Apparatus and method for detecting arc faults

Abstract

An apparatus (100) for detecting arcing faults caused by power lines (130, 135, 230, 235) is disclosed. The apparatus includes an antenna (105, 205) disposed within the near field of at least one power line. The apparatus also includes a receiver (215) coupled to the antenna and processing circuitry (115, 260) coupled to the receiver and configured to identify arcing faults based on signals received from the receiver. A method for detecting arcing faults caused by power lines corresponding to the apparatus is also disclosed.

Description

[Technical Field]

[0001] This disclosure claims priority to UK patent application number 2219811.3 filed December 29, 2022, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure is in the field of apparatus and methods for detecting arc faults generated by power lines, and is particularly relevant to power meters that include apparatus for detecting such arc faults. [Background technology]

[0003] An arc fault is a high-power electrical discharge that occurs between two or more conductors. Such a discharge can generate extremely high temperatures and potentially ignite combustible materials, causing an electrical fire. Arc faults occurring on residential and commercial power lines can cause significant damage and pose a serious safety risk.

[0004] Arc fault currents can range from a few amperes to thousands of amperes and can be of varying duration.

[0005] Arc faults can be classified into three main categories: ground arc faults, parallel arc faults, and series arc faults.

[0006] Parallel arc faults and ground arc faults are typically caused by short circuits between power lines with high currents, so conventional short circuit breakers or fuses can effectively detect arc faults and provide appropriate protection.

[0007] The current magnitude of a series arc fault may be limited by the load in the circuit. The current magnitude of a series arc fault may be the same as or slightly less than the normal operating current, and its frequency spectrum characteristics are typically centered in the frequency band from 2 kHz to 20 MHz.

[0008] As a result, conventional breakers may not provide reliable protection because they may not be able to react quickly enough to sudden series arc faults due to the low current magnitude or wide frequency bandwidth of the series arc fault.

[0009] In some regions, some level of arc fault detection is required by law. For example, in the United States, the National Electrical Code (NEC) includes provisions for arc fault detection.

[0010] Conventional solutions for achieving arc fault detection include the use of current transformers (CTs) and Hall effect sensors. However, a drawback of these means is that their frequency bandwidth can be limited to a maximum of approximately 200 kHz. As previously mentioned, a typical series arc fault can have frequency components up to 20 MHz or even higher.

[0011] Therefore, there is a need to provide a relatively low-complexity, reliable, and effective method and apparatus for detecting arc faults within the above-mentioned frequency bands.

[0012] There is also a need for such arc fault detection to be integrated with the power meter, so that such arc fault detection can be performed without interfering with co-located transceivers and / or circuitry within the power meter.

[0013] It is therefore an object of at least one embodiment of at least one aspect of the present disclosure to obviate or at least mitigate at least one of the above-mentioned disadvantages in the prior art. Summary of the Invention

[0014] The present disclosure is in the field of apparatus and methods for detecting arc faults, and particularly relates to power meters including such apparatus for detecting arc faults. According to a first aspect of the present disclosure, an apparatus for detecting arc faults caused by power lines is disclosed. The apparatus includes an antenna. The antenna may be located within a near-field of at least one power line. The apparatus includes a receiver coupled to the antenna. The apparatus includes processing circuitry coupled to the receiver. The processing circuitry may be configured to identify an arc fault, such as an arc fault caused by at least one power line, based on a signal received from the receiver.

[0015] Advantageously, such an apparatus provides a relatively low-complexity, reliable, and effective means for detecting arc faults.

[0016] Furthermore, such a solution can be implemented without interfering with co-located transceivers or circuitry within the power meter, as will be described in more detail below. That is, the use of such an antenna effectively provides a relatively non-invasive series arc fault current detection sensor. The antenna described above functions as a near-field magnetic pickup, generating a detectable and measurable current proportional to its magnetic field. Advantageously, the use of such an antenna minimizes interference from and to transceivers in the immediate vicinity of the antenna, e.g., within the power machine. This avoids receiver desensitization, as will be described in more detail below.

[0017] The near field of the at least one power line may occur in close proximity to the at least one power line, and the antenna may be located in close proximity to the at least one power line such that a magnetic field induced by an arcing fault in the power line may induce a current in the antenna.

[0018] The antenna may provide near-field magnetic pickup, i.e., the antenna can perform the function of near-field magnetic pickup when placed in the near field of at least one power line.

[0019] The disclosed device provides an accurate, reliable, and low-cost solution while minimizing / eliminating interference to and from other co-located wireless devices.

[0020] Furthermore, the disclosed apparatus can alleviate the need to implement other relatively complex and / or relatively expensive solutions for series arc fault detection, such as solutions that use current transformers (CTs) or Hall effect sensors.

[0021] The antenna may include a coil antenna, which may include multiple turns.

[0022] The magnitude of the current induced in the antenna is roughly proportional to the number of turns provided in the antenna, although the number of turns in the antenna may be increased, which may be limited by the space available on the printed circuit board (PCB) on which the antenna is mounted.

[0023] The antenna may include a planar antenna.

[0024] That is, the antenna can be formed in a metal layer of a PCB, thereby making the antenna substantially planar. Advantageously, such a planar antenna, e.g., a planar coil, minimizes interference with other transceivers and / or radio frequency circuits in the vicinity of the antenna while providing sufficient sensitivity to detect arcing faults.

[0025] The antenna may be provided on one or more metal layers of a printed circuit board.

[0026] For example, the antenna may be mounted on the top layer of the PCB as close as possible to at least one power line. The antenna may also be mounted on multiple layers of the PCB, thereby increasing the overall number of turns on the antenna and improving its sensitivity.

[0027] The receiver may be configured to receive signals within a frequency range of at least 2 kHz to 20 MHz.

[0028] Series arc faults exhibit a frequency spectrum characteristic that is typically concentrated in the frequency band between 2 kHz and 20 MHz, which allows the receiver to be optimized for detecting arc faults.

[0029] Furthermore, the disclosed apparatus can alleviate the need to implement relatively complex and / or relatively expensive solutions for series arc fault detection, such as solutions using current transformers (CTs) or Hall effect sensors. A technical drawback of such prior art solutions is that their frequency bandwidth may be limited to approximately 200 kHz.

[0030] The receiver may be a wideband receiver.

[0031] The processing circuitry may be configured to identify peaks in the signal.

[0032] In some embodiments, the processing circuitry may include one or more Digital Signal Processors (DSPs) and / or processors configured to execute DSP routines.

[0033] The processing circuitry may be configured to analyze the signal based on the peaks and identify and / or locate the arc fault.

[0034] That is, the processing circuitry may be configured to distinguish signals generated by arc faults from general noise and / or other signals.

[0035] The processing circuitry may include an amplifier configured to amplify the current provided by the antenna.

[0036] The processing circuitry may include a peak detection circuit for demodulating the output of the receiver.

[0037] The processing circuitry may include a comparator that conditions the output of the peak detection circuitry.

[0038] The processing circuitry may include at least one processor configured to analyze the output of the comparator to identify an arc fault.

[0039] In one embodiment, the antenna can function as a near-field magnetic pickup. The antenna can generate a current proportional to its magnetic field. That is, a current induced in the antenna by a signal caused by an arc fault on at least one power line can be proportional to the antenna's magnetic field. The current can be amplified by a receiver. The receiver can be provided with sufficient gain to amplify the current. The receiver output can be demodulated via a peak detector to provide a peak detection signal. The peak detection signal can undergo signal conditioning via a comparator. The comparator can generate a pulse based on the characteristics of the arc fault. The pulse can be analyzed by processing circuitry, such as a measurement microprocessor. Such analysis can be performed by an algorithm, such as a proprietary algorithm. The algorithm can be selected / configured to reliably detect the arc fault.

[0040] The device may include at least one power line.

[0041] The at least one power line may be electrically isolated from the antenna.

[0042] The at least one power line extends across the antenna in a plane substantially parallel to a plane defined by the antenna.

[0043] The at least one power line may extend across the antenna in a plane substantially parallel to a plane defined by the antenna. The receiver may be located relatively close to the antenna, thereby maximizing receiver sensitivity. This technique may also minimize re-radiation from the antenna and reduce interference caused by other radiation sources, such as other radios.

[0044] The near field may be an inductive near field.

[0045] According to a second aspect of the present disclosure, there is provided a power meter including an apparatus according to the first aspect.

[0046] The processing circuitry may be configured as a metrology processor.

[0047] That is, the processing circuitry may be configured to measure power consumption based on measurements of current and / or voltage on at least one power line.

[0048] The power meter may include a sub-gigahertz radio. The power meter may include a Bluetooth radio. The power meter may include a Wi-Fi radio. The power meter may include a ZigBee radio. The power meter may include one or more DC-DC converters.

[0049] The antenna may be formed on the same substrate as the processing circuitry.

[0050] Advantageously, by implementing the antenna as a planar antenna, on a plane defined by a substrate such as a PCB, interference between the antenna and other radios or transceivers can be limited.

[0051] That is, the disclosed arc fault detection solution is suitable for implementation in "smart power meters," e.g., power meters with communications capabilities. The disclosed antenna solution is suitable for operation with co-located potential interference sources, such as ZigBee radios, Wi-Fi radios, and / or sub-gigahertz radios, microprocessors, and / or one or more DC-DC converters. Implementing a relatively thin, planar PCB coil antenna can reduce desensitization of the arc detection receiver due to potential interference sources and, conversely, reduce interference from the arc detection receiver.

[0052] In response to detecting an arc fault, the processing circuitry may be configured to transmit a message indicating the occurrence of an arc fault.

[0053] In response to detecting an arc fault, the processing circuitry may be configured to interrupt power supply to at least one power line.

[0054] For example, the processing circuitry may be configured to actuate (trigger) a service disconnect switch to isolate at least one power line from the load as a safety measure.

[0055] According to a third aspect of the present disclosure, there is provided a method for detecting arcing faults generated by power lines, the method including providing an antenna within a near field of at least one power line, the antenna coupled to a receiver, and processing circuitry coupled to the receiver and configured to identify an arcing fault based on signals received from the receiver.

[0056] The foregoing summary is illustrative only and is not intended to be limiting. The present disclosure includes one or more corresponding aspects, embodiments, or features, whether specifically described or not (including in the claims), each alone or in various combinations. Features defined above according to any aspect of the disclosure, or described in connection with any specific embodiment described below, can be used alone or in combination with any other defined features in other aspects or embodiments, or to form yet further aspects or embodiments.

[0057] These and other aspects of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0058] [Figure 1a] FIG. 1 shows a photograph of a top surface of an exemplary device including an antenna, according to one embodiment of the present invention. [Figure 1b] FIG. 1 shows a photograph of the bottom surface of an exemplary device including an antenna, according to one embodiment of the present invention. [Figure 2] FIG. 1 illustrates another exemplary device including an antenna, in accordance with an embodiment of the present invention. [Figure 3] 1 is a block diagram of an exemplary power meter, in accordance with one embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0059] Figure 1a shows a partial photograph of the top of an exemplary device 100 including an antenna 105, according to one embodiment of the present invention. Figure 1b shows a partial photograph of the bottom of the exemplary device 100.

[0060] The apparatus 100 is suitable for detecting arcing faults caused by power lines, as will be described in more detail below.

[0061] The exemplary device 100 includes a substrate 110, which in the illustrated embodiment is a printed circuit board (PCB).

[0062] The antenna 105 is formed on the substrate 110. That is, the antenna 105 is implemented as a planar antenna 105. The antenna 105 does not protrude from the surface of the substrate 110. The antenna 105 is not formed as a separate component mounted on the substrate 110. Instead, the antenna 105 is formed on the substrate 110 or on an inner layer of the substrate 110. Advantageously, such a planar antenna, e.g., a planar coil, minimizes interference with other transceivers and / or high frequency circuits in the vicinity of the antenna 105 while providing sufficient sensitivity to detect arc faults.

[0063] Antenna 105 can perform the function of near-field magnetic pickup, i.e., when placed in the near field of at least one power line, as described in more detail below with reference to FIG.

[0064] The exemplary antenna 105 is implemented as a coil antenna having multiple turns. While only four turns are shown in the embodiment depicted in FIG. 1 , it will be understood that in other embodiments, the antenna 105 may be implemented with fewer or more than four turns. The magnitude of the current induced in the antenna 105 may be substantially proportional to the number of turns provided on the antenna 105. Thus, more turns may be added to the antenna 105 if, for example, the antenna is limited by available space within the substrate 110.

[0065] Similarly, the exemplary antenna 105 has a substantially elongated shape, and accordingly each turn has a substantially rectangular shape, although other shapes such as squares or polygons are also possible.

[0066] In a preferred embodiment, at least a portion of antenna 105 is mounted on the top metal layer of substrate 110, i.e., mounted at or near the surface of substrate 110. This minimizes the distance and / or shielding between antenna 105 and one or more power lines that are located relatively close to the substrate.

[0067] 1a, a first layer of antenna 105 is mounted on the top metal layer of substrate 110, and a second layer of antenna 105 is mounted on the bottom metal layer of substrate 110. A first via 120 and a second via 125 connect the first layer of antenna 105 to the second layer of antenna 105. By mounting antenna 105 on multiple layers of substrate 110, the overall number of turns of antenna 105 can be increased within the available space, thereby improving the sensitivity of antenna 105.

[0068] In some embodiments, a ground shield and / or power plane may be implemented within the substrate, and the ground shield and / or power plane may extend at least partially around the antenna 105 to minimize potential interference between the antenna 105 and surrounding circuitry and / or components.

[0069] The apparatus 100 further includes circuitry 115. Exemplary circuitry 115 includes a processing circuit and a receiver coupled to the processing circuit.

[0070] In the illustrated embodiment, circuit 115 includes various discrete components, such as resistors, comparators, etc. Circuit 115 is for illustrative purposes only; in other embodiments, circuit 115 may include one or more integrated circuits. Circuit 115 may be configured to identify arc faults, such as arc faults caused by at least one power line, based on signals received from the receiver. The receiver may be configured to receive signals in a frequency range of at least 2 kHz to 20 MHz. A further example circuit is shown in FIG. 3 as follows: As shown, the receiver circuit is relatively close to antenna 105, thereby maximizing its sensitivity.

[0071] Figure 2 illustrates a further example of an apparatus 100 including an antenna 105, according to one embodiment of the present disclosure. In the example of Figure 2, a first power line 130 and a second power line 135 are shown.

[0072] The first power line 130 and / or the second power line 135 may be an AC power line, for example, a power line that can be measured by a power meter.

[0073] In one embodiment, the first power line 130 is a neutral line and the second power line 135 corresponds to one phase of a power source, such as a 120 or 240 volt, 50 Hz or 60 Hz AC power source.

[0074] 3, the power lines 130, 135 extend across the antenna 105 in a plane substantially parallel to the plane defined by the antenna 105. Although the power lines 130, 135 are shown attached to the substrate 110 by fasteners, in other embodiments the power lines 130, 135 may be glued to the substrate or embedded within the substrate.

[0075] The antenna 105 is positioned within the inductive near field of the power lines 130,135 to receive signals in the range of 20 kHz to 20 MHz that may be generated by an arc fault event in the power lines 130,135.

[0076] The power lines 130, 135 are located sufficiently close to the antenna 105 that the disclosed antenna 105 acts as a near-field magnetic pickup, generating a detectable and measurable current substantially proportional to its magnetic field, which can be received, amplified, and processed by receiver and processing circuitry, as described below.

[0077] FIG. 3 is a block diagram of an example power meter 200 according to an embodiment of the present disclosure.

[0078] The power meter 200 includes an antenna 205, which generally corresponds to the antenna 105 in the embodiment of Figures 1a-2. That is, the antenna 205 may be a planar coil antenna. Also shown are a first power line 230 and a second power line 235 extending over the antenna 205. As described above, the antenna can function as a near-field magnetic pickup for the first power line 230 and the second power line 235 extending over the antenna 205.

[0079] Shown is an arc detection receiver and peak detector circuit 215. In one embodiment, such circuit 215 may include at least one of an amplifier configured to amplify the current provided by the antenna, a peak detector circuit for demodulating the receiver output, and a comparator for conditioning the output of the peak detector circuit.

[0080] The output of the arc detection receiver and peak detector circuit 215 is provided to processing circuitry 230. Processing circuitry 260 may be configured to analyze the output of the comparator to identify arc faults. In some embodiments, the processing circuitry may be further configured as a measurement processor for measuring power consumption using voltage and / or current detection and signal conditioning circuitry 235. In other embodiments, a separate processor for arc fault detection may be provided.

[0081] Various potential interference sources that may be components of power meter 200 are also shown by way of example. For example, a sub-gigahertz radio 240 is shown. In some embodiments, the sub-gigahertz radio may be configured to transmit and receive signals in the 915 MHz band. Also shown are an IEEE 802.11-compliant "Wi-Fi" radio 245 and an IEEE 802.11-compliant "ZigBee" radio 250. It should be understood that these are merely examples, and that in other examples, additional or alternative communication means may be implemented, such as an IEEE 802.15.1-compliant Bluetooth radio. Other potential interference sources include various power supplies, such as switching power supplies that include a DC-DC converter 255.

[0082] Advantageously, the antenna 205 is implemented as a planar antenna 205 that does not extend or protrude from the PCB, and thus can act as a near-field magnetic pickup for the power lines 230, 235, generating a detectable and measurable current proportional to their magnetic fields. Advantageously, the use of such an antenna 205 minimizes interference to and from nearby transceivers in the antenna's immediate vicinity, such as gigahertz radios 240, Wi-Fi radios 245, and ZigBee radios 250, and avoids receiver desensitization.

[0083] Although the present disclosure has been described based on the above-mentioned specific embodiments, it should be understood that these embodiments are merely illustrative and that the claims are not limited to these embodiments. Those skilled in the art can make modifications and alternatives based on the present disclosure, and these modifications and alternatives are included in the scope of the appended claims. Each feature disclosed or illustrated in this specification may be incorporated into any embodiment alone or in appropriate combination with other features disclosed or illustrated in this specification. [Explanation of symbols]

[0084] 100 devices 105 Antenna 110 Substrate 115 Circuit Configuration 120 First Via 125 Second Via 130 First Power Line 135 Second Power Line 200 wattmeter 205 Antenna 215 Receiver and Peak Detector Circuit 230 First Power Line 235 Second Power Line 240 GHz radio 245 Wi-Fi radio 250 ZigBee Radio 255 DC-DC converter 260 Processing Circuit

Claims

1. An apparatus (100) for detecting arc faults generated by a power line (130, 135, 230, 235), comprising: an antenna (105, 205) located within the near field of at least one of said power lines; a receiver (215) coupled to the antenna; a processing circuit (115, 260) coupled to the receiver and configured to identify an arc fault based on signals received from the receiver; Including, Apparatus (100).

2. The antenna (105, 205) comprises a coil antenna, the coil antenna comprising a plurality of turns. The apparatus (100) of claim 1.

3. The antenna (105, 205) includes a planar antenna.

3. The apparatus (100) according to claim 1 or 2.

4. The antenna (105, 205) is mounted on one or more metal layers of a printed circuit board.

3. The apparatus (100) according to claim 1 or 2.

5. The receiver (215) is configured to receive signals within a frequency range of at least 2 kHz to 20 MHz. An apparatus (100) according to any one of claims 1 to 4.

6. The processing circuit (115, 260) identifying peaks in the signal; Analyzing the signal based on the peaks to identify and / or locate the arc fault. It is configured as follows: An apparatus (100) according to any one of claims 1 to 5.

7. The processing circuit (115, 260) an amplifier configured to amplify the current provided by the antenna (105, 205); a peak detection circuit for demodulating the output of said receiver (215); a comparator for conditioning the output of the peak detection circuit; at least one processor (230) configured to analyze the output of the comparator and identify an arc fault; Including, An apparatus (100) according to any one of claims 1 to 6.

8. The device (100) further includes at least one of the power lines (130, 135, 230, 235); the at least one power line is electrically isolated from the antenna (105, 205); the at least one power line extends across the antenna in a plane substantially parallel to a plane defined by the antenna; An apparatus (100) according to any one of claims 1 to 7.

9. the near field is an inductive near field; An apparatus (100) according to any one of claims 1 to 8.

10. A power meter (200) comprising the device (100) according to any one of claims 1 to 9.

11. the processing circuit (115, 260) is configured as a metrology processor; The power meter (200) of claim 10.

12. Sub-gigahertz radio (240), Bluetooth® radio, a Wi-Fi® radio (245), and / or ZigBee (registered trademark) radio Further comprising at least one of A power meter (200) according to claim 10 or 11.

13. The antenna (105, 205) is formed on the same substrate as the processing circuit (115, 260). A power meter (200) according to any one of claims 10 to 12.

14. The processing circuit (115, 260) responds to detecting an arc fault by: Sending a message indicating the occurrence of an arc fault; and / or Cutting off the power supply to the at least one power line (130, 135, 230, 235); It is configured as follows: A power meter (200) according to any one of claims 10 to 12.

15. A method for detecting arc faults generated by a power line (130, 135, 230, 235), comprising: Providing an antenna (105, 205) within the near field of at least one of said power lines. Including, the antenna is coupled to a receiver (215), and a processing circuit (115, 260) is coupled to the receiver and configured to identify an arc fault based on signals received from the receiver. method.

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