Patent Description:
Many residential and commercial premises include electric meters to allow utility companies to monitor the consumption of electricity within the premises. To do so, an electric meter is electrically connected to a meter socket, which is usually located in a utility box positioned on an outside wall of the premises. The electric meter may include meter blades, which are received in the meter socket and held in place by a tension force applied to the blades by the meter socket.

In some instances, the installation of a new meter to replace an old meter may create a phenomenon known as "arcing" where an electrical arc is formed in a gap between a meter blade and a corresponding socket jaw of the meter socket as the meter is installed. Arcing may also occur randomly, subsequent to the installation period. For example, if the tension force of the socket is lessened, then gaps may occur between the blades and the socket. The gaps provide an environment conducive to arcing. The presence of arcing in an electric metering system may cause high heat, and in some instances, a fire that may cause significant damages to the components of the electric meter systems, the premises, and may also injure humans, such as workers assisting with a meter replacement. Therefore, it is important to detect arcing conditions before any damage or endangerment occurs.

To detect the arcing conditions, an electric meter can be configured with an arc detection component. However, because of the high voltage condition near the location where the arcing occurs, the arc detection component is typically placed at a location within the meter that is away from the meter blades and the meter sockets. The large distance between the arc detection component and the location of the arcing can lead to inaccurate detection of the arcing. Prior art <CIT> teaches such an electricity meter comprising a meter base that connects to a meter socket via blades, the meter comprising two current transformers for measuring current flow in two separate paths, where a secondary coil is also used as an antenna that picks up electromagnetic radiation caused by arcing and passes the signal to an arc detection circuit. Alternatively, a winding of an electric actuator motor is used as the arc detection antenna. Prior art <CIT> discloses a circuit breaker with an arc fault detection circuit connected to an arc detector antenna transducer. The transducer comprises a current transformer coaxially arranged with an electrical field sensor loop antenna.

Aspects and examples are disclosed for an electric meter capable of detecting electrical arcing between the electrical meter and a meter socket in a utility box that is connected to a power line. In an example implementation, the electric meter includes a baseplate assembly and a housing assembly. The baseplate assembly includes an electrical conductor connecting two meter blades. Each of the meter blades is configured to be positioned in a corresponding socket jaw of the meter socket to electrically connect the electric meter to the meter socket. The baseplate assembly further includes a current-transformer structure including a current transformer holder and a current transformer cover forming an enclosed space. The current-transformer structure also includes a current transformer positioned in the enclosed space and inductively coupled to the electrical conductor. The current-transformer structure further includes an arc detection antenna placed in the enclosed space and adjacent to the current transformer. The leads of the arc detection antenna extend outside the current-transformer structure. The housing assembly is configured to be coupled to the meter baseplate assembly and includes a circuit board hosting an arc detection circuit configured to detect electrical arcing. The leads of the arc detection antenna are electrically connected to the arc detection circuit.

In another example, a current-transformer structure includes a current transformer holder and a current transformer cover forming an enclosed space when connected to the current transformer holder. The current-transformer structure also includes a current transformer positioned in the enclosed space. The current-transformer structure further includes an arc detection antenna placed in the enclosed space and adjacent to the current transformer. The leads of the arc detection antenna extend outside the current-transformer structure. The arc detection antenna is located between the current transformer and either the cover or the holder.

These illustrative embodiments are mentioned not to limit or define the disclosure, but to provide examples to aid understanding thereof. Additional embodiments are discussed in the Detailed Description, and further description is provided there.

Features, embodiments, and advantages of the present disclosure are better understood when the following Detailed Description is read with reference to the accompanying drawings, where:.

Certain aspects and examples of the present disclosure relate to an electric meter for detecting arcing conditions between the electric meter and a meter socket in the utility box at premises. In some aspects, an electric meter may include a baseplate assembly containing a baseplate and at least an electrical conductor connecting two meter blades. Each of the meter blades extends from the baseplate and is configured to engage a corresponding socket jaw of the meter socket to electrically connect the electric meter to the meter socket that is connected to a power line. The baseplate assembly further includes a current transformer inductively coupled to the electrical conductor to provide a current to a metrology circuit of the meter so that the meter can monitor the electrical current levels in the power line. The current transformer is placed inside an enclosed space of a current-transformer structure formed by a current transformer holder and a current transformer cover.

To detect the arcing conditions, the current-transformer structure further includes an arc detection antenna, such as a loop antenna. The arc detection antenna can be placed inside the enclosed space of the current-transformer structure and adjacent to the current transformer. Leads of the arc detection antenna and leads of the current transformer extend outside the current-transformer structure and are isolated from each other.

The electric meter may further include a housing assembly configured to be coupled to the baseplate assembly to form a complete meter assembly. The housing assembly includes at least one circuit board hosting an arc detection circuit configured to detect the electrical arcing conditions based on the signal generated by the arc detection antenna. The leads of the arc detection antenna are electrically connected to the arc detection circuit. The same circuit board or a different circuit board in the housing assembly may host a measurement circuit configured to measure the power consumed by the premises. For example, the leads of the current transformer can be electrically connected to the measurement circuit for measurement purposes.

In certain configurations of the electric meter, the current-transformer structure is placed next to the baseplate of the meter and the circuit board hosting the arc detection circuit is placed at one end of the housing assembly that is further away from the baseplate. As a result, the arc detection antenna is in close proximity to the place where the arcing occurs (i.e., the blades) and thus can detect the arcing with higher accuracy. In addition, because the arc detection antenna is placed inside the current-transformer structure which is properly insulated, the arc detection antenna is not exposed to the high voltage condition near the blades and thus can function properly. Compared with the prior approaches where the arc detection antenna is placed on the circuit board to avoid exposure to the high voltage condition, the electric meter disclosed herein can provide more accurate arc detection. Furthermore, the current-transformer structure generally provides a larger space for placing the arc detection antenna than the circuit board. As a result, the detection sensitivity of the arc detection antenna can be increased and/or the number of turns of the arc detection antenna can be reduced. This leads to more flexibility in the design or performance of the arc detection antenna than the prior approach.

<FIG> show block diagrams of an electric meter, a utility box, and a meter socket. <FIG> is a diagram depicting an electric meter <NUM> that includes one or more blades, such as blades <NUM>. <FIG> also shows a utility box <NUM> including a meter socket <NUM>. The meter socket <NUM> includes receptacles <NUM>, also referred to as "socket jaws" <NUM>, into which the blades <NUM> may be positioned or engaged. The socket jaws <NUM> include utility-side socket jaws 105A and premises-side socket jaws 105B. The electric meter <NUM> may be fitted into the meter socket <NUM>, as indicated by the dotted lines in <FIG>, such that the blades <NUM> are positioned in the socket jaws <NUM>. Positioning the blades <NUM> within the socket jaws <NUM> electrically connects the electric meter <NUM> to the meter socket <NUM>. The meter socket <NUM> may include springs or other means to provide a tension force on the blades to maintain the position of the blades within the socket jaws of the meter socket <NUM>. The meter socket <NUM> and blades may each include one or more surfaces made out of a conductive material to allow electricity to flow between the meter socket <NUM> and the blades.

The blades <NUM> and the socket jaws <NUM> may be configured such that electrical signals are transmitted between a utility side of the meter socket <NUM> and the electric meter <NUM>, and between the electric meter <NUM> and a premises side of the meter socket <NUM>. For example, electrical signals received from the utility company may be transmitted to the electric meter <NUM> via the utility-side socket jaws 105A and blades (not visible in <FIG>) on the utility side of the electric meter <NUM>. In addition, the electrical signals may be transmitted to the premises via the blades <NUM> on the premises side of the electric meter <NUM> and the premises-side socket jaws 105B. The electric meter <NUM> may perform operations as the electrical signals are transmitted between the utility side and the premises side, including generating voltage sense or current sense signals, determining measurements, and other operations. In addition, the electric meter <NUM> may also be configured to detect arcing conditions near the blades <NUM> and the socket jaws <NUM>.

<FIG> is a diagram depicting an example configuration of the utility box <NUM> with the electric meter <NUM> installed. The electric meter <NUM> may be installed by being positioned in the meter socket <NUM> (not visible in <FIG>). The utility box <NUM> may be positioned proximate to a premises <NUM> which receives power from a utility company. Power lines <NUM> may be electrically connected to the utility box <NUM> to supply power to the premises <NUM> from the utility company. The power from the power lines <NUM> may be routed through the meter socket <NUM> included in the utility box <NUM>, such as by being transmitted between utility-side and premises-side meter socket jaws via the installed electric meter <NUM>. The installed electric meter <NUM> may measure various aspects of the power supplied via the power lines <NUM>, such as to determine an overall power usage by the premises <NUM>.

In additional aspects, the installed electric meter <NUM> may also detect the arcing conditions between the electrical meter <NUM> and the meter socket <NUM> in the utility box <NUM>. The detected arcing conditions can be utilized to determine whether to disconnect the electric meter <NUM> from the meter socket <NUM>, thereby disconnecting the electric meter <NUM> from the power line <NUM>, or to instruct the electric meter <NUM> to open one or more disconnect switches in the electric meter <NUM>.

<FIG> is a block diagram depicting a simplified example of components contained in an electric meter <NUM> capable of detecting an electrical arc between the electric meter <NUM> and the meter socket <NUM>, according to some aspects of the present disclosure. The electric meter <NUM> shown in <FIG> includes a meter base <NUM>, a metrology circuit <NUM>, and a communication component <NUM> that are supported by and at least partially contained within a housing of the electric meter <NUM>.

The meter base <NUM> includes two pairs of terminals 224A/228A and 224B/128B (such as the meter blades <NUM> shown in <FIG>) that are electrically connected together by electrical conductors 226A and 226B, respectively. Each of the terminals 224A, 224B, 228A, and 228B extends from the housing of the electric meter <NUM> to engage a meter socket (e.g., the meter socket <NUM> shown in <FIG>) that is connected to a power line (e.g., the power line <NUM> shown in <FIG>). Each of the terminal pairs 224A/228A and 124B/128B is configured to connect in-line with a conductor in the power line where all of the electrical signals that pass through the power line from an energy source to a load passes through the terminal pairs 224A/228A and 224B/228B to the load. The terminal pairs 224A/228A and 224B/228B and the electrical conductors 226A and 226B effectively become part of the power line connected between the generation source and the load when the electric meter <NUM> is connected to the meter socket.

The meter base <NUM> further includes current transformers 232A and 232B that are inductively coupled to the electrical conductors 226A and 226B, respectively. The current transformers 232A and 232B are electrically connected to a measurement circuit <NUM> of the metrology circuits <NUM>. The alternating current waveforms in the electrical conductors 226A and 226B induce a current in the current transformers 232A and 232B, respectively. The current can be utilized to monitor electrical current levels in the power line such as by a current sense circuit in the measurement circuit <NUM>. The measurement circuit <NUM> may include other circuits for measuring purposes, such as a voltage sense circuit for measuring the voltage of the power line. The voltage sense circuit may be connected to the terminals 224A, 228A, 124B, and 128B to measure the voltage. Voltage sense signals and current sense signals generated by the voltage sense circuit and the current sense circuit, respectively, may be routed to a processing device (not shown in <FIG>) of the metrology circuits <NUM> to, for example, determine the power consumed by the premises.

To detect the arcing conditions, the meter base <NUM> also includes arc detection antennas 234A and 234B placed adjacent to the current transformers 232A and 232B, respectively. The arc detection antennas 234A and 234B are electrically connected to an arc detection circuit <NUM> of the metrology circuits <NUM>. The arc detection antennas 234A and 234B provide detected signals to the arc detection circuit <NUM> for detecting arcing conditions between the terminals 224A, 224B, 228A, and 228B and their respective socket jaws in the meter socket. For instance, the arc detection circuit <NUM> can analyze the signals received from an arc detection antenna by filtering the received signals to focus on the signal in a certain frequency band to detect the arcing conditions. The current transformer 232A (or 232B) and the arc detection antenna 234A (or 234B) are placed in an enclosed structure referred to herein as a current transformer structure 236A (or 236B).

The electric meter <NUM> may be communicatively coupled to a remote device (not shown in <FIG>) through a communication component <NUM>. In some aspects, the communication component <NUM> may include one or more communication devices, such as a communication antenna and a radio, to send and receive message signals through a network between the electric meter <NUM> and the remote device. For example, the electric meter <NUM> may send a message containing the measured power consumption or other data to the remote device. The remote device may be communicatively coupled to multiple meters and may communicate the message across a network to a central system, such as a central system associated with an operator of the power utility. In some aspects, the communication component <NUM> may also transmit a message indicating an arcing condition in the utility box <NUM>. The central system may process the message and, in response, transmit a signal instructing the electric meter <NUM> to disconnect the power to the premises when arcing occurs.

The electric meter <NUM> can disconnect the power to the premises by opening disconnect switches 240A and/or 240B as shown in <FIG>. Each of the disconnect switches 240A and 240B moves between a closed position and an opened position. In the closed position the disconnect switches 240A and 240B establish an electrical connection between the terminal pairs 224A/228A and 224B/228B, respectively. In the opened position, the disconnect switches 240A and 240B disconnect the terminal pairs 224A/228A and 224B/228B, respectively. The disconnect switches 240A and 240B move between the closed and opened positions based on control signals from the metrology circuits <NUM>. For example, the metrology circuits <NUM> can include a disconnect circuit <NUM> which can include an actuation device or other means to control the disconnect switches 240A and 240B to move between the closed position and the opened position.

<FIG> shows a cutaway side view of an electric meter <NUM> capable of detecting arcing conditions in a utility box according to some aspects of the present disclosure. As shown in <FIG>, the electric meter <NUM> includes a baseplate assembly <NUM> and a housing assembly <NUM>. In some examples, the various components of the meter base <NUM> discussed above with respect to <FIG> are installed in the baseplate assembly <NUM>. For example, in <FIG>, two meter blades <NUM> and <NUM> are connected by an electrical conductor <NUM> that passes through the ring formed by a current-transformer structure <NUM>. The meter blades <NUM> and <NUM> extend from the outer side of a baseplate <NUM> of the baseplate assembly <NUM> so that they can be positioned into the socket jaws of the meter socket when being installed into the utility box.

In <FIG>, the housing assembly <NUM> of the electric meter <NUM> includes a register cover <NUM>, one or more printed circuit boards <NUM> and other components. When the register cover <NUM> is connected to the baseplate <NUM>, it encloses the printed circuit boards <NUM>. In some examples, the printed circuit boards <NUM> are installed on the front end of the housing assembly <NUM>, i.e., the end that is away from the baseplate <NUM>. In some examples, the measurement circuit <NUM> and the arc detection circuit <NUM> discussed above with respect to <FIG> are placed on one printed circuit board <NUM>. In other examples, the measurement circuit <NUM> and the arc detection circuit <NUM> may be placed on separate printed circuit boards <NUM>.

<FIG> shows an expanded view of the electric meter <NUM> including the baseplate assembly <NUM> and the housing assembly <NUM> and two alternative outer covers <NUM> of the electric meter <NUM>. As shown in <FIG>, the housing assembly <NUM> is used to hold the printed circuit boards <NUM> on the end that is away from the baseplate <NUM>. The baseplate assembly <NUM> includes the current-transformer structure <NUM> and the current-transformer structure <NUM> (not visible in <FIG>). The current-transformer structures <NUM> and <NUM> corresponds to the current transformer components 236A and 236B shown in <FIG>, respectively. An electrical conductor <NUM> (or <NUM>) passes through the ring formed by the current-transformer structure <NUM> (or <NUM>) and connects two blades configured to be placed in the meter socket. The leads <NUM> (or <NUM>) of the current transformer and the arc detection antenna extend outside the current-transformer structure <NUM> and can be connected to their respective circuits. As shown in <FIG> and <FIG>, the current-transformer structures <NUM> and <NUM> are installed on the inner side of the baseplate <NUM> and is in proximity to the baseplate <NUM>.

As can be seen from <FIG>, the current-transformer structure <NUM> is in proximity to the blades and thus to the place where the arcing occurs. Therefore, by placing the arc detection antenna inside the current-transformer structure <NUM>, a more accurate arc detection can be achieved than placing the arc detection antenna in locations such as on or near the printed circuit board <NUM>. In the meantime, the arc detection antenna can be shielded from the high voltage by leveraging the existing high-voltage protection of the current-transformer structure <NUM>.

<FIG> show an example of a current-transformer structure <NUM> that can be installed in an electric meter for detecting an arcing condition in the utility box, according to some aspects of the present disclosure. The current-transformer structure <NUM> can be used as the current-transformer structure <NUM> or <NUM> shown in <FIG>. More specifically, <FIG> shows the assembled current-transformer structure <NUM> and <FIG> shows various components of the current-transformer structure <NUM>.

As shown in <FIG>, the current-transformer structure <NUM> includes a current transformer holder <NUM>, a current transformer <NUM>, an arc detection antenna <NUM>, and a current transformer cover <NUM>. The current transformer <NUM> corresponds to the current transformer 232A or 232B described above with respect to <FIG>, and the arc detection antenna <NUM> corresponds to the arc detection antenna 234A or 234B in <FIG>. The current transformer holder <NUM> can be connected to the current transformer cover <NUM> to form an enclosed donut-shaped space. The current transformer <NUM> and the arc detection antenna <NUM> are placed adjacent to each other in this enclosed donut-shaped space and between the current transformer holder <NUM> and the current transformer cover <NUM>. The current transformer cover <NUM> can be connected or affixed to the transformer holder <NUM> through, for example, a latch <NUM> or other mechanical means to securely hold the current transformer <NUM> and the arc detection antenna <NUM> within the enclosed space.

According to the invention, the arc detection antenna <NUM> is placed between the current transformer <NUM> and the current transformer cover <NUM> as shown in <FIG>, or, alternatively, the arc detection antenna <NUM> is placed between the current transformer <NUM> and the current transformer holder <NUM>. If the arc detection antenna <NUM> is placed between the current transformer <NUM> and the current transformer cover <NUM>, the arc detection antenna <NUM> can be affixed to the top surface of the current transformer <NUM> through, for example, glue (e.g., epoxy), tape, or other adhesive materials or mechanism means. Alternatively, or additionally, the arc detection antenna <NUM> may be affixed to the inner surface of the current transformer cover <NUM> using adhesive materials or mechanical affixing means. Similarly, if the arc detection antenna <NUM> is placed between the current transformer <NUM> and the current transformer holder <NUM>, the arc detection antenna <NUM> can be affixed to the bottom surface of the current transformer or the inner surface of the current transformer holder <NUM> using proper affixing means. In some examples, the current transformer cover <NUM> or the current transformer holder <NUM> may include a custom housing portion to hold the arc detection antenna <NUM>.

The leads <NUM> of the current transformer <NUM> and the leads <NUM> of the arc detection antenna <NUM> are isolated from each other and extend outside the enclosed space of the current-transformer structure <NUM>. The leads <NUM> and the leads <NUM> can extend outside the current-transformer structure <NUM> through the same openings <NUM> as shown in <FIG>. In other configurations, they may pass through different openings.

It should be understood that while the above figures depict a two-phase solution for the electric meter where two current-transformer structures are installed in an electric meter, the presented technique can be applied to other types of electric meters. For example, a single-phase electric meter can include the current-transformer structure presented herein to detect arc detection occurring on the single-phase line. Likewise, a three-phase electric meter can include three current-transformer structures presented herein to detect the arcing conditions in the respective phases. <FIG> shows an example of a baseplate assembly of a three-phase electric meter incorporating three current-transformer structures presented herein. It should be further understood that in some examples, only one of the current transformer structures in a multi-phase electric meter is equipped with an arc detection antenna to detect arcing condition. In these examples, the arc detection antenna can be placed in the current transformer structure on the centrally located phase such that the arc detection antenna is more equidistant to all of the blades.

Claim 1:
An electric meter (<NUM>) capable of detecting electrical arcing between the electric meter (<NUM>) and a meter socket (<NUM>) in a utility box (<NUM>) that is connected to a power line (<NUM>), the electric meter (<NUM>) comprising:
a baseplate assembly (<NUM>) comprising:
an electrical conductor connecting two meter blades (<NUM>), each of the meter blades (<NUM>) configured to be positioned in a corresponding socket jaw (<NUM>) of the meter socket (<NUM>) to electrically connect the electric meter (<NUM>) to the meter socket <NUM>); and
a current-transformer structure (<NUM>) comprising:
a current transformer holder (<NUM>) and a current transformer cover (<NUM>) forming an enclosed space;
a current transformer (<NUM>) positioned in the enclosed space and inductively coupled to the electrical conductor; and
an arc detection antenna (<NUM>) placed in the enclosed space and adjacent to the current transformer (<NUM>), wherein leads (<NUM>) of the arc detection antenna (<NUM>) extend outside the current-transformer structure (<NUM>); and
a housing assembly (<NUM>) configured to be coupled to the baseplate assembly (<NUM>), the housing assembly (<NUM>) comprising:
a circuit board (<NUM>) hosting an arc detection circuit (<NUM>) configured to detect electrical arcing, wherein the leads (<NUM>) of the arc detection antenna (<NUM>) are electrically connected to the arc detection circuit (<NUM>).