chip U2, the voltage output pin of the power management chip U2 is connected to the cathode of the rectifying diode D1 and the first end of the inductor L1, the cathode of the rectifier diode D1 is grounded, the second end of the inductor L1 is connected to the first end of capacitor C4, the first end of capacitor C5, the first end of capacitor C6, the first end of resistor R3 The first end and the drain of the MOS tube Q1, the second end of the capacitor C4 and the second end of the capacitor C5 are both grounded, the second end of the capacitor C6 is connected to the feedback pin of the power management chip U2, the second end of the resistor R3 and the first end of the resistor R4, the second end of the resistor R4 is connected to the first end of the resistor R5, the output current detection pin of the power management chip U2, the first end of the capacitor C7, the first end of the resistor R6 and the emitter of the transistor Q2, the second end of the resistor R5 is grounded, the second end of the capacitor C7 is connected to the positive electrode of the diode D2, the second end of the resistor R6 and the first end of the resistor R7, the negative electrode of the diode D2 is connected to the power input pin of the power management chip U2, the second end of the resistor R7 is connected to the base of the transistor Q2, the collector of the transistor Q2 is connected to the gate of the MOS tube Q1, the first end of the resistor R9 and the positive electrode of the diode D3 through the resistor R8, and the second end of the resistor R9 and the negative electrode of the diode D3 are both connected to the source of the MOS tube Q1. Among them, the power management chip U2 adopts the power management chip model XL4301, the rectifier diode D1 adopts the surface mount Schottky diode model SS34, and the MOS tube is set to prevent current backflow.

[0030] When using the leakage current detector, first close the power switch. At this time, the digital tube displays "00.00" to indicate that the leakage current detector is in working state. If the digital tube does not display, it means that the leakage current detector may be out of power. Please charge it. Its charging interface is TYPE_C interface. Before the leakage current detector detects the device to be detected, the gear selection switch needs to be turned to the 220V position to prevent the current shock from damaging the device. If the current displayed on the digital tube is less than 20mA, it can be turned to the 24V position as needed. In addition, before the device to be detected is detected, it is also necessary to determine whether the device to be detected is a DC device or an AC device, and turn the AC / DC selection switch to the appropriate position as needed.

[0031] The above disclosure is only the preferred implementation mode of the utility model, but the utility model is not limited thereto. Any non-creative changes that can be thought of by technicians in this field, as well as several improvements and modifications made without departing from the principle of the utility model, should fall within the scope of protection of the utility model.

Claims

1. A leakage current detector, characterized in that: The invention comprises a first detection pen, a second detection pen, a rectifier circuit, a gear selection circuit, a current limiting resistor, a shunt resistor, an AC / DC selection switch, a current display unit, a power management circuit, a power switch and a power supply. The first end of the first detection pen is connected to the first end of a device to be detected, the second end of the first detection pen is connected to the first end of the rectifier circuit, the second end of the rectifier circuit is connected to the second end of the device to be detected through the second detection pen, the third end of the rectifier circuit is connected to the first end of the current limiting resistor and the first end of the current display unit through the gear selection circuit, the second end of the current limiting resistor is connected to the first static contact of the AC / DC selection switch and the first end of the shunt resistor, the moving contact of the AC / DC selection switch, the second end of the shunt resistor and the fourth end of the rectifier circuit are all connected to the second end of the current display unit, the positive pole of the power supply is connected to the input end of the power management circuit through the power switch, the output end of the power management circuit is connected to the first power supply end of the current display unit, and the negative pole of the power supply, the ground end of the power management circuit and the second power supply end of the current display unit are all grounded.

2. A leakage current detector according to claim 1, characterized in that: The rectifier circuit includes a fuse FU1 and a rectifier bridge U1, the first end of the fuse FU1 is connected to the second end of the first detection pen, the second end of the fuse FU1 is connected to the first end of the rectifier bridge U1, the second end of the rectifier bridge U1 is connected to the second end of the device to be detected through the second detection pen, the third end of the rectifier bridge U1 is connected to the first end of the current limiting resistor and the first end of the current display unit through the gear selection circuit, and the fourth end of the rectifier bridge U1 is connected to the second end of the current display unit.

3. A leakage current detector according to claim 2, characterized in that: The rectifier bridge U1 adopts the Yinglingfei KBPC2510 rectifier bridge.

4. A leakage current detector according to claim 2, characterized in that: The gear selection circuit includes a gear resistor R1, a gear resistor R2 and a gear selection switch S1. The first end of the gear resistor R1 and the first end of the gear resistor R2 are both connected to the third end of the rectifier bridge U1, the second end of the gear resistor R1 is connected to the first static contact of the gear selection switch S1, the second end of the gear resistor R2 is connected to the second static contact of the gear selection switch S1, and the moving contact of the gear selection switch S1 is connected to the first end of the shunt resistor and the first end of the current display unit.

5. A leakage current detector according to claim 1, characterized in that: The current display unit includes a voltage collection element, a controller and a digital tube. The first end of the voltage collection element is connected to the first end of the shunt resistor, the second end of the voltage collection element is connected to the moving contact of the AC / DC selection switch, the third end of the voltage collection element is connected to the input end of the controller, and the output end of the controller is connected to the digital tube.

6. A leakage current detector according to claim 1, characterized in that: The power management circuit includes capacitor C1, capacitor C2, capacitor C3, power management chip U2, rectifier diode D1, inductor L1, capacitor C4, capacitor C5, capacitor C6, resistor R3, MOS tube Q1, resistor R4, resistor R5, capacitor C7, resistor R6, diode D2, resistor R7, transistor Q2, resistor R8, resistor R9 and diode D3; The first end of capacitor C1, the first end of capacitor C2 and the first end of capacitor C3 are all connected to the power input pin of power management chip U2, the second end of capacitor C1 and the second end of capacitor C2 are both grounded, the second end of capacitor C3 is connected to the voltage adjustment pin of power management chip U2, the voltage output pin of power management chip U2 is connected to the cathode of rectification diode D1 and the first end of inductor L1, the cathode of rectification diode D1 is grounded, the second end of inductor L1 is connected to the first end of capacitor C4, the first end of capacitor C5, the first end of capacitor C6, the first end of resistor R3 and the drain of MOS tube Q1, the second end of capacitor C4 and the second end of capacitor C5 are both grounded, the second end of capacitor C6 is connected to the feedback pin of power management chip U2, resistor R3 The second end of the resistor R4 is connected to the first end of the resistor R5, the output current detection pin of the power management chip U2, the first end of the capacitor C7, the first end of the resistor R6 and the emitter of the transistor Q2, the second end of the resistor R5 is grounded, the second end of the capacitor C7 is connected to the anode of the diode D2, the second end of the resistor R6 and the first end of the resistor R7, the cathode of the diode D2 is connected to the power input pin of the power management chip U2, the second end of the resistor R7 is connected to the base of the transistor Q2, the collector of the transistor Q2 is connected to the gate of the MOS tube Q1, the first end of the resistor R9 and the anode of the diode D3 through the resistor R8, and the second end of the resistor R9 and the cathode of the diode D3 are both connected to the source of the MOS tube Q1.

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