WO2021211019A1

WO2021211019A1 - Arc-fault protection device

Info

Publication number: WO2021211019A1
Application number: PCT/RU2021/050082
Authority: WO
Inventors: Александр Сергеевич МКРТУМОВ; Алексей Николаевич НЕМЦОВ; Федор Николаевич НЕМЦОВ
Original assignee: Общество с ограниченной ответственностью "Эколайт" (ООО "Эколайт")
Priority date: 2020-04-17
Filing date: 2021-03-29
Publication date: 2021-10-21
Also published as: CN218783576U

Abstract

The utility model relates to arc-fault protection devices. An arc-fault protection device (1) comprises a voltage reading unit (2), a current sensor (3), a unit (4) for extracting high-frequency current signals, a unit (5) for extracting medium-frequency current signals, a microcontroller (6), a power supply unit (7), a disconnection member (8) and a self-testing unit (11). The self-testing unit (11) is connected at the protected circuit side so as to be able to supply a self-testing signal to the protected circuit for recording thereof by the current sensor (3). The technical result consists in increasing the reliability of operation of an arc-fault protection device (1) by extending the functional capabilities thereof, which allow the operation of the device and of the components thereof to be checked without the operation of the device being interrupted, and make it possible to use real test pulses to adjust the response of the device to an arcing current threshold.

Description

ARC BREAKTHROUGH PROTECTION DEVICE

The utility model relates to the field of electrical engineering and electronics, namely, to protection devices for arc breakdown in electrical networks, and can be used in everyday life and at work to protect electrical circuits during arc breakdown.

Arc fault protection device (ARC) is designed to reduce the undesirable effects arising from arcing (arc breakdown) in the controlled or protected circuit by disconnecting the supply network and the protected circuit. Requirements for SPDD are defined by GOST IEC 62606-2016 “Protection devices for household and similar purposes in case of arc breakdown. General Requirements ", or other technical requirements for UZDP in electrical networks and electrical installations.

Electrical networks are usually protected by modular circuit breakers and residual current devices (RCDs). However, these devices are not able to detect intermittent arcing and arcing faults in time and, thus, do not provide complete protection against possible ignition and fire. Accidentally occurring sparks are not always serious, but electric arcs can very quickly lead to large localized temperature rises.

From the RF patent RU2660285 (published on 10/05/2017; IPC G01R31 / 08, G01R15 / 14, Н02Н7 / 26) an arcing protection device (AFDD) is known, which contains a power supply unit, at least one voltage reading unit, at least one sensor current, a block for extracting high-frequency current signals, a block for extracting medium-frequency current signals, a microcontroller and a shutdown organ. The microcontroller interacts with these units to measure and analyze current signals in the high-frequency and mid-frequency regions, as well as voltage signals in the mid-frequency and low-frequency regions, on the basis of which it determines the event of a single spark discharge, accumulates information about single spark discharges, saves it as an arcing parameter and generates a shutdown signal when the arcing parameter reaches the specified value. The shutdown device is designed to disconnect the protected circuit from the network by a shutdown signal.

The known AFDD provides an increase in the accuracy of determining the sparking event, a decrease in the number of false alarms, an increase in the service area, the number of connected electrical appliances, the length and branching of the protected circuit. However, it is also characterized by the absence of a self-test function, which increases the likelihood of incorrect detection of an arcing event, or even the impossibility of such a determination, for example, due to a malfunction of the current sensor.

Also known is the AFDP of the SIEMENS 5SM6 family (see the link https: //assets.new.siemens.eom/siemens/assets/api/uuid: 8591eald52328862b34a9b9925defa4062 aa3f2a / version: 1527519761 / afd-5sm6-ru.pd 2012 C ), which was chosen as the closest analogue of this utility model.

Like the AFDD described above, the SPDD of the SIEMENS 5SM6 family allows, by means of the control module, to determine the sparking event in the protected circuit and generate a signal to the release (tripping device) to disconnect the supply network and the protected circuit. In addition, the closest analogue implements a self-test function, the diagram of which from the description of SIEMENS 5SM6 is shown in Fig. 1. Self-test is automatically started at set intervals in order to check the operability of the microprocessor and detection algorithms. The microcontroller software generates synthetic high-frequency and current signals - self-test signals that are similar to arcing signals, and these self-test signals are fed into the system detection circuit after the current sensor and high frequency sensor, and then evaluated by the analog circuit and the microcontroller. Next, the microcontroller generates a trip command, and during the self-test, the trip signal for the trip relay is disconnected for a short time to avoid a practical trip of the device. After successful completion of the test, the trip path is re-enabled. A negative test result will result in an immediate shutdown of the device. The self-test will be delayed if there are initial indications of a real arcing fault or an increased above average current consumption in the associated distribution circuit. As follows from the description and the self-test circuit of the closest analogue, the device generates self-test signals that only simulate an arc breakdown during self-testing, and feeds them into the circuit in parallel with the signals of the current sensor and the high-frequency sensor. In this case, a malfunction of any sensor (for example, in the event of an open circuit, incorrect polarity, inadequate transformer core, etc.) will not be detected during self-testing, which means that accurate and unambiguous detection of an arc breakdown will become impossible, which is a significant drawback of the closest analogue.

The objective of this utility model is to eliminate the above disadvantage of known devices and create such a SPL11, in which the self-test function provides for the supply of real, rather than simulated, test pulses directly to the protected circuit, which, as a result, ensures the verification of the sensors of the device and almost all signal transmission circuits and making decisions on the presence of an sparking (breakdown) event in the protected circuit without interrupting the operation of the device.

The technical result is to increase the reliability of the operation of the UZD11 with a self-test function by expanding its functionality, which ensures the verification of the operation of the device and its components and the possibility of adjusting the operation of the device according to the spark current threshold by evaluating the response to an amplitude-calibrated current surge produced in a specific circuit protected by the data UZD11.

The problem is solved, and the claimed technical result is achieved in the proposed arc breakdown protection device, which includes a voltage reading unit, a current sensor, a high-frequency current signal extraction unit, a medium-frequency current signal extraction unit, a microcontroller, a power supply unit, a shutdown organ and a self-test unit. In this case, the self-test unit is included from the side of the protected circuit with the possibility of supplying a self-test signal to the protected circuit for their registration by the current sensor.

In contrast to the closest analogue, in which the self-test signal is fed in parallel to the current sensor and the high-frequency sensor, in the declared SPLD, the self-test signal is fed to the protected line and is detected by the current sensor, which makes it possible to check the operation of almost all signal flow and decision-making circuits in the device, as well as to carry out initial and periodic automatic adjustment of the sparking current threshold to the real parameters of the protected circuit in the given installation of the device.

The task is being solved, and the claimed technical result is also achieved in private versions of the UZD11 according to this utility model.

So, in the preferred embodiment of the UZD11, the self-test unit contains a controllable switch and a high-precision resistor. In this case, the microcontroller can be configured to generate a control pulse with an amplitude sufficient to transfer the controlled key to a fully open state.

In addition, the voltage sensing unit can be configured to read the low frequency voltage and the mid frequency voltage.

Next, the utility model is explained in more detail with reference to the figures, where: FIG. 1 shows a diagram of the internal self-testing function of the closest analogue according to the technological manual for the SPDD of the SIEMENS 5SM6 family; in fig. 2 shows a simplified block diagram of an embodiment of the claimed

UZDP; in fig. 3 shows a diagram of an embodiment of a self-testing unit for use in the declared AFDD; in fig. 4 shows an example of the waveform of the measured current signals from the self-test signal.

In general, apart from the presence of a self-testing unit and the implementation of the corresponding self-testing function, the declared ultrasonic detector can be implemented on the basis (or similarly) of the ultrasound device described in the RF patent RU2660285. For this reason, a brief description of similar components of the claimed AFDD and the specified known AFDD and their functioning will be given below, and more detailed data can be found in the specified patent.

The claimed UZDP 1 contains a voltage reading unit 2, a current sensor 3, a unit 4 for selecting high-frequency current signals, a unit 5 for separating medium-frequency current signals, a microcontroller 6, a power supply unit 7, a shutdown organ 8 and a self-test unit 11 (Fig. 2).

UZDP 1 is included in the line between the lead-in shield 9 or another power source, or network, and electrical installations 10 of the protected circuit. The voltage sensing unit 2 may include a low frequency voltage sensor and a mid frequency voltage sensor. The low-frequency voltage sensor together with the microcontroller 6 is used for recording and subsequent analysis of the current value of the mains voltage with a sufficiently high sampling frequency, in particular, 10-40 kHz. The mid-frequency voltage sensor together with the microcontroller 6 is used for recording and subsequent analysis of voltage pulses in the mid-frequency region from about 1 to 50 kHz. The voltage sensing unit 2 can have any known design and, in the simplest case, is a voltage divider for measuring in the low-frequency region and a differentiating circuit for measuring in the mid-frequency region. The specialist will understand that the voltage sensing unit 2 can have another suitable design, which is determined, inter alia, by the algorithm for establishing an arcing event in the protected circuit.

The current sensor 3 is designed to receive current signals, of which, further, by means of block 4 for extracting high-frequency current signals, block 5 for extracting mid-frequency current signals and microcontroller 6, mid-frequency current signals are separated and analyzed, respectively (current measurement in the region from about 0.1 to 20 kHz) and high-frequency current signals (current measurement in the region of about 1 to 10 MHz). The current sensor 3 can have any known design and in the simplest case is a current transformer. The specialist will understand that the current sensor 3 can have another suitable design, which is determined, inter alia, by the algorithm for establishing an arcing event in the protected circuit.

The microcontroller 6 is designed to process signals coming from the voltage reading unit 2, the unit 4 for extracting high-frequency current signals and the unit 5 for extracting medium-frequency current signals, determining the event of arcing in the protected line and generating a control signal for the shutdown organ 8. In addition, the microcontroller 6 generates a control pulse to activate the self-test unit 11, which will be described in detail below.

The power supply unit 7 provides power to the microcontroller 6 and, if necessary, the shutdown organ 8.

The shutdown organ 8, when a control signal is received from the microcontroller 6, breaks the power supply circuit of the electrical installations 10, i.e. disconnects the protected circuit from the network. An open circuit, depending on the design of the device, can produced not only in the path L of the phase current (as shown for an example in Fig. 2), but also in the path N of the neutral current.

The operation of the UZD11 1 in the normal circuit protection mode, which does not include the self-test mode, generally corresponds to the operation of the ultrasound device known from the RF patent RU2660285. Therefore, the following is a brief description of the operation of the AFDP 1 in normal mode.

The microcontroller 6 analyzes the signals coming from the voltage readout unit 2 and the signals coming from the current sensor 3 through the unit 4 for extracting high-frequency current signals and unit 5 for extracting medium-frequency signals. The decision on the presence of sparking in the protected circuit is made in two stages.

At the first stage, the microcontroller 6 determines the presence and evaluates the parameters of a single spark discharge (EIR) in the current half-cycle of the mains voltage by analyzing and comparing the signal from the low-frequency voltage sensor to determine the current network voltage, the signal from the current sensor 2 in the high-frequency region, the signal from the sensor 2 current in the mid-frequency region and the signal from the mid-frequency voltage sensor. After receiving and analyzing these signals, the microcontroller 6 determines whether there is an EIR, and in the case of a positive answer, further, at the second stage of operation, the sequence of the confirmed EIR is analyzed in order to determine the sparking. When the sparking is confirmed, the microcontroller 6 generates a signal for the shutdown organ 8 to disconnect the protected circuit from the network.

The signal from the low-frequency voltage sensor determines the phase of the mains voltage zero crossing. Then the time intervals in which the subsequent measurements will be made are determined. These time intervals correspond to the growth section of the mains voltage module, since repeated breakdown is extremely unlikely in the regions of the mains voltage module decay.

After confirming the EIR in the protected circuit in this half-period, the SPLD 1 proceeds to the second stage of the analysis. At the second stage, the transition from the identification of the EIR to the identification of the actual sparking is carried out. This stage can be implemented in various ways, for example, those known from the RF patent RET2660285 and other sources of information mentioned therein.

As a result, when the sparking event is confirmed, the microcontroller 6 generates a control signal for the shutdown organ 8, and the shutdown organ 8 disconnects the protected circuit of electrical installations 10 from the network. As mentioned above, UZD11 1 according to the present utility model contains a self-test unit 11, included from the side of the protected circuit, i.e. at the output of the UZD11 1, and made with the possibility of supplying a self-test signal directly to the protected circuit. The self-test signal is detected by the current sensor 3, like any event occurring in the protected circuit, and then processed by the microcontroller 6. This allows you to check the operation of almost all signal flow and decision-making circuits in the UZD11 1.

An example of the implementation of the self-testing unit 11 is shown in FIG. 3 in the form of a schematic diagram.

In the selected for self-testing half-period of the mains voltage when this voltage reaches a certain value U0 (for example, 200 V), measured by the low-frequency voltage sensor, to the input (marked as "Input" in Fig. 3) of the key element Q, for example, based on the field-effect transistor IPN95R1K2P7 , a pulse is supplied from the output of microcontroller 6 with a duration of about 100 μs and an amplitude sufficient to transfer the key element Q to a fully open state. The load of the key element Q is a resistor R, placed between the drain of the transistor and, through connector P, the output phase line of the SPLD 1 at a point after the current sensor 3. As a result, a current jump occurs between the phase and neutral wires with an amplitude I = U0 / R at the output of the UZDP 1, similar to the current jump in the protected circuit. The waveforms of the current signals from the self-test signal at the outputs of the block 5 for separating medium-frequency current signals (upper curve 1) and block 4 for separating high-frequency current signals (lower curve 2) are shown in FIG. 4, where time is plotted along the horizontal axis, and the current value is plotted along the vertical axis.

Since current pulses during self-testing are generated at the output of the SPLD 1 by means of a controlled key Q and a high-precision resistor R at a known current voltage U0 of the network, the amplitude of these pulses is set with a sufficiently high accuracy. This makes it possible to use the response of the SPD 1 sensors during self-testing for its automatic adjustment by the spark current threshold to the real parameters of the protected circuit in this SPD 1 installation.

Thus, the present utility model provides new functionalities of the SPLD, such as the supply of real, rather than simulated, test pulses directly to the protected circuit, which ensures the verification of the sensors. devices and practically all circuits for passing signals and making decisions about the presence of an sparking (breakdown) event in the protected circuit without interrupting the operation of the UZD11.

Claims

FORMULA

1. A device (1) protection in case of arc breakdown, comprising: a voltage reading unit (2), a current sensor (3), a unit (4) for separating high-frequency current signals, a unit (5) for separating medium-frequency current signals, a microcontroller (6), a unit (7) power supply, a shutdown organ (8) and a self-test unit (11), while the voltage reading unit (2) is connected to the microcontroller (6) for recording and subsequent analysis of the current value of the mains voltage, the current sensor (3) is connected to the unit ( 4) the selection of high-frequency current signals and the block (5) for the selection of medium-frequency current signals, which are connected to the microcontroller (6), for recording and analyzing, respectively, high-frequency and medium-frequency current signals, the microcontroller (6) is connected to the shutdown organ (8) to disconnect the protected circuit from the network, and the microcontroller (6) is connected to the self-test unit (11) to provide a self-test signal, characterized in that the self-test unit (11) is switched on from the side of the protected circuit with the possibility by giving a self-test signal to the protected circuit for their registration by the current sensor (3).

2. Device (1) on and. 1, in which the self-test unit (11) contains a controllable switch (Q) and a high-precision resistor (R).

3. Device (1) on and. 2, in which the microcontroller (6) is configured to generate a control pulse with an amplitude sufficient to transfer the controlled key (Q) to a fully open state.

4. Device (1) on and. 1, in which the voltage sensing unit (2) is configured to read the low frequency voltage and the mid frequency voltage.