CN110658388A

CN110658388A - Detection method and device for ground resistance and electronic equipment

Info

Publication number: CN110658388A
Application number: CN201910963865.0A
Authority: CN
Inventors: 马九洋
Original assignee: Signal and Communication Research Institute of CARS
Current assignee: Signal and Communication Research Institute of CARS
Priority date: 2019-10-11
Filing date: 2019-10-11
Publication date: 2020-01-07

Abstract

The embodiment of the invention discloses a method and a device for detecting a ground resistance and electronic equipment, wherein the method comprises the following steps: the method comprises the steps of obtaining a first auxiliary resistor between a target station to be detected and each auxiliary detection station of at least two auxiliary detection stations, obtaining a second auxiliary resistor between every two auxiliary detection stations of the at least two auxiliary detection stations, obtaining a first loop resistor between the target station and each auxiliary detection station of the at least two auxiliary detection stations, obtaining a second loop resistor between every two auxiliary detection stations of the at least two auxiliary detection stations, and determining the grounding resistance of the target station based on the first loop resistor, the second loop resistor, the first auxiliary resistor and the second auxiliary resistor. By the method, the grounding resistance of the target station can be determined based on the measured first loop resistance, second loop resistance, first auxiliary resistance and second auxiliary resistance.

Description

Detection method and device for ground resistance and electronic equipment

Technical Field

The invention relates to the technical field of computers, in particular to a method and a device for detecting a ground resistance and electronic equipment.

Background

Rail transit systems (such as subways and trams) gradually become a preferred public transportation mode for people to go out, and in order to ensure the reliable operation of the rail transit systems, the grounding performance of each station in the rail transit systems gradually becomes a focus of attention of people.

At present, a three-level method can be used for measuring the grounding resistance of each station (ground network) in a rail transit system, and the grounding performance of each station can be judged according to the grounding resistance. For example, taking a subway as an example, a voltage difference between each station and a corresponding voltage pole and a current in a loop formed by the station and a corresponding current pole may be measured, and then a ratio of the voltage difference to the current may be used as a ground resistance of the station, and the ground performance of the station may be determined according to the ground resistance.

However, since the three-stage method is used on the premise that a test space with a larger range is required in the vertical direction of the tested station, the test space is at least 1.5-2 times of the ground grid of the tested building (such as the building corresponding to the tested subway station), and large buildings or buried metals are not suitable to be arranged around the ground grid of the tested building, and most stations in the rail transit system are distributed in a crowded section of the building (or distributed in an underground space), it is difficult to use the three-stage method to measure the ground resistance of each station in the rail transit system, and therefore, a method capable of effectively measuring the ground resistance of each station in the rail transit system is required.

Disclosure of Invention

The embodiment of the invention aims to provide a method and a device for detecting a ground resistance and electronic equipment, so as to solve the problem that the ground resistance of each station in a rail transit system cannot be effectively measured in the prior art.

To solve the above technical problem, the embodiment of the present invention is implemented as follows:

in a first aspect, an embodiment of the present invention provides a method for detecting a ground resistance, where the method includes:

acquiring a first auxiliary resistor between a target station to be detected and each auxiliary detection station of at least two auxiliary detection stations and a second auxiliary resistor between every two auxiliary detection stations of the at least two auxiliary detection stations, wherein the first auxiliary resistor is a resistor of a loop formed by two power supply wires in a traction network between the target station and the auxiliary detection station, and the second auxiliary resistor is a resistor of a loop formed by two power supply wires in the traction network between every two auxiliary detection stations of the at least two auxiliary detection stations;

acquiring a first loop resistance between the target station and each of the at least two auxiliary detection stations and a second loop resistance between each of the at least two auxiliary detection stations, wherein the first loop resistance is a resistance of a loop formed by any power supply wire in the traction network and the ground between the target station and the auxiliary detection station, and the second loop resistance is a resistance of a loop formed by any power supply wire in the traction network and the ground between each two auxiliary detection stations in the at least two auxiliary detection stations;

and determining the grounding resistance of the target station based on the first loop resistance, the second loop resistance, the first auxiliary resistance and the second auxiliary resistance.

Optionally, the two power supply wires in the traction network include an uplink power supply wire and a downlink power supply wire, and a loop formed by the two power supply wires in the traction network further includes a test lead, and the test lead is used for connecting the uplink power supply wire and the downlink power supply wire.

Optionally, the auxiliary detection stations include two, the first loop resistance includes a first sub-loop resistance and a second sub-loop resistance between the target station and each of the auxiliary detection stations, the first auxiliary resistance includes a first sub-auxiliary resistance and a second sub-auxiliary resistance between the target station and each of the auxiliary detection stations, and the determining the ground resistance of the target station based on the first loop resistance, the second loop resistance, the first auxiliary resistance and the second auxiliary resistance includes:

based on the first loop resistance, the second loop resistance, the first auxiliary resistance and the second auxiliary resistance, passing a formula

Calculating the grounding resistance of the target station;

wherein R is the grounding resistance of the target station, R′₁Is the first sub-auxiliary resistor, R₁Is the first sub-loop resistance, R'₂Is the second sub-auxiliary resistor, R₂Is the second sub-loop resistance, R'₃Is said second auxiliary resistance, R₃Is the second loop resistance.

Optionally, the determining the ground resistance of the target station based on the first loop resistance, the second loop resistance, the first auxiliary resistance and the second auxiliary resistance includes:

determining a first ground resistance of the target site based on the first loop resistance, the second loop resistance, the first auxiliary resistance, and the second auxiliary resistance;

when a preset time period is reached, determining a second grounding resistance of the target station based on the acquired third auxiliary resistance between the target station and each of the at least two auxiliary detection stations, the acquired fourth auxiliary resistance between each of the at least two auxiliary detection stations, the acquired third loop resistance between the target station and each of the at least two auxiliary detection stations, and the acquired fourth loop resistance between each of the at least two auxiliary detection stations;

and determining the grounding resistance of the target site based on the first grounding resistance and the second grounding resistance.

Optionally, the determining the ground resistance of the target station based on the first ground resistance and the second ground resistance includes:

carrying out abnormity statistical analysis on the first grounding resistor and the second grounding resistor, and processing the first grounding resistor and the second grounding resistor according to the result of the abnormity statistical analysis to obtain a processed first grounding resistor and a processed second grounding resistor;

and determining the grounding resistance of the target station based on the processed first grounding resistance and the second grounding resistance.

In a second aspect, an embodiment of the present invention provides a device for detecting a ground resistance, where the device includes:

the first resistance acquisition module is used for acquiring a first auxiliary resistance between a target station to be detected and each auxiliary detection station of at least two auxiliary detection stations and a second auxiliary resistance between each two auxiliary detection stations of the at least two auxiliary detection stations, wherein the first auxiliary resistance is a resistance of a loop formed by two power supply wires in a traction network between the target station and the auxiliary detection station, and the second auxiliary resistance is a resistance of a loop formed by two power supply wires in the traction network between each two auxiliary detection stations of the at least two auxiliary detection stations;

a second resistance obtaining module, configured to obtain a first loop resistance between the target station and each of the at least two auxiliary detection stations, and a second loop resistance between each of the at least two auxiliary detection stations, where the first loop resistance is a resistance of a loop formed by any one power supply wire in the traction network and the ground between the target station and the auxiliary detection station, and the second loop resistance is a resistance of a loop formed by any one power supply wire in the traction network and the ground between each two auxiliary detection stations in the at least two auxiliary detection stations;

and the grounding resistance determining module is used for determining the grounding resistance of the target station based on the first loop resistance, the second loop resistance, the first auxiliary resistance and the second auxiliary resistance.

Optionally, the auxiliary detection stations include two auxiliary detection stations, the first loop resistance includes a first sub-loop resistance and a second sub-loop resistance between the target station and each auxiliary detection station, the first auxiliary resistance includes a first sub-auxiliary resistance and a second sub-auxiliary resistance between the target station and each auxiliary detection station, and the ground resistance determination module is configured to:

based on the first loop resistance, the second loop resistance, the first auxiliary resistance and the second auxiliary resistance, passing a formulaCalculating the grounding resistance of the target station;

wherein R is the grounding resistance of the target site, R'₁Is the first sub-auxiliary resistor, R₁Is the first sub-loop resistance, R'₂Is the second sub-auxiliary resistor, R₂Is the second sub-loop resistance, R'₃Is said second auxiliary resistance, R₃Is the second loop resistance.

Optionally, the ground resistance determining module is configured to:

In a third aspect, an embodiment of the present invention provides an electronic device, which includes a processor, a memory, and a computer program stored in the memory and being executable on the processor, where the computer program, when executed by the processor, implements the steps of the method for detecting a ground resistance provided in the foregoing embodiments.

In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, where a computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the computer program implements the steps of the method for detecting a ground resistance provided in the foregoing embodiment.

As can be seen from the above technical solutions provided by the embodiments of the present invention, in the embodiments of the present invention, a first auxiliary resistor between a target station to be detected and each of at least two auxiliary detection stations is obtained, and a second auxiliary resistor between each two auxiliary detection stations of the at least two auxiliary detection stations is obtained, where the first auxiliary resistor is a resistor of a loop formed by two power supply wires in a pull network between the target station and the auxiliary detection station, the second auxiliary resistor is a resistor of a loop formed by two power supply wires in the pull network between each two auxiliary detection stations of the at least two auxiliary detection stations, the first loop resistor between the target station and each auxiliary detection station of the at least two auxiliary detection stations is obtained, and the second loop resistor between each two auxiliary detection stations of the at least two auxiliary detection stations is obtained, the first loop resistance is the resistance of a loop formed by any power supply wire in the traction network and the ground between the target station and the auxiliary detection station, the second loop resistance is the resistance of a loop formed by any power supply wire in the traction network and the ground between every two auxiliary detection stations in at least two auxiliary detection stations, and the ground resistance of the target station is determined based on the first loop resistance, the second loop resistance, the first auxiliary resistance and the second auxiliary resistance. Therefore, the ground resistance of the target station can be determined by acquiring the first loop resistance and the first auxiliary resistance between the target station and the auxiliary detection station and the second loop resistance and the second auxiliary resistance between every two auxiliary detection stations in at least two auxiliary detection stations, and the ground resistance of each station (ground network) in the rail transit system can be effectively measured without the need that the target station has a large-range test space.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, it is obvious that the drawings in the following description are only some embodiments described in the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a flow chart of an embodiment of a method for detecting ground resistance according to the present invention;

FIG. 2 is a schematic diagram of a site (earth mat) partitioning method according to the present invention;

FIG. 3 is a schematic diagram of an accessory resistance measurement method of the present invention;

FIG. 4 is a schematic diagram of a loop resistance measurement method according to the present invention;

FIG. 5 is a schematic diagram of another loop resistance measurement method according to the present invention;

FIG. 6 is a flow chart of another embodiment of a method for detecting ground resistance according to the present invention;

FIG. 7 is a schematic structural diagram of a device for detecting ground resistance according to the present invention;

fig. 8 is a schematic structural diagram of an electronic device according to the present invention.

Detailed Description

The embodiment of the invention provides a method and a device for detecting a ground resistance and electronic equipment.

In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention, and it is obvious that the described embodiment is only a part of the embodiment of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example one

As shown in fig. 1, an execution main body of the method may be an electronic device, and the electronic device may be a terminal device or a server, where the terminal device may be a device such as a personal computer, or a mobile terminal device such as a mobile phone and a tablet computer, and the server may be an independent server, or a server cluster composed of multiple servers. The method may specifically comprise the steps of:

in step S102, a first auxiliary resistance between the target station to be detected and each of the at least two auxiliary detection stations and a second auxiliary resistance between each of the at least two auxiliary detection stations are obtained.

The target station and the auxiliary detection station may be stations in the rail transit system that may be connected by a power supply wire in the traction network, the first auxiliary resistor may be a resistor of a loop formed by two power supply wires in the traction network between the target station and the auxiliary detection station, and the second auxiliary resistor may be a resistor of a loop formed by two power supply wires in the traction network between every two auxiliary detection stations in the at least two auxiliary detection stations.

In practice, rail transit systems (such as subways and trams) gradually become public transportation modes preferred by people for traveling, and in order to ensure reliable operation of the rail transit systems, grounding performance of each station in the rail transit systems gradually becomes a focus of attention. At present, a three-level method can be used for measuring the grounding resistance of each station (ground network) in a rail transit system, and the grounding performance of each station can be judged according to the grounding resistance. For example, taking a subway as an example, a voltage difference between each station and a corresponding voltage pole and a current in a loop formed by the station and a corresponding current pole may be measured, and then a ratio of the voltage difference to the current may be used as a ground resistance of the station, and the ground performance of the station may be determined according to the ground resistance.

However, since the three-stage method is used on the premise that a test space with a larger range is required in the vertical direction of the tested station, the test space is at least 1.5-2 times of the ground grid of the tested building (such as the building corresponding to the tested subway station), and large buildings or buried metals are not suitable to be arranged around the ground grid of the tested building, and stations in urban rail transit are generally distributed in crowded areas of the building (or distributed in the underground space of a city), it is difficult to use the three-stage method to measure the ground resistance of each station in the rail transit system, and therefore, a method capable of effectively measuring the ground resistance of each station in the rail transit system is required.

In addition, in the prior art, the ground resistance of each station in the rail transit system can be measured by a clamp meter method, for example, the resistance of a parallel loop between a ground grid of a target station, a tower overhead ground wire and a grounding body close to the tower can be measured and used as the ground resistance of the target station.

However, since the ground resistance of each station in the rail transit system is small, when the ground resistance of the station is measured by using a clamp meter method, the error is large, and the ground resistance of each station cannot be effectively measured.

Therefore, an embodiment of the present invention provides a technical solution capable of solving the above problems, which may specifically include the following:

in order to measure the grounding resistance of the stations, the grounding grid of the stations can be formed into an independent grounding body, and particularly, the grounding grid of each station in the rail transit system can be isolated from the grounding structure, the auxiliary grounding facility and the line structure of an electric and electronic system inside the station, so that each station can be used as an independent grounding body. In practical applications, one or more concentrated ground bars are usually disposed inside each station in the rail transit system, and the connection between the ground grid and the ground bars of each station can be broken (for example, terminals between the ground grid and the ground bars of each station are thrown away and kept insulated) so that the stations form independent ground bodies.

Meanwhile, one or more power supply wires in the traction network laid between each station in the rail transit system can be transformed into test wires, for example, an electric connection isolating switch between the power supply wires in the traction network can be opened, so that each power supply wire in the traction network becomes an independent wire and does not generate a parallel connection relation with other wires. Then, the power supply wires related to the target station and the auxiliary detection station can be electrically connected at the positions where gaps or breakpoints exist, so that the power supply wires are in a conducting state among all stations (including the target station to be detected and the auxiliary detection station).

For example, as shown in fig. 2, there may be a station 1, a station 2 and a station 3 in the rail transit system, the three stations may be isolated from the earth grid so that the three stations may act as independent earthed bodies, and then two power supplies in the traction grid between the three stations may be modified to be independent test wires.

After the transformation is completed, assuming that the station 2 is a target station to be detected, and the stations 1 and 3 are auxiliary detection stations, a first auxiliary resistance between the station 2 and the station 1 and a first auxiliary resistance between the station 2 and the station 3 can be obtained.

For example, as shown in fig. 3, at the end of an auxiliary test station (e.g., station 1 or station 3), two power supply wires may be shorted, and the two power supply wires may be connected to a test device at a target station (e.g., station 2) to form a complete loop, and then the resistance on the loop is measured by the test device (e.g., an ac resistance test device) and used as a first auxiliary resistance between the target station and the auxiliary test station. Likewise, a second auxiliary resistance between each two secondary test stations (i.e., station 1 and station 3) may also be measured.

In addition, in order to improve the detection accuracy of the ground resistance of the target station to be detected in an actual application scenario, a plurality of (e.g., 4, 6, etc.) auxiliary detection stations having a correlation with the target station (e.g., auxiliary detection stations of a power supply wire in the same traction network as the target station) may be selected.

In step S104, a first loop resistance between the target station and each of the at least two auxiliary detection stations and a second loop resistance between each of the at least two auxiliary detection stations are obtained.

The first loop resistance may be a resistance of a loop formed by any one power supply wire in the traction network and the ground between the target station and the auxiliary detection station, and the second loop resistance may be a resistance of a loop formed by any one power supply wire in the traction network and the ground between every two auxiliary detection stations in the at least two auxiliary detection stations.

In implementation, as shown in fig. 4, any one of the power supply wires in the traction network between the target station and the auxiliary detection station may be connected to the ground to form a loop, and then the resistance on the loop is detected by the test equipment, and the detected resistance is used as the first loop resistance between the target station and the auxiliary detection station. Likewise, a second loop resistance between each two secondary test sites may also be obtained. In addition, different test equipment can be adopted to detect the resistance on the loop according to different power supply systems of the rail transit system. For example, the power supply system of each station in fig. 4 may be an ac power supply system, and the corresponding test device may be an ac resistance test device, while as shown in fig. 5, the power supply system of each station may be a dc power supply system, and the corresponding test device may also be a dc resistance test device.

In addition, when loop resistance (including the first loop resistance and the second loop resistance) is measured, if obvious frequency (such as power frequency) interference exists in the loop, the test frequency of the test equipment can be avoided from the power frequency of 50Hz, and a proper frequency is selected as the test frequency (such as 40Hz and the like) in a frequency range near the power frequency.

In addition, the execution sequence of the step S102 and the step S104 is an optional and realizable execution sequence, in an actual application scenario, the two steps S102 and the step S104 may be executed simultaneously, or the step S104 may be executed first and the step S102 is executed, and the execution sequence of the step S102 and the step S104 is not specifically limited in the embodiment of the present invention.

In step S106, a ground resistance of the target station is determined based on the first loop resistance, the second loop resistance, the first auxiliary resistance, and the second auxiliary resistance.

In implementation, the relationship between the first loop resistance, the second loop resistance, the first auxiliary resistance and the second auxiliary resistance and the ground resistance may be obtained in advance through a set algorithm, and then, the ground resistance of the corresponding target station may be determined based on the obtained relationship and the obtained first loop resistance, second loop resistance, first auxiliary resistance and second auxiliary resistance.

In addition, in an actual application scenario, there may be a plurality of methods for determining the target site ground resistance, which is not specifically limited in the embodiment of the present invention.

The embodiment of the invention provides a method for detecting a ground resistance, which comprises the steps of obtaining a first auxiliary resistance between a target station to be detected and each auxiliary detection station of at least two auxiliary detection stations, and a second auxiliary resistance between each two auxiliary detection stations of the at least two auxiliary detection stations, wherein the first auxiliary resistance is the resistance of a loop formed by two power supply wires in a traction network between the target station and the auxiliary detection station, the second auxiliary resistance is the resistance of a loop formed by two power supply wires in the traction network between each two auxiliary detection stations of the at least two auxiliary detection stations, obtaining the first loop resistance between the target station and each auxiliary detection station of the at least two auxiliary detection stations, and the second loop resistance between each two auxiliary detection stations of the at least two auxiliary detection stations, the first loop resistance is the resistance of a loop formed by any power supply wire in the traction network and the ground between the target station and the auxiliary detection station, the second loop resistance is the resistance of a loop formed by any power supply wire in the traction network and the ground between every two auxiliary detection stations in at least two auxiliary detection stations, and the ground resistance of the target station is determined based on the first loop resistance, the second loop resistance, the first auxiliary resistance and the second auxiliary resistance. Therefore, the grounding resistance of the target station can be determined directly by acquiring the first loop resistance and the first auxiliary resistance between the target station and the auxiliary detection station and the second loop resistance and the second auxiliary resistance between every two auxiliary detection stations in at least two auxiliary detection stations, and the grounding resistance of each station (ground network) in the rail transit system can be effectively measured without the need that the target station has a large-range test space.

Example two

As shown in fig. 6, an execution main body of the method may be a mobile terminal that performs information transmission based on a non-independent architecture, where the mobile terminal may be a device such as a personal computer, or a mobile terminal such as a mobile phone and a tablet computer, and the mobile terminal may perform information transmission based on two information transmission modes at the same time. The method may specifically comprise the steps of:

in step S602, a first auxiliary resistor between the target station to be detected and each of the at least two auxiliary detection stations and a second auxiliary resistor between each of the at least two auxiliary detection stations are obtained.

The two power supply wires in the traction network can comprise an uplink power supply wire and a downlink power supply wire, the uplink power supply wire and the downlink power supply wire can be two commonly used power supply wires in a rail transit system, trains with opposite running directions can respectively run on an uplink and a downlink, a loop formed by the two power supply wires in the traction network can further comprise a test lead, and the test lead can be used for connecting the uplink power supply wire and the downlink power supply wire. For example, as shown in fig. 3, at the end of the auxiliary detection station, the upstream power supply conductor and the downstream power supply conductor may be shorted by the test lead, so that the upstream power supply conductor and the downstream power supply conductor form a loop.

In step S604, a first loop resistance between the target station and each of the at least two auxiliary detection stations and a second loop resistance between each of the at least two auxiliary detection stations are obtained.

For the specific processing procedures of the steps S602 to S604, reference may be made to relevant contents in the steps S102 to S104 in the first embodiment, and details are not repeated here.

After the first loop resistance, the second loop resistance, the first auxiliary resistance and the second auxiliary resistance are obtained, steps S608 to S612 may be continuously performed to determine the ground resistance of the target station. In addition, if there are two auxiliary site building sites, step S606 may be performed to obtain the ground resistance of the target site.

In step S606, a formula is applied based on the first loop resistance, the second loop resistance, the first auxiliary resistance and the second auxiliary resistance

And calculating the grounding resistance of the target site.

Wherein the first loop resistance may include a first sub-loop resistance and a second sub-loop resistance between the target station and each auxiliary detection station, the first auxiliary resistance may include a first sub-auxiliary resistance and a second sub-auxiliary resistance between the target station and each auxiliary detection station, and R may be a ground resistance, R 'of the target station'₁May be a first sub-auxiliary resistor, R₁May be a first sub-loop resistance, R'₂May be a second sub-auxiliary resistor, R₂May be a second sub-loop resistance, R'₃May be a second auxiliary resistor, R₃Can be used forIs a second loop resistance.

In implementation, taking fig. 2 as an example, there are 3 stations, where station 1 may be a target station to be detected, and stations 2 and 3 may be auxiliary detection stations, and may obtain a first sub-loop resistance and a first auxiliary resistance between stations 1 and 2, a second sub-loop resistance and a second auxiliary resistance between stations 1 and 3, and a second loop resistance and a second auxiliary resistance between stations 2 and 3. And the following relationships are obtained:

wherein R can be the grounding resistance of the target site, R_AMay be the ground resistance, R, of the station 2_BMay be ground resistance of site 3, R'₁May be the first sub-auxiliary resistance, R, between the target station and station 2₁May be a first sub-loop resistance, R ', between target site and site 2'₂May be a second sub-auxiliary resistance, R, between the destination station and station 3₂Can be a target station and a station 3 second sub-loop resistance R'₃May be a second auxiliary resistance, R, between station 2 and station 3₃May be the second loop resistance between station 2 and station 3.

After solving this relation, the following relation can be obtained:

then, based on the relational expression, the ground resistances of the target station, the station 2, and the station 3 can be obtained.

In step S608, a first ground resistance of the target station is determined based on the first loop resistance, the second loop resistance, the first auxiliary resistance, and the second auxiliary resistance.

The specific processing procedure of step S608 may refer to the relevant contents in step S106 in the first embodiment, and is not described herein again.

In step S610, each time a preset time period is reached, a second ground resistance of the target station is determined based on the obtained third auxiliary resistance between the target station and each of the at least two auxiliary detection stations, the obtained fourth auxiliary resistance between each of the at least two auxiliary detection stations, the obtained third loop resistance between the target station and each of the at least two auxiliary detection stations, and the obtained fourth loop resistance between each of the at least two auxiliary detection stations.

In an implementation, assuming that the preset time period is 5 minutes, the corresponding third auxiliary resistance, fourth auxiliary resistance, third loop resistance and fourth loop resistance may be obtained at four time points of 12:00, 12:05, 12:10 and 12:15, and then the second ground resistances corresponding to the four time points may be calculated based on the obtained third auxiliary resistance, fourth auxiliary resistance, third loop resistance and fourth loop resistance.

In step S612, the ground resistance of the target site is determined based on the first ground resistance and the second ground resistance.

In the implementation, the average value of the first ground resistance and the second ground resistance may be used as the borrow point resistance of the target site, or if there is a large amount of second ground resistance, the resistance with the largest frequency number in the first ground resistance and the second ground resistance may be used as the ground resistance of the target site. For example, assuming that the second ground resistances corresponding to the four time points of 12:00, 12:05, 12:10, and 12:15 can be obtained, the second ground resistances may be 0.02 Ω, 0.05 Ω, 0.03 Ω, and 0.02 Ω, and if the first ground resistance is 0.02 Ω, the ground resistance of the corresponding target station may be 0.02 Ω with the largest frequency.

In practical applications, the processing manner of the step 610 may be various, and an alternative implementation manner is provided below, which may specifically refer to the following step one to step two processing.

The method comprises the steps of firstly, carrying out abnormity statistical analysis on a first grounding resistor and a second grounding resistor, and processing the first grounding resistor and the second grounding resistor according to the results of the abnormity statistical analysis to obtain the processed first grounding resistor and the processed second grounding resistor.

In implementation, in order to reduce the calculation error of the target site ground resistance, the first ground resistance and the second ground resistance may be subjected to anomaly statistical analysis. For example, a scatter diagram may be drawn based on the first ground resistance and the second ground resistance, and then the drawn scatter diagram may be subjected to an abnormal statistical analysis by a preset statistical analysis method (e.g., a regression analysis method), and then the first ground resistance and the second ground resistance may be processed to obtain the processed first ground resistance and second ground resistance.

In addition, in order to ensure the calculation accuracy of the ground resistance of the target site, a plurality of (e.g., greater than or equal to 5) second ground resistances may be obtained.

And step two, determining the grounding resistance of the target site based on the processed first grounding resistance and the second grounding resistance.

In implementation, an average value of the processed first ground resistance and the processed second ground resistance may be used as the ground resistance of the target site, or a minimum value of the processed first ground resistance and the processed second ground resistance may be used as the ground resistance of the target site.

EXAMPLE III

Based on the same idea, the above method for detecting a ground resistance according to the embodiment of the present invention further provides a device for detecting a ground resistance, as shown in fig. 7.

The detection device of the grounding resistance comprises: a first resistance obtaining module 701, a second resistance obtaining module 702, and a ground resistance determining module 703, wherein:

a first resistance obtaining module 701, configured to obtain a first auxiliary resistance between a target station to be detected and each of at least two auxiliary detection stations, and a second auxiliary resistance between every two auxiliary detection stations of the at least two auxiliary detection stations, where the first auxiliary resistance is a resistance of a loop formed by two power supply wires in a traction network between the target station and the auxiliary detection station, and the second auxiliary resistance is a resistance of a loop formed by two power supply wires in the traction network between every two auxiliary detection stations of the at least two auxiliary detection stations;

a second resistance obtaining module 702, configured to obtain a first loop resistance between the target station and each of the at least two auxiliary detection stations, and a second loop resistance between each of the at least two auxiliary detection stations, where the first loop resistance is a resistance of a loop formed by any one power supply wire in the traction network and the ground between the target station and the auxiliary detection station, and the second loop resistance is a resistance of a loop formed by any one power supply wire in the traction network and the ground between each two auxiliary detection stations in the at least two auxiliary detection stations;

a ground resistance determining module 703, configured to determine a ground resistance of the target site based on the first loop resistance, the second loop resistance, the first auxiliary resistance, and the second auxiliary resistance.

In the embodiment of the present invention, the two power supply wires in the traction network include an uplink power supply wire and a downlink power supply wire, and a loop formed by the two power supply wires in the traction network further includes a test lead, and the test lead is used for connecting the uplink power supply wire and the downlink power supply wire.

In an embodiment of the present invention, the auxiliary detection stations include two auxiliary detection stations, the first loop resistance includes a first sub-loop resistance and a second sub-loop resistance between the target station and each auxiliary detection station, the first auxiliary resistance includes a first sub-auxiliary resistance and a second sub-auxiliary resistance between the target station and each auxiliary detection station, and the ground resistance determining module 703 is configured to:

Calculating the grounding resistance of the target station;

In this embodiment of the present invention, the ground resistance determining module 703 is configured to:

The ground resistance detection apparatus according to the embodiment of the present invention may further perform the method performed by the electronic device shown in fig. 1 to 6, and implement the functions of the electronic device in the embodiment shown in fig. 1 to 6, which are not described herein again.

The embodiment of the invention provides a detection device of a ground resistance, which obtains a first auxiliary resistance between a target station to be detected and each auxiliary detection station of at least two auxiliary detection stations, and a second auxiliary resistance between each two auxiliary detection stations of the at least two auxiliary detection stations, wherein the first auxiliary resistance is a resistance of a loop formed by two power supply wires in a traction network between the target station and the auxiliary detection station, the second auxiliary resistance is a resistance of a loop formed by two power supply wires in the traction network between each two auxiliary detection stations of the at least two auxiliary detection stations, the first loop resistance between the target station and each auxiliary detection station of the at least two auxiliary detection stations, and the second loop resistance between each two auxiliary detection stations of the at least two auxiliary detection stations are obtained, the first loop resistance is the resistance of a loop formed by any power supply wire in the traction network and the ground between the target station and the auxiliary detection station, the second loop resistance is the resistance of a loop formed by any power supply wire in the traction network and the ground between every two auxiliary detection stations in at least two auxiliary detection stations, and the ground resistance of the target station is determined based on the first loop resistance, the second loop resistance, the first auxiliary resistance and the second auxiliary resistance. Therefore, the grounding resistance of the target station can be determined directly by acquiring the first loop resistance and the first auxiliary resistance between the target station and the auxiliary detection station and the second loop resistance and the second auxiliary resistance between every two auxiliary detection stations in at least two auxiliary detection stations, and the grounding resistance of each station (ground network) in the rail transit system can be effectively measured without the need that the target station has a large-range test space.

Example four

Figure 8 is a schematic diagram of a hardware configuration of an electronic device implementing various embodiments of the invention,

the electronic device 800 includes, but is not limited to: a radio frequency unit 801, a network module 802, an audio output unit 803, an input unit 804, a sensor 805, a display unit 806, a user input unit 807, an interface unit 808, a memory 809, a processor 810, and a power supply 811. Those skilled in the art will appreciate that the electronic device configuration shown in fig. 8 does not constitute a limitation of the electronic device, and that the electronic device may include more or fewer components than shown, or some components may be combined, or a different arrangement of components. In the embodiment of the present invention, the electronic device includes, but is not limited to, a mobile phone, a tablet computer, a notebook computer, a palm computer, a vehicle-mounted terminal, a wearable device, a pedometer, and the like.

The processor 810 is configured to obtain a first auxiliary resistor between a target station to be detected and each of at least two auxiliary detection stations, and a second auxiliary resistor between every two auxiliary detection stations of the at least two auxiliary detection stations, where the first auxiliary resistor is a resistor of a loop formed by two power supply wires in a traction network between the target station and the auxiliary detection station, and the second auxiliary resistor is a resistor of a loop formed by two power supply wires in the traction network between every two auxiliary detection stations of the at least two auxiliary detection stations;

the processor 810 is further configured to obtain a first loop resistance between the target station and each of the at least two auxiliary detection stations, and a second loop resistance between each of the at least two auxiliary detection stations, where the first loop resistance is a resistance of a loop formed by any one power supply wire in the traction network and the ground between the target station and the auxiliary detection station, and the second loop resistance is a resistance of a loop formed by any one power supply wire in the traction network and the ground between each two auxiliary detection stations in the at least two auxiliary detection stations;

the processor 810 is further configured to determine a ground resistance of the target station based on the first loop resistance, the second loop resistance, the first auxiliary resistance, and the second auxiliary resistance.

In addition, two power supply wires in the traction network comprise an uplink power supply wire and a downlink power supply wire, and a loop formed by the two power supply wires in the traction network further comprises a test lead wire which is used for connecting the uplink power supply wire and the downlink power supply wire.

Additionally, the processor 810 is further configured to formulate a formula based on the first loop resistance, the second loop resistance, the first auxiliary resistance, and the second auxiliary resistance

Calculating the grounding resistance of the target station;

In addition, the processor 810 is further configured to determine a first ground resistance of the target station based on the first loop resistance, the second loop resistance, the first auxiliary resistance, and the second auxiliary resistance;

in addition, the processor 810 is further configured to determine, each time a preset time period is reached, a second ground resistance of the target station based on the obtained third auxiliary resistance between the target station and each of the at least two auxiliary detection stations, a fourth auxiliary resistance between each of the at least two auxiliary detection stations, a third loop resistance between the target station and each of the at least two auxiliary detection stations, and a fourth loop resistance between each of the at least two auxiliary detection stations;

in addition, the processor 810 is further configured to determine a ground resistance of the target site based on the first ground resistance and the second ground resistance.

In addition, the processor 810 is further configured to perform anomaly statistical analysis on the first ground resistance and the second ground resistance, and process the first ground resistance and the second ground resistance according to a result of the anomaly statistical analysis to obtain processed first ground resistance and processed second ground resistance;

in addition, the processor 810 is further configured to determine the ground resistance of the target site based on the processed first ground resistance and the second ground resistance.

The embodiment of the invention provides an electronic device, which obtains a first auxiliary resistor between a target station to be detected and each of at least two auxiliary detection stations, and a second auxiliary resistor between each two auxiliary detection stations of the at least two auxiliary detection stations, wherein the first auxiliary resistor is a resistor of a loop formed by two power supply wires in a traction network between the target station and the auxiliary detection station, the second auxiliary resistor is a resistor of a loop formed by two power supply wires in the traction network between each two auxiliary detection stations of the at least two auxiliary detection stations, obtains a first loop resistor between the target station and each auxiliary detection station of the at least two auxiliary detection stations, and a second loop resistor between each two auxiliary detection stations of the at least two auxiliary detection stations, the first loop resistor is between the target station and the auxiliary detection station, the second loop resistance is the resistance of a loop formed by any power supply wire in the traction network and the ground between every two auxiliary detection stations in the at least two auxiliary detection stations, and the ground resistance of the target station is determined based on the first loop resistance, the second loop resistance, the first auxiliary resistance and the second auxiliary resistance. Therefore, the grounding resistance of the target station can be determined directly by acquiring the first loop resistance and the first auxiliary resistance between the target station and the auxiliary detection station and the second loop resistance and the second auxiliary resistance between every two auxiliary detection stations in at least two auxiliary detection stations, and the grounding resistance of each station (ground network) in the rail transit system can be effectively measured without the need that the target station has a large-range test space.

It should be understood that, in the embodiment of the present invention, the radio frequency unit 801 may be used for receiving and sending signals during a message sending and receiving process or a call process, and specifically, receives downlink data from a base station and then processes the received downlink data to the processor 810; in addition, the uplink data is transmitted to the base station. In general, radio frequency unit 801 includes, but is not limited to, an antenna, at least one amplifier, a transceiver, a coupler, a low noise amplifier, a duplexer, and the like. Further, the radio frequency unit 801 can also communicate with a network and other devices through a wireless communication system.

The electronic device provides wireless broadband internet access to the user via the network module 802, such as to assist the user in sending and receiving e-mails, browsing web pages, and accessing streaming media.

The audio output unit 803 may convert audio data received by the radio frequency unit 801 or the network module 802 or stored in the memory 809 into an audio signal and output as sound. Also, the audio output unit 803 may also provide audio output related to a specific function performed by the electronic apparatus 800 (e.g., a call signal reception sound, a message reception sound, etc.). The audio output unit 803 includes a speaker, a buzzer, a receiver, and the like.

The input unit 804 is used for receiving an audio or video signal. The input Unit 804 may include a Graphics Processing Unit (GPU) 8041 and a microphone 8042, and the Graphics processor 8041 processes image data of a still picture or video obtained by an image capturing device (such as a camera) in a video capturing mode or an image capturing mode. The processed image frames may be displayed on the display unit 806. The image frames processed by the graphics processor 8041 may be stored in the memory 809 (or other storage medium) or transmitted via the radio frequency unit 801 or the network module 802. The microphone 8042 can receive sound, and can process such sound into audio data. The processed audio data may be converted into a format output transmittable to a mobile communication base station via the radio frequency unit 801 in case of a phone call mode.

The electronic device 800 also includes at least one sensor 805, such as light sensors, motion sensors, and other sensors. Specifically, the light sensor includes an ambient light sensor that can adjust the brightness of the display panel 8061 according to the brightness of ambient light and a proximity sensor that can turn off the display panel 8061 and/or the backlight when the electronic device 800 is moved to the ear. As one type of motion sensor, an accelerometer sensor can detect the magnitude of acceleration in each direction (generally three axes), detect the magnitude and direction of gravity when stationary, and can be used to identify the posture of an electronic device (such as horizontal and vertical screen switching, related games, magnetometer posture calibration), and vibration identification related functions (such as pedometer, tapping); the sensors 805 may also include fingerprint sensors, pressure sensors, iris sensors, molecular sensors, gyroscopes, barometers, hygrometers, thermometers, infrared sensors, etc., which are not described in detail herein.

The display unit 806 is used to display information input by the user or information provided to the user. The Display unit 806 may include a Display panel 8061, and the Display panel 8061 may be configured in the form of a Liquid Crystal Display (LCD), an Organic Light-Emitting Diode (OLED), or the like.

The user input unit 807 may be used to receive input numeric or character information and generate key signal inputs related to user settings and function control of the electronic apparatus. Specifically, the user input unit 807 includes a touch panel 8071 and other input devices 8072. The touch panel 8071, also referred to as a touch screen, may collect touch operations by a user on or near the touch panel 8071 (e.g., operations by a user on or near the touch panel 8071 using a finger, a stylus, or any other suitable object or accessory). The touch panel 8071 may include two portions of a touch detection device and a touch controller. The touch detection device detects the touch direction of a user, detects a signal brought by touch operation and transmits the signal to the touch controller; the touch controller receives touch information from the touch sensing device, converts the touch information into touch point coordinates, sends the touch point coordinates to the processor 810, receives a command from the processor 810, and executes the command. In addition, the touch panel 8071 can be implemented by various types such as a resistive type, a capacitive type, an infrared ray, and a surface acoustic wave. In addition to the touch panel 8071, the user input unit 807 can include other input devices 8072. In particular, other input devices 8072 may include, but are not limited to, a physical keyboard, function keys (e.g., volume control keys, switch keys, etc.), a trackball, a mouse, and a joystick, which are not described in detail herein.

Further, the touch panel 8071 can be overlaid on the display panel 8061, and when the touch panel 8071 detects a touch operation on or near the touch panel 8071, the touch operation is transmitted to the processor 810 to determine the type of the touch event, and then the processor 810 provides a corresponding visual output on the display panel 8061 according to the type of the touch event. Although in fig. 8, the touch panel 8071 and the display panel 8061 are two independent components to implement the input and output functions of the electronic device, in some embodiments, the touch panel 8071 and the display panel 8061 may be integrated to implement the input and output functions of the electronic device, and the implementation is not limited herein.

The interface unit 808 is an interface for connecting an external device to the electronic apparatus 800. For example, the external device may include a wired or wireless headset port, an external power supply (or battery charger) port, a wired or wireless data port, a memory card port, a port for connecting a device having an identification module, an audio input/output (I/O) port, a video I/O port, an earphone port, and the like. The interface unit 808 may be used to receive input (e.g., data information, power, etc.) from external devices and transmit the received input to one or more elements within the electronic device 800 or may be used to transmit data between the electronic device 800 and external devices.

The memory 809 may be used to store software programs as well as various data. The memory 809 may mainly include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required by at least one function (such as a sound playing function, an image playing function, etc.), and the like; the storage data area may store data (such as audio data, a phonebook, etc.) created according to the use of the cellular phone, and the like. Further, the memory 809 can include high speed random access memory, and can also include non-volatile memory, such as at least one magnetic disk storage device, flash memory device, or other volatile solid state storage device.

The processor 810 is a transmission center of terminal information, connects various parts of the whole electronic device by various interfaces and lines, performs various functions of the electronic device and processes data by running or executing software programs and/or modules stored in the memory 809 and calling data stored in the memory 809, thereby performing overall monitoring of the electronic device. Processor 810 may include one or more processing units; preferably, the processor 810 may integrate an application processor, which mainly handles operating systems, user interfaces, application programs, etc., and a modem processor, which mainly handles wireless communications. It will be appreciated that the modem processor described above may not be integrated into processor 810.

The electronic device 800 may also include a power supply 811 (e.g., a battery) for powering the various components, and preferably, the power supply 811 may be logically coupled to the processor 810 via a power management system to manage charging, discharging, and power consumption management functions via the power management system.

Preferably, an embodiment of the present invention further provides an electronic device, which includes a processor 810, a memory 809, and a computer program stored in the memory 809 and capable of running on the processor 810, where the computer program is executed by the processor 810 to implement each process of the above-mentioned method for detecting a ground resistance, and can achieve the same technical effect, and in order to avoid repetition, details are not repeated here.

EXAMPLE five

The embodiment of the present invention further provides a computer-readable storage medium, where a computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the computer program implements each process of the above-mentioned method for detecting a ground resistance, and can achieve the same technical effect, and in order to avoid repetition, the detailed description is omitted here. The computer-readable storage medium may be a Read-only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk.

The embodiment of the invention provides a computer-readable storage medium, which obtains a first auxiliary resistance between a target station to be detected and each of at least two auxiliary detection stations, and a second auxiliary resistance between each two auxiliary detection stations of the at least two auxiliary detection stations, wherein the first auxiliary resistance is a resistance of a loop formed by two power supply wires in a traction network between the target station and the auxiliary detection station, the second auxiliary resistance is a resistance of a loop formed by two power supply wires in the traction network between each two auxiliary detection stations of the at least two auxiliary detection stations, the first loop resistance between the target station and each auxiliary detection station of the at least two auxiliary detection stations, and the second loop resistance between each two auxiliary detection stations of the at least two auxiliary detection stations, the first loop resistance is the resistance of a loop formed by any power supply wire in the traction network and the ground between the target station and the auxiliary detection station, the second loop resistance is the resistance of a loop formed by any power supply wire in the traction network and the ground between every two auxiliary detection stations in at least two auxiliary detection stations, and the ground resistance of the target station is determined based on the first loop resistance, the second loop resistance, the first auxiliary resistance and the second auxiliary resistance. Therefore, the grounding resistance of the target station can be determined directly by acquiring the first loop resistance and the first auxiliary resistance between the target station and the auxiliary detection station and the second loop resistance and the second auxiliary resistance between every two auxiliary detection stations in at least two auxiliary detection stations, and the grounding resistance of each station (ground network) in the rail transit system can be effectively measured without the need that the target station has a large-range test space.

As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

In a typical configuration, a computing device includes one or more processors (CPUs), input/output interfaces, network interfaces, and memory.

The memory may include forms of volatile memory in a computer readable medium, Random Access Memory (RAM) and/or non-volatile memory, such as Read Only Memory (ROM) or flash memory (flash RAM). Memory is an example of a computer-readable medium.

Computer-readable media, including both non-transitory and non-transitory, removable and non-removable media, may implement information storage by any method or technology. The information may be computer readable instructions, data structures, modules of a program, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), other types of Random Access Memory (RAM), Read Only Memory (ROM), Electrically Erasable Programmable Read Only Memory (EEPROM), flash memory or other memory technology, compact disc read only memory (CD-ROM), Digital Versatile Discs (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include transitory computer readable media (transmyedia) such as modulated data signals and carrier waves.

It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

The above description is only an example of the present invention, and is not intended to limit the present invention. Various modifications and alterations to this invention will become apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for detecting ground resistance, the method comprising:

2. The method of claim 1, wherein the two power supply wires in the traction network comprise an upstream power supply wire and a downstream power supply wire, and wherein the loop formed by the two power supply wires in the traction network further comprises a test lead for connecting the upstream power supply wire and the downstream power supply wire.

3. The method of claim 2, wherein the auxiliary detection stations comprise two, wherein the first loop resistance comprises a first sub-loop resistance and a second sub-loop resistance between the target station and each of the auxiliary detection stations, wherein the first auxiliary resistance comprises a first sub-auxiliary resistance and a second sub-auxiliary resistance between the target station and each of the auxiliary detection stations,

the determining the ground resistance of the target station based on the first loop resistance, the second loop resistance, the first auxiliary resistance and the second auxiliary resistance comprises:

Calculating the grounding resistance of the target station;

4. The method of any one of claims 1-3, wherein the determining the ground resistance of the target site based on the first loop resistance, the second loop resistance, the first auxiliary resistance, and the second auxiliary resistance comprises:

5. The method of claim 4, wherein determining the ground resistance of the target station based on the first ground resistance and the second ground resistance comprises:

6. A device for detecting ground resistance, the device comprising:

7. The apparatus of claim 6, wherein the two power supply wires in the traction network comprise an upstream power supply wire and a downstream power supply wire, and wherein the loop formed by the two power supply wires in the traction network further comprises a test lead for connecting the upstream power supply wire and the downstream power supply wire.

8. The apparatus of claim 7, wherein the auxiliary test sites comprise two, the first loop resistance comprises a first sub-loop resistance and a second sub-loop resistance between the target site and each of the auxiliary test sites, the first auxiliary resistance comprises a first sub-auxiliary resistance and a second sub-auxiliary resistance between the target site and each of the auxiliary test sites, and the ground resistance determination module is configured to:

Calculating the grounding resistance of the target station;

9. The apparatus of any one of claims 6-8, wherein the ground resistance determination module is configured to:

10. The apparatus of claim 9, wherein the ground resistance determination module is configured to:

11. An electronic device, characterized in that it comprises a processor, a memory and a computer program stored on the memory and executable on the processor, the computer program, when executed by the processor, implementing the steps of the method for detecting the ground resistance according to any one of claims 1 to 5.

12. A computer-readable storage medium, characterized in that a computer program is stored on the computer-readable storage medium, which computer program, when being executed by a processor, realizes the steps of the method for detecting a resistance of earth ground as claimed in any one of claims 1 to 5.