Voltage warning device and method for protection against electric shock in a flooded area

Description

[0001] The invention relates to a voltage warning device and a method for protecting against electric shock in a flooded area containing electrical equipment.

[0002] Due to heavy rainfall events, rescue services such as firefighters are increasingly confronted with operations in flooded areas. Often, the premises of private households or industrial buildings are flooded with water due to overflowing sewers or rivers overflowing their banks. Direct entry into the flooded areas is often unavoidable, especially when saving lives. The incoming water is often highly contaminated, resulting in poor underwater visibility and increased electrical conductivity.

[0003] In connection with electrical systems, there is a high risk of electric shock in flooded areas. It is often unknown which parts of the system are live, because depending on the type of building, electrical installations can be at different voltage levels, from a simple electrical outlet to a grid feed-in. A safe shutdown of the electrical system, e.g., by the responsible energy supplier, is not always feasible in a timely manner. If electrical energy storage units or inverters for PV systems are installed, shutdown is often not possible.

[0004] Not only entering the flooded area directly, but also moving within it is dangerous, especially if the person in the water inadvertently moves along electric field lines with corresponding potential differences (voltages). If a current flows through the human body as a result of body parts coming into contact with the water, adverse physiological effects must be expected in conjunction with the increased conductivity of the water. These effects manifest themselves, for example, in the form of strong involuntary muscle contractions, difficulty breathing, or reversible disturbances in cardiac function.

[0005] For personal protection, voltage testers are known from the state of the art, which are intended to increase safety in such operational situations.

[0006] These voltage testers, such as the P2 voltage warning device from Martina Zimmermann GmbH (https: / / zimmermann.expert / unser-p2 / ) or the DSP-HW 2 model from Rudolph Tietzsch GmbH & Co. KG (https: / / www.tietzsch.de / produkt / dsp-hw-2-fuer-hochwasser / or https: / / en.tietzsch.de / produkt / dsp-hw-2-for-flooded-installations / ), are based on a two-pole voltage measurement with earth potential as the reference potential. These devices feature a grounding cable with a grounding clamp or grounding rod to provide the ground potential, as well as a measuring probe that is held or placed in the water.

[0007] The main disadvantage of this technical design is the mandatory requirement for reliable grounding as a measurement reference potential. Depending on the soil conditions and structural conditions in the surrounding area, grounding is neither practically easy nor electrically safe, for example, in dry soil or if metal parts of the building are not connected to a foundation earth electrode. As a result, the trigger thresholds of the measuring devices can be shifted, meaning that hazardous voltages are only detected when the limit values ​​are significantly exceeded, or in the worst case, not detected at all.

[0008] Another disadvantage is the measurement method itself. Since the measuring probe only detects a single potential measurement point of a potentially prevailing electric flow field, this single measurement is not very representative of the potential distribution in the entire flooded area. In the worst case, no potential difference to the ground potential would be detectable if the measuring probe (potential measurement point) were located on an equipotential surface with ground potential, comparable to a symmetrical star point without an N-conductor connection in a three-phase network.

[0009] It is also a hindrance that the well-known voltage testers either have to be held, carried or constantly moved to secure locations, meaning that the hands are not always free for the actual work.

[0010] Document US2017 / 0109994A1 discloses a voltage warning device for protection against electric shock.

[0011] The present invention is therefore based on the object of proposing a voltage warning device and a method for protection against electric shock in a flooded area with electrical equipment, which, in addition to reliable detection of the danger posed by electrical voltages, enable simplified handling.

[0012] This object is achieved with a voltage warning device for protection against electric shock in a flooded area with electrical devices according to claim 1.

[0013] For this purpose, the voltage warning device has a number n of measuring probes which are distributed in the flooded area and, as potential measuring points, each have a measuring potential for determining an electrical potential distribution in the flooded area.

[0014] In contrast to prior art designs with only a single measuring probe, the voltage warning device proposed here comprises multiple measuring probes, which, due to their spatially distributed arrangement, can map an electric flow field in the flooded area. The electric flow field is described by an electric potential distribution resulting from the relative reference potential specified by a reference probe, which is independent of the ground potential, and the measuring potentials recorded by the remaining measuring probes as additional potential measuring points.

[0015] Each measuring probe consists of a buoyant body with several measuring electrodes distributed across the outer surface of the body, each with a different electrode potential. This ensures direct contact with the water surface, allowing reliable measurement of the electrical potentials in the immediate vicinity of the respective measuring probe.

[0016] The measuring probes each include an electronic unit and a signal generator.

[0017] The electronic units process the measured electrode potentials on a digital level and can be designed differently depending on the function of the measuring probe (measuring probe with or without reference function) (see below).

[0018] The signaling devices emit warnings in the form of visual or acoustic signals indicating voltage levels that are hazardous to persons and / or directional information about voltage changes.

[0019] The measuring probes are connected to each other via connecting cable sections and thus form a probe chain that floats on the water surface.

[0020] The connecting cable sections establish both an electrical and a mechanical connection between the measuring probes.

[0021] By designating one of the measuring probes, preferably the first or the last measuring probe in the probe chain, as a reference probe, i.e. by defining its measuring potential as a relative reference potential for detecting measuring potential differences compared to the other measuring probes, there is no need to connect to an external, possibly difficult to access and electrically unsafe grounding point.

[0022] This eliminates the problem of insecure ground connections. Furthermore, handling such a voltage warning device during use is significantly simplified.

[0023] Advantageously, the electronics unit of the measuring probes not designed as reference probes has an analog-digital converter for converting the electrode potentials recorded at the relevant measuring electrodes into digital signals.

[0024] With the exception of the reference probe, each measuring probe is equipped with an analog-to-digital converter to transmit the recorded electrode potentials in digital form and thus make them accessible for evaluation by digital signal processing methods.

[0025] Furthermore, the electronics unit of the reference probe has a microcontroller for central digital signal processing.

[0026] All evaluation and control processes take place centrally in the microcontroller of the reference probe.

[0027] In further advantageous embodiments, the microcontroller is configured to detect a measuring potential difference compared to the reference potential at the measuring probes that are not designed as reference probes.

[0028] After commissioning, the microcontroller continuously checks the measurement potentials for the probes not configured as reference probes to determine whether the measurement potential detected by the respective probe exhibits a measurement potential difference compared to the reference potential (long-range evaluation). If a preset measurement potential difference limit is exceeded, the signal generator of the corresponding probe is notified via the connecting cable and signaled visually and / or acoustically.

[0029] Furthermore, the microcontroller is configured to calculate the measuring potential for the measuring probes that are not designed as reference probes from the electrode potentials recorded at the measuring electrodes of the respective measuring probe.

[0030] To calculate the measuring potential of each measuring probe – excluding the reference probe – a representative measured value for this measuring probe is determined from the electrode potentials recorded at the measuring electrodes of the respective measuring probe, for example, by averaging, as the measuring potential (short-range evaluation). The measuring potentials thus determined at the locations of the measuring probes (potential measuring points) result in the potential distribution, from which further calculations, such as the determination of an electric field strength vector (gradient generation), can be derived.

[0031] Furthermore, the microcontroller is configured to calculate the direction of the largest voltage change from the potential distribution using gradient formation.

[0032] From the potential distribution—represented by the individual measuring potentials of the measuring probes—the direction of the greatest voltage change is calculated using gradient formation. From the spatial change in the electrical potential, i.e., the measuring potential at the location of a specific measuring probe, the electric field strength and thus the direction of the greatest voltage change can be determined and signaled using the signal generators. In this way, the danger posed by electrical current can be not only detected but also located.

[0033] Furthermore, the microcontroller is configured to generate control signals for the signal generators to signal an exceedance of a presettable measuring potential difference limit value.

[0034] In addition to digital signal processing for evaluating the recorded electrode potentials, the microcontroller generates control signals that trigger the signal transmitters of the measuring probes to signal when a presettable measurement potential difference limit has been exceeded. The presettable measurement potential difference limit can be adjusted to suit the hazard levels.

[0035] Furthermore, the reference probe can be connected to a defined earth potential as a reference potential via an earth wire.

[0036] Although the function of the reference potential is fulfilled by the relative reference potential determined by the reference probe, which is independent of the earth potential, it is still possible to connect this reference potential to the earth potential via an earth wire.

[0037] Preferably, the reference probe has an energy storage device for supplying energy to the measuring probes.

[0038] The measuring probes are powered by an energy storage device designed as a rechargeable storage element (accumulator) or as a battery, which is preferably arranged in the reference probe and connected to the other measuring probes via a supply line.

[0039] Preferably, a connecting line consisting of the connecting line sections comprises a communication line, a ground conductor and a supply line.

[0040] The connecting cable has a ground conductor that can optionally be connected to the earth potential via the earth wire.

[0041] Preferably, the communication line is configured for data transmission of the digital electrode potentials and the control signals.

[0042] The transmission of the digital electrode potentials and the control signals takes place in digital form, for example via a communication line designed as RS485, SPI bus or CAN bus.

[0043] Preferably, the buoyant bodies are spherical and made of translucent plastic, wherein the signal transmitter is a sound transducer and / or a lighting device radiating through the translucent plastic with different color representation and several lighting modes for signaling different danger levels.

[0044] The transparent plastic material allows the floating bodies to be equipped with internal lighting devices that illuminate in different colors and with different lighting modes depending on whether a preset measurement potential difference limit is exceeded, i.e. according to the different danger levels - for example, in continuous green lighting when the voltage level in the flooded area is safe, with a red flashing light in case of danger, and as a running light to signal the direction of the greatest voltage change (gradient).

[0045] The voltage warning device according to the invention described above implements the method steps described in independent method claim 14. In this respect, the aforementioned technical effects and resulting process-related advantages also apply to the method features.

[0046] Further advantageous design features will become apparent from the following description and the drawings, which illustrate a preferred embodiment of the invention using examples. They show: Fig. 1: a voltage warning device according to the invention, Fig. 2: a voltage warning device according to the invention with potential distribution in a flooded area, Fig. 3: a functional block diagram of the voltage warning device according to the invention, Fig. 4: Simulation of the potential distribution with a socket under water, Fig. 5: Simulation of the potential distribution with two sockets under water and Fig. 6: Simulation of the potential distribution with a socket with only one active conductor under water.

[0047] In order to clarify the problem underlying the present invention, the Fig. 4 bis 6 First, simulation results of distributions of the electrical potential 19 in an area 50 flooded with contaminated water are shown. The basis is a room flooded with contaminated water with a base area of ​​5m*5m, in which a ( Fig. 4 ) or two ( Fig. 5 ) 230V sockets and one 230V socket with only one active conductor ( Fig. 5 ) is / are recreated underwater.

[0048] Especially in Fig. 4 und Fig. 6 With only one voltage source - considered as a point source - an almost circular course of the potential distribution 19 with equipotential lines 60 and a gradient 62 of the electric field strength perpendicular to the equipotential lines 60 can be seen.

[0049] Under these assumptions, voltage levels that are hazardous to persons are reached over large areas. Reliable detection of potential differences (voltages) therefore appears essential.

[0050] Fig. 1 shows a voltage warning device 2 according to the invention with n=4 measuring probes 4, which are connected to one another via connecting cable sections 30 to form a probe chain 40. The distances between the individual measuring probes 4 should be between 0.5 m and 2 m. However, the number of measuring probes 4 and the distances can vary depending on the location.

[0051] The measuring probes 4 are designed as buoyant bodies 7, on whose outer surfaces measuring electrodes 6 are arranged, which ensure direct electrical contact with the water in the flooded area 50 ( Fig. 2 ). The measuring electrodes 6 should be made of rust-proof metals, such as stainless steel or brass.

[0052] The measuring probes 4 are preferably spherical and made of translucent plastic, so that a signal generator 26 located inside the measuring probe 4 and designed as a lighting device can emit warnings visible from the outside.

[0053] Each measuring electrode 6 of each measuring probe 4 has a specific electrode potential 16, wherein one of the measuring probes 6 acts as a reference probe 5, whose measuring electrodes 6 as reference electrodes 15 all have an identical electrode potential 16, which corresponds to a relative reference potential 17 as measuring potential 14 of the reference probe 5 without connection to an earth potential PE.

[0054] Although the provision of a relative reference potential 17 independent of the earth potential PE represents an essential aspect of the invention, it is possible to set the relative reference potential 17 to an absolute reference potential with earth potential PE by means of an earth line 39.

[0055] The measuring probes 4 as well as the connecting cable consisting of the connecting cable sections 30 should have protection class IP68 (dust and watertight).

[0056] The connecting cable sections can be reinforced with inserts and at the same time act as a flexible mechanical connection between the measuring probes.

[0057] Fig. 2 shows the voltage warning device 2 in a flooded area 50 with a simulated voltage source under water and the resulting potential distribution 19. At the locations of the measuring probes 4, a measuring potential 14 is determined according to the resulting potential distribution 19 in the electric flow field or is specified at the location of the reference probe 5 by the relative reference potential 17.

[0058] The probe chain 40 is first thrown into the water, secured, for example, to a rope. If the probe chain 40 does not signal a warning (alarm), the flooded area 50 can be entered at this point. If the person continues to move forward in the flooded area 50, the probe chain 40 is continuously swung around the person in front. If voltage levels that endanger people are detected, an alarm is triggered. Further action should then be avoided.

[0059] In Fig. 3 a functional block diagram of the voltage warning device 2 according to the invention with n measuring probes 4 is shown.

[0060] The measuring probe 4 at the point i=1 forms the reference probe 5 and, by means of the measuring electrodes 6 acting as reference electrodes 15, provides the electrode potential 16 at the reference probe 5 via a ground conductor 36, which corresponds to the relative reference potential 17 ( Figs. 1 , 2 ) corresponds.

[0061] The subsequent measuring probes 4 at the locations i=2 to n detect the electrode potential 16 prevailing there via their respective measuring electrodes 6 and, after the analog-to-digital conversion 22 (ADC), transmit this potential via the communication line 32 to the microcontroller 24 of the reference probe 5.

[0062] The microcontroller 24 determines the respective measuring potential 14 ( Figs. 1 , 2 ) at locations i=2 to n, by calculating a representative value for the measurement potential 14 as a potential measurement point from the electrode potentials 16 recorded there in the near range (around locations i=2 to n), for example, by averaging in conjunction with digital filter operations (near-range evaluation). The measurement potentials 14 thus determined spatially map the potential distribution 19, so that measurement potential differences can be reliably detected (long-range evaluation).

[0063] The measuring probes 4 are supplied with energy from the energy storage device 28 of the reference probe 5 via a supply line 34.

[0064] The combination of short-range evaluation and long-range evaluation can be used, starting from the image of the potential distribution 19, to calculate the gradient 62 of the electric field strength ( Figs. 4 bis 6 ) can be used. This allows the movement directions that pose a risk to personnel (along the gradient 62) and the less dangerous movement directions (along the equipotential lines 60) of the person acting to be identified in advance of the operation.

Claims

1. A shock alert warning device (2) for protection from electric shock in a flooded area (50) having electric installations (52), having a number n of measuring probes (4) which are distributed in the flooded area (50) and which each have a measuring potential (14) as a potential measuring point for detecting an electric potential distribution (19) in the flooded area (50) and which each consist of a buoyant body (7) having measuring electrodes (6) disposed on its outer side and having an electrode potential (16), of an electronics unit (20, 22, 24) and of a signal generator (26), characterized in that the measuring probes (4) are connected to each other via connection lead sections (30) to form a buoyant probe chain (40), and in that one of the measuring probes (4) is configured as a reference probe (5) for establishing a relative reference potential (17) as a measuring potential (14) without a connection to a ground potential (PE).

2. The shock alert warning device according to claim 1, characterized in that the electronics unit (20) of the measuring probes (4) not configured as a reference probe (5) has an analog-to-digital converter (22) for converting the electrode potentials (16) registered at the corresponding measuring electrodes (6) to digital signals.

3. The shock alert warning device according to claim 1 or 2, characterized in that the electronics unit (20) of the reference probe (5) has a microcontroller (24) for central digital signal processing.

4. The shock alert warning device according to claim 3, characterized in that the microcontroller (24) is configured for identifying a measuring potential difference with respect to the reference potential (17) at the measuring probes (4) not configured as the reference probe (5).

5. The shock alert warning device according to claim 3 or 4, characterized in that the microcontroller (24) is configured for calculating the measuring potential (14) for the measuring probes (4) not configured as the reference probe (5) from the electrode potentials (16) registered at the measuring electrodes (6) of the corresponding measuring probes (4).

6. The shock alert warning device according to any one of the claims 3 to 5, characterized in that the microcontroller (24) is configured to calculate the direction of the largest voltage change by means of forming gradients from the potential distribution (19).

7. The shock alert warning device according to any one of the claims 3 to 6, characterized in that the microcontroller (24) is configured for generating control signals (18) for the signal generator (26) in order to signal when a preset measuring-potential difference threshold is exceeded.

8. The shock alert warning device according to any one of the claims 1 to 7, characterized in that the reference probe (5) is connected to a defined ground potential (PE) as a reference potential (17) via a ground lead (39).

9. The shock alert warning device according to any one of the claims 1 to 7, characterized in that the reference probe (5) has an energy storage (28) for supplying power to the measuring probes (4).

10. The shock alert warning device according to any one of the claims 1 to 9, characterized in that a connection lead consisting of connection lead sections (30) has a communication lead (32), a ground conductor (36) and a supply lead (34).

11. The shock alert warning device according to claim 10, characterized in that the communication lead (32) is configured for transmitting data of the digital electrode potentials and the control signals (18).

12. The shock alert warning device according to any one of the claims 1 to 11, characterized in that the buoyant bodies (7) are spheroid and consist of transparent plastic.

13. The shock alert warning device according to any one of the claims 1 to 12, characterized in that the signal generator (26) is a sound converter and / or an illumination apparatus having different color depictions and several light modes for signaling different danger levels.

14. A method for protection from electric shock in a flooded area (50) having electric installations (52), the method comprising the following steps: detecting an electric potential distribution (19) in the flooded area (50) by means of a number n of measuring probes (4) which are distributed in the flooded area (50) and each have a measuring potential (14) as a potential measuring point and each consist of a buoyant body (7) having measuring electrodes (6) disposed on its outer side and having electrode potentials (16), of an electronics unit (20) and of a signal generator (26) and of a power supply (28), characterized in that the measuring probes (4) are connected to each other via connection lead sections (30) to form a buoyant probe chain (40) and in that the measuring potential (14) of a reference probe (5) is established as a relative reference potential (17) without being connected to a ground potential (PE).

15. The method according to claim 14, characterized in that at the measuring probes (4) not configured as reference probes (5), the electrode potentials (16) registered by the corresponding measuring probes (6) are converted to digital signals in the electronics unit (20) of the measuring probes (4) not configured as a reference probe (5) by means of an analog-to-digital converter (22).

16. The method according to claim 14 or 15, characterized in that digital signal processing steps are implemented centrally in the electronics unit (20) of the reference probe (5) via a microcontroller (24).

17. The method according to claim 16, characterized in that at the measuring probes (4) not configured as a reference probe (5), measuring potential differences occurring with respect to the reference potential (17) are identified by the microcontroller (24).

18. The method according to claim 16 or 17, characterized in that the measuring potential (14) for each measuring probe (4) not configured as a reference probe (5) is calculated in the microcontroller from the electrode potentials (16) registered at the measuring electrodes (6) of the corresponding measuring probe (4).

19. The method according to any one of the clams 16 to 18, characterized in that the direction of the largest voltage change is calculated in the microcontroller (24) from the potential distribution (19) by means of gradient formation.

20. The method according to any one of the claims 16 to 19, characterized in that control signals (18) are generated by the microcontroller (24) for the signal generator (24) in order to signal when a preset measuring-potential difference threshold is exceeded.

21. The method according to any one of the claims 14 to 20, characterized in that the reference probe (5) is connected to a defined ground potential (PE) as a reference potential (17) via a ground lead (39).

22. The method according to any one of the claims 14 to 21, characterized in that the measuring probes are supplied with power via an energy storage (28) of the reference probe (5).

23. The method according to any one of the claims 14 to 22, characterized in that a connection lead consisting of the connection lead sections (30) has a communication lead (32), a ground conductor (36) and a supply lead (34), the digital electrode potentials and the control signals (18) being transmitted via the communication lead (32).

24. The method according to any one of the claims 14 to 23, characterized in that the buoyant bodies (7) are spheroid and consist of transparent plastic, different danger levels being signaled by means of the signal generator (26) configured as a sound converter and / or an illumination apparatus having different color depictions and several light modes.