METHOD FOR DETERMINING A GROUNDING RESISTANCE, GROUNDING RESISTANCE SURVEILLANCE SYSTEM AND MEASUREMENT DEVICE

Abstract

A grounding resistance surveillance system comprises a plurality of measurement devices configured for measuring a grounding resistance value and being arrangeable at different locations within a target area, and at least one gateway device. Each of the plurality of gateway devices is communicatively coupled to at least one further measurement device of the plurality of measurement devices, and at least one measurement device of the plurality of measurement devices is in direct communication to the at least one gateway device and at least one measurement device of the plurality of measurement devices is only in indirect communication to the at least one gateway device such that a mesh network of coupled measurement devices is formed. The grounding resistance surveillance system is configured to execute a method for determining a grounding resistance in the target area.

Further, a measurement device for a grounding resistance surveillance system is described.

Claims

1. A method for determining a grounding resistance in a target area, the method comprising the following steps: a) Providing a grounding resistance surveillance system with a plurality of measurement devices configured for measuring a grounding resistance value and being arranged at different locations within the target area, and at least one gateway device, wherein each of the plurality of measurement devices is communicatively coupled to at least one further measurement device of the plurality of measurement devices, and wherein at least one measurement device of the plurality of measurement devices is in direct communication with the at least one gateway device and at least one measurement device of the plurality of measurement devices is only in indirect communication with the at least one gateway device such that a mesh network of coupled measurement devices is formed; b) Measuring a grounding resistance value by each of the plurality of measurement devices at a pre-determined time stored in a control module of the respective measurement device; c) Forwarding the measured grounding resistance values to the gateway device; d) Forwarding, by the gateway device, an updated pre-determined time to the plurality of measurement devices; and e) Repeating steps b) to d) at least once with the pre-determined time being the updated pre-determined time.

2. The method of claim 1, wherein the grounding resistance surveillance system further comprises a central computation device communicatively coupled to the at least one gateway device and wherein the measured grounding resistance values are sent by the at least one gateway device to the central computation device.

3. The method of claim 2, wherein the measured grounding resistance values are sent by the at least one gateway device to the central computation device only when a measured grounding resistance value has been received by the at least one gateway device from each of the plurality of measurement devices.

4. The method of claim 1, wherein the difference between the pre-determined time and the updated pre-determined time is 24 hours or more.

5. The method of claim 1, wherein the measurement devices forward a confirmation message to the at least one gateway device when the updated pre-determined time has been received.

6. The method of claim 1, wherein the at least one gateway device comprises a seismic sensor for detecting seismic activity in the target area and, if a magnitude of the seismic activity detected by the seismic sensor is larger than a magnitude threshold value stored in a memory of the gateway device, the at least one gateway device forwards an alarm signal to the plurality of measurement devices.

7. Grounding resistance surveillance system comprising a plurality of measurement devices configured for measuring a grounding resistance value and being arrangeable at different locations within a target area, and at least one gateway device, wherein each of the plurality of measurement devices is communicatively coupled to at least one further measurement device of the plurality of measurement devices, and wherein at least one measurement device of the plurality of measurement devices is in direct communication to the at least one gateway device and at least one measurement device of the plurality of measurement devices is only in indirect communication to the at least one gateway device such that a mesh network of coupled measurement devices is formed, the grounding resistance surveillance system being configured to execute the method of claim 1.

8. The grounding resistance surveillance system of claim 7, wherein the measurement devices are free from user interfaces.

9. The grounding resistance surveillance system of claim 7, wherein the at least one gateway device of the grounding resistance surveillance system is connected to an external power source.

10. Measurement device for measuring a grounding resistance value for use in a grounding resistance surveillance system according to claim 7.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Further advantages and features of the present disclosure will become more apparent from the following description of preferred embodiments of the present disclosure and from the Figures. In the Figures,

[0048] FIG. 1 shows a schematic depiction of a grounding resistance surveillance system according to an embodiment of the present disclosure with a plurality of measurement devices according to an embodiment of the present disclosure, and

[0049] FIG. 2 shows a block scheme of a method for determining a grounding resistance in a target area according to an embodiment of the present disclosure using the grounding resistance surveillance system of FIG. 1.

DETAILED DESCRIPTION

[0050] The detailed description set forth below in connection with the appended drawings, where like numerals reference like elements, is intended as a description of various embodiments of the disclosed subject matter and is not intended to represent the only embodiments. Each embodiment described in this disclosure is provided merely as an example or illustration and should not be construed as preferred or advantageous over other embodiments. The illustrative examples provided herein are not intended to be exhaustive or to limit the claimed subject matter to the precise forms disclosed.

[0051] For the purposes of the present disclosure, the phrase at least one of A, B, and C, for example, means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C), including all further possible permutations when more than three elements are listed. In other words, the term at least one of A and B generally means A and/or B, namely A alone, B alone or A and B.

[0052] FIG. 1 shows a schematic depiction of a grounding resistance surveillance system 10 which comprises a plurality of measurement devices 12 to 22 distributed throughout a target area 24.

[0053] The target area 24 is an area to be surveilled by the grounding resistance surveillance system 10, e.g. a plant facility with one or more (not shown) plant structures which are protected by lightning protection systems, like a building. To each plant structure, at least one of the measurement devices 12 to 22 is associated.

[0054] Each of the measurement devices 12 to 22 comprises a grounding resistance sensor 26 capable of measuring a ground resistance value at the location at which the respective measurement device 12 to 22 is installed.

[0055] Further, each of the measurement devices 12 to 22 has a control module 28, an internal energy storage 30 and a communication module 32.

[0056] The control module 28 controls the operation of the respective measurement device 12 to 22. Especially, the control module 28 is configured to switch the control module 28 between an active mode and a sleep mode, wherein in the sleep mode some or all components of the measurement device 12 to 22 other than the control module 28 are disconnected from the internal energy storage 30. Thus, only the control module 28 and selected other components of the measurement device 12 to 22 needs to be powered by the internal energy storage 30 in the sleep mode, reducing the overall energy consumption of the measurement device 12 to 22.

[0057] In the active mode, the measurement device 12 to 22 can obtain ground resistance values via the ground resistance sensor 26 and communicate with further devices in the grounding resistance surveillance system 10 via the communication module 32.

[0058] In the control module 28, a pre-determined time is stored at which the control module 28 switches the measurement device 12 to 22 from the sleep mode in the active mode and takes a grounding resistance measurement, as will be described in more detail later on.

[0059] It is also possible that the measurement device 12 to 22 comprises one or more additional sensor elements other than the ground resistance sensor 26 for obtaining additional measurement values in the active mode. E.g., the additional sensor elements are configured to measure a pH, a temperature and/or a humidity value.

[0060] The measurement device 12 to 22 does not comprise any user interface like speakers or displays such that a user of the grounding system surveillance system 10 cannot directly access any data collected by the measurement device 12 to 22.

[0061] This allows to further minimize the energy consumption of the measurement device 12 to 22, such that an exchange of the internal energy storage 30 can be avoided as long as possible to reduce the amount of maintenance necessary to reliably run the grounding system surveillance system 10.

[0062] The grounding system surveillance system 10 further comprises two gateway devices 34 and 36.

[0063] Each gateway device 34 and 36 comprises a gateway control module 37, an internal gateway energy storage 38, a memory 39, a gateway communication module 40 and a seismic sensor 42.

[0064] The gateway control module 37 is configured to operate the other components of the gateway device 34, 36.

[0065] The gateway device 34 is further operably connected with an external power source 44 which is capable of providing the gateway device 34 with electricity such to be operable. That is, even in case the internal gateway energy storage 38 of the gateway device 34 is fully discharged, operation of the gateway device 34 is ensured by the external power source 44. In principle, the gateway device 34 could also have no internal gateway energy storage 38 and only rely on the power supply by the external power source 44. The external power source e.g. provides a voltage in the range of from 9 to 36 V.

[0066] In contrast, the gateway device 36 only comprises an internal gateway energy storage 38 but is not connected to an external power source. Thus, though the operation of the gateway device 36 can only be ensured by the internal gateway energy storage 38, the gateway device 36 can be more flexibly placed within the target area 24, as there is no need for a connection to an external power source.

[0067] It is also possible that one or all of the gateway devices 34, 36 are placed outside the target area 24, as long as at least one of the measurement devices 12 to 22 can still establish a direct communication link to the respective gateway device 34, 36.

[0068] In the shown embodiment, two gateway devices 34 and 36 are used. However, the grounding system surveillance system 10 can also only have a single gateway device, which preferably is the gateway device 34 connected to the external power source 44, or more than two gateway devices 34, 36.

[0069] Further, the grounding system surveillance system 10 can comprise more or less measurement devices 12 to 22 than shown in FIG. 1. The number of measurement devices 12 to 22 especially is dependent on the size of the target area 24 and/or the number of plant structures within the target area 24 which are to be protected against lightning strikes and therefore should be supervised in terms of the grounding resistance.

[0070] The measurement devices 12 to 22 are bi-directionally communicatively coupled to each other by the respective communication modules 32, as indicated by double-arrows in FIG. 1.

[0071] However, not every single measurement device 12 to 22 is directly coupled to each other measurement device 12 to 22. Instead, some of the measurement devices 12 to 22 are only indirectly coupled to each other, wherein at least one further measurement device can serve in a relay-like manner to enable communication between the indirectly coupled measurement devices.

[0072] E.g., measurement device 12 is directly coupled to measurement devices 14 and 16, but only indirectly coupled to measurement devices 18, 20 and 22.

[0073] Overall, the measurement devices 12 to 22 form a mesh network of measurement devices.

[0074] Further, the measurement device 12 is directly bi-directionally communicatively coupled to the gateway device 34 and the measurement device 22 is directly bi-directionally communicatively coupled to the gateway device 36, as is also indicated by the double-arrows in FIG. 1. More specifically, the respective communication modules 32 and gateway communication modules 40 are communicatively coupled.

[0075] In contrast, the measurement devices 14 to 20 are only indirectly bi-directionally communicatively coupled to the gateway devices 34 and 36, wherein at least one further measurement device serves as a relay station.

[0076] Of course, the number of directly and indirectly to the gateway devices 34, 36 coupled measurement devices 12 to 22 can be different than in the shown embodiment. However, according to the present disclosure, at least one measurement device 12 to 22 is directly coupled to at least one of the gateway devices 34, 36 and at least one measurement device 12 to 22 is only indirectly coupled to the gateway devices 34, 36.

[0077] Further, the measurement devices 12 to 18 are generally associated to the gateway device 34, while the measurement devices 20 and 22 are generally associated to the gateway device 36. Generally associated here defines that the respective measurement devices preferentially communicate with the associated gateway device and only communicate with the other gateway device by using an altered relay path including further measurement devices, if the associated gateway device cannot be reached. This is indicated in FIG. 1 by the dot-dashed double arrows between the measurement device 14 and the measurement devices 20 and 22.

[0078] Thus, each of the gateway devices 34, 36 is responsible for an associated number of measurement devices. The maximum number of measurement devices associated to a single gateway device 34, 36 can be limited to a pre-determined group number, e.g. to a maximum of up to 255 different measurement devices.

[0079] Within the target area 24, further components can be arranged which are also communicatively coupled to the gateway device 34 and/or 36. In the embodiment shown in FIG. 1, an exemplary sensor device 45 configured to obtain measurement data other than grounding resistance values, e.g. temperature, humidity and/or pH values, is shown. The sensor device 45 is bi-directionally and communicatively coupled to the gateway device 34.

[0080] The grounding resistance surveillance system 10 further comprises a central computation device 46 which in the shown embodiment comprises a server unit 48 and a user interface 50.

[0081] The server unit 48, and therefore the central computation device 46, is bi-directionally communicatively coupled to each of the gateway devices 34 and 36, as indicated by double-arrows in FIG. 1.

[0082] The server unit 48 is located outside the target area 24 and provides e.g. an Internet-of-Things environment (IoT-environment) which is generally accessible via the internet and/or a local network structure, e.g. by the user interface 50.

[0083] In the following, the mode of action of the grounding system surveillance system 10 will be described in the framework of a method for determining the grounding resistance in the target area 24.

[0084] First, the grounding resistance surveillance system 10 as described before is provided, wherein the measurement devices 12 to 22 are placed distributed throughout the target area 24 (step S1 in FIG. 2).

[0085] E.g., the measurement devices 12 to 22 are each connected to a (not shown) main earthing connection of the plant structure the respective measurement device 12 to 22 is associated to.

[0086] Within the control module 28 of each of the measurement devices 12 to 22, a pre-determined time is stored at which a first measurement of the grounding resistance value at the location of the measurement devices 12 to 22 is to be started.

[0087] The pre-determined time can be set by the user of the grounding resistance surveillance system 10 via the user interface 50 and then forwarded via the gateway device 34, 36 to each of the measurement devices 12 to 22. Thus, each of the measurement devices 12 to 22 receives the same pre-determined time.

[0088] For synchronizing the operation of the measurement devices 12 to 22, the control module 28 of the measurement devices 12 to 22 can comprise a real-time clock (RTC). If further synchronization is necessary, the RTCs of all measurement devices 12 to 22 can be coordinated by the server unit 48 acting as NTP server (network time protocol server).

[0089] At the pre-determined time, each of the plurality of measurement devices 12 to 22 measures a grounding resistance value (step S2 in FIG. 2).

[0090] For this, the control module 28 switches the measurement device 12 to 22 from its sleep mode to its active mode such that the grounding resistance value can be measured via the grounding resistance sensor 26.

[0091] The grounding resistance value can be determined by any known method for determining a grounding resistance, e.g. a 3-pole method. Preferably, the measurement does not exceed a measurement time of one minute such to reduce the time in which the measurement device 12 to 22 needs to be in the active mode as much as possible.

[0092] The obtained measured grounding resistance value is then forwarded to the gateway device 34, 36 associated to the respective measurement device 12 to 22 (step S3 in FIG. 2).

[0093] However, the communication path for a given measurement device 12 to 22 used for forwarding the measured grounding resistance value depends on its position within the mesh network of measurement devices 12 to 22.

[0094] Measurement devices 12 and 22 are directly coupled to the gateway device 34 and 36, respectively, and thus can directly send the measured grounding resistance value to the respective gateway device 34 and 36.

[0095] In contrast, measurement devices 14 to 20 are only indirectly coupled to any of the gateway devices 34 and 36 and thus forward the measured grounding resistance values over a relay path to the associated gateway device 34 to 36.

[0096] E.g., measurement device 18 sends its measured grounding resistance value to measurement device 14, which in turn sends both the measured grounding resistance value of measurement device 14 and the measured grounding resistance value of measurement device 18 to measurement device 12. Measurement device 12 then sends all of the received measured grounding resistance values to the gateway device 34.

[0097] The relay path chosen by any given measurement device 14 to 20 can be chosen according to the proximity of the measurement devices 12 to 22 to each other, the signal strength of the communication link between the measurement devices 12 to 22 and/or the gateway device 34, 36 to which the respective measurement device 14 to 20 is associated.

[0098] The chosen relay path does not necessarily correspond to the overall shortest distance between two given measurement devices 12 to 22. Termed differently, the overall relay path can be longer than the shortest distance. E.g., measurement device 16 can use a relay path including measurement devices 18, 14 and 12 instead of a relay path in which measurement device 16 directly communicates with measurement device 12. Due to the meshed structure of the mesh network, the grounding resistance surveillance system 10 provides a high flexibility in the communication and relay pathways actually used for forwarding data.

[0099] Together with the grounding measurement value, at least one additional information can be forwarded by the respective measurement device 12 to 22. The additional information can include a measurement device identifier, a status of the internal energy storage 30, a time-stamp and/or a relay path identifier.

[0100] The gateway devices 34 and 36 collect the measured grounding resistance values and send the measured grounding resistance values to the central computation device 46.

[0101] Preferably, the gateway device 34, 36 waits for sending the measured grounding resistance values until the gateway device 34, 36 has received a measured grounding resistance value for each of the measurement devices 12 to 22 associated to the respective gateway device 34, 36. Thus, the gateway device 34, 36 only needs one data transfer to the central computation device 46, such that the energy consumption of the gateway device 34 and 36 can be minimized.

[0102] If any additional values like additional sensor values have been collected by the measurement devices 12 to 22 and/or the sensor device 45, these values are also sent by the gateway device 34, 36 to the central computing unit 46, preferably together with the measured grounding resistance values.

[0103] The gateway devices 34 and 36 then determine an updated pre-determined time which is the time at which the next measurement of the grounding resistance values shall take place. The updated pre-determined time is especially determined such that a difference between the pre-determined time and the updated pre-determined time is 20 hours or more. E.g., the updated pre-determined time is chosen such that the next measurement of grounding resistance values is taken 24 hours after the current measurement has been started.

[0104] In principle, the updated pre-determined time can also be determined by the central computation device 46 and sent to the gateway devices 34, and 36.

[0105] The updated pre-determined time is then forwarded by the gateway device 34, 36 to the plurality of measurement devices 12 to 22 (step S4 in FIG. 2).

[0106] The updated pre-determined time is especially distributed within the mesh network of measurement devices 12 to 22 by using the same relay paths which have been used for forwarding the measured grounding resistance values to the gateway devices 34 and 36, but in opposite direction. However, it is also possible that the updated pre-determined time is distributed within the mesh network using different relay paths, as long as the updated pre-determined time can be forwarded to every measurement device 12 to 22.

[0107] As soon as the updated pre-determined time is received by a measurement device 12 to 22, the respective measurement device 12 to 22 can forward a confirmation message to the associated gateway device 34, 36, the confirmation message being indicative for a successful transmission of the updated pre-determined time.

[0108] If the gateway device 34, 36 does not receive a confirmation message from all associated measurement devices 12 to 22 within a defined waiting period, the gateway device 34, 36 can forward the updated pre-determined time again.

[0109] After the updated pre-determined time has been received by the measurement devices 12 to 22, the control module 28 can set the respective measurement device 12 to 22 back to the sleep mode in which only the control module 28 or the control module 28 and a selected number of components is powered by the internal energy storage 30 such to minimize the energy consumption of the measurement devices 12 to 22.

[0110] When the updated pre-determined time is reached, the above-described steps are repeated with the pre-determined time being the updated pre-determined time. Thus, further grounding resistance values will be determined and forwarded, a further updated pre-determined time will be determined etc. In this way, the grounding system surveillance system 10 provides grounding system values on a regular basis in a highly-automated manner.

[0111] The central computation device 46 thus collects and stores a history of grounding resistance values which can be inspected by the user of the grounding system surveillance system 10.

[0112] Further, the central computation device 46 can analyze the grounding resistance values for identifying trends which allow to draw conclusions on the state of the target area 24, especially the plant structures within the target area 24.

[0113] As described before, the gateway device 34, 36 comprises a seismic sensor 42. In case a seismic event occurs in the target area 24, the grounding resistance values obtained by the measurement devices 12 to 22 can be distorted, which can negatively affect long-term evaluations of the grounding resistance values stored in the central computation device 46.

[0114] Thus, if a magnitude of a seismic activity detected by the seismic sensor 42 is larger than a magnitude threshold value stored in the memory 39 of the gateway device 34, 36, the gateway device 34, 36 forwards an alarm signal to the plurality of measurement devices 12 to 22, i.e. throughout the mesh network of measurement devices 12 to 22.

[0115] In addition, an alarm signal can also be sent to the central computation device 46 such to inform the user of the grounding resistance surveillance system about the seismic event.

[0116] Upon receiving the alarm signal, the control module 28 keeps the measurement devices 12 to 22 in the sleep mode until a re-start signal is received from the gateway device 34, 36. In consequence, the measurement devices 12 to 22 will not measure grounding resistance values until the re-start signal has been received.

[0117] It is also possible that an additional alarm signal is sent to the further device 45 which also stops measuring values upon receiving the alarm signal until a re-start signal is received.

[0118] The re-start signal is forwarded by the gateway device 34, 36 after the magnitude of the seismic activity is lowered below the magnitude threshold value again and/or after a pre-determined seismic delay time after a seismic activity with a magnitude larger than the magnitude threshold value has been detected.

[0119] If the re-start signal is forwarded at a point in time which is later than the current pre-determined time stored in the measurement devices 12 to 22, an updated pre-determined time is forwarded by the gateway device 34 and 36 together with the re-start signal.

[0120] Thus, normal operation of the grounding resistance surveillance system 10 can be resumed.

[0121] Overall, the grounding resistance surveillance system 10 according to the present disclosure provides for an easy and reliable method for obtaining grounding resistance values. The grounding resistance surveillance system can operate in a highly-automated manner and has low demands regarding maintenance.

[0122] Certain embodiments disclosed herein, particularly the respective module(s) and/or unit(s), utilize circuitry (e.g., one or more circuits) in order to implement standards, protocols, methodologies or technologies disclosed herein, operably couple two or more components, generate information, process information, analyze information, generate signals, encode/decode signals, convert signals, transmit and/or receive signals, control other devices, etc. Circuitry of any type can be used.

[0123] In an embodiment, circuitry includes, among other things, one or more computing devices such as a processor (e.g., a microprocessor), a central processing unit (CPU), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a system on a chip (SoC), or the like, or any combinations thereof, and can include discrete digital or analog circuit elements or electronics, or combinations thereof. In an embodiment, circuitry includes hardware circuit implementations (e.g., implementations in analog circuitry, implementations in digital circuitry, and the like, and combinations thereof).

[0124] In an embodiment, circuitry includes combinations of circuits and computer program products having software or firmware instructions stored on one or more computer readable memories that work together to cause a device to perform one or more protocols, methodologies or technologies described herein. In an embodiment, circuitry includes circuits, such as, for example, microprocessors or portions of microprocessor, that require software, firmware, and the like for operation. In an embodiment, circuitry includes one or more processors or portions thereof and accompanying software, firmware, hardware, and the like.

[0125] The present application may reference quantities and numbers. Unless specifically stated, such quantities and numbers are not to be considered restrictive, but exemplary of the possible quantities or numbers associated with the present application. Also in this regard, the present application may use the term plurality to reference a quantity or number. In this regard, the term plurality is meant to be any number that is more than one, for example, two, three, four, five, etc. The terms about, approximately, near etc., mean plus or minus 5% of the stated value.