Method and device for checking protective conductor of electrical installation or electrical device

Abstract

The present invention relates to the field of checking the correct state of a protective conductor connection of an electrical installation or electrical device, in particular a medical device. The invention relates to a device and to a method for evaluating the quality of a protective conductor connection on the basis of the signal transmission of a uniquely encoded electrical signal, the signal transmission being carried out by coupling at least two conductors and incorporating the protective conductor connection therein.

Description

Field of the Invention

[0001] The present invention relates to the field of checking the correct status of the protective conductor connection of electrical installations or electrical equipment, in particular medical equipment. Background Art

[0002] Electrical equipment has the possibility that people may come into physical contact with its live parts, so special requirements need to be met. This is especially true for medical equipment. To prevent, for example, high voltage from being applied to the parts of the device that people may touch in the event of a fault, or to minimize the amperage of the current flowing through the human body in such a case, it is usually stipulated that such conductive device parts be connected to the protective conductor (PE) of the electrical installation at ground potential with low resistance. For medical equipment, especially for equipment in which the patient is conductively connected to the medical device at least indirectly via extracorporeal blood circulation, the presence of the protective conductor connection is particularly important.

[0003] In a hemodialysis device, the conductive dialysis fluid pumped by the dialysis device is guided through the patient's blood via a semipermeable membrane in the dialysis filter, and the blood is also pumped by the dialysis device in extracorporeal blood circulation. In addition to the contact on the membrane, there are usually other fluid connections from the dialysis device to the patient's blood, such as via a dilution fluid, which is added to the patient's blood via a corresponding fluid connection. The blood in extracorporeal blood circulation is drawn out of the patient's body via a cannula, filtered during dialysis, and then returned again. In this case, the access to the patient's vascular system usually occurs in patients who require long-term dialysis, and a connection, i.e., a so-called fistula, is created surgically between an artery and a vein in the patient's arm, which can achieve a high enough blood flow.

[0004] In the case of acute dialysis treatment, such a fistula does not yet exist. In these cases, access to the patient's vascular system can be achieved via a so-called central venous catheter, the end of which is spatially close to the patient's heart.

[0005] If contact between the dialysis fluid and voltage occurs due to a fault event, in both cases, there is a conductive connection between the dialysis fluid and the patient's vascular system, so there is a risk of serious harm to the patient, especially in the case of acute dialysis with the central venous catheter close to the patient's heart.

[0006] To minimize this risk, a protective device can be provided via which a well-conductive connection from the dialysis fluid to the protective conductor of the electrical installation is produced. In the event of a fault, the current is thus mainly discharged via said connection rather than via the patient's vascular system. Additional protective elements, such as residual current circuit breakers and fuses, also provide protection against electric shock (so-called earth short circuits). However, the fault current recognized by a residual current circuit breaker is usually several orders of magnitude higher than the discharge current tolerated for the particular application in a dialysis machine.

[0007] Therefore, for the operational safety of a device with a protective conductor connection, it is important that the protective conductor connection persists and conducts electricity as well as possible. Thus, for the above-mentioned medical devices, in particular dialysis devices, a correct connection to the protective conductor of the electrical installation is of particular importance. Summary of the Invention

[0008] Therefore, an object of the present invention is to provide a device and a method for checking the correct electrical connection of a device, in particular a medical device, to the protective conductor of an electrical installation.

[0009] This object is achieved by the device according to claim 1 and the method according to claim 11. The dependent claims describe advantageous embodiments of the present invention.

[0010] Therefore, a device for checking the protective conductor connection of an electrical installation 101 or electrical devices 100, 105 is proposed, the electrical devices 100, 105 being configured to be electrically connected to the electrical installation 101, wherein the electrical device has at least conductors A and B, wherein conductor A is at least indirectly electrically connectable to conductor C of the electrical installation, and wherein conductor B is at least indirectly electrically connectable to conductor D of the electrical installation, wherein conductor C is a protective conductor, and wherein the electrical connection of the electrical device to the electrical installation is optionally effected by means of a mains supply line 105 which has at least conductors E and F, wherein conductor E is connectable to conductors A and C, and wherein conductor F is connectable to conductors B and D.

[0011] The proposed device further comprises a coupling device 102 for coupling a uniquely encoded electrical signal into a first conductor selected from the first group of conductors A, C, E or the second group of conductors B, D, F at a coupling point.

[0012] The proposed device further comprises a receiving device 103, which is configured to receive the encoded signal at a receiving point on the second conductor if the encoded signal is transmitted by a transmitting device 106 to the second conductor, the transmitting device 106 being configured to transmit the signal coupled into the first conductor to the second conductor at least indirectly at a transmission point, wherein the second conductor is selected from another group different from the group of the first conductor.

[0013] The proposed device further comprises an evaluation device 104, which is configured to evaluate the quality of the protective conductor connection based on the signal received by the receiving unit 103.

[0014] Furthermore, a method for checking the protective conductor connection of an electrical installation 101 or electrical devices 100, 105 is proposed, the electrical devices 100, 105 being configured for electrical connection to the electrical installation 101, wherein the electrical device 100 has at least a conductor A and a conductor B, wherein the conductor A is at least indirectly electrically connectable to a conductor C of the electrical installation 101, and wherein the conductor B is at least indirectly electrically connectable to a conductor D of the electrical installation 101, wherein the conductor C is a protective conductor, and wherein the electrical connection of the electrical device 100 to the electrical installation is optionally effected by means of a mains power supply line 105, the mains power supply line 105 having at least a conductor E and a conductor F, wherein the conductor E is connectable to the conductor A and the conductor C, and wherein the conductor F is connectable to the conductor B and the conductor D.

[0015] The proposed method comprises the following steps: coupling a uniquely encoded electrical signal into a first conductor selected from the first group of conductors A, C, E or the second group of conductors B, D, F at a coupling point; transmitting the coupled signal from the first conductor to the second conductor at least indirectly at a transmission point, wherein the second conductor is selected from another group different from the group of the first conductor; receiving the encoded signal at a receiving point on the second conductor; evaluating the quality of the protective conductor connection based on the signal received by the receiving unit.

[0016] Thus, the proposed device and method evaluate the quality of the protective conductor connection based on signal transmission according to a uniquely encoded electrical signal, wherein the signal transmission is effected by coupling at least two conductors and incorporating the protective conductor connection therein.

[0017] The invention is particularly applicable to checking the protective conductor connection of a dialysis device, which is an example of an embodiment of a medical device and an electrical device. As mentioned above, the proper state of the protective conductor connection is particularly important in a dialysis device. However, the device and method according to the invention are applicable to checking the correct state of the protective conductor connection of any electrical device or any device provided for the protective conductor connection to an electrical installation, or the protective conductor connection of the electrical installation itself. Description of the Drawings

[0018] More details and aspects of the present device and method will be described in more detail based on the exemplary embodiments shown in the drawings.

[0019] In the drawings:

[0020] Figure 1 An exemplary illustration of an embodiment of a device according to the present invention is shown;

[0021] Figure 2 Another exemplary illustration of an embodiment of a device according to the present invention is shown;

[0022] Figure 3 Another exemplary illustration of an embodiment of a device according to the present invention is shown;

[0023] Figure 4 An exemplary illustration of an embodiment of a mains power supply line according to the present invention is shown;

[0024] And

[0025] Figure 5 An exemplary illustration of a circuit embodiment suitable for implementing the present invention is shown. Detailed Description of the Invention

[0026] Figure 1 An exemplary illustration of an embodiment of a device according to the present invention is shown. In the exemplary embodiment, the electrical device 100 includes three conductors A, B, and G for supplying electrical energy, and these three conductors are at least indirectly connected to the conductors C, D, and I of an electrical installation that provides electrical energy.

[0027] Generally, an electrical device having a protective conductor connection is provided with three conductors for connection to an electrical installation, namely a voltage-carrying conductor (L), a neutral conductor (N), and a protective conductor (PE). In contrast, an embodiment of an electrical installation, also known as "classical earthing", has only two conductors, namely a voltage-carrying conductor (L) and a combined protective conductor / neutral conductor (PEN). This type of electrical installation is no longer typical. To further explain the present invention, it does not matter whether the electrical device 100 and the electrical installation 101 have two or three conductors for energy supply. Instead, what is important is that the electrical device 100 is provided for connection to a protective conductor or a combined protective conductor / neutral conductor (PE or PEN). The term protective conductor hereinafter refers to both the PE conductor of a three-pole electrical installation and the PEN conductor of a two-pole electrical installation.

[0028] When the term "conductor" is used hereinafter, it means an electrical conductor, in particular a cable. When a conductor is described hereinafter as being electrically connected to another conductor, this means, unless otherwise described, a low-resistance electrical connection of the two conductors, for example by corresponding plug contacts, screw connections, soldering, crimping, welding, etc.

[0029] In Figure 1 the exemplary embodiment of, the connection of conductors A, B, and G to conductors C, D, and I of the electrical installation is effected indirectly via the mains supply line 105, which is also implemented as a three-pole having conductors E, F, and H.

[0030] Such a mains supply line can be implemented as pluggable, for example using a so-called cold device plug connection on the device side, which is fitted in the corresponding counterpart of the electrical device 100; while on the mains side, via a safety plug connection, which is fitted in a typical socket, for example a wall socket.

[0031] It can also be provided that the mains supply line 105 (shown by the dashed line in Figure 1 is fixedly connected to the electrical device 100 on the device side. In addition, it can be provided that the electrical device is directly connected or connectable to the electrical installation without a dedicated mains supply line 105. This is especially the case for fixedly installed electrical devices, in particular those installed in a wall.

[0032] In any case, conductor A of the electrical device 100 is at least indirectly electrically connectable to conductor C, and conductor B of the electrical device 100 is at least indirectly electrically connectable to conductor D. The electrical connection can be established via the mains supply line 105, where conductor A is connected to E and E is connected to C, conductor B is connected to F and F is connected to D, or directly without a dedicated supply line 105, so that A is connected to C and B is connected to D.

[0033] For the sake of completeness, it should be noted that conductor G (if present) can also be connected to conductor I of the electrical device via conductor H of the mains supply line, or directly to conductor I of the electrical installation without a dedicated mains supply line.

[0034] Conductor C of the electrical installation must be a protective conductor.

[0035] The device according to the invention comprises a coupling device 102 for coupling a uniquely encoded electrical signal into a first conductor at a coupling point, said first conductor being selected from the first group of conductors A, C, E or the second group of conductors B, D, F. In accordance with Figure 1In an exemplary embodiment, the coupling device 102 is coupled to conductor B of the electrical device 100 at the point marked by the black circle. The uniquely encoded electrical signal can be arbitrary, preferably a digitally encoded signal. The encoding can uniquely identify the electrical device 100. For example, the encoding can encode the serial number that uniquely identifies the electrical device. In this case, the type of digital encoding is not important. The only important thing is that the encoding is suitable for being coupled into one of conductors A, B, C, D, E, F and is suitable for being transmitted to the corresponding other conductor of conductors A, B, C, D, E, F by means of the transmission device 106. As an exemplary embodiment of such an encoding, a sequential digital signal with a sufficiently high amplitude (e.g., 5V or 12V) and a fixed period can be envisioned, which represents a specific sequence of digital "0" and "1" symbols, where the sequence forms a unique encoding. In an improved scheme, the sequential digital signal is modulated onto a periodic analog carrier signal, for example, onto a sine signal with a frequency significantly different from the mains frequency, for example, 10 kHz.

[0036] Another embodiment may also include frequency encoding, where the periodic signal is switched on and off at a fixed period, which is preferably at a frequency significantly different from the mains frequency, where the on signal represents the digit "1" and the off signal represents the digit "0". Those skilled in the art are also aware of other embodiments of suitable signal encodings, such as FSK (Frequency Shift Keying) or PSK (Phase Shift Keying).

[0037] The uniquely encoded electrical signal can also be an analog signal, such as a sine signal with a specific frequency significantly different from the mains frequency.

[0038] The coupling of the uniquely encoded electrical signal occurs in a first conductor selected from the first group of conductors A, C, E or the second group of conductors B, D, F.

[0039] In Figure 1 the exemplary embodiment, the power supply occurs in conductor B, i.e., in the conductor of the electrical device 100, where, according to the present invention, conductor B is associated with the second group B, D, F.

[0040] The transmission device 106 is configured to be able to transmit the signal coupled into the first conductor at the transmission point to a second conductor, where the second conductor is selected from the other group different from the first conductor. In Figure 1 the current example, it is selected from the first group of conductors A, C, E.

[0041] In Figure 1 the exemplary embodiment, the transmission from conductor D to conductor C occurs at the transmission point assigned to the electrical facility.

[0042] According to the present invention, conductor C is a protective conductor of an electrical installation. Therefore, conductors A and E are provided for at least indirectly connecting to the protective conductor of the electrical installation.

[0043] Such a transmission point can be located, for example, in the fuse box of the electrical installation 101 or in the household junction box that connects the building where the electrical installation is located to the public power supply network.

[0044] In Figure 1 the exemplary embodiment of , the electrically encoded signal coupled into conductor B, when the electrical device is correctly connected, is applied to the electrical installation 101 at conductor D via the mains power supply line 105 using conductor F and is transmitted to conductor C through the transmission device 106.

[0045] The transmission device is configured such that it can transmit a uniquely encoded electrical signal from any conductor to any other conductor. In this case, the transmission can be carried out capacitively through a capacitor, or inductively through a power transformer, where two transformer coils are respectively located in the signal paths of the two conductors, or it can also be carried out resistively through a resistor connecting the two conductors. Any combination of the above devices is also conceivable. In a preferred embodiment, the transmission is carried out through a capacitor that capacitively connects the first conductor to the second conductor, for example, a so-called Y capacitor, which has sufficient dielectric strength and a capacitance of, for example, 4.7 nF. The capacitance of the capacitor is selected such that the uniquely encoded electrical signal is transmitted as well as possible, but the mains frequency of the mains is blocked as much as possible. The higher the (carrier) transmission frequency of the uniquely encoded electrical signal, the smaller the coupling capacitor that can be selected.

[0046] In Figure 1 the exemplary embodiment of , for example, conductors D and C are capacitively connected to each other through the above capacitor. For example, due to the capacitor, the uniquely electrical encoded signal applied to conductor D under correct conditions is transmitted to conductor C. Depending on the transmission device and its embodiment, the signal will experience more or less strong attenuation here, which can be calculated or measured. Therefore, the amplitude of the transmitted signal applied to conductor C is characteristic of the correct situation. This will not change significantly due to the appropriate (i.e., correct) electrical connection via conductors E and A.

[0047] Therefore, the transmitted uniquely encoded electrical signal is also applied to conductor A, where the electrical signal is received or decoupled by the receiving device 103 and supplied to the evaluation device 104.

[0048] The coupling and decoupling of the uniquely encoded electrical signal by means of the coupling device 102 and the receiving device 103 can be carried out arbitrarily, but in particular capacitively via a capacitor and / or inductively via a power transformer. For this purpose, a person skilled in the art can utilize known embodiments of so-called power line communication (PLC). A direct coupling via an ohmic connection of the uniquely encoded electrical signal is also conceivable, for example via a high-ohmic resistor or a high-ohmic resistor network. Figure 5 Possible embodiments of the devices 102 and 103 are shown.

[0049] The evaluation unit 104 examines the signal supplied to it and infers the quality of the protective conductor connection based on said examination.

[0050] According to the invention, the quality of the protective conductor connection means the quality of the electrical connection of the conductor or conductor connection of the protective conductor provided for connection to an electrical installation.

[0051] In Figure 1 the exemplary embodiment, the signal transmission starts at the coupling point in conductor B in the electrical device, via conductor F of the mains supply line 105 and conductor D of the electrical installation 101, and from there via the transmission device 106, conductor C of the electrical installation 101, conductor E of the mains supply line 105 to conductor A of the electrical device 100.

[0052] According to the invention, conductor C is the protective conductor, so for normal three-pole power supply, conductor D is the neutral conductor N or the voltage-carrying conductor L, and conductor I of the electrical installation is accordingly the voltage-carrying conductor L or the neutral conductor N. For the device and method according to the invention, conductors D and I of the electrical installation are interchangeable.

[0053] A fault event in the neutral conductor or the voltage-carrying conductor, such as an interruption, will directly affect the function of the electrical device. However, an interruption of the connection to the protective conductor of the electrical installation or an interruption in the protective conductor of the electrical installation is usually not noticed.

[0054] In contrast, since no signal is detected at the receiving point, the invention can be used to detect an interruption of the conductor in the signal path of the coupled signal (i.e., from the respective conductor up to the transmission point), which conductor is provided for connection to the protective conductor of the electrical installation. Therefore, the evaluation device 104 will infer that the protective conductor connection is interrupted due to the lack of signal and can output a corresponding signal or initiate further measures.

[0055] It is also possible to recognize that the connection of the protective conductor is of defective quality. This is the case if the electrical connection has an excessive resistance, for example due to improper or defective plug connections or other electrical connections (such as screw connections, welded connections, fusion or crimp connections). Corrosion can also cause the connection of the protective conductor to have an excessive resistance and / or can cause parasitic effects, which impair the signal transmission of the uniquely encoded electrical signal from the coupling point to the receiving point. Such impairment affects the attenuation increase of the decoupled signal and / or an unexpected phase shift.

[0056] Therefore, the evaluation device 104 can infer problems in the protective conductor connection not only based on the absence of a signal, but also based on a too low amplitude or an unexpected signal profile. In fact, due to the parasitic capacitive coupling between the mains conductors, in the case of an interruption of the protective conductor connection, a very small uniquely encoded electrical signal is usually also detected. When it is mentioned hereinafter that a uniquely encoded electrical signal cannot be detected, according to the invention, this also includes only detecting a very small amplitude, for example less than 10%, 5% or 1% of the amplitude of the coupled uniquely encoded electrical signal.

[0057] The uniquely encoded signal is characteristic of the electrical device (such as the electrical equipment 100 or the electrical installation 101) whose protective conductor connection is to be checked.

[0058] Therefore, since the uniquely encoded electrical signal can be uniquely assigned to the electrical device to be checked, this ensures that interference or secondary signals of additional devices according to the invention are not inadvertently used for the evaluation, and such interference or secondary signals may also be coupled into the protective conductor of the electrical installation via an undesired coupling process.

[0059] The evaluation device 104 is configured in such a way that the evaluation device 104 decodes the electrical signal transmitted to it from the decoupling device 103, that is, recognizes the information content of the encoded signal, in order to check whether the signal is assigned to the electrical device to be checked. In addition, the evaluation device 104 is configured to detect at least one signal parameter of the electrical signal transmitted from the decoupling device 103 to the evaluation device 104. Such a signal parameter is, for example, the signal amplitude and / or the signal profile. The evaluation device 104 is configured to compare the acquired signal parameter with an expected signal parameter value, which exists in the correct protective conductor connection of the electrical device or the electrical equipment to be checked, and to initiate further measures based on the comparison.

[0060] Such measures can include output signals, for example, which can be arranged to output a warning on a display or output a warning tone in the case where the deviation of the detected signal parameter from the expected signal parameter exceeds a minimum amount. Another measure can be to activate a disconnecting device, such as an electrical disconnect relay, which electrically disconnects the electrical device to be inspected from the connection to the electrical installation, such that the electrical device to be inspected is switched to a non-operating state and de-energized.

[0061] In an exemplary embodiment according to Figure 1 components 102, 103, and 104 are located inside the electrical device 100 or are part of the electrical device 100. For the present invention, it is not important where these components are located, or whether they are part of the electrical device 100 or at least partially not part of the electrical device 100, or form an independent unit.

[0062] The placement of the transmission device 106 occurs at a point in the observed electrical system such that a statement can be made regarding the protective conductor connection of the desired electrical device or electrical installation or a combination of electrical devices and electrical installations. Thus, according to the present invention, the transmission of the uniquely encoded electrical signal is performed at least indirectly by the transmission device 106 at the transmission point on the second conductor. This means that, according to the present invention, the uniquely encoded electrical signal is coupled into the first conductor and directly transmitted by the first conductor, or indirectly transmitted by the transmission device 106 on the second conductor via a conductor electrically connected to the conductor. Such transmission on the second conductor can occur directly immediately at the transmission point on the second conductor, or indirectly when the transmission device 106 transmits the uniquely encoded electrical signal to a conductor electrically connected to the second conductor. As long as the system is correct, the uniquely encoded electrical signal is applied in both cases where the second conductor has a specific minimum signal parameter.

[0063] In Figure 1 the example, the uniquely encoded electrical signal is coupled into the first conductor B according to the present invention from the conductor group B, D, F. Due to the electrical connections (conductor B to conductor F and conductor F to conductor D), the uniquely encoded electrical signal is also applied to conductor D. At the transmission point on conductor D, the uniquely encoded electrical signal is transmitted by the transmission device 106 to conductor C and thus indirectly to the second conductor A according to the present invention in the conductor group A, C, E, because there is an electrical connection between conductor C and conductor A (conductor C to conductor E and conductor E to conductor A).

[0064] The selection of the coupling point, the transfer point, and the receiving point determines the length of the protective conductor connection to be inspected, as well as the entities (electrical device 100, mains power supply line 105, electrical installation 101) in which the protective conductors are electrically connected to each other or are to be electrically connected to each other, and whether corresponding devices configured for this purpose already exist or are allocated in each entity. Therefore, by appropriately selecting the coupling point, the transfer point, and the receiving point, the protective conductor connections of the electrical device 100, the mains power supply line 105, and the electrical installation 101 can be inspected individually or in isolation, or the protective conductor connections of any partial combination of the electrical device 100, the mains power supply line 105, and the electrical installation 101 can be inspected.

[0065] In the exemplary embodiment according to Figure 2 the devices 102, 103, 104, and 106 are located inside the electrical device 100.

[0066] Similar to Figure 1 , conductor A is provided for connection to the protective conductor of the electrical installation. Correspondingly, the respective other conductors are connected to the voltage-carrying conductor L or the neutral conductor N. In practice, it is usually not possible to predict whether the respective other conductors B and G are connected to the voltage-carrying conductor L or the neutral conductor N, because the mains plug typically used for this purpose can be connected to the mains socket at two freely selectable positions, where the contact of the voltage-carrying conductor L and the neutral conductor N of the electrical installation 101 with the conductors of the mains power supply line is exchanged. The only thing that is ensured is that, regardless of the direction of the plug connection, the protective conductor is always connected to the conductor of the mains power supply line provided for this purpose.

[0067] However, even if the mains plug / mains socket combination only allows one possible plug position, it cannot be determined which pole of this position is the neutral conductor or the voltage-carrying conductor. In such an embodiment, only the protective conductor is uniquely assigned to one pole.

[0068] The positioning of the transfer device 106 inside the device preferably occurs directly at the boundary of the device housing, and thus, for example, as a capacitor between the corresponding poles of a cold device socket.

[0069] Similar to Figure 2 The method performed is the same as according to Figure 1The methods of the exemplary embodiments shown are not different. The only difference lies in the positioning of the transmission device. In the exemplary embodiment, it can be checked whether the protective conductor connection is properly implemented to the electrodes of the cold device socket provided for this purpose, or up to the transmission point at which the transmission device 106 electrically couples the two conductors A and B to each other. For this purpose, the electrical supply of the components 102, 103, 104, 106 can be obtained externally via the mains connection. However, the components can also be powered by a battery or accumulator independently of the mains connection of the electrical device.

[0070] It can also be provided that the components 102, 103 and 104 form an independent device 300. This is as Figure 3 shown.

[0071] For example, the device 300 is equipped with a cable 305 which is connected to the device 300 on one side. In the example, the cable 305 includes three conductors which are provided for connection to the conductors A, B and G of the electrical device 100. For this purpose, the cable can be equipped with a plug connector on one side which matches the socket of the electrical device 100, for example equipped with a cold device plug which is configured for connection to the cold device socket of the electrical device.

[0072] In the exemplary embodiment, the coupling of the uniquely encoded electrical signal takes place within the device 300, using the coupling device 102 to couple into the conductor K which is provided for connection to the conductor B of the electrical device 100. Inside the electrical device, the uniquely encoded electrical signal which is applied to the conductor B in the correct case is transmitted from the conductor B to the conductor A using the transmission device 106. The conductor A is provided for connection to the protective conductor of the electrical installation during normal operation. The conductor A of the electrical device 100 is connected to the conductor of the cable 305 and thus also to the conductor J of the device 300.

[0073] The uniquely encoded electrical signal can be received by the receiving device 103 on the conductor J and transmitted to the evaluation device 104. The evaluation device 104 evaluates the received signal in the manner already described. The device 300 also advantageously includes a signal device 301 which signals the evaluation result. This device can be implemented as required, for example as a display on which a text message corresponding to the evaluation is output, one or more corresponding optical displays, a tone generator, or an interface which can transmit data outwards.

[0074] As Figure 3As shown by the dashed line in [0], another transmission device 306 can also be provided in the electrical device 100, which is configured to transmit the uniquely encoded electrical signal from the conductor G to the conductor A. This is to ensure that no matter which conductor the device 300 couples the uniquely encoded signal to, the signal can be transmitted to the conductor A under the correct circumstances, and the conductor A is provided for connection to the protective conductor of the electrical installation.

[0075] Alternatively or additionally, it can be provided that in the device 300, the uniquely encoded signal is coupled to two conductors K and M (see the dashed-line connection originating from 102).

[0076] For the present invention, it is not important to which conductor or conductors the uniquely encoded electrical signal is coupled. The only thing that matters is that the signal flow of the uniquely encoded electrical signal reaches the receiving point from the coupling point via at least one transmission point and the conductor of the electrical device 100 provided for connection to the protective conductor of the electrical installation.

[0077] Thus, in [9] Figure 3 for example, the uniquely encoded electrical signal can also be coupled to the conductor J and received on one or both of the conductors K and M (not shown in

[11] ). Figure 3 not shown in

[13] .

[0078] The above alternatives can be used in any disclosed embodiment, even if they are not explicitly shown in the drawings.

[0079] It is also possible to check whether the protective conductor connection of the electrical installation is correct. Similar to

[19] Figure 2 in this case, one or two transmission devices within the electrical installation will be used, for example in a fuse box or a household junction box. This is not limited to a three-pole installation, but according to the present invention, transmission devices can be provided on the protective conductor pole from each pole of the electrical installation. Optionally, the coupling device 102 can also be part of the electrical installation 101 or can be assigned to the electrical installation 101.

[0080] According to the present invention, the term "electrical device 100" should be understood broadly. The mains supply line 105 can thus also be understood as an electrical device.

[0081] Figure 4 The mains supply line 105 implemented as a cold device cable is schematically shown, which has a transmission device according to the present invention. In

[28] Figure 4In an exemplary embodiment, two capacitors C1 and C2 are shown as transmission means which act within a safety plug 401 configured to be connected to a mains socket and which serve as transmission means according to the invention. Embodiments with only one capacitor C1 or C2 are also conceivable. Capacitors C1 and C2 connect the protective contact PE to two further electrodes L and N respectively and are thus configured according to the invention to transmit an encoded electrical signal on the protective conductor connection. The conductor names E, F, H are similar to Figure 1 .

[0082] Such a mains power supply line can be fixedly connected to an electrical device or can be pluggable (safety plug 401 and cold device plug 402), as in the example Figure 4 shown.

[0083] It can be provided that the plug connection is designed such that the connection between the electrical device 100 and the mains power supply line 105 does not follow the general specifications but is individually designed such that only a mains power supply line having a transmission means according to the invention can be connected to the electrical device 100.

[0084] It can also be provided that, similar to Figure 4 , the mains power supply line is optically uniquely identified such that the user receives an indication that the mains power supply line 105 has a transmission means according to the invention.

[0085] According to the invention, the inspection of the protective conductor connection is carried out such that a uniquely encoded signal is coupled into a first conductor at the coupling point and is transmitted in the correct case at least indirectly from the first conductor or from a conductor conductively connected to the first conductor into a second conductor at the transmission point. Furthermore, the transmitted uniquely encoded signal is received at the receiving point on the second conductor and the received signal is checked. Thus, the uniquely encoded electrical signal is transmitted from the coupling point to the receiving point via a transmission path. The transmission path must include the protective conductor connection to be inspected. However, in this case, it does not matter in the correct case whether the first or second conductor or a conductor conductively connected thereto is the protective conductor. In other words, in the correct case, it does not matter whether the coupling takes place in the protective conductor or in a conductor having good conductivity with the protective conductor, or whether decoupling takes place from the protective conductor or from a conductor conductively connected to the protective conductor in the correct case, or whether reception takes place there.

[0086] According to the invention, the protective conductor connection is defined as a part of the connection which can be at least indirectly conductively connected to the protective conductor of an electrical installation. According to the invention, the protective conductor of the electrical installation itself is also included in such a part.

[0087] Based on the inspection of the received signal, the quality of the protective conductor connection is inferred in the manner already described.

[0088] With the aid of the invention, a plurality of protective conductor connections can be inspected accordingly.

[0089] Reference Figures 1 to 4 , different protective conductor connections can be inspected as follows:

[0090] The protective conductor connection of the electrical device 100, wherein, for example, a transmission device 106 is provided between conductors A and B, and coupling occurs in conductor A or B, and reception occurs on the respective other conductor. The transmission device 106 is advantageously directly attached at the housing boundary between conductors A and B, for example at the electrodes of the mains socket of the electrical device 100 to which the mains supply line 105 can be connected. In Figure 2 a, an embodiment is shown for the case where all components required for this purpose are part of the device 100. Alternatively, as Figure 3 shown, only a part of the components required for this purpose can also be part of the device 100. In this case, the positioning of the transmission device advantageously does not occur at the electrodes of the mains socket of the electrical device 100, but further inside the device, in order to ideally inspect the entire length of the protective conductor connection in the device.

[0091] Furthermore, the protective conductor connection of an electrical device with a fixedly attached mains supply line 105 can be inspected. In this case, the transmission device 106 is advantageously directly attached between the two poles of the mains plug 401, as Figure 4 shown. Then coupling occurs, coupling occurs in one conductor A or B of the electrical device 100, and reception occurs on the respective other conductor. Thus, it is checked whether the protective conductor connection of the electrical device is properly implemented up to the transmission point in the mains supply line 105, and thus in the given example, up to the contact parts in the mains plug 401.

[0092] Furthermore, the protective conductor connection of a mains supply line 105 implemented as pluggable can be inspected. In this case, the mains supply line is advantageously implemented as Figure 4 shown. Then, similar to Figure 3 , coupling is carried out using a device 300 configured accordingly for this purpose, the difference being that instead of the device 100, the mains supply line 105 is connected to the device 300, as Figure 4 shown.

[0093] Furthermore, the protective conductor connection of the electrical installation 101 can be inspected. Thus, the transmission device 106 is arranged, for example, between conductors C and D, as Figure 1shown. The coupling and reception of the uniquely coded electrical signal then proceeds analogously to Figure 3 this, for example, with the difference that instead of device 100, electrical installation 101 is connected to device 300. This can thus be achieved, for example, in such a way that the conductors J, K, and M of the device can be connected to the mains socket at least indirectly using a mains plug. Other connectors for making electrical contact with electrical contact parts such as terminals or probe tips are also possible.

[0094] Figure 5 Schematic embodiments of the coupling device 102, the receiving device 103, and the transmission device 106 (dashed lines respectively) are shown by way of example.

[0095] The coupling device is formed by the transformer T1, the coil L1, and the capacitor C1. The signal generator G generates a uniquely coded electrical signal which is applied as S1 to the primary side of the transformer T1. The signal is transmitted via the transformer T1 to the secondary side of T1 and is coupled to the conductor L. In the exemplary embodiment, the conductor L is the first conductor according to the invention and is a conductor which is at least indirectly connectable to the voltage-carrying conductor L of the electrical installation. The series circuit of L1 and C1 forms a bandpass which is designed such that the mains frequency of the electrical installation is attenuated and the transformer is loaded little or not at all, but the frequency of the signal S1 is designed such that it is attenuated as little as possible by the bandpass.

[0096] Via the capacitor C3, which is one embodiment of the transmission device 106 according to the invention, the uniquely coded signal coupled to the conductor L is transmitted to the conductor PE which is at least indirectly connectable to the protective conductor PE of the electrical installation. In the exemplary embodiment, the conductor PE is the second conductor according to the invention.

[0097] Via the series circuit of L2 and C2 (which forms a bandpass in the same way as L1 and C1) and the transformer T2, the signal transmitted on the conductor PE is transmitted on the secondary side of the transformer T2. The optional parallel circuit of L3 and C4 ensures further suppression of frequencies which do not correspond to the (carrier) frequency of the uniquely coded electrical signal. The component values of the coils L1, L2 and the capacitors C1, C2 are designed such that the (carrier) frequency of the uniquely coded electrical signal is attenuated as little as possible, but the mains frequency is attenuated as well as possible. The person skilled in the art uses in this case the calculation or simulation methods which are conventional for him. Thus, if at the transmission point and the reception point (at Figure 5If a protective conductor connection (PE) is appropriately implemented between the identification in [the text] as path x), then the uniquely encoded signal S2 with signal S1 is applied on the secondary side. For example, if the protective conductor connection is interrupted on said path x, then signal S2 is not detected or only a very small signal S2 is detected. The evaluation circuit 104 then infers a break in the protective conductor and can initiate the measures already described, such as isolating the electrical equipment assigned to the protective conductor connection or outputting an alarm message. A conductor connection with an excessive resistance on path x also affects the signal parameters of signal S2 in the manner already described.

Claims

1. A device for checking the protective conductor connection of an electrical installation (101) or an electrical device (100, 105), the electrical device (100, 105) being configured for electrical connection to an electrical installation (101), wherein, The electrical device has at least conductor A and conductor B, wherein conductor A can be electrically connected at least indirectly to conductor C of the electrical installation (101), and wherein conductor B can be electrically connected at least indirectly to conductor D of the electrical installation (101), wherein conductor C is a protective conductor, and wherein the electrical connection between the electrical device (100) and the electrical installation (101) is optionally effected by means of a mains power supply line (105), which mains power supply line (105) has at least conductor E and conductor F, wherein conductor E can be connected to conductor A and conductor C, and wherein conductor F can be connected to conductor B and conductor D, the device comprising: a coupling device (102) for coupling a uniquely coded electrical signal into a first conductor selected from the first group of conductors A, C, E or the second group of conductors B, D, F at a coupling point, a receiving device (103) configured to receive the coded signal at a receiving point on a second conductor if the coded signal is transmitted by a transmitting device (106), which transmitting device (106) is configured to transmit the signal coupled into the first conductor at least indirectly to the second conductor at a transmission point, wherein the second conductor is selected from another group different from the first conductor, an evaluation device (104) configured to evaluate the quality of the protective conductor connection based on the signal received by the receiving device (103).

2. The device according to claim 1, the device having a disconnecting device, wherein, The device is configured to disconnect the electrical connection between the electrical device (100, 105) and the electrical installation (101) by means of a disconnecting device if the evaluation device (104) evaluates the quality of the protective conductor connection as unsatisfactory.

3. The device according to any one of the preceding claims, wherein, The transmitting device (106) transmits the coded electrical signal by capacitive coupling.

4. The device according to any one of the preceding claims, wherein, According to the device, at least the coupling device (102) and the evaluation device (104) are part of the electrical device (100), or according to the device, the coupling device (106) is part of the electrical installation (101) or is assigned to the electrical installation (101).

5. The apparatus according to claim 4, wherein, The device is implemented as a medical device.

6. The apparatus according to claim 5, wherein, The medical device is implemented as a blood treatment device and is in particular configured for hemodialysis, hemofiltration, hemodiafiltration, plasma exchange or automated peritoneal dialysis.

7. The apparatus according to any one of the preceding claims, wherein, The device is configured such that the coded electrical signal is a digitally coded electrical signal.

8. The apparatus according to any one of the preceding claims, wherein, The device comprises a signaling device (301) configured to be able to output at least one signal on the signaling device (301) according to the evaluation of the evaluation device (104).

9. Use of the coupling device (102), evaluation device (104), isolation device, transmitting device (106) in a device according to any one of the preceding claims.

10. A mains power supply line (105) for a device according to any one of claims 1 - 8, which comprises at least one transmitting device (106).

11. A method for checking the connection of a protective conductor of an electrical installation (101) or an electrical device (100, 105), the electrical device (100, 105) being configured to be electrically connected to the electrical installation (101), wherein, The electrical device has at least a conductor A and a conductor B, wherein the conductor A can be electrically connected at least indirectly to a conductor C of an electrical installation (101), and wherein the conductor B can be electrically connected at least indirectly to a conductor D of the electrical installation (101), and wherein the conductors are protective conductors, and wherein the electrical connection of the electrical device (100) to the electrical installation is optionally effected by means of a mains power supply line (105) which has at least a conductor E and a conductor F, wherein the conductor E can be connected to the conductor A and the conductor C, and wherein the conductor F can be connected to the conductor B and the conductor D, the method comprising the steps of: coupling a uniquely coded electrical signal into a first conductor selected from the first group of conductors A, C, E or the second group of conductors B, D, F at a coupling point, transmitting the coupled signal from the first conductor at least indirectly to a second conductor at a transmission point, wherein the second conductor is selected from another group different from the first conductor, receiving the coded signal at a receiving point on the second conductor, evaluating the quality of the protective conductor connection based on the signal received by the receiving unit.

12. The method according to claim 11, wherein, The method has the following steps: if the quality of the protective conductor connection from the coupling point to the receiving point is evaluated as unacceptable, disconnecting the electrical connection between the electrical device (100, 105) and the electrical installation (101).

13. The method according to claim 11 or 12, wherein, The coded electrical signal is capacitively transmitted.

14. The method according to any one of claims 11-13, wherein At least the coupling and receiving of the coded electrical signal and the evaluation of the quality of the protective conductor connection are performed by means forming part of the electrical device, or according to the method, the coupling of the coded electrical signal is performed by means forming part of the electrical installation (101).

15. The method according to any one of claims 11 - 14, wherein, The coded electrical signal is generated as a digitally coded electrical signal.

16. The method according to any one of claims 11-15, wherein The method includes the step of outputting at least one signal according to the evaluation.

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