CN103777112B - Test instrument grounding detection warning device - Google Patents

Abstract

The invention discloses a grounding detection and alarm device for a test instrument, which comprises a box body, a control panel is arranged in the box body, an electrically connected power supply access port and a power switch are arranged on the control panel, and a power switch connected to the power supply is also arranged on the control panel. The electrically connected grounding detection module, the grounding lead-in conductor connected to the input end of the grounding detection module and the alarm device connected to the output end of the grounding detection module; the grounding detection module is a grounding resistance detection module, including an AC coupling amplifier circuit and a multivibrator Circuit: the grounding lead-in conductor is electrically connected to the AC coupling amplifier circuit of the grounding detection module, and the alarm device is electrically connected to the multivibrator circuit of the grounding detection module. The detection module of the present invention has simple circuit structure, high sensitivity, high accuracy, compact overall structure and portability, and is suitable for rapid detection of various electrical equipment and test instruments in electric power construction and installation.

Description

Test instrument ground detection alarm device

technical field

The invention belongs to the technical field of electrical equipment grounding detection devices, and in particular relates to a device for detecting the grounding status of an electrical test instrument and giving a warning.

Background technique

Good grounding protection for electrical equipment and test instruments is the basic requirement for electrical safety. When the equipment and test instruments have no protective grounding, or if the grounding is poor, once the insulation of a certain part of the equipment or instrument is damaged, the shell will be charged, and the operator is easily exposed to the danger of electric shock. According to the requirements of electricity standards, the grounding resistance should generally be below 4 ohms. If the instruments and equipment are grounded, but the resistance is too large, it will also affect the safety of use. At the same time, good grounding can provide a ground discharge path for the electrostatic charge of the instrument and equipment, avoiding the generation of electric sparks or arcs, and is conducive to the safety of equipment and use. In the installation test and application of power equipment, due to the influence of the environment and the limitation of use conditions, there is no instrument that can conveniently and quickly detect the grounding of equipment and instruments. Threat to personal and equipment safety.

Contents of the invention

The technical problem to be solved by the present invention is to provide a device with simple structure that can quickly detect the grounding conditions of electrical equipment and test instruments.

In order to solve the above-mentioned technical problems, the present invention includes a box body, a control panel is arranged in the box body, an electrically connected power supply access port and a power switch are arranged on the control panel, and the structural feature is that the control panel is also provided with A grounding detection module electrically connected to the power switch, a grounding lead-in conductor connected to the input end of the grounding detection module and an alarm device connected to the output end of the grounding detection module; the grounding detection module is a grounding resistance detection module, which includes an AC coupling Amplifying circuit and multivibrator circuit; the grounding lead-in conductor is electrically connected to the AC coupling amplifying circuit of the grounding detection module, and the alarm device is electrically connected to the multivibrator circuit of the grounding detection module.

Preferably, the AC coupling amplifying circuit includes a voltage regulating circuit, an amplifying circuit and a 4N25 photocoupler, the input end of the voltage regulating circuit is electrically connected to the power switch, and the output end of the voltage regulating circuit and the grounding lead-in conductor are connected to the amplifying circuit respectively. On the two input terminals; the two output terminals of the amplifier circuit are respectively connected to the anode and cathode of the 4N25 photocoupler; the multivibrator circuit includes the LM555 time base circuit and the peripheral circuit; the collector of the 4N25 photocoupler and the reset of the LM555 time base circuit terminal connection; the alarm device is connected to the output terminal of the LM555 time base circuit.

The alarm device includes a light alarm device and an acoustic alarm device.

An alarm release device is connected between the alarm device and the output end of the LM555 time base circuit.

The control panel is provided with a leakage protector and a power output port, the leakage protector is connected to the rear end of the power switch, and the power output port is electrically connected with the leakage protector.

The grounding lead-in conductor is provided with connection screw holes.

The beneficial effect of the present invention is that: the control panel in the box of the present invention is provided with an electrically connected power supply port, a grounding detection module, an alarm device and a grounding lead-in body, and the grounding detection module is a grounding resistance detection module. When in use, the test instrument is connected to the grounding lead-in body, and the grounding condition of the test instrument can be tested after connecting the power input port to the power supply. If the alarm device will send out an alarm signal, it means that the test instrument is not grounded, or the grounding resistance is too large (usually 4 ohms). Conversely, if the alarm device does not send out an alarm signal, it means that the test instrument is well grounded and its grounding resistance is within the normal range. The grounding resistance detection module includes an AC coupling amplifier circuit and a multivibrator circuit. The grounding lead-in conductor is electrically connected to the AC coupling amplifier circuit, and the alarm device is electrically connected to the multivibrator circuit. The circuit structure of the detection module is simple, and the detection sensitivity is strong and accurate. high degree. All components are concentrated in the box, compact in structure, easy to carry, and suitable for on-site rapid detection of various electrical equipment and test instruments in electric power construction and installation.

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing and embodiment:

Fig. 1 is the overall schematic diagram of the present invention;

Fig. 2 is each parts circuit connection block diagram of the present invention;

Fig. 3 is a circuit diagram of the ground detection module of the present invention.

detailed description

Referring to Fig. 1 and Fig. 2, the grounding detection and alarm device of the test instrument comprises a box body 1, on which a movable box cover 11 is arranged, and a control panel 2 is arranged inside the box body 1. The control panel 2 is provided with an electrically connected power input port 3 , a power switch 4 , a leakage protector 5 , a power output port 6 , an alarm device 7 , a grounding lead-in conductor 9 and a grounding detection module 10 . The power switch 4 is used to control the on-off of the electric current in the detection alarm device. Leakage protector 5 is located at the rear end of power switch 4, and is provided with several power output ports 6 at the rear end of leakage protector 5, and power output port 6 can be used as the electrical interface of other external devices. The ground detection module 10 is a ground resistance detection module, which includes an AC coupling amplifier circuit and a multivibrator circuit; the ground detection module 10 is electrically connected with the power switch 4, the ground lead-in conductor 9 is electrically connected with the ground detection module 10, and the alarm device 7 is electrically connected with the ground detection module 10. The multivibrator circuit of the ground detection module 10 is electrically connected. The alarm device 7 includes a light alarm device 71 and an audio alarm device 72 . The front end of the alarm device 7 is connected with an alarm release device 8. During the test, if the alarm device 7 sends out an alarm, but the test instrument has been grounded after field inspection, the alarm is caused by the grounding resistance exceeding the alarm value, and the alarm release device 8 can be used. Temporarily turn off the alarm and continue the test work. The grounding lead-in conductor 9 is a copper base body, which is provided with a plurality of connecting screw holes 91, so that a plurality of instruments can be tested one by one.

Referring to Figure 3, the ground resistance detection module is composed of an AC coupling amplifier circuit and a multivibrator circuit. The AC coupling amplifying circuit includes a voltage regulating circuit 113 , an amplifying circuit 112 and a 4N25 photocoupler 111 . Wherein, the input terminal of the voltage regulating circuit 113 is electrically connected with the power switch, the output terminal of the voltage regulating circuit 113 and the grounding lead-in conductor 9 are respectively connected to the two input terminals of the amplifying circuit 112; the two output terminals of the amplifying circuit 112 are respectively connected to the 4N25 Anode and cathode of optocoupler 111. The multivibrator circuit includes an LM555 time base circuit 121 and a peripheral circuit 122; the collector of the 4N25 photocoupler 111 is connected to the reset terminal of the LM555 time base circuit 121. The ground lead-in conductor 9 is connected with the amplifier circuit 112, and the alarm device 7 is connected with the output end of the LM555 time base circuit 121. The alarm release device 8 is a key switch, which is located between the alarm device 7 and the output end of the LM555 time base circuit.

During work, the two ends of the voltage regulating circuit 113 are connected to 220 volts alternating current. Before the test, at first carry out self-inspection: ground and disconnect the grounding conductor 9, check whether the alarm device 7 is alarming; in the alarm state, press the alarm release device 8, and check the working condition of the alarm release device 8. When the device itself works normally, the detection test can be carried out, and the experimental instrument is connected to the grounding lead-in conductor 9. If the experimental instrument is not grounded or the grounding resistance is too large, the collector of the 4N25 photocoupler 111 will be connected to the LM555 time base circuit 121. The reset end of the reset terminal sends an electric signal, and the LM555 time base circuit 121 outputs an electric signal through the output end after receiving the signal, and the alarm device 7 sends out sound and light alarms.

Claims (5)

1. A grounding detection and alarm device for a test instrument, comprising a box body (1), a control panel (2) is provided inside the box body (1), and a power access port for electrical connection is provided on the control panel (2) ( 3) and a power switch (4), characterized in that the control panel (2) is also provided with a grounding detection module (10) electrically connected to the power switch (4), connected to the input terminal of the grounding detection module (10) The grounding lead-in conductor (9) and the alarm device (7) connected to the output terminal of the grounding detection module (10); the grounding detection module (10) is a grounding resistance detection module, which includes an AC coupling amplifier circuit and a multivibrator circuit; the grounding lead-in conductor (9) is electrically connected to the AC coupling amplifier circuit of the grounding detection module (10), and the alarm device (7) is electrically connected to the multivibrator circuit of the grounding detection module (10); the control panel ( 2) There is a leakage protector (5) and a power output port (6), the leakage protector (5) is connected to the rear end of the power switch (4), the power output port (6) and the leakage protector (5) ) electrical connection. 2. The grounding detection and alarm device for testing instruments according to claim 1, characterized in that the AC coupling amplifier circuit includes a voltage regulating circuit (113), an amplifier circuit (112) and a 4N25 photocoupler (111); the voltage regulating circuit The input terminal of (113) is electrically connected with the power switch, and the output terminal of the voltage regulating circuit (113) and the grounding lead-in conductor (9) are respectively connected to the two input terminals of the amplifying circuit (112); the two output terminals of the amplifying circuit (112) The terminals are respectively connected to the anode and cathode of the 4N25 optocoupler (111); the multivibrator circuit includes the LM555 time base circuit (121) and the peripheral circuit (122); the collector of the 4N25 optocoupler (111) and the LM555 time base circuit The reset terminal of (121) is connected; the alarm device (7) is connected with the output terminal of the LM555 time base circuit (121). 3. The ground detection alarm device for testing instruments according to claim 2, characterized in that the alarm device (7) includes a light alarm device (71) and an acoustic alarm device (72). 4. The ground detection and alarm device for testing instruments according to claim 2 or 3, characterized in that an alarm release device (8) is connected between the alarm device (7) and the output end of the LM555 time base circuit. 5. The grounding detection and alarm device for testing instruments according to claim 1, characterized in that the grounding lead-in conductor (9) is provided with a connecting screw hole (91).