Monitoring of the operation of electric coil devices

Abstract

A method for monitoring the operation of an electrical device (30) is disclosed, the electrical device having a plurality of coils (32, 51, 52, 53) electrically arranged in a parallel circuit. The method comprises the following steps: detecting the voltage (12) applied to each coil without power by means of taps on the turns; determining for each coil the AC component contained in the respectively detected voltage (13); determining the average value (14) of the voltage applied to the coil; evaluating for each coil the determined AC component relative to the determined average value of the voltage, wherein weighting is performed (15); and outputting a signal (17) if the weighted deviation of the value describing the AC component of the coil contained in the detected voltage from the value describing the average value of the voltage exceeds a specified limit value (16).

Description

Technical Field

[0001] The invention relates to a method for monitoring the operation of an electrical device, in particular a choke device, which has a plurality of coils or coil windings arranged electrically in parallel. The invention also relates to an electrical device, in particular a choke device, and a method for operating such a device. Background Art

[0002] Coils electrically arranged in parallel circuits are used, for example, with transformers or electrical chokes, such as air chokes, oil-insulated chokes, or gas-insulated chokes. In rare cases, short circuits between turns can occur in such coils. To prevent further damage, in particular fires caused by such short circuits, such as in the choke, it is advantageous to be able to diagnose short circuits as quickly and reliably as possible.

[0003] WO 2019 / 219196 A1 describes a method and device for detecting interturn short circuits in coils connected in parallel. For the coils connected in parallel, the current difference between the current flowing through each coil and the average value of the current flowing through the coils is determined. Based on this current difference, it is possible to detect when an interturn short circuit has occurred in one of the coils.

[0004] In addition to detecting the appropriate signal to reliably indicate a short circuit between turns, reliably transmitting that signal to the corresponding monitoring unit is also a challenge. Wireless signal transmission is generally simple and cost-effective, but it is not as reliable as hard-wired signal transmission. Until now, protection-related data, events, or signals have been transmitted almost exclusively via wires or optical waveguides. Wiring or laying such optical waveguides at high voltage potentials is expensive. Radio sensors used for signal transmission are susceptible to interference and, particularly when powered by batteries, can malfunction. The long chain of signal detection, digitization in the radio sensor node, preparation, and transmission using radio modules contains many potential sources of error, making it impractical to use radio technology solely for protection-related functions. Acoustic signals can be disrupted by background noise levels. Optical signals can be disrupted by scattered light or shadows in the receiver. Despite this, wireless signal transmission remains attractive, but the integration of redundant transmission paths has not yet been practical.

[0005] A fire in a choke is typically caused by a short circuit in the winding, usually as a result of an insulation fault. In chokes, which typically have multiple concentric winding layers connected in parallel, a short-circuited winding forms due to the insulation fault. The high currents induced by the choke's magnetic field cause the winding to heat up very quickly. Depending on the material composition, the winding insulation may begin to burn. If the short-circuited winding is located inside the choke body, detection using ultraviolet light (UV light) via fire alarm equipment is ineffective. Because the equipment reacts slowly to the generated smoke, the entire choke body may heat up so much during this time that the fire does not extinguish itself. UV detection can be particularly difficult if the choke is installed indoors due to the high level of indoor pollution. Furthermore, there is a risk of the fire spreading to adjacent equipment.

[0006] Therefore, it is desirable to ensure reliable early identification of faulty short-circuited windings.Additional optical monitoring systems, in particular optical monitoring systems with optical waveguide transmission and a dedicated evaluation unit, are relatively cost-intensive. Summary of the Invention

[0007] The present invention is therefore directed to providing a simple, reliable, and cost-effective method for monitoring the operation of an electrical device having a plurality of coils arranged electrically in parallel. A further object is to provide an advantageous electrical device and a method for operating the same.

[0008] The first technical problem described above is solved by the method according to the present invention for monitoring the operation of an electrical device, such as a choke device or a transformer device, which has a plurality of coils or coil windings electrically arranged in parallel. Another technical problem is solved by the electrical device according to the present invention, which has a plurality of coils or coil windings electrically arranged in parallel, and by the method according to the present invention for operating such a device. The following description contains further advantageous embodiments of the present invention.

[0009] In the following, the term “coil” is to be understood to mean both coil windings arranged spatially parallel to one another and coil windings arranged concentrically to one another.

[0010] The method for monitoring the operation of an electrical device according to the present invention involves a device having a plurality of coils electrically arranged in a parallel circuit. The device may be, for example, a choke or a transformer. The device may, for example, have at least two or at least three coils electrically arranged in a parallel circuit. During normal operation of the device, current flows through the coils.

[0011] The method according to the present invention includes the following steps: Using taps or lead-outs arranged on the turns, the voltage applied to each coil is detected, for example, measured, without power. For each coil, the alternating voltage component (AC component) contained in the corresponding detected voltage is determined. The average value of the voltage applied to the coil is determined. For each coil, the AC component contained in the detected voltage is evaluated relative to the determined average value. A weighting is performed. A signal is then output if the weighted deviation of the value describing the coil's AC component contained in the measured voltage from the value describing the average value of the voltage exceeds a specified limit value.

[0012] Preferably, during the method, the operating current of the device is detected and weighted using the detected operating current. Alternatively, the deviations of the individual coil voltages can be proportional to the absolute value of the voltage currently measured at the tap, for example, to the average value of the voltage measured at the tap. This also allows for the elimination of noise at low voltages or currents. Therefore, additional current measurement is unnecessary or optional.

[0013] For example, the effective value and / or amplitude and / or peak-to-peak value of the AC component and / or the time variation of the detected voltage relative to the mean value, i.e., the differential, can be determined as a value describing the AC component of the coil contained in the measured voltage. The average value of the DC voltage component (DC component) of the voltage of each coil and / or the average value of the effective value of the AC component of the voltage and / or the average value of the amplitude and / or the average value of the peak-to-peak value and / or the time variation of the mean value, i.e., the differential, can be determined as a value describing the mean value of the voltage. Taking these differentials into account during the evaluation process has the advantage that the monitoring accuracy is thereby increased, and turn-to-turn short circuits can be detected very quickly, even before the associated high currents occur.

[0014] The coil can be, for example, a dry-insulated air-core coil or a liquid-insulated coil with an iron core or a gas-insulated coil or a combination of individual variants of these.

[0015] The method according to the present invention has the advantage of enabling the identification of turn-to-turn short circuits before a fire can be detected using conventional UV or infrared sensors or by smoke detection. This allows for early detection, thereby preventing further damage to the device and, if necessary, other components. Furthermore, a coil short circuit can be associated with a specific coil. This allows for targeted replacement and / or repair of the specific coil, without the need for additional diagnostic steps to identify the affected coil. This saves time and costs. Overall, the present invention enables cost-effective and efficient fault detection.

[0016] In one advantageous variant, each of the coils has a main connection terminal. The voltage applied to each coil is preferably detected without power, for example measured, between the main connection terminal and a tap. The tap is preferably arranged on the first turn starting from the main connection terminal. In this case, the tap is preferably arranged at a distance from the main connection terminal that is less than the turn length. For example, the tap can be arranged at a distance of no more than two-thirds of the conductor length of the first turn starting from the main connection terminal, in particular in the case of air chokes. The tap is preferably arranged at a position approximately half the turn length, i.e. at a distance of half the turn length from the main connection terminal. Since the voltage per turn of a choke or reactor in an oil-insulated transformer is typically 800 V, this design makes it possible to achieve a voltage that is still well-processable using a signal voltage divider in the electronic device when using a (smaller) part of the first turn.

[0017] The tap is electrically conductively connected to the first turn of the coil via the connecting terminal, viewed from the main terminal. These connecting terminals offer the advantage of flexible connection and removal of the tap. This is advantageous, for example, when replacing a coil or tap, as it allows for quick and easy handling.

[0018] In another variant, the device can include a supporting star to which the coil is attached. In this variant, the taps are preferably designed so that the insulated signal lines lead out of the coil taps in the direction of the supporting star, i.e., they are insulated and routed over the shortest possible path to the supporting star, where they are connected to the measuring electronics. This is advantageous from a safety perspective because, in this design, the resulting voltage is well controllable even in transient situations. For example, an AC voltage of 20 volts can be drawn as the nominal voltage for the AC component. This allows, in the event of an incoming transient overvoltage, the signal voltage to be limited to a peak voltage of, for example, between 50 volts and several kilovolts using a small surge arrester.

[0019] In another variant, the AC current component (AC component) of the operating current is detected. The operating current should be understood as the total current flowing through a plurality of coils. The detected AC component of the operating current can be used for weighting. Additionally or alternatively, the deviation of the value describing the AC component of the coil contained in the measured voltage relative to the value describing the average value of the voltage can be determined as a ratio to the AC component of the operating current. If this ratio exceeds a specified limit value, a signal can be output. By taking into account the AC component of the operating current as described, the accuracy of the assessment of small operating currents is improved, while at the same time, a coarser assessment with a greater tolerance is possible in the case of large operating currents to avoid erroneous estimates.

[0020] In another variant, the magnetic field of each coil, particularly in the case of spatially separated individual coils, can be measured, and the proportional relationship of the magnetic field to the operating current and / or to the AC component of the operating current can be determined. If this proportional relationship reaches a predetermined threshold value for a coil, for example, a threshold value weighted according to the operating current, a signal can be output. Thus, changes in the magnetic field of each coil can be used as an indicator of the presence of a turn-to-turn short circuit, thereby making the assessment more precise.

[0021] Furthermore, the signal describing the AC component of the voltage and / or the signal describing the AC component of the detected operating current can be rectified and / or smoothed. Smoothing can be performed, for example, with a defined time constant, for example, a time constant of 300 milliseconds. In this way, the representation of the signal is improved. Transient deviations, ie deviations that are very limited in time, do not lead to erroneous signals that trigger further measures during rectification and smoothing.

[0022] The signals output during the method according to the present invention are preferably transmitted to the monitoring device via multiple redundant signal transmission paths. This can be done using optical waveguides, acoustic transmission, UV light transmission, and / or radio wave transmission. In this way, multiple redundant signal transmission paths can be created, ensuring reliable and durable signal transmission.

[0023] In another variant, energy can be obtained from the alternating field of the coil by means of an induction coil, for example an air-core coil. This energy can be used to evaluate and / or generate signals and / or to transmit signals. This design has the advantage that a potentially error-prone battery operation of the monitoring method can be avoided. In addition, this design contributes to improving the cost-effectiveness of the method and the device and reducing the probability of errors. In addition, the complexity of the corresponding monitoring and the costs associated with the conversion are reduced. The cross-sectional area of ​​the induction coil can have a diameter of between 10 cm and 20 cm, for example 15 cm. Alternatively, a saturable converter ( Stromwandler) to obtain energy, if necessary, can be used to obtain energy by DC pre-magnetization (DC-Vormagnetisierung) in the iron core.

[0024] The electrical device according to the present invention, which can be, for example, a choke device or a transformer device, has a plurality of coils electrically arranged in a parallel circuit. During normal operation of the device, current flows through the coils. Each coil has a tap on one turn. The electrical device includes a device for detecting, for example, measuring, the voltage applied to each coil using the taps without power, and an evaluation device. The electrical device according to the present invention is designed to carry out the method according to the present invention described above. The device according to the present invention has the features and advantages already mentioned above in conjunction with the method according to the present invention. Optionally, the device can include a device for detecting the operating current of the device.

[0025] The evaluation device can be designed, for example, to detect, for each coil, the AC component contained in the corresponding measured voltage, and / or to determine an average value of the voltage applied to the coils, and / or to evaluate, for each coil, the AC component contained in the measured voltage relative to the determined average value of the voltage. The evaluation device can also be designed to perform weighting during the evaluation, for example using the detected operating current or voltage. It can also be designed to output a signal if the weighted deviation of the value describing the AC component of the coil contained in the measured voltage relative to the value describing the average value of the voltage exceeds a specified limit value.

[0026] The device according to the invention can include at least two or at least three coils. The coils can be, for example, air-core coils, oil-insulated coils, or gas-insulated coils. The coils can be arranged not only spatially parallel to one another, but also concentrically relative to one another (choke structure consisting of different layers). This also means that a single single-phase choke (in particular an air choke) that exists physically and electrically as a unit with only two electrical connection points can be monitored using the approach described here by measuring in its individual concentric, parallel-connected layers. The device can include at least one induction coil for energy collection.

[0027] Each coil preferably has a main connection terminal, and the tap is arranged on the first turn of the coil from the main connection terminal. The device for detecting the voltage applied to each coil without power is preferably designed to detect the voltage between the main connection terminal and the tap. The tap can have a connection terminal. The connection terminal can be connected to the turn of the coil to be tapped. Advantageously, the tap is arranged at a distance of no more than two-thirds of the conductor length of the first turn from the main connection terminal, for example, at a distance of approximately half the conductor length of the first turn.

[0028] The device may include a supporting star to which the coil is fixed. The tap may be designed so that it leads from the coil in the direction of the supporting star. The advantages and other design features associated with this have already been described above in conjunction with the method according to the invention.

[0029] The device may also include at least one signal-damping inductor and / or at least one surge arrester. The surge arrester may be connected downstream of the signal-damping inductor. Furthermore, a device for rectifying and / or smoothing the AC signal may be provided.

[0030] The method according to the present invention for operating the aforementioned device is characterized by operating the device in a conventional manner, wherein the method according to the present invention for monitoring the operation of the device, as described above, is performed. If, during the monitoring method, at least one signal received by the monitoring device on at least two redundant transmission paths is output to the monitoring device, the operation of the device is interrupted, for example, the device is switched off. This allows reliable and cost-effective fault detection, in particular the detection of turn-to-turn short circuits.

[0031] Within the scope of the present invention, the signals of the individual coils or individual layers are compared. If the coil voltage or layer voltage deviates significantly from the average layer voltage, this indicates a layer short circuit. The deviation is preferably weighted by the total current or operating current of the device, such as the choke. When the total current is high, the layer voltage deviation must be greater than when the operating current is low to reliably detect a turn-to-turn short circuit. In the electronic circuit, a trigger signal weighted by the operating current measurement is formed from the differential voltage. This trigger signal then controls a wireless signal transmission chain, which is advantageously redundant, for the protection or monitoring device. For differential evaluation, inexpensive, less accurate measurement techniques can be used. For this purpose, the measured voltages are compared differentially, similar to the H circuit of a Wheatstone bridge.

[0032] In principle, it is possible to distinguish between parallel chokes and single chokes with multiple layers. Depending on the behavior of the fault location in the shorted turns, the individual layer currents, and therefore the layer voltages at the taps, change differently or to similar degrees when a fault occurs. Low-resistance short-circuit faults are easily detected because only the current or voltage at the fault location changes, and fault identification can be immediately used for disconnection. High-resistance faults result in a smaller increase in the layer current. The current in adjacent, fault-free layers of the device may also increase. In this case, a comparison of the layer currents and / or layer voltages may not be sufficient criteria for disconnection. In this case, the layer currents can be compared with external current measurements in the same current path of the device, and / or the currents of adjacent phase coils can be used to assess the fault, and / or intelligent sensor nodes can be used to detect the entry and exit of arcs in the fault location, which is typical of high-resistance faults. This manifests itself, for example, as a jump or fluctuation proportional to the layer current in a high-resistance turn short circuit (or inter-turn short circuit) or turn fault, which can develop into a low-resistance fault over time. A signal transition can be used to issue an alarm message, which can trigger further correlation of information. This correlation can also be the response of individual fire detectors or a weak acoustic indication detected by a microphone. The sum of the indications can then serve as a sufficient criterion for shutting down.

[0033] The following possibilities can be considered as signal paths to monitoring devices, for example, for triggering protection: In a first variant, UV light can be generated by a UV light source and directed to sensors in the fire protection system. Alternatively or additionally, the light can be transmitted via an optical waveguide to an evaluation device at ground potential. In a second variant, an acoustic warning signal can be emitted by a loudspeaker. In a third variant, a radio signal can be transmitted. If two of the three aforementioned signal transmissions are present, a shutdown of the entire system can be triggered. The inductance and insulation of coils, such as chokes, can then be carefully checked and, if necessary, repaired.

[0034] The present invention enables highly precise and undelayed detection of high currents flowing through short-circuited turns of coils, such as air-insulated chokes, where AC currents or mixed AC and DC currents flow through the coils. In principle, no additional wiring or optical waveguides are required, which translates to cost savings. Different or independent fault detection technologies are advantageous for error-free detection of impermissible operating states. The present invention provides an alternative detection technology for this purpose. Redundant signal transmission enables reliable signal transmission. High-performance UV monitoring already available in the corresponding equipment room can be used not only for fire detection but also for early detection of high currents in faulty turns of coils, such as chokes. Installing acoustic signal detection in the choke hall also enables detection of partial discharges, local flashovers, and developing mechanical defects in the choke body. Acoustic signal transmission enables reliable signal transmission in partially metallic installations, such as in converter chambers, due to the good diffraction and reflection of sound waves. This allows multiple uses of the acoustic reception signal, for example, for different transmitters or for different types of acoustic error messages. This can be achieved, for example, at different frequencies or by signal modulation. Furthermore, the energy of the measurement signal can be used to power the transmission technology and can be stored as needed, so that no battery supply is required. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will be described in more detail below with reference to the accompanying drawings and by way of examples. Although the present invention is described and illustrated in more detail through preferred embodiments, the present invention is not limited to the disclosed examples, and those skilled in the art may deduce other variations therefrom without departing from the scope of protection of the present invention.

[0036] The accompanying drawings are not necessarily true to detail and to scale, but may be shown enlarged or reduced to provide a better overview. Therefore, the functional details disclosed herein should not be understood as limiting, but only as an illustrative basis to provide guidance to those skilled in the art for various uses of the present invention.

[0037] As used herein, the expression "and / or," when used in connection with a list of two or more elements, means that each of the listed elements may be used alone or in any combination of two or more of the listed elements. For example, if a combination comprising elements A, B, and / or C is described, the combination may comprise A alone; B alone; C alone; the combination of A and B; the combination of A and C; the combination of B and C; or the combination of A, B, and C.

[0038] Figure 1The method for monitoring the operation of an electrical device according to the present invention is schematically shown in the form of a flow chart.

[0039] Figure 2 The method according to the invention for operating an electrical device having a plurality of coils electrically arranged in a parallel circuit is schematically illustrated in the form of a flow chart.

[0040] Figure 3 An electrical device according to the invention is schematically shown in a perspective view.

[0041] Figure 4 A cross section of a conductor bundle of a coil is schematically shown.

[0042] Figure 5 The apparatus according to the present invention and the principles of the present invention are schematically illustrated in the form of a block diagram. DETAILED DESCRIPTION

[0043] Figure 1 The method for monitoring the operation of an electrical device according to the present invention is schematically illustrated in the form of a flow chart. During the method for monitoring the operation of an electrical device having multiple coils arranged in parallel, the operating current of the device is detected in optional step 11. In step 12, the voltage applied to each coil is detected, e.g., measured, without power, using taps arranged on the turns. Steps 11 and 12 can also be performed in reverse order or simultaneously.

[0044] In step 13, the AC component contained in the respectively measured voltage is determined, for example, detected, for each coil. In step 14, the average value of the voltage applied to the coil is determined. In step 15, the AC component contained in the measured voltage is evaluated for each coil relative to the determined average value, with weighting being performed, for example, using the detected operating current. For example, the effective value and / or amplitude and / or peak-to-peak value of the AC component determined for each coil can be divided by the operating current or proportional to the operating current and weighted in this manner for further evaluation. Alternatively, the weighting can be performed using the voltage.

[0045] Alternatively or additionally, for each coil, the differential, i.e., the time derivative, of the AC component of the voltage measured for the corresponding coil can be weighted with the detected operating current, or the differential, i.e., the time derivative, of the detected operating current can be weighted. For the AC component, the effective value, amplitude, or peak-to-peak value can be used.

[0046] In step 16, a check is performed to determine whether the value describing the AC component of the coil contained in the measured voltage, i.e., the weighted value determined in step 15, such as the effective value, amplitude, or peak-to-peak value, exceeds a specified limit value relative to the value describing the average value of the voltage, i.e., the weighted deviation of the average voltage or the differential or the differential of the average value applied to the coil in question. If this is the case, a signal is output in step 17, preferably to a monitoring device. If the limit value has not been exceeded, the method returns to step 11.

[0047] Optionally, the magnetic field of each coil can also be measured and the ratio of the magnetic field to the operating current and / or the AC component of the operating current can be determined, and a signal can be output if the ratio exceeds a predetermined threshold value for a coil.

[0048] The signal transmission to the monitoring device can be performed by acoustic signal transmission and / or signal transmission by means of UV light waves and / or signal transmission by means of optical waveguides and / or signal transmission by means of radio signals. Preferably, the signal is transmitted in at least three different ways.

[0049] Figure 2 A method for operating an electrical device having a plurality of coils, for example, at least two or at least three coils, arranged electrically in parallel is schematically illustrated in the form of a flow chart. In step 21, the device is operated in a conventional manner. To this end, current flows through the plurality of coils. For example, a high voltage may be applied to the coils. The electrical device may be, for example, a choke or a transformer.

[0050] In step 22, the method according to the invention is carried out, for example Figure 1 . After outputting a signal during the method, a check is performed in step 23 to determine whether a specified number of redundant signals have been received by the monitoring device. If this is not the case, the method returns to step 21. If this is the case, operation of the device is interrupted in step 24, and further measures, such as shutdown, maintenance, or repair, are initiated if necessary. The number of redundant signals that the monitoring device must receive in order to transition from step 23 to step 24 can be, for example, the receipt of at least two of three signals.

[0051] Figure 3 The electrical device 30 according to the invention is schematically shown in a partial perspective view. The device 30 comprises a plurality of coils electrically arranged in a parallel circuit. The device 30 can be, for example, a choke or a transformer. The device 30 comprises a supporting star 31. A plurality of coils 32 are fixed to the supporting star 31. Figure 3Only one coil is schematically shown. Other coils can be arranged concentrically within the illustrated coil 32. Each coil 32 includes a main connection terminal 33. A tap 35 is arranged on the first turn 34 starting from the main connection terminal 33. A connection terminal 36 can be arranged on the first turn 34, which is designed to be connected to a tap cable.

[0052] The tap 35 and / or the connection terminal 36 are arranged close to the main connection terminal 33. Preferably, the tap 35 or the connection terminal 36 is arranged at a distance from the main connection terminal 33 that is less than half the length of the first turn 34, for example, at a distance between 20 cm and 50 cm from the main connection terminal 33, preferably at a distance of about 30 cm.

[0053] The main connecting terminal 33 and the tap 35 are connected to a device 37 for detecting, for example measuring, the voltage present between the main connecting terminal 33 and the tap 35 without power. The device 37 for detecting the voltage present at the corresponding coil without power is connected to an evaluation device 38 for signal transmission. The evaluation device 38 can optionally also be connected to a device 39 of the device for detecting the operating current for signal transmission.

[0054] The evaluation device 38 is designed to, based on the signals received from the device 37 for power-free detection of the voltage present at the individual coils and optionally from the signal from the device 39 for detecting the operating current, determine the operating current according to the above-described method, for example by means of Figure 1 The described method generates and outputs a signal. In this case, the evaluation device 38 can be designed to transmit the corresponding signal to the monitoring device by means of at least two, preferably at least three redundant signal transmission paths.

[0055] Figure 4 A schematic cross-section through a conductor bundle 40 of a coil 32 is shown. This can be a cross-section of a first turn 34. The sub-conductors of the sub-conductor bundle 40 are numbered 1 to 10, and the insulation of the conductor bundle 40 is marked with reference numeral 41. The tap 35 is connected to the sub-conductor 2 via a connecting terminal 36 in the illustrated embodiment via the insulation 41. Such a connecting terminal 36 can also be retrofitted relatively easily into existing coils.

[0056] Figure 5 The device according to the present invention and the principle of the present invention are schematically illustrated in the form of a block diagram. Three exemplary coils of the device according to the present invention are labeled with reference numerals 51, 52, and 53. A device for detecting the total current applied to the coils is labeled with reference numeral 54. Each of the coils 51, 52, and 53 has a main connection terminal 33 and a tap, preferably a connection terminal 36.

[0057] Each of coils 51, 52, and 53 is connected to a device 37 for detecting the voltage applied between the corresponding main terminal 33 and tap 35. Each of devices 37 is connected to an evaluation device 38 for signal transmission, as indicated by arrows. Evaluation device 38, which is optionally also designed to receive signals from device 39 for detecting the total current, is designed to generate and output signals according to the method according to the present invention described above. The signals can optionally be output to a monitoring device 54.

[0058] Reference Signs List

[0059] 1-10 sub-conductors

[0060] 11 Operating current of the detection device

[0061] 12 Detect the voltage applied to each coil without power

[0062] 13 Determine the AC component contained in the voltage measured for each coil

[0063] 14 Determine the average value of the voltage applied to the coil

[0064] 15 For each coil, evaluate the AC component relative to the mean value of the determined voltage

[0065] 16 Does the value describing the AC component of the coil contained in the measured voltage, as a weighted deviation from the value describing the mean value of the voltage, exceed a specified limit value?

[0066] 17 Output signal

[0067] 21 Operating device

[0068] 22 Execute the method for monitoring

[0069] 23 Check whether the specified number of redundant signals are received at the monitoring device

[0070] 24 Interrupt operation

[0071] 30 Electrical installations

[0072] 31 Support star

[0073] 32 coils

[0074] 33 Main connection terminals

[0075] 34 First Turn

[0076] 35 taps

[0077] 36 connection terminals

[0078] 37 Device for detecting the voltage applied to the corresponding coil without power

[0079] 38 evaluation devices

[0080] 39 Device for detecting operating current

[0081] 40 conductor bundles

[0082] 41 Insulation

[0083] 51 Coil

[0084] 52 Coil

[0085] 53 Coil

[0086] 54 surveillance device

[0087] J is

[0088] N No.

Claims

1. A method for monitoring the operation of an electrical device having a plurality of coils electrically arranged in a parallel circuit, It is characterized in that The method comprises the following steps: - power-free detection of the voltage applied to each coil by means of taps on the turns, - determining, for each coil, the AC component contained in the respectively detected voltage, - determine the average value of the voltage applied to the coil, - for each coil, evaluating the determined alternating current component relative to the mean value of the determined voltages, wherein a weighting is performed, - outputting a signal if the weighted deviation of the value describing the alternating component of the coil contained in the detected voltage from the value describing the mean value of the voltage exceeds a prescribed limit value, Each of the coils has a main connection terminal, and a power-free detection is performed on the voltage applied to each coil between the main connection terminal and the tap. The tap is arranged on the first turn starting from the main connection terminal.

2. The method according to claim 1, It is characterized in that The tap is arranged at a distance of a maximum of two thirds of the conductor length of the first turn starting from the main connection terminal.

3. The method according to claim 1 or 2, It is characterized in that The operating current of the device is detected and used for weighting and / or weighted relative to the absolute value of the voltage currently measured at the tap or relative to the average value of the voltage measured at the tap.

4. The method according to claim 1 or 2, It is characterized in that Determine the change over time of the effective value and / or amplitude and / or peak-to-peak value of the AC component and / or the deviation of the detected voltage from the average value as a value describing the AC component of the coil contained in the detected voltage, and / or determine the average value of the DC component of the voltage and / or the average value of the effective value of the AC component of the voltage of each coil and / or the average value of the amplitude and / or the average value of the peak-to-peak value and / or the change over time of the average value of the voltage as a value describing the average value of the voltage.

5. The method according to claim 1 or 2, It is characterized in that The AC component of the operating current is detected and used for weighting and / or a deviation of a value describing the AC component of the coil contained in the detected voltage from a value describing the mean value of the voltage is determined as proportional to the AC component of the operating current, and a signal is output if the proportionality exceeds a specified limit value.

6. The method according to claim 1 or 2, It is characterized in that The magnetic field of each coil is measured, and the ratio of said magnetic field to the operating current and / or the AC component of the operating current is determined, and a signal is output if this ratio reaches a predetermined threshold value for the coil.

7. The method according to claim 1 or 2, It is characterized in that The signal describing the AC component of the detected voltage and / or the signal describing the AC component of the detected operating current is rectified and / or smoothed.

8. The method according to claim 1 or 2, It is characterized in that At least one signal is transmitted to a monitoring device via a plurality of redundant signal transmission paths.

9. The method according to claim 1 or 2, It is characterized in that Energy is obtained from the alternating field of the coil by means of the induction coil and is used for evaluation and / or for signal generation and / or for signal transmission.

10. An electrical device having a plurality of coils electrically arranged in a parallel circuit, It is characterized by: Each coil has a tap of the turns, the device comprising means for detecting the voltage present at each coil in a power-free manner by means of the tap and an evaluation device, and The device is designed to carry out the method according to any one of claims 1 to 9, Each of the coils has a main connection terminal, the tap is arranged on the first turn starting from the main connection terminal, and the device for detecting the voltage applied to each coil without power is designed to detect the voltage between the main connection terminal and the tap.

11. The device according to claim 10, It is characterized by: The device comprises at least one induction coil for obtaining energy.

12. The device according to claim 10, It is characterized by: The tap is arranged at a distance of a maximum of two thirds of the conductor length of the first turn starting from the main connection terminal.

13. The device according to any one of claims 10 to 12, It is characterized by: The device comprises a supporting star to which the coil is fixed and the taps are designed to lead out from the coil in the direction of the supporting star.

14. The device according to any one of claims 10 to 12, It is characterized by: The device comprises a signal-damping choke and / or a surge arrester.

15. A method for operating a device according to any one of claims 10 to 14, It is characterized by: The device is operated, wherein the method for monitoring the operation of the device according to any one of claims 1 to 9 is performed, and if at least one signal is output to a monitoring device during the method for monitoring, and the monitoring device receives the signal on at least two redundant transmission paths, the operation of the device is interrupted.

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