Safety warning shoe and system

Abstract

A safety warning shoe (16) for detecting electric fields is specified, with a detection unit (20) integrated in the safety warning shoe (16) which is configured to measure at least one representative quantity of a capacitive displacement current (I) caused by the electric field (E). V ) to detect between a floor and a person (10) wearing the safety warning shoe (16). Furthermore, a system (15) is specified comprising a safety warning shoe (16) and a warning device (18) separately designed from the safety warning shoe (16).

Description

[0001] The invention relates to a safety warning shoe for detecting electric fields and a system comprising a safety warning shoe and a warning device separately designed from the safety warning shoe.

[0002] Electric fields are invisible to humans. If a person is in a switchgear or other electrical environment, it is possible that they may unknowingly approach live parts from which the electric field originates.

[0003] When a person works in an electrical environment, voltage detectors are used to warn them of high voltages. These detectors react capacitively to the alternating electric field emanating from the live component. Therefore, a capacitive displacement current can be measured within the voltage detector.

[0004] However, the voltage warning devices known from the state of the art generally have the disadvantage that the capacity of the voltage warning device is low, so that the measured displacement currents are in the range of a few tens to hundreds of nanoamperes.

[0005] Furthermore, voltage warning devices are usually attached to a discreet point on the person, for example on a helmet, on an arm joint or on clothing in the chest area.

[0006] The voltage detectors can be wirelessly connected to a separately trained warning device, for example a mobile device such as a smartphone, to trigger a warning signal in the form of vibrations or an acoustic warning signal on the mobile device when the person approaches a live part.

[0007] Another disadvantage of such voltage detectors is that a person can unknowingly shield the detector from the electric field with their own body, for example, by holding their arm in front of the detector or by standing with their back to a live part, if the detector is designed for the chest area. To avoid this, the person would have to use several voltage detectors simultaneously, which is associated with correspondingly high costs and reduced convenience.

[0008] DE 10 2022 105 066 A1 describes a system for detecting electric fields that detects at least one representative quantity for a capacitive displacement current caused by the electric field.

[0009] DE 10 2020 108 390 A1 discloses a system for the protection of a person in which a current flowing over the person and the ground is detected.

[0010] DE 103 23 030 A1 describes a system in which an electric field is detected by means of a displacement current caused by the electric field.

[0011] It is therefore an object of the present invention to increase occupational safety in an environment of live parts in a cost-effective and convenient manner.

[0012] This problem is solved according to the invention by a safety warning shoe for detecting electric fields. The safety warning shoe has a detection unit integrated into the shoe, which is configured to detect at least a representative quantity of a capacitive displacement current caused by the electric field between a floor and a person wearing the safety warning shoe.

[0013] The safety shoe can therefore be used to detect changes in an electric field by measuring changes in the quantity representative of the capacitive displacement current. The capacitive displacement current is caused by the alternating electric field, specifically by the change in electric flux over time, with the electric field originating, for example, from a live component. Specifically, a change in the electric field generates the displacement current, allowing the approach of a person wearing the safety shoe to a live component to be detected by means of this displacement current.

[0014] The live part is, for example, an electrical conductor.

[0015] This method exploits the fact that a person has low specific electrical conductivity, allowing them to act as a sensor element or coupling surface. More precisely, the person has an equipotential surface in the form of their body surface, and the potential difference changes when they approach an electrical conductor. This change in potential difference, in turn, influences the capacitive displacement current between the person and the live part, thus enabling the detection of whether a person is approaching a current-carrying electrical conductor.

[0016] When a person approaches a live part with their extremities, the capacitance changes, causing the capacitive displacement current between the live part and the person to increase. The current then flows through the earth, i.e., the capacitive coupling between the person and the earth, specifically between the person's feet and the earth. The safety warning shoe according to the invention therefore measures the quantity representative of the capacitive displacement current, e.g., a voltage dependent on the capacitive displacement current, which determines whether an electric field is nearby or whether the person has approached a live part.

[0017] Since the current flow must be closed via the earth, the detection unit can be located in the sole of the safety warning shoe to ensure that the displacement current can be reliably measured.

[0018] An advantage of the solution according to the invention is that no shadowing effect occurs due to the person themselves, as is still the case with portable voltage detectors known from the prior art, since the person cannot "shadow" themselves, but rather serves as a coupling surface or sensor element for the electric field. Even if the person merely moves an arm or their head towards the live part, a capacitive displacement current is caused, which is detected by the detection unit integrated into the safety warning shoe.

[0019] An approach to the live part can therefore be detected regardless of the person's orientation to the live part, for example, even if the person approaches the live part backwards.

[0020] Because the human body presents a very large surface area to the electric field, the displacement or coupling current is not below one microampere as with known voltage detectors, but can be one to two orders of magnitude higher, which is advantageous for detection and evaluation.

[0021] The detection unit can include a resistor. This unit can be configured to measure the voltage drop across the resistor, which is the representative quantity for the displacement current. Specifically, the displacement current flows through the resistor, so an increase in the displacement current also results in an increase in the measured voltage. The resistor has a defined resistance value, allowing the displacement current to be determined from the measured voltage. The construction of such a detection unit is particularly simple, which has a positive impact on the manufacturing costs of the safety shoe.

[0022] In general, the measuring circuit corresponds to an RC series circuit, where the resistance of the RC series circuit is formed by the resistance of the detection unit and the capacitance of the RC series circuit is formed by the equipotential surface of the person in relation to the live part.

[0023] According to one aspect, the safety shoe contains an electrically conductive surface to which the resistor is electrically connected. This conductive surface is formed, in particular, by a metal electrode that is associated with, and specifically contacts, the wearer's foot. The conductive surface results in a defined contact resistance.

[0024] For example, the safety shoe includes a transmitter unit configured to send a trigger signal to a separate warning device, which then issues a warning signal. Consequently, a person is warned if they get too close to a live part, thus increasing workplace safety. Existing devices controlled by the transmitter unit can be used for the warning.

[0025] The warning device is, for example, a mobile device that can emit a visual and / or acoustic warning signal, such as a mobile phone or smartphone.

[0026] The transmitter unit is, for example, a wireless transmitter unit, so that the trigger signal is transmitted wirelessly.

[0027] Alternatively or additionally, a vibration element can be integrated into the safety shoe, designed to provide tactile feedback to the wearer. Such feedback is clearly perceptible even in noisy work environments. Furthermore, this allows for a warning without the need for an additional device, i.e., a separate warning system. This increases the level of safety, as a separate warning system could be forgotten or misplaced.

[0028] According to one aspect, the safety shoe has a power supply unit for providing the detection unit with electrical energy. This power supply unit is designed to store the kinetic energy generated when the person walks as electrical energy and to use this stored electrical energy to power the detection unit. In particular, the power supply unit includes a piezoelectric element. Such a power supply is particularly sustainable and cost-effective. Furthermore, it ensures a continuous power supply.

[0029] The piezo element can also serve as a vibration element, which contributes to a compact design of the safety warning shoe.

[0030] Alternatively, or as a backup, the power supply unit can also include a rechargeable battery or a battery.

[0031] In the case of a rechargeable battery, it is conceivable that excess kinetic energy is stored as electrical energy in the battery.

[0032] The safety warning shoe can include an evaluation unit designed to compare the representative value of the displacement current detected by the detection unit with a threshold value. This comparison with the threshold value makes it easy to determine whether a person is in a critical area near the live part.

[0033] More precisely, a warning threshold can be stored in the evaluation unit. When this threshold is exceeded, the evaluation unit sends a control signal to the transmitter and / or the vibration element, which then triggers a warning signal from the warning device and / or a vibration signal from the vibration element. Consequently, the person is not informed with every change in the displacement current, but only when a warning is actually necessary.

[0034] The evaluation unit is, for example, a microcontroller that evaluates the voltage drop measured by the detection unit. The microcontroller can be powered by the power supply.

[0035] In principle, the detection unit and / or the evaluation unit can be powered by the energy provided by the power supply.

[0036] According to one variant, the safety shoe can be designed as an overshoe to be worn over a conventional shoe. This allows the safety shoe to be used by different people, thus saving costs and ultimately reducing overall costs for the plant operator.

[0037] The problem is further solved according to the invention by a system comprising a safety warning shoe according to the invention and a warning device designed separately from the safety warning shoe. The warning device has an acoustic and / or optical warning output module.

[0038] A transmitter unit of the safety shoe is configured to send a trigger signal to the warning device. In addition to the advantages already described in connection with the safety shoe according to the invention, the system according to the invention has the further advantage that the warning device can be arranged in such a way that the person can perceive an acoustic and / or visual warning signal particularly reliably.

[0039] For example, the separately trained warning device could be a mobile device such as a mobile phone or smartphone carried by the person. Alternatively, the warning device could be a freestanding unit that is clearly visible in a work environment.

[0040] Further advantages and features of the invention will become apparent from the following description and from the accompanying drawings, to which reference is made. The drawings show: - Fig. 1 a person near a live part that generates an electric field, - Fig. 2 a system according to the invention with a safety warning shoe according to the invention, and - Fig. 3 schematically another representation of a person in an electric field.

[0041] In Fig. Figure 1 shows a person 10 who is located in an electric field E, the field lines of which are shown. More precisely, the person 10 is in the vicinity of a live part 12, which in the exemplary embodiment is, for example, a current-carrying electrical conductor from which the electric field E originates.

[0042] For example, the live part 12 is a medium-voltage or high-voltage line.

[0043] In the following, medium voltage is defined as an alternating voltage of 1 kV to 35 kV, whereas high voltage is defined as an alternating voltage of 35 kV to 110 kV. However, the invention is fundamentally applicable to any voltage range, for example, also to extra-high voltages, i.e., voltages from 110 kV to 1,150 kV.

[0044] Person 10, for example, is standing on a grounded surface 14, meaning that electrical charge can be dissipated via the surface 14.

[0045] At the in Fig. In the scenario shown, the body surface of person 10 represents a coupling surface for the electric field E.

[0046] Specifically, the body surface of person 10 is an equipotential surface, meaning that the same electrical potential prevails at every point on the body surface.

[0047] If a person 10 approaches the live part 12, even if only with a single body part such as the arm or the head, or moves away from it, the potential changes on the entire body surface of the person and a capacitive displacement current I V The relationship between person 10 and the grounded ground 14 changes because the capacitive coupling between person 10 and the voltage-carrying part 12 has changed.

[0048] For example, when person 10 approaches the live part 12, the capacitive displacement current I increases. V , which is measurable between the grounded ground 14 and the person 10.

[0049] For this purpose, a system 15 is provided which includes a safety warning shoe 16 and a warning device 18 designed separately from the safety warning shoe 16, for example in the form of a mobile phone or smartphone.

[0050] The warning device 18 therefore has an acoustic and / or optical warning output module 19, namely a loudspeaker or a display.

[0051] System 15 is in Fig. 2 illustrated.

[0052] A detection unit 20 is integrated into the safety warning shoe 16.

[0053] In the exemplary embodiment, the detection unit 20 is arranged in a shoe sole 22 of the safety warning shoe 16. However, other options are also conceivable.

[0054] Instead of a complete shoe, the safety warning shoe 16 can also be designed as an overshoe to be pulled over a conventional shoe. For the sake of simplicity, a separate illustration of the overshoe has been omitted. It is conceivable that the overshoe comprises a shoe sole with attached straps that allow the overshoe to be fastened to a conventional shoe.

[0055] The detection unit 20 is set up to measure a representative quantity for a capacitive displacement current I caused by the electric field E. V to detect between the floor 14 and the person 10, who is wearing the safety warning shoe 16.

[0056] Specifically, the detection unit 20 comprises a resistor 24 and an electrically conductive surface 26, to which the resistor 24 is electrically connected. The conductive surface 26 is arranged on the upper side of the shoe sole 22, i.e., in contact with the foot of person 10. In this embodiment, the conductive surface 26 is a metal electrode.

[0057] The detection unit 20 is set up to detect a voltage drop U V to measure via the resistance 24, which is the representative quantity for the displacement current, since the resistance value has a defined quantity, so that via the measured voltage drop U V via directly onto the displacement current I Vcan be closed. Resistor 24, for example, has a resistance value of 100 kOhms.

[0058] The safety warning shoe 16 also includes an evaluation unit 28, a transmitter unit 30 and a power supply unit 32.

[0059] The evaluation unit 28 is connected to the detection unit 20 via signal transmission, which measures the representative quantity for the displacement current I detected by the detection unit 20. V to compare with a threshold value.

[0060] Alternatively, it is conceivable that the evaluation unit 28 uses the measured voltage drop U V the displacement current I V It calculates the value and compares it to a threshold value.

[0061] The evaluation unit 28 can include a microprocessor 34 for this purpose.

[0062] The threshold value, for example, is stored directly in the evaluation unit 28, more precisely on the microprocessor 34, i.e. in a memory module.

[0063] The evaluation unit 28 is also configured to send a control signal to the transmitter unit 30, on the basis of which a warning signal is issued by the warning device 18, namely when the measured voltage drop or the determined displacement current I V exceeds the threshold value or if there is any displacement current I V is determined.

[0064] More precisely, the transmitting unit 30 is set up to send a trigger signal to the warning device 18 based on the control signal of the evaluation unit 28, for example wirelessly, in order to issue a warning signal via the warning device 18.

[0065] The warning signal is, for example, an acoustic and / or a visual warning signal.

[0066] The power supply unit 32 serves to supply the components of the safety warning shoe 16 with electrical energy, for example the detection unit 20, the evaluation unit 28 and / or the transmitter unit 30.

[0067] In the exemplary embodiment, the energy supply unit 32 is configured to store the kinetic energy generated when the person walks as electrical energy and to use the stored electrical energy to power the detection unit 20. For the conversion of kinetic energy into electrical energy, the energy supply unit 32 includes, for example, a piezoelectric element 36.

[0068] The piezoelectric element 36 can simultaneously be used to provide tactile feedback to person 10 wearing the safety shoe 16. In this case, the piezoelectric element 36 serves as a vibration element 38.

[0069] It is also conceivable to provide a vibration element 38 arranged independently of the power supply unit 32, especially if the power supply unit 32 only comprises a rechargeable battery or accumulator.

[0070] In order to generate a tactile warning signal using the vibration element 38, the evaluation unit 28 sends a control signal to the vibration element 38, as a result of which a vibration signal is generated by the vibration element 38.

[0071] The following will be based on the Fig. 1 to 3 describe the triggering of the safety warning shoe 16.

[0072] If a person 10 approaches a live part 12, either with their whole body or with only a body part, for example with their arm, as is the case in Fig. As shown in Figure 3, the potential of the body surface of person 10, which serves as a coupling surface for the electric field E, changes.

[0073] When the potential of the body surface of person 10 changes, the capacitance or capacitive coupling changes, resulting in a displacement current I. V This is caused by the current flowing through resistor 24, resulting in a corresponding voltage drop U. V via resistor 24.

[0074] Since a person represents a large surface area for the electric field E, the displacement current I is also V correspondingly large, especially in the two to three-digit microampere range.

[0075] The magnitude of the displacement current I V influences the voltage drop U measured across resistor 24 V , which is a representative quantity for the displacement current I caused by the electric field E of the live part 12 V represents.

[0076] The measured voltage drop U Vis recorded by evaluation unit 28 and optionally compared with a threshold value.

[0077] If the threshold is exceeded, this means that person 10 is too close to the live part and their safety is at risk. Therefore, person 10 must be warned.

[0078] Instead of evaluating the recorded value with a threshold value, it may also be sufficient to have a displacement current I V is recorded at all, or rather, the one responsible for the displacement current I V representative size.

[0079] The evaluation unit 28 then sends a control signal to the transmitter unit 30 and / or the vibration element 38.

[0080] The transmitter unit 30 processes the control signal and in turn sends a trigger signal to the warning device 18, whereupon the warning output module 19 outputs an optical and / or acoustic warning signal, e.g. displaying a symbol on a screen or playing a warning tone via a loudspeaker.

[0081] Alternatively or additionally, the vibration element 38 generates a tactile warning signal directly at the foot of person 10 in response to the control signal.

[0082] Person 10 is warned by the warning signals not to approach the live part 12 any further, resulting in improved workplace safety.

[0083] The safety warning shoe 16 therefore includes a warning device for electric fields.

[0084] Furthermore, it is ensured that shielding of the warning device by person 10 is not possible, which was the case in the prior art, since person 10 acts as part of the warning device, as the body surface serves as a sensor element or coupling surface for the electric field.

Claims

[1] Safety warning shoe (16) for detecting electric fields, with a detection unit (20) integrated in the safety warning shoe (16) which is configured to measure at least one representative quantity for a capacitive displacement current (I) caused by the electric field (E). V ) between a floor and a person (10) wearing the safety warning shoe (16). [2] Safety warning shoe (16) according to claim 1, characterized by , that the detection unit (20) comprises a resistor (24), in particular wherein the detection unit (20) is configured to provide a voltage drop (U) V ) to measure via the resistance (24), which is the representative quantity for the displacement current (I) V ) is. [3] Safety warning shoe (16) according to claim 2, characterized by , that in the safety warning shoe (16) there is an electrically conductive surface (26) with which the resistor (24) is electrically connected. [4] Safety warning shoe (16) according to one of the preceding claims, characterized by , that the safety warning shoe (16) includes a transmitting unit (30) which is configured to send a trigger signal to a warning device (18) separate from the safety warning shoe (16) in order to issue a warning signal via the warning device (18). [5] Safety warning shoe (16) according to one of the preceding claims, characterized by , that a vibration element (38) is integrated into the safety warning shoe (16) which is designed to provide tactile feedback to the person (10) wearing the safety warning shoe (16). [6] Safety warning shoe (16) according to one of the preceding claims, characterized by, that the safety warning shoe (16) has a power supply unit (32) for supplying the detection unit (20) with electrical energy, wherein the power supply unit (32) is configured to store the kinetic energy generated when the person (10) walks as electrical energy and to use the stored electrical energy to supply the detection unit (20), in particular wherein the power supply unit (32) comprises a piezoelectric element (36). [7] Safety warning shoe (16) according to one of the preceding claims, characterized by , that the safety warning shoe (16) includes an evaluation unit (28) which is configured to compare the representative quantity for the displacement current detected by the detection unit (20) with a threshold value. [8] Safety warning shoe (16) according to one of the preceding claims, characterized by, that the safety warning shoe (16) is designed as an overshoe to be put over a conventional shoe. [9] System (15) comprising a safety warning shoe (16) according to one of the preceding claims and a warning device (18) formed separately from the safety warning shoe (16), wherein the warning device (18) has an acoustic and / or optical warning output module (19), wherein a transmitter unit (30) of the safety warning shoe (16) is configured to send a trigger signal to the warning device (18).

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