Electricity meter hot socket detection.

(54) Title: DETECTION OF THE HEATING OF THE RECEPTACLE OF AN ELECTRICITY METER. (54) Title: ELECTRICITY METER HOT SOCKET DETECTION.

(57) Summary

When there is a poor connection between an electricity meter and its receptacle, there is a possibility of arcing, which can result in overheating of the receptacle and the occurrence of a fire. Methods for the meter to detect arcing in the receptacle are described in the present application by analyzing RF (Radio Frequency) noise in the channels of the communication spectrum used by the publisher to communicate with its measurement system. For example, keeping a record of normal background noise and monitoring for a wideband increase in noise on all channels can detect arcing. Meter parameters such as temperature, current, voltage, and harmonic content can also be used in isolation or in combination with broadband RF noise to detect arcing. A disconnect switch contained in the meter can be activated to eliminate arcing fault.

(57) Abstract

When a poor meter to Socket connection occurs, there is the potential for arcing to develop which can result in a hot socket and a fire. Disclosed herein are methods for a meter to detect the occurrence of an are condition in the Socket by analyzing the RF noise on the channels of the communicafion speefrum used by the meter fo communicafe wifhin ifs metering system. For example, by keeping a record of the normal background noise and looking for a broadband increase in the noise on all channels, are detection can be achieved. Meter quantities such as temperature, current, voltage, and harmonic content may also be used in a standalone manner or in combination with broadband RF noise to detect an are condition. A disconnect switch within the meter can be opened to remove the are fault.

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I KNOW

PATENT TITLE NO. 337808

SfCeraitiA 1 »« BNOMlA

Institute

Mexican Property

Industrial

Owner (s): ELSTER SOLUTIONS, LLC

Address: 208 South Rogers Lañe, Raleigh, North Carolina, 27610, USA

Name: DETECTION OF THE HEATING OF THE RECEPTACLE OF AN ELECTRICITY METER

Classification:

Inventor (s):

lnt.CI.8: G01R31 / 02

KENNETH C. SHUEY; ROBERTT. MASON

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tfggji

14/005237

ΙΗΒΒΙ

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Presentation:

April 2014

PRIORITY

Hours

14:23

Country:

US

Validity: Twenty years _toExpiration Date: | θ April 2034

Date:

May 2013

Number:

61/818,037

The reference patent is granted with fument in the

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fraction V, 6th fraction lll, and 59 of the Industrial Property Law.

This patent is valid for twenty unsustainable years, from the rate to keep the rights in force. £ j articles e® sections lll and 7 ° bis 2 of the By of refcr m I on 08/02 * 1994. 8ffig / 19 *&gt;. 12/26/1997, 17/5/1999, 06/28/2010. 27: 01 / 20-13 riHplK2012); articles 1, 3 fiction V «jdfaWjWadaMMfcfftéil (DOF 12/14/1999, renewed in 2004 and 7 / B / 2007); articles 1, 3, 4, 5, fraction ^ n ^^^ Wftaceiones I and lll and 30 of the Organic Statute of piety 1. 3rd and 5th subsection a) of the Agreement that delegates powers to the Deputy Directors General, Coordinator, Divisional Directors, Holders of Regional Offices, Divisional Deputy Directors, Departmental Coordinators and other subordinates of the Mexican Institute of Industrial Property. (DOF 12/15/1999, amended on 02/04/2000, 07/29/2004, 08/04/2004 and 09/13/2007).

From &lt;

I with article 23 of the L (of the Property. Gives from the filing date of the application tfí

Quigi signs this Industrial Property (Diado 26 / (^ / 2004, 16/06/2005, 25/0 ¡nol® a), 4 ° and 12 ° fractioni 01 / CÍ / 2002, 07/15/2004, del ilo He did it with the fundamental principle of the -doration (DOF /

1006, 06 / ¡72009,06 / 01/2010, 1B / ÓI and lll of the regulations of the Institute Me:

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Issue Date: March 16, 2016

THE DIVISIONAL DIRECTOR OF PATENTS

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NAHANNY CANAL REYES

Sand! No. 550, Floor 1,

Coi. Santa Mana Tepepan town. Xochimilco CP 16020, 'Mexico City

Tel (55? 53 34 07 00 wwwiinpi.gob.iit,

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MX / 2016/22380

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DETECTION OF THE HEATING OF THE RECEPTACLE OF AN ELECTRICITY METER

FIELD OF THE INVENTION [0001] The present invention relates to an electricity measurement and, more particularly, to systems, methods and apparatus for detecting receptacle heating conditions in an electricity meter installation.

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BACKGROUND [0002] The “Smart Grld” concept for updating electrical systems led to the change of millions of electricity meters. Old electromechanical meters have been swapped out for newer solid-state electricity meters with communication capabilities, and most of these new meters include an entire house disconnect switch mechanism. Many of the replaced electricity meters were in service in residential areas for years. An electricity meter facility is generally not serviced or maintained, so many of the old meter receptacles in which those meters were installed may have deteriorated over time. Installing a new electricity meter into a damaged meter receptacle can create a poor electrical connection even though the meter has been installed in a correct working order.

[0003] Typically, a single phase ANSI meter has four blades that extend out of a thermoplastic base. These blades are inserted into spring loaded jaws of a meter receptacle that is typically mounted on the wall of a residence. In some of the older residential areas, the jaws of a meter receptacle may have lost contact force to engage firmly with the meter blades. An installer may not

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Acknowledge that one or more blades are not making as good a contact as desired at the time of installation.

[0004] A poor electrical connection between the meter and receptacle can create a situation where an arc can form at the meter-receptacle interface. There have been times when house fires have occurred from a sustained condition where arches form in this type of meter receptacle.

[0005] Attempts have been made to detect "receptacle heating" conditions by measuring the blade temperature, receptacle temperature, or meter temperature. Unfortunately, sensing the temperature of these elements during an arc event requires that the arc exist for a long enough time to generate intense heat. There is a possibility that, by the time heat is detected, the condition in which arcs form may degrade the equipment sufficiently to create a hazardous situation.

[0006] Attempts were also made to solve a related problem using AFCI devices for residential applications. These AFCI devices detect voltage and / or current associated with a load and attempt to develop a "signature or pattern" that is associated with a condition in which arcs form. Arc characteristics are typically detected by looking for different noise frequencies that may be present in the voltage and current signals on the power line. If an arc is detected, the AFCI device can interrupt the load current and suppress the condition in which arcs form if it is in the circuit being monitored. Other solutions that were attempted to detect arcs involved detecting light generated by an arc.

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SYNTHESIS

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[0007] This description refers to an electricity meter and a method of determining whether there is a condition in which arcs form between the meter and a receptacle. The electricity meter is used to measure electrical energy supplied from a voltage source to an electrical load. The meter is arranged between the voltage source and the electrical load. The meter includes blades, a radio frequency (RF) transceiver, and a processor. The blades serve to connect the meter to the receptacle. The RF transceiver is used for meter communications to transmit data collected from the meter to an electrical power station through a wireless communication network. In this sense, the RF transceiver will transmit and receive communications on a given frequency. The transceiver can also measure the intensity of the received signals on a communication channel or frequency and generate a value indicative of the received signal intensity. These values ​​are commonly referred to as received signal strength indicator (RSSI) values. The transceiver can generate RSSI values ​​in the RF communications spectrum for all communication channels used by the transceiver for communications. The processor receives the RSSI values ​​generated by the transceiver and determines from them whether there is a condition in which arcs form between the blades and the receptacle.

BRIEF DESCRIPTION OF THE DRAWINGS [0008] The above synthesis, as well as the following detailed description of illustrative embodiments of the present application will be better understood when read in conjunction with the accompanying drawings. In order to illustrate the present application, illustrative embodiments of the disclosure are shown in the drawings. Without going ii ¡¡¡¡¡¡¡TJTÓ;

DEL /, i '

However, it is to be understood that the application is not limited to the precise provisions and instruments shown. In the drawings:

[0009] FIG. 1 illustrates by way of example, an embodiment of a measurement system in which the arc detection methods disclosed in the present disclosure can be implemented;

[0010] FIG. 2 is a schematic of an electricity meter with a transceiver and a disconnect switch; and [0011] FIG. 3 is a diagram illustrating an embodiment of a method for detecting a condition in which arcs are formed.

DETAILED DESCRIPTION [0012] Methods and systems for detecting arcing in an electrical meter and receptacle facility are described herein by examining the characteristics of radio frequency (RF) communications performed by an electric meter transceiver in the spectrum Industrial, Scientific and Medical Communications (ISM). By keeping a record of the normal background noise on the ISM channels used by the meter and detecting an increase in broadband noise on all ISM channels, arc detection can be achieved. In one embodiment, a disconnect switch can be opened within the meter to eliminate arcing fault. In other embodiments, other measurements, alone or in combination with RF detection, can be used to detect a condition in which arcs form, including, for example, current magnitude, voltage magnitude, and / or temperature information. .

[0013] FIG. 1 provides an illustrative diagram of a measurement system 110, in which the arc detection methods described herein can be employed. System 110 comprises a plurality of meters 114,

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Ni! TI UTO // i '' · -. ·, '//' ^v of 17j '.', '/.'. 7, '7 / that can be operated to detect and record the consumption or use of a service such as electricity, water or gas. Meters 114 may be located in Customer Facilities such as, for example, a home or a workplace. The meters 114 comprise circuits to measure the consumption of the service consumed in their respective locations and to generate the data that reflects the consumption, as well as other related data. Meters 114 may also comprise circuits for Wireless transmission of data generated by the meter to a remote location. The meters 114 can also comprise circuits to receive data, orders or instructions also by wireless route. Meters that can be operated to both receive and transmit data can be referred to as "bi-directional" or "two-way" meters, while meters that are only capable of transmitting data may be referred to as "transmit only" or " one way ”. In bidirectional meters, the transmit and receive circuits may comprise a transceiver. In an illustrative embodiment, meters 114 may be, for example, electricity meters manufactured by Elster Solutions, LLC and sold under the trademark REX. An example of a transceiver that can be used in such a meter and that can be used in connection with the arc detection method disclosed herein is a Silicon Labs SI4461.

[0014] System 110 also comprises manifolds 116. In one embodiment, manifolds 116 are also meters operable to detect and record the use of a service such as, for example, electricity, water or gas. Furthermore, the collectors 116 are operable to send data and receive data from meters 114. Thus, like meters 114, collectors 116 may comprise both circuits for measuring consumption of a service and for generating data reflecting consumption and circuits for transmitting and receiving data. In one embodiment, manifold 116 and meters 114 communicate with each other using either

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various wireless techniques such as, for example, frequency hopping spread spectrum (FHSS) and direct sequence spread spectrum (DSSS).

[0015] A collector 116 and the meters 114 with which it communicates define a subnet / LAN 120 of the system 110. As used herein, the meters

114 and collectors 116 may be referred to as "nodes" on subnet 120. On each subnet / LAN 120, each meter transmits data related to the consumption of the service or flow being measured at the meter location. Collector 116 receives the data transmitted by each meter 114, effectively "collecting" them, and then periodically transmits the data from all the meters on the subnet / LAN

120 to a data collection server 206. The data collection server

206 stores data for analysis and invoice preparation, for example. The data collection server 206 can be a specially programmed general-purpose computing system and can communicate with collectors 116 through a network 112. Network 112 can comprise any form of network, including a wireless network or a wired network, such as a local area network (LAN), a wide area network, the Internet, an intranet, a telephone network such as the public switched telephone network (PSTN), a frequency hopping spread spectrum radio network (FHSS), an ISM mesh network, a Wi-Fi network (802.11), a Wi-Max network (802.16), a land line network (POTS ) or any combination of the above.

[0016] FIG. 2 is a schematic diagram of one embodiment of an electricity meter 300, which may be one of meters 114 or manifolds 116 in the system of FIG. 1. As shown, meter 300 may be disposed between an electrical power source 8 and an electrical load 14 and operates to measure electrical energy supplied from source 8 to load 14 through power lines 320 at the location of a subscriber. A Disconnect Switch 304 can be interposed on power lines 320, to

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Hee! Ai: S ίΊΏ.- ·. I toggle between an open position in which no electrical errergy is supplied to the electrical charge 14 and a closed position in which electrical energy is supplied to the electrical charge.

[0017] Meter 300 also comprises a processor 302, such as a microprocessor, that executes computer-readable instructions (program code) that can be stored within a memory (not shown) of the meter. These computer-executable instructions, when executed by the processor, cause the processor to perform various functions within the meter, such as determining power consumption and operating other components within the meter. Also as shown, meter 300 further includes a transceiver 350 that can be used by the processor to transmit and receive information from a meter network, such as the meter network illustrated in FIG. one.

In one embodiment, the transceiver can comprise a Silicon Labs SI4461.

[0018] Transceiver 350 can be configured to measure the intensity of signals received on an RF communication frequency or a channel of a wireless communication network and to generate a value indicating signal strength (RSSI) received from there the value. RSSI is an indication of the power level received by the transceiver antenna. Typically, the higher the RSSI value, the stronger the signal. RSSI can be used internally in a transceiver to determine when the amount of radio energy in a channel is below a certain threshold at which point the transceiver may be free to transmit on the channel. Conversely, an RSSI value above a certain threshold may be an indication that another device may be transmitting on the channel, in which case the transceiver may attempt to block the signal being transmitted on that channel.

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DE [0019] Transceiver 350 can be used by the processor to communicate with a remote control site of an installation 360. As also shown, meter 300 may further comprise a current sensor 330 and a voltage sensor of Side source 340 that can supply current and voltage signals to processor 302 for use in determining power consumption.

[0020] In accordance with the arc detection methods described herein, meters in a meter communication network employing ISM mesh communications, such as the meters illustrated in FIG. 1 and FIG. 2, can be configured to detect conditions in which arcs are formed based on an examination of the intensity of signals present at the frequencies (ie channels) used in the communication system. Measurement nodes (eg, meters 114 and collectors 116) in an ISM mesh network typically scan all frequencies within an ISM communication band to detect a signal to be received. For example, the communication system may employ twenty-five (25) or even fifty (50) discrete frequencies / channels. The transceiver on a meter typically scans each frequency in an attempt to detect a transmission from another node in the network on that frequency. When a given channel is scanned, the transceiver will measure the signal strength on that channel and generate a received signal strength indicator (RSSI) value indicative of the RF energy detected on that channel. The transceiver can then compare the RSSI value with a threshold to determine if another device is trying to transmit on that channel. If so, the transceiver may try to block the signal that is being transmitted on that channel.

[0021] FIG. 3 is a flowchart illustrating a method of detecting the conditions in which arcs are formed using detected RF energy, in particular RSSI values, to determine whether a condition in which arcs are present, according to a embodiment. The method can be performed

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!&gt; · ;; --¾ using a meter like the one illustrated in FIG. 2, however, it can be appreciated that the method disclosed herein can be implemented in any appropriate meter configuration employing an RF transceiver. In this embodiment, the meter transceiver is assumed to be an ISM mesh radio or other radio device capable of detecting signals within the ISM communication band. Although a non-synchronous ISM system already scans at all frequencies within the ISM frequency band, a synchronous system can also be adapted to periodically search for RSSI magnitudes to determine if there is a condition in which arcs form. Thus, the methods disclosed herein can be implemented in any wireless network communication system for reading Wireless meters.

[0022] According to the present embodiment, as shown in FIG. 3, in step 402, the transceiver (eg, transceiver 350 in FIG. 2) can measure the intensity of signals received at various frequencies / channels within its frequency spectrum, during normal scanning of those channels in connection with their normal communication functions. In step 404, the meter processor may record or store the measured RSSI values ​​on those channels, for example, in the internal memory of the meter processor (eg, processor 302) or in a memory separate from the processor.

At a later point, in step 406, the processor can compare the RSSI values ​​just received from the transceiver 350 with the previously obtained values ​​stored in step 404. Based on this comparison, in step 408, the processor can then determine if there is a condition in which arcs form in or around the meter receptacle. Several different methods of making this determination are discussed based on the RSSI comparison in greater detail below. IF it has been determined that a condition exists in which arcs are formed, then in step 410, a

Á Ί, \ / ί ¡j PPÁ [Nuil internal disconnection inside the meter (for example, disconnect switch 304) to the open position, disconnecting the meter from the source and removing the load from the meter and, thus, the condition in which arcs are formed. In step 412, the removal of the condition in which arcs are formed can then be verified and, in step 414, the processor may generate a signal indicating that a condition in which arcs were detected and may send that signal to the facility via the meter transceiver. If, on the other hand, an arcing condition is not detected in step 408, then control can return to step 402 where the transceiver continues its normal scanning operations and repeats the process.

[0023] An electrical condition in which arcs form is characterized by extremely high temperatures (thousands of degrees Kelvin). In experiments associated with this description, it was determined that a welding arc has energy not only at hundreds of kHz and in the light spectrum, but also that there is energy within the 900 MHz ISM spectrum. Indeed, the arc energy is developed in the broadband "signature or pattern" RF noise signal through almost all frequencies in the RF spectrum.

[0024] To test this arcing problem, a meter with special firmware was used to evaluate the instantaneous RSSI values ​​for all communication channels in the 900 MHz ISM spectrum. A condition was established in a residential site where there were no arcs and the RSSI values ​​of the background noise were recorded. Then an arc was generated and with the arc present, the RSSI values ​​for the 900 MHz ISM channels were re-read. For this group of tests, the RSSI values ​​for all narrowband channels across the ISM spectrum were determined to increase 10-15 dB when the arc was present. This type of result several meters from the arc implies that the meter can use the ISM transceiver or radio - in particular its ability to measure RSSI on ISM channels - to detect the presence of a condition in which arcs form. This is especially true if the condition in which arcs are formed is close to a radio antenna of the transceiver, which would be the case where the arc exists at the connection of the meter blades to the meter receptacle.

[0025] Since an arc energy characteristic can follow an AC voltage and / or current waveform that dies out at the zero current intersection and restarts soon after when the voltage rises, it is preferable to look for the RSSI values ​​outside zero intersection of AC voltage or current. This location or time scan within the AC waveform can be incorporated into the "arc scan" method of FIG. 3 along with comparisons between average broadband background noise (RSSI values) and newly measured broadband noise (RSSI values).

[0026] Because the radio transceiver or meter might be able to scan a condition in which arcs are formed almost instantaneously (eg less than 1 msec), the condition in which arcs can be detected quickly after it is produced and an early warning signal can be generated at installation. As illustrated in step 410 of FIG. 3, the meter can also make a decision to open an internal meter disconnect switch to remove the meter load and thereby eliminate the condition in which arcs form. A condition in which arcs form requires that there be a finite level of current (typically a minimum of at least 0.5-1 Amp for most metals), thus, when opening the Disconnect Switch, all loads At the location of the subscriber, the condition in which arcs are formed will be eliminated and extinguished. This is particularly important since even a moderately high current condition in which arcs form can be extremely destructive in a short period of time. After operating the disconnect switch to the open position, elimination of the arcing condition can be verified.

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[0027] Determination of whether a condition exists in the arc tíOSrSé'Tormárí in step 408 of FIG. 3 can Incorporate a variety of Information and techniques. In one embodiment, the determination is made as described in connection with FIG. 3 by simply checking the current RF noise levels (RSSI values) for all channels in the ISM spectrum and then comparing the new readings with previously stored readings (eg stored within the internal memory of the meter processor ). If the comparisons result in immediate increases in broadband noise (for example, a Threshold Increment of 10-15 dB or more) that cover most, if not all, ISM channels, this can be determined as a condition in which arches are formed. As mentioned above, arc noise can follow the AC current waveform, so that an increase in wideband RF noise at the peak of the current waveform coupled with a significant reduction in noise Broadband RF at or near the Zero Voltage / Current Intersection can also be determined as an indication of an arc.

[0028] In other embodiments, the method for determining whether an arcing condition exists can directly compare the RF noise per channel (RSSI value) at the peak of the current waveform compared to noise (RSSI value) on the same channel at or near the Zero Intersection of the current waveform. Alternatively, an arcing condition may be indicated when the number of channels in which RSSI is greater than the previous RSSI readings for the same channels by more than, for example, 15 db, is greater than, for For example, 80% of the total number of channels scanned. In various embodiments, the threshold db value (eg, 15db) and the channel threshold amount (eg, 80%) may be configurable and / or may be set to default values. Preferably, the change in db value is

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[0029] In other embodiments, other meter measurements, such as current magnitude, voltage magnitude, and / or meter temperature, can be coupled with the RF arc detection method described above to allow better prediction of the Conditions under which arcs are formed or those other measurements can be used independently. For example, a sudden 10% reduction in current magnitude coupled with higher broadband RF noise or higher harmonic noise could be predictive of a condition where arcs form (arc voltage would reduce current normal). Similarly, a sudden 10% reduction in input voltage coupled with higher broadband RF noise or higher harmonic noise could be predictive of a condition in which arcs form (the arc voltage at the input would reduce the detected input voltage.) In addition, a continuous rise meter temperature coupled with higher broadband RF noise and / or higher harmonic noise could be predictive of an arcing condition. In yet another embodiment, an increase in the harmonic content of the input voltage and / or AC current waveforms alone or coupled with an increase in RF broadband RF noise could be used to trigger a condition in which arcs are formed. Any or all of these conditions, in any possible combination, could be included as part of the arc detection methods disclosed herein. And any or all of these conditions and / or measurements can be used in a separate detection system that is based on broadband RF noise levels and / or harmonic noise as part of the arc detection system.

[0030] In an alternative embodiment, an unsafe condition can be detected by computing a relative temperature of the meter using the

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measured internal temperature of the meter and various other data channels that can be measured with the meter or downloaded to the meter. For example, the following channels can be used: (i) internal temperature of the meter as measured with the meter's electronic assembly; (ii) by phase current, that is, amps rms, measured by the meter; and / or (ii) temperature profile, where a temperature profile can be downloaded periodically, eg daily, and can provide the approximate ambient air temperature for each time period of the day.

[0031] In one embodiment, for an average window, for example,

5 minutes, the meter records the above amounts (for example, in an internal memory of the meter processor) and these Interval data channels can be read from the meter. In addition, the meter can compute a relative temperature by first subtracting a temperature offset from the meter's internal temperature, where the temperature offset is computed based on the average per phase current measured by the meter. The displacement of the temperature by phase current can be computed or supplied as an input, where typically the displacement of the temperature is from 0 degrees in the zero current to a maximum displacement of the temperature, for example, 15 degrees C, in the maximum current rating on the meter, for example 200A. The computed relative temperature can then be compared to the discharged temperature for the corresponding time period of the day and if the difference between the relative temperature and the value of the temperature profile is greater than a configurable threshold, the meter indicates a “overtemperature warning ”And you can optionally open the service disconnect switch.

[0032] In other embodiments, additional inputs can be used to further define the relative temperature computation and could be based on: (i) different ambient temperature profiles based on the direction of the meter and the

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estimated charge of the sun; and / or (¡I) a parameter based on the load of the measured power supply. Optionally, the power supply load can be estimated based on the known duty cycle of key loads, for example, radio transmission duty cycle.

[0033] The above temperature-based alerting mechanism improves on methods based on simple temperatures the fact that they do not account for differences in ambient temperature or other loads that affect the meter's internal air temperature.

[0034] It is understood that any or all of the arc detection methods, processes and systems described herein such as, for example, the steps illustrated in FIG. 3, can be performed in the form of Computer Executable Instructions (i.e., program code) stored on a computer-readable storage medium with instructions that, when executed by a processor (eg, processor 302 of FIG. 2), carry out and / or implement the methods, processes and systems described herein. Computer readable storage media Include both volatile and nonvolatile, removable and nonremovable media implemented in any method or technology for information storage. Computer-readable storage media Include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CDROMs, digital versatile discs (DVDs) or other optical disk storage, magnetic cassettes, magnetic tape, storage on magnetic disk or other magnetic storage devices or any other means that can be used to store the desired information and which can be accessed by a computer. These storage media can be integrated into a processor 302 of FIG. 3 or may be separate components within meter 300, for example. As used herein, the term "computer readable storage medium" does not include signs.

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'' ^ í: 7 J'J.^λ· ^ ...... [0035] While the invention is described herein in a limited number of embodiments, these specific embodiments are for illustrative purposes and are not intended to limit the scope of the invention beyond the final form in the claims. There are modifications and variations of the described embodiments. The scope of the invention is defined by means of the appended claims.

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