Digital leakage ammeter for wired lightning arrester

Abstract

The utility model provides a digital leakage ammeter for a wired lightning arrester, and relates to the technical field of ammeters. The ammeter comprises a die-casting aluminum shell, a current acquisition module, a signal processing module and a communication module. According to the ammeter, the current acquisition module is connected with the grounding end of the lightning arrester through a high-voltage lead, and leakage current is acquired in real time. And an output signal of the current acquisition module is transmitted to the signal processing module through the photoelectric isolation interface for conversion and processing. The processed data is connected with an external monitoring terminal by the communication module through an RS-485 communication interface by utilizing a shielded twisted pair, so that remote monitoring and data transmission are realized. The ammeter solves the technical problem of integration of remote high-precision monitoring of the leakage current of the lightning arrester and anti-interference reliable transmission in an outdoor complex environment, and realizes integration of the remote high-precision monitoring of the leakage current of the lightning arrester and the anti-interference reliable transmission in the outdoor complex environment.

Description

Technical Field

[0001] This utility model relates to the field of ammeter technology, and more specifically, to a digital leakage current meter for a wired surge arrester. Background Technology

[0002] With the intelligent upgrading of high-voltage power transmission and transformation systems, online monitoring of zinc oxide surge arresters (MOAs) has become a crucial link in power grid condition awareness. Traditional surge arrester monitoring devices generally adopt a combination of mechanical ammeters and electromagnetic counters. Although this can achieve local leakage current display and lightning strike counting, it suffers from drawbacks such as limited functionality, inability to transmit data remotely, and weak resistance to electromagnetic interference. Especially in 750kV and above ultra-high-voltage scenarios, problems such as low efficiency of manual inspections and distortion of analog signal transmission become prominent, leading to delayed equipment condition assessment and failing to meet the needs of intelligent substations for full life-cycle management of surge arresters.

[0003] In existing technologies, some improved solutions involve adding a PT voltage signal acquisition module to the monitor and calculating the resistive current using an analog filtering circuit. However, this requires an additional voltage transformer, significantly increasing system complexity and installation costs. Another solution uses a stainless steel casing to improve sealing, but this cannot effectively suppress zero drift caused by high-frequency interference, and the response speed of the mechanical counter (≤5 times / second) is insufficient for dense lightning strike conditions. Furthermore, traditional RS-485 communication interfaces lack integrated waterproofing, making them susceptible to communication failures due to moisture intrusion during long-term outdoor operation.

[0004] In summary, how to solve the problem of integrating remote high-precision monitoring of surge arrester leakage current with reliable transmission under complex outdoor environments is an urgent issue that needs to be addressed. Utility Model Content

[0005] The main objective of this invention is to provide a wired digital leakage current meter for surge arresters, which solves at least the problem of integrated technology for remote high-precision monitoring of surge arrester leakage current and reliable transmission against interference in complex outdoor environments, thus realizing the integrated technology of remote high-precision monitoring of surge arrester leakage current and reliable transmission against interference in complex outdoor environments.

[0006] To achieve the above objectives, this utility model provides a digital leakage current meter for wired surge arresters, the current meter comprising:

[0007] The die-cast aluminum housing, the current acquisition module, the signal processing module, and the communication module disposed within the die-cast aluminum housing;

[0008] The input terminal of the current acquisition module is connected to the grounding terminal of the surge arrester via a high-voltage conductor;

[0009] The input terminal of the signal processing module is provided with an opto-isolation interface, which is electrically connected to the output terminal of the current acquisition module, and the output terminal of the signal processing module is connected to the communication module.

[0010] The communication module is equipped with an RS-485 communication interface, and the A and B signal terminals of the RS-485 communication interface are connected to an external monitoring terminal through shielded twisted pair cables.

[0011] Specifically, the bottom of the die-cast aluminum shell is provided with an inclined mounting base, the angle between the inclined mounting base and the horizontal plane is greater than or equal to 30° and less than or equal to 75°, and the end of the inclined mounting base is provided with a grounding bolt.

[0012] Specifically, the side of the die-cast aluminum housing is provided with a four-core waterproof connector, which includes a first core, a second core, a third core, and a fourth core. The first core is connected to the positive terminal of an external DC power supply, the second core is connected to the negative terminal of an external DC power supply, the third core is connected to the A signal terminal of the RS-485 communication interface, and the fourth core is connected to the B signal terminal of the RS-485 communication interface.

[0013] Specifically, the shielded twisted pair cable is provided with impedance matching resistors at both ends, and the resistance value of the impedance matching resistors is 120Ω±5%.

[0014] Specifically, the signal processing module includes an analog-to-digital conversion unit, the sampling period of which is 20ms ± 0.01ms.

[0015] Specifically, an electromagnetic counter is connected in parallel to the output of the current acquisition module, and the trigger current threshold of the electromagnetic counter is 50A to 100kA.

[0016] This invention provides a wired digital leakage current meter for surge arresters. The meter includes a die-cast aluminum housing and integrates a current acquisition module, a signal processing module, and a communication module. The current acquisition module is connected to the grounding terminal of the surge arrester via a high-voltage conductor to capture leakage current signals in real time. The signal processing module is equipped with an opto-isolated interface to ensure safe isolation while efficiently processing the current signal and transmitting the processing results to the communication module. The communication module has a built-in RS-485 communication interface, enabling stable communication with an external monitoring terminal via shielded twisted-pair cable, achieving remote data transmission and monitoring. This current meter solves the integrated technical problem of remote high-precision monitoring of surge arrester leakage current and reliable anti-interference transmission in complex outdoor environments, achieving integrated remote high-precision monitoring of surge arrester leakage current and reliable anti-interference transmission in complex outdoor environments. Attached Figure Description

[0017] The drawings constituting a part of the specification illustrate the present application and, together with the description, serve to explain the principles of the present application. In the drawings:

[0018] Figure 1 is a longitudinal sectional view of a wired lightning arrester digital leakage current meter according to an embodiment of the present application;

[0019] 10, die-cast aluminum housing; 20, current acquisition module; 21, high-voltage wire; 22, electromagnetic counter; 30, signal processing module; 31, optoelectronic isolation interface; 32, analog-digital conversion unit; 40, communication module; 41, RS-485 communication interface; 42, shielded twisted pair; 43, impedance matching resistor; 11, inclined mounting base; 12, grounding bolt; 13, four-core waterproof connector; 131, first core; 132, second core; 133, third core; 134, fourth core. DETAILED DESCRIPTION

[0020] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0021] The GIS gas chamber SF6 micro-water density monitoring sensor according to the embodiment of the present application, like Figure 1The utility model provides a kind of wired lightning arrester digital leakage ammeter, the current meter includes: die-cast aluminium shell 10, current acquisition module 20 being set in the die-cast aluminium shell 10, signal processing module 30 and communication module 40;The input end of the current acquisition module 20 is connected lightning arrester ground end by high voltage wire 21;The input end of the signal processing module 30 is equipped with photoelectric isolation interface 31, the photoelectric isolation interface 31 is electrically connected with the output end of the current acquisition module 20, and the output end of the signal processing module 30 is connected the communication module 40;The communication module 40 is equipped with RS-485 communication interface 41, and the A, B signal end of the RS-485 communication interface 41 is connected external monitoring terminal by shielded twisted pair 42.In specific implementation, the wired lightning arrester digital leakage current meter comprises a die-cast aluminum shell 10, which adopts a rectangular structure and is provided with M6 mounting holes at four corners. The inner wall of the die-cast aluminum shell 10 is provided with heat dissipation fins with a thickness of 3 mm. The die-cast aluminum shell 10 has an IP65 protection level. The die-cast aluminum shell 10 is internally and fixedly provided with a current acquisition module 20, a signal processing module 30 and a communication module 40. The current acquisition module 20 comprises a Hall sensor with a model number of HSTS016L. The Hall sensor is connected with a copper bolt at a grounding end of the lightning arrester through a high-voltage wire 21 with a length of 1.5 m. The high-voltage wire 21 is coated with a silicon rubber insulation layer with a thickness of 2 mm. The output end of the Hall sensor is connected with an optical isolation interface 31 of the signal processing module 30 through a tinned copper wire with a length of 0.1 m. The optical isolation interface 31 adopts an optical coupler with a model number of HCPL-2630. The input side pin of the optical coupler is welded with the voltage output end of the Hall sensor. The output side pin of the optical coupler is connected with an AD conversion circuit of the signal processing module 30 through a flexible circuit board with a length of 0.05 m. The AD conversion circuit adopts a Σ-Δ type 24-bit analog-to-digital converter ADS1256. The AD conversion circuit converts analog signals into digital signals at a sampling rate of 1000 times per second. The digital signals output by the AD conversion circuit are transmitted to a microcontroller with a model number of STM32F407 through an SPI bus. The microcontroller internally has a digital filtering algorithm for noise reduction processing of signals. The digital filtering algorithm adopts a Butterworth low-pass filter with a cutoff frequency of 50 Hz. The data processed by the microcontroller is transmitted to the communication module 40 through a flat cable with a length of 0.15 m. The communication module 40 comprises an RS-485 drive chip with a model number of SN65HVD72. The A signal end and the B signal end of the RS-485 drive chip are welded to the pin 1 and the pin 2 of an RS-485 communication interface 41, respectively. The RS-485 communication interface 41 adopts a DB9 type metal connector. The RS-485 communication interface 41 is connected with an RJ45 port of an external monitoring terminal through a shielded twisted pair wire 42 with a length of 50 m. The copper mesh shielding layer of the shielded twisted pair wire 42 is connected with a grounding terminal of the die-cast aluminum shell 10 through a yellow-green double-color wire with a diameter of 4 square millimeters. The twist pitch of the shielded twisted pair wire 42 is 20 mm. The heat dissipation fins of the die-cast aluminum shell 10 dissipate heat generated by the Hall sensor to the external environment through heat conduction to realize temperature stability. The non-contact measurement mode of the Hall sensor avoids the influence on the grounding circuit. The optical coupler realizes electrical isolation between the current acquisition module 20 and the signal processing module 30 through optical signal transmission to suppress common-mode interference. The Butterworth low-pass filter improves the signal-to-noise ratio by eliminating high-frequency noise. The RS-485 drive chip realizes data communication with anti-electromagnetic interference in the shielded twisted pair wire 42 through a differential signal transmission mechanism.The ammeter solves the technical problem of integrated integration of remote high-precision monitoring of lightning arrester leakage current and reliable anti-interference transmission in outdoor complex environment, and realizes the integrated integration of remote high-precision monitoring of lightning arrester leakage current and reliable anti-interference transmission in outdoor complex environment.

[0022] Specifically, the bottom of the die-cast aluminum shell 10 is provided with an inclined mounting base 11, the included angle between the inclined mounting base 11 and the horizontal plane is greater than or equal to 30° and less than or equal to 75°, and the end of the inclined mounting base 11 is provided with a grounding bolt 12. In specific implementation, the bottom of the die-cast aluminum shell 10 is provided with an inclined mounting base 11, the inclined mounting base 11 is made of die-cast aluminum material which is integrally formed with the die-cast aluminum shell 10, the upper surface of the inclined mounting base 11 forms an included angle of 55° with the horizontal plane, the inclined angle of the inclined mounting base 11 is set to be in the range of 30° to 75°, the bottom surface of the inclined mounting base 11 is provided with four M8 threaded holes, the M8 threaded holes are symmetrically distributed along the longitudinal center line of the inclined mounting base 11, the end of the inclined mounting base 11 is provided with a grounding bolt 12, the grounding bolt 12 is made of 304 stainless steel with a diameter of 10 mm, the thread specification of the grounding bolt 12 is M10x1.5, the head of the grounding bolt 12 is fixedly connected with the end plane of the inclined mounting base 11 through argon arc welding, the exposed length of the screw rod part of the grounding bolt 12 is 25 mm, the screw rod end of the grounding bolt 12 is provided with a circular hole with a diameter of 8 mm, a brass braid with a cross-sectional area of 6 square millimeters is inserted into the circular hole, and the other end of the brass braid is connected with a galvanized flat steel bolt of the external grounding net through an M8 copper terminal; the 55° inclined angle of the inclined mounting base 11 promotes the natural sliding of rainwater to prevent water accumulation and corrosion by increasing the gap between the bottom of the die-cast aluminum shell 10 and the mounting surface, the M8 threaded holes of the inclined mounting base 11 are fixed with the concrete column through stainless steel expansion bolts to realize wind pressure resistance stability, the M10x1.5 thread specification of the grounding bolt 12 reduces the grounding resistance value by increasing the contact area, and the brass braid eliminates the influence of equipment vibration on the reliability of the grounding circuit through the flexible structure.

[0023] Specifically, the side of the die-cast aluminum shell 10 is provided with a four-core waterproof connector 13, the four-core waterproof connector 13 includes a first core 131, a second core 132, a third core 133 and a fourth core 134, the first core 131 is connected to the positive pole of the external DC power supply, the second core 132 is connected to the negative pole of the external DC power supply, the third core 133 is connected to the A signal end of the RS-485 communication interface 41, and the fourth core 134 is connected to the B signal end of the RS-485 communication interface 41. In specific implementation, the side of the die-cast aluminum shell 10 is provided with a four-core waterproof connector 13, the four-core waterproof connector 13 adopts a waterproof aviation plug with a model JL-4P-IP68, the shell of the four-core waterproof connector 13 is connected to the side wall of the die-cast aluminum shell 10 through M20x1.5 thread cooperation and the joint surface is filled with a nitrile rubber sealing ring with a thickness of 2mm, the four-core waterproof connector 13 includes the first core 131, the second core 132, the third core 133 and the fourth core 134, the first core 131 is a gold-plated copper pin with a diameter of 2mm, the pin length of the first core 131 is 15mm, the first core 131 is press-connected to the copper terminal of the positive pole of the external DC power supply through a red silica gel insulating wire with a cross-sectional area of 1.5mm2, the second core 132 is a gold-plated copper pin with a diameter of 2mm, the second core 132 is press-connected to the copper terminal of the negative pole of the external DC power supply through a black silica gel insulating wire with a cross-sectional area of 1.5mm2, the third core 133 is a silver-plated copper pin with a diameter of 1.5mm, the third core 133 is welded to the A signal end of the RS-485 communication interface 41 through the A signal line of a shielded twisted pair wire 42 with a cross-sectional area of 0.75mm2, the fourth core 134 is a silver-plated copper pin with a diameter of 1.5mm, the fourth core 134 is welded to the B signal end of the RS-485 communication interface 41 through the B signal line of the shielded twisted pair wire 42 with a cross-sectional area of 0.75mm2, the shielded twisted pair wire 42 has a twisting pitch of 20mm and an outer aluminum foil shielding layer with a thickness of 0.1mm, the locking nut of the four-core waterproof connector 13 is made of nylon and has a thread specification of M20x1.5 to realize waterproof sealing; the gold-plated copper pin of the first core 131 ensures the stability of the positive pole of the DC power supply by reducing the contact resistance, the black silica gel insulating wire of the second core 132 prevents the negative pole line from aging by high-temperature resistance, the silver-plated copper pins of the third core 133 and the fourth core 134 guarantee the differential signal integrity of the RS-485 communication interface 41 by improving the high-frequency signal transmission efficiency, the aluminum foil shielding layer of the shielded twisted pair wire 42 realizes signal transmission anti-interference by absorbing electromagnetic interference, and the nitrile rubber sealing ring of the four-core waterproof connector 13 reaches the IP68 protection level by compression deformation to prevent rainwater from penetrating into the die-cast aluminum shell 10.

[0024] Specifically, the two ends of the shielded twisted pair wire 42 are respectively provided with impedance matching resistors 43, and the resistance value of the impedance matching resistor 43 is 120Ω±5%. Specifically, the two ends of the shielded twisted pair wire 42 are respectively provided with impedance matching resistors 43, and the resistance value of the impedance matching resistor 43 is 120Ω±5%, the impedance matching resistor 43 adopts a metal film resistor with a model number of ERJ-6ENF1203V, the rated power of the metal film resistor is 1 / 4W, the temperature coefficient is ±100ppm / ℃, the pin diameter of the impedance matching resistor 43 is 0.6mm, the first pin of the impedance matching resistor 43 is welded and connected with the A signal line of the shielded twisted pair wire 42 through lead-free solder, the second pin of the impedance matching resistor 43 is welded and connected with the B signal line of the shielded twisted pair wire 42 through lead-free solder, the core of the A signal line and the B signal line of the shielded twisted pair wire 42 is a tinned copper wire with a diameter of 0.5mm, the aluminum foil shielding layer of the shielded twisted pair wire 42 is welded with the metal shell of the impedance matching resistor 43 through a tinned copper wire with a cross-sectional area of 0.3mm to realize equipotential connection, the copper mesh shielding layer of the shielded twisted pair wire 42 is connected with the grounding bolt 12 of the die-cast aluminum shell 10 through a cross-sectional area of 1mm of brass braid; the resistance value of 120Ω±5% of the impedance matching resistor 43 reduces signal reflection through the transmission line characteristic impedance of the matching RS-485 communication interface 41, the temperature coefficient of ±100ppm / ℃ of the metal film resistor reduces temperature drift to ensure the stability of the impedance matching, the aluminum foil shielding layer and the copper mesh shielding layer of the shielded twisted pair wire 42 suppress common-mode interference through a double shielding structure, the Sn96.5Ag3.0Cu0.5 composition of the lead-free solder improves the high melting point characteristics to improve the thermal fatigue resistance of the solder joint, the A signal line and the B signal line of the shielded twisted pair wire 42 are provided with a heat shrink sleeve with a length of 15mm outside the solder joint to prevent short circuit, and the material of the heat shrink sleeve is polyolefin and the wall thickness is 1mm.

[0025] Specifically, the signal processing module 30 includes an analog-to-digital conversion unit 32, and a sampling period of the analog-to-digital conversion unit 32 is 20 ms ± 0.01 ms. Specifically, the signal processing module 30 includes an analog-to-digital conversion unit 32, the analog-to-digital conversion unit 32 is a 24-bit sigma-delta analog-to-digital converter with a model number of ADS1256, a sampling period of the analog-to-digital conversion unit 32 is driven by a 16 MHz crystal oscillator and is configured to be 20 ms ± 0.01 ms, the 16 MHz crystal oscillator has a stability of ± 5 ppm, a voltage input end of the analog-to-digital conversion unit 32 is welded and connected with an output pin of the opto-isolation interface 31 through a tinned copper wire with a cross-sectional area of 0.5 square millimeters, a reference voltage source of the analog-to-digital conversion unit 32 is a 5V reference source with a model number of LT1236, an output voltage error of the LT1236 reference source is ± 0.05% and a temperature coefficient is 3 ppm / °C, an SPI communication interface of the analog-to-digital conversion unit 32 is connected with PA4, PA5, PA6 and PA7 pins of a microcontroller with a model number of STM32F407 through a 0.1-meter-long flat cable, a working mode of the SPI bus is configured to be a full-duplex mode and a clock frequency is set to be 8 MHz, a sampling period of the analog-to-digital conversion unit 32 is triggered by a TIM2 timer of the microcontroller, a pre-frequency division register of the TIM2 timer is set to be 7999 and an automatic reload register is set to be 399 to realize a 20 ms timing interruption; the 20 ms ± 0.01 ms sampling period of the analog-to-digital conversion unit 32 ensures a time reference accuracy through the ± 5 ppm stability of the 16 MHz crystal oscillator, the sigma-delta modulator distributes input signal quantization noise in a higher frequency band through a 128 times oversampling rate, the 3 ppm / °C temperature coefficient of the LT1236 reference source improves conversion accuracy of the analog-to-digital conversion unit 32 by reducing voltage drift, the 8 MHz clock frequency of the SPI bus reduces transmission delay error by matching a flat cable length and a signal rise time, an input buffer of the analog-to-digital conversion unit 32 reduces a load effect on an output end of the opto-isolation interface 31 through a 1MΩ input impedance, a power supply pin of the analog-to-digital conversion unit 32 is connected in series with a 3.3V voltage stabilizing circuit through a 0805 packaged 10μF ceramic capacitor to suppress high-frequency noise, sampling data of the analog-to-digital conversion unit 32 is transmitted to the microcontroller together with a data frame after a check code is generated through a CRC-16 check algorithm, a polynomial of the CRC-16 check algorithm is 0x8005 and an initial value is 0xFFFF.

[0026] Specifically, the output end of the current acquisition module 20 is connected in parallel with an electromagnetic counter 22, and the trigger current threshold of the electromagnetic counter 22 is 50A to 100kA. Specifically, the output end of the current acquisition module 20 is connected in parallel with an electromagnetic counter 22, and the electromagnetic counter 22 adopts an electromagnetic mechanical counter with a model number of EMC-50K, the trigger current threshold of the electromagnetic counter 22 is set to an adjustable range of 50A to 100kA by adjusting a built-in variable resistor, the model number of the variable resistor is RV24YN20S, the resistance adjustment range is 0Ω to 10kΩ, the coil winding of the electromagnetic counter 22 is wound with enameled copper wire with a cross-sectional area of 2.5 square millimeters for 500 turns, the direct current resistance of the coil winding is 5Ω±1%, the gap between the moving contact and the static contact of the electromagnetic counter 22 is set to 0.5 millimeters, the counting mechanism of the electromagnetic counter 22 is linked with the armature through a stainless steel shaft with a diameter of 3 millimeters, the shell of the electromagnetic counter 22 is made of 304 stainless steel with a thickness of 1.5 millimeters and is sprayed with epoxy anti-rust paint with a thickness of 0.1 millimeter on the surface, the mounting base of the electromagnetic counter 22 is fixed to the inner side wall of the die-cast aluminum shell 10 through four M5 stainless steel bolts, the thread length of the M5 stainless steel bolt is 8 millimeters and a fastening torque of 5N·m is applied, the input end of the electromagnetic counter 22 is connected in parallel with the Hall sensor output end of the current acquisition module 20 through a tinned copper wire with a cross-sectional area of 4 square millimeters, and the two ends of the tinned copper wire are respectively fixed on the binding post of the electromagnetic counter 22 and the output terminal of the Hall sensor by OT type copper terminals after crimping and M4 stainless steel nuts; the 50A to 100kA trigger current threshold of the electromagnetic counter 22 realizes the overcurrent protection function by adjusting the excitation current of the coil winding through the variable resistor, the stainless steel shell guarantees the service life of the electromagnetic counter 22 in the outdoor humid environment through the corrosion-resistant characteristics, the enameled copper wire winding reduces the current transmission loss through the low resistance characteristics, the armature gap of the electromagnetic counter 22 is precisely adjusted to ensure reliable attraction to trigger the counting action when the threshold current is reached, the epoxy anti-rust paint prevents the surface of the stainless steel shell from electrochemical corrosion by isolating oxygen and moisture, the parallel connection mode of the electromagnetic counter 22 avoids the load influence on the normal sampling circuit of the current acquisition module 20 through the shunt effect, the counting mechanism of the electromagnetic counter 22 realizes one-way cumulative counting through the ratchet structure to prevent data rollback, and the polycarbonate material window of the electromagnetic counter 22 allows external direct reading of the counting value through the transparency design.

[0027] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Those skilled in the art can make various changes and modifications to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A wired arrester digitalizing leakage current meter, characterized by, The application relates to a digital leakage current meter for a wired lightning arrester. The input end of the current collection module (20) is connected with the grounding end of the lightning arrester through a high-voltage wire (21). The input end of the signal processing module (30) is provided with an optoelectronic isolation interface (31) which is electrically connected with the output end of the current collection module (20), and the output end of the signal processing module (30) is connected with the communication module (40). The communication module (40) is provided with an RS-485 communication interface (41), and the A and B signal ends of the RS-485 communication interface (41) are connected with an external monitoring terminal through a shielded twisted pair wire (42).

2. The digital leakage current meter for a wired lightning arrester according to claim 1, wherein the bottom of the die-cast aluminum shell (10) is provided with an inclined mounting base (11), the included angle between the inclined mounting base (11) and a horizontal plane is greater than or equal to 30 DEG and smaller than or equal to 75 DEG, and the end of the inclined mounting base (11) is provided with a grounding bolt (12).

3. The digital leakage current meter for a wired lightning arrester according to claim 1, wherein the side surface of the die-cast aluminum shell (10) is provided with a four-core waterproof connector (13), the four-core waterproof connector (13) comprises a first core (131), a second core (132), a third core (133) and a fourth core (134), the first core (131) is connected with the positive pole of an external direct-current power supply, the second core (132) is connected with the negative pole of the external direct-current power supply, the third core (133) is connected with the A signal end of the RS-485 communication interface (41), and the fourth core (134) is connected with the B signal end of the RS-485 communication interface (41).

4. The digital leakage current meter for a wired lightning arrester according to claim 1, wherein the two ends of the shielded twisted pair wire (42) are respectively provided with impedance matching resistors (43), and the resistance value of the impedance matching resistors (43) is 120 omega plus or minus 5%.

5. The digital leakage current meter for a wired lightning arrester according to claim 1, wherein the signal processing module (30) comprises an analog-digital conversion unit (32), and the sampling period of the analog-digital conversion unit (32) is 20 ms plus or minus 0.01 ms.

6. The digital leakage current meter for a wired lightning arrester according to claim 1, wherein the output end of the current collection module (20) is connected in parallel with an electromagnetic counter (22), and the trigger current threshold value of the electromagnetic counter (22) is 50 A to 100 kA. ​ ​ ​ ​ ​ ​

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