Electronic meter having user-interface and central processing functionality on a single printed circuit board

A digital electrical power and energy meter integrates a primary processing module and a user interface module onto a single printed circuit board to reduce overall meter size, assembly time, and cost.

FIELD

The present disclosure relates generally to the field of intelligent electronic devices for electrical utility services and, more specifically, to digital electrical power and energy meters for electrical utility services.

BACKGROUND

Producers, suppliers, and consumers of electrical power rely on energy meters to monitor power consumption and quality for numerous purposes, including billing, revenue, power distribution management, and process management. Traditionally, the primary means of measuring power consumption was an electromechanical power meter. A number of other types of meters and equipment measured other parameters of power generation, distribution, usage, and quality. As technology has improved, intelligent electronic devices (IEDs), such as digital power and energy meters, Programmable Logic Controllers (PLCs), electronically-controlled Remote Terminal Units (RTUs), protective relays, fault recorders, and the like, have slowly replaced their electromechanical and analog counterparts.

The shift to using IEDs instead of or in addition to analog and electromechanical devices provides a vast array of advantages including improvements in measurement accuracy (e.g., measurements of voltage, current, power consumption, power quality, etc.) and system control (e.g., allowing a meter to trip a relay or circuit breaker). As a result of the advent of digital metering, a single device can now implement functionality previously implemented in two or more separate devices. Communication enabled by digital processors allows devices to share information with each other, with remote terminals, and even directly with remote users via electronic mail and the World Wide Web.

Some of the functionality resulting from the improvements in technology may be implemented without increasing the number of components, and by extension the size, of the IED. Such is the case, for example, where a single microprocessor may be programmed to perform multiple functions. However, this is not always true. Some of the additional functions included in IEDs require specialized hardware. For example, the inclusion of a specialized communication interface, such as a fiber optic port or an infrared transceiver, requires specialized interface hardware. These and other functions may also require a specialized set of integrated circuits (ICs) (i.e., a chipset) to implement the unique communication protocols required. Moreover, some functions (or combinations of functions) require more processing power than a single processor can deliver, and other functions are more appropriately implemented on a specialized processor that is designed for a particular task or a particular type of processing. Additional processors and specialized hardware necessarily increase the size of the IED.

Despite the pace at which manufacturers release IEDs with new features and functionality, market pressure continues to favor smaller and, of course, less expensive devices. These types of improvements have been hampered because of physical space limitations on a printed circuit board. For example, traditional digital meters utilized Light Emitting Diodes (LEDs) for indication and a display of a user interface. These diodes, among other components were mounted onto a printed circuit board using through-hole technology. Through-hole technology refers to the mounting scheme used for electronic components that involves the use of pins on the components that are inserted into holes drilled in printed circuit boards (PCBs) and soldered to pads on the opposite side of the PCB. While through-hole mounting provides strong mechanical bonds, the additional drilling required makes the board more expensive to produce. It also limits the available routing area for signal traces on layers immediately below the top layer on multilayer boards since the holes must pass through all layers to the opposite side. Furthermore, components mounted by this technique makes it virtual impossible to mount additional components on the opposite side of the board.

Because of these limitations, multiple printed circuit boards needed to be used to support the display in addition to electronics and connectors. Often three or more printed circuit boards were used to support and/or accommodate the needed components. The boards generally included a display board connected to an electronics board using connectors. The electronics board which included a processor was then connected by an additional set of connectors to another board to hold interface connectors, a power supply, communication, etc. Due to the fact that all these connectors were used to connect the boards together, the space on these printed circuit boards was used inefficiently. This made the power meters bulky and large and difficult to retrofit within existing analog enclosures. Therefore, further improvements to intelligent electronic devices are desirable.

SUMMARY OF THE DISCLOSURE

A disclosed digital electrical power and energy meter is smaller and easier to assemble compared to other meters with similar features. Specifically, the meter includes a motherboard and a plurality of interface boards. The motherboard is a two-sided printed circuit board (PCB) having, on one side, a user interface for allowing an operator of the device to program and use the device. The other side of the motherboard contains the main processing hardware for the meter, and a plurality of connectors for communicatively coupling the motherboard to the plurality of interface boards. The present disclosure provides for techniques for mounting various components, e.g., a high density connector and display technology, to a multilayer board for example a single printed circuit board motherboard utilizing a very small footprint, which avoids the conventional technique of utilizing three printed circuit boards for the display board, the electronics board and connector board. Techniques of the present disclosure provide the user with an ability to utilize advanced technology such as a meter with Ethernet and expandable I/O that retro fits easily into existing enclosures wherein analog meters traditionally were used.

To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures, except that suffixes may be added, when appropriate, to differentiate such elements. The images in the drawings are simplified for illustrative purposes and are not depicted to scale.

The appended drawings illustrate exemplary embodiments of the present disclosure and, as such, should not be considered as limiting the scope of the disclosure that may admit to other equally effective embodiments. It is contemplated that features or steps of one embodiment may beneficially be incorporated in other embodiments without further recitation.

DETAILED DESCRIPTION

While the figures and description herein are specifically directed to digital electrical power and energy meters, including revenue quality certified meters, the concepts disclosed in the present application may also be applied in the context of other types of Intelligent Electronic Devices (IEDs) including, for example, Programmable Logic Controllers (PLCs), Remote Terminal Units (RTUs), protective relays, fault recorders, and other devices or systems used to quantify, manage, and control quality, distribution, and consumption of electrical power. Thus, as used herein, the term “digital electrical power and energy meter” refers broadly to any IED adapted to record, measure, communicate, or act in response to one or more parameters of an electrical service. These parameters may include, for example, supply currents and supply voltages, their waveforms, harmonics, transients and other disturbances, and other corresponding parameters, such as power, power quality, energy, revenue, and the like. A variety of electrical service environments may employ IEDs and, in particular, digital electrical power and energy meters. By way of example and not limitation, these environments include power generation facilities (e.g., hydroelectric plants, nuclear power plants, etc.), power distribution networks and facilities, industrial process environments (e.g., factories, refineries, etc.), and backup generation facilities (e.g., backup generators for a hospital, a factory, etc.).

FIGS. 1A & 1Bdepict an exemplary digital electrical power and energy meter100. The meter100generally comprises a plurality of modules, each module having a dedicated task. A meter housing105houses the modules, and is designed to allow a user to mount the meter100in a desired enclosure or other mounting location and to allow any necessary connection interfaces to be located outside of the meter housing105for easy setup. The meter housing105includes an opening or cover107for a user interface, and one or more openings109at a rear portion of the housing for inserting swappable modules (e.g., modules implementing various communication protocols, adding features to the meter, etc.) Further, the meter housing105may be designed to fit the enclosed modules, and may be designed to conform to an industry standard.

FIG. 2depicts a block diagram of the exemplary digital meter100. A metering module110includes voltage and current sensing circuitry and, in the preferred embodiment, measures or calculates one or more parameters associated with the electrical load or service (e.g., voltage, current, energy, etc.). A processing module120facilitates operation and administration of the meter100and processes data obtained from the metering module110. A user interface module130displays results of measurements and calculations and allows configuration of the meter100, via a display132, a plurality of indicators134, and a plurality of user controls136. A communications module140facilitates communication of data to one or more an external devices (not shown), couples the meter100to one or more remote terminals, and/or allows remote configuration of the meter100. The communications module140includes an infrared communication device (and related circuitry)146, and may optionally include a network communication card142. The communications module140may also include one or more input/output (I/O) cards144. A power supply module150provides power to the various components and modules of the meter100.

While some of these modules (e.g., the metering module110, the processing module120, and the power supply module150) may be required for operation of the meter100, other modules in the illustrated embodiment are optional and may be omitted or replaced with different modules. Each of the modules110,130,140, and150is connected to the processing module120. The power supply150is coupled to each of the modules110,120,130, and140. Typically, a plurality of traces in the printed circuit boards (PCBs) within the meter connect the power supply150to the other modules of the meter100, the various PCBs in the meter100being connected by a known method (e.g., card-edge connector, header/receptacle connector, etc.). The power supply150is also coupled to a source of power. For example, a connection151may couple the power supply150to an external power source (not shown), or a connection153may couple the power supply150directly to the electrical service101. As used herein, the terms “coupled” and “connected” are defined to mean directly connected to or indirectly connected to through one or more intermediate components. Such intermediate components may include both hardware and software based components.

One or more interfaces connect each of the metering module110, the user interface130, and the communications module140to the processing module120. For example, the interfaces126,131, and125connect the processing module120to the various sub-modules comprising the communications module140(e.g., the infrared communication device146, the network communication card142, and the I/O cards144). The interfaces127and129connect the user interface130to the processing module120. Likewise, the interface123connects the metering module110to the processing module120. Each of the interfaces123,125,126,127,129,130, and131may be any suitable type of interface, and may be one or more similar or different interfaces. For example, in the presently described embodiment, the interface123includes a serial peripheral interface (SPI), a control interface, data and address buses, an energy test pulse (i.e., KYZ pulse) output, etc.

During normal operation, the metering module110is coupled to an electrical service101to be measured and/or monitored, such as the three-phase electrical service101ofFIG. 2. A current interface111and a voltage interface113couple the meter100to supply lines A, B, C, and N of the electrical service101. Each of the interfaces111and113may comprise a plurality of connections (e.g., connections to each of phases A, B, C, and N, in the depicted embodiment). U.S. patent application Ser. No. 11/003,064, hereby incorporated by reference into the present disclosure, details some methods of coupling digital electrical power and energy meters to various electrical services. The connections of the interfaces111,113may be, for example, screw-type connections, blade-jaw connections, etc. Those of ordinary skill in the art will be familiar with other methods for coupling meters to electrical services, thus these methods need not be described further in this patent.

FIG. 3shows a plurality of PCBs210,220,142, and1441-144N. In one embodiment, one of the PCBs is a main PCB210, or motherboard, comprising a multi-layer PCB. The motherboard210comprises a plurality of electrical and electronic parts, disposed on each of its two planar surfaces133,135(seeFIG. 7). As used herein, the term “motherboard” denotes a central or primary circuit board, and may also be referred to interchangeably as a mainboard, a baseboard, a backplane, or a system board. The motherboard210connects the primary circuitry, in this case the processing module120, to the other functional blocks of the meter100. In particular, each of an input PCB220, the network communication card142, and any included I/O cards1441-144Nconnect to the system through the motherboard210.

Various components, e.g., connectors, modules, etc., are coupled to the motherboard210via surface mount technology. Surface mount technology (SMT) is a method for constructing electronic circuits in which the components (SMC, or Surface Mounted Components) are mounted directly onto the surface of the printed circuit board (PCB) avoiding the necessity of thru-holes. An SMT component is usually smaller than its through-hole counterpart because it has either smaller leads or no leads at all for example it may have short pins or leads of various styles, flat contacts, a matrix of balls (BGAs), or terminations on the body of the component. The use of surface mount components allows the motherboard to support or accommodate the user interface, the processing system and the connector for expandable I/O connections. In this exemplary design, the motherboard structural integrity is based on the fact that there are not many through-hole components on the board. Utilizing such through-hole components would render the motherboard to flimsy and thus susceptible to bending. This bending action would cause the solder components of the display and processing system to possible crack the solder connections to the components thereon.

In one embodiment, each of the processing module120, the user interface module130(i.e., the display132, the indicators134, the user controls136, and associated hardware (not shown), described below), and the infrared communication device146of the communications module140are disposed on the motherboard210. In particular, the user interface module130and the infrared communication device146are disposed on one side of the motherboard210, while the processing module120is disposed on the opposite side of the motherboard210. Also disposed on the motherboard210, on the same side as the processing module120, are a plurality of connectors214,216, and2181-218N, for connecting the motherboard210to the input PCB220via a connector241, the network communication card142via a connector222, and the I/O cards1441-144Nvia a plurality of connectors2261-226N, respectively. Each of the connectors214,216, and2181-218N, which mate with the connectors241,222, and2261-226N, respectively, may be any type of appropriate connector. This arrangement allows the user interface module130and the infrared communication device146to be disposed such that they face the outside of the meter100(i.e., so the user interface130is visible to a user of the meter100), while the processing module120and the plurality of connectors214,216, and218project toward the inside of the meter100to allow the interface cards220,142, and144to connect thereto. Of course,FIG. 4Adepicts each of the interface cards220,142, and144being perpendicular to the motherboard210(and, thus, parallel to each other), the motherboard210and interface cards220,142, and144could also be disposed in parallel, with each card being communicatively coupled to the motherboard210via any intervening connectors219(and PCBs) between any card and the motherboard210, as inFIG. 4B. In the embodiment ofFIG. 4B, each of the interface cards220,142,144would have one or more connectors on each planar surface, allowing connections to other cards on both sides.

Referring again toFIG. 3, the power supply150and the metering module110are each disposed on the input PCB220. As described above, either the interface151or the interface113couples the power supply150to either the electrical service101or an external power source (not shown). A connector232may be provided on the input PCB220for coupling the input PCB220to the voltage interfaces113and/or151. A similar connector234may be provided on the input PCB220for coupling the metering module110on the input PCB220to the current interface111.

In one embodiment, the metering module110on the input PCB220includes a sensing circuit242, for sensing the voltages and currents on each of the supply lines A, B, C, and N of the electrical service101, and generating analog signals representative of the voltages and currents. The metering module110also includes a gain control unit244. The input to the gain control unit244is the output of the sensing circuit242(i.e., the plurality of voltage and current signals representative of the voltages and currents on supply lines A, B, C, and N of electrical service101). The output of the gain control unit244is a plurality of analog signals proportional to the input signals, and adjusted by a gain factor. The gain factor need not be the same for each of the signals. The gain-adjusted output signals of the gain control unit244serve as the input signals to a data acquisition system246. The data acquisition system246includes an analog-to-digital converter (not shown) for converting the analog signals to digital data streams and a processor (not shown) for measuring or calculating a parameter of the electrical system101.

The processing module120, includes a processor160(e.g., a micro-processor, a digital signal processor (DSP), etc.) and a memory module180having one or more computer-readable storage devices (e.g., memories). For example, the memory module180may include an electrically erasable programmable read-only memory (EEPROM)182, a flash memory184, and/or a random access memory (RAM)186. An interface178connects the processing module120to the memory module180. The interface178may be any known interface compatible with both the particular memory devices182,184,186and the particular processor160. The processing module120may also include additional elements, such as a real-time clock196, a backup power source (e.g., a battery)194, and various other support circuitry192.

The communication module140comprises the network communication card142, and each of any I/O cards144included in the meter100. Each card of the communication module140includes circuitry adapted to the particular configuration contemplated by the manufacturer and/or purchaser. For example, the network communication card142may be an Ethernet card, including an Ethernet chipset and an RJ-45 receptacle, as well as other auxiliary hardware supporting the Ethernet communications and allowing the network communication card142to interface with the processing module120on the motherboard210. Alternatively, the network communication card142may be a fiber optic card having hardware associated with such a card (e.g., fiber optic transceivers, etc.). The network card shall be capable of supporting a host of protocols including but not limited to FTP, HTTP, Modbus TCP, DNP over Ethernet, IEC 61850, and a host of email functions. Said email functions include the ability to send of receive emails consisting of data, computer readable information or simple text messages. Additionally, said email functions also include the ability to provide new programmable settings to the IED, new processor firmware (e.g., embedded software used to run the processor in the processing system) or any other power management or control events. The network communications card142may be configured to communicate using any known protocol, including, for example, 10/100BaseT Ethernet, RS-485, Modbus, DNP 3.0, etc. The network communications card142may also be configured to output a KYZ energy pulse output.

In a similar manner, each of the I/O cards144may be configured to communicate with other devices including, by way of example and not limitation, a 10/100BaseT Ethernet I/O card, a Modbus/TCP I/O card, an analog I/O card (e.g., outputting 0-1 mA, 4-20 mA, 0-5 V, etc.), a relay I/O card, a solid-state I/O card, or a fiber optic I/O card. In general, the network communication card142and the I/O cards144may be any known type of network communication card or I/O card. Further, each of the network communication card142and the I/O cards144includes at least one connector222,226for connecting the network communication card142or the I/O card144to the processing module120on the motherboard210though the corresponding mating connector216,218. Each card (excluding input PCB220) also includes at least one connector224,228for connecting the card to a device (not shown) external to the meter100(e.g., a relay, a slave device, fiber optic cable, Cat-5 cable, etc.). It shall be noted that the interface cards can utilize the printed circuit board itself to operate as a connector so that the motherboard will accept an “edge” connector in which the connector accepts the input of the printed circuit board itself to create the connection between the motherboard and the interface cards.

The network communication card142and the I/O cards144communicate with the processing module120on the motherboard210and, in particular, with a processor in the processing module120(e.g., a microprocessor, a digital signal processor (DSP), etc.), using one or more serial data interfaces. The serial data interfaces may be any known interface, including a serial peripheral interface (SPI) or an RS-485 interface. By communicating with the processing module120, the communication module140(i.e., the communication card142and/or the I/O cards144) allows the meter100to send results of measurements and/or calculations performed in either of the processing module120or the metering module110, to an external device, and may optionally allow the meter100to send to or receive from an external device the configuration settings of the meter100.

Referring now toFIG. 5, the user interface module130includes the front panel display132, the indicators134, and the user controls136. The user interface module130may also include various support circuitry, such as a controller138and a decoder139. The infrared communication device146may also be disposed on the motherboard210with the user interface module130and, in as much as it allows a user to program or receive data from the meter100, may also be said to be included in the user interface module130. The front panel display132may be any type of suitable display technology (e.g., liquid crystal display (LCD), light emitting diode (LED), organic light emitting diode (OLED), etc.). In the depicted embodiment, the display132includes a plurality of LED segments250, and each of the segments250is capable of displaying a single alpha-numeric character (including numbers 0-9 and at least some letters or recognizable portions thereof) and a decimal point. The LED segments250are arranged such that they may, as a group, display one or more lines252of numeric data or text. For example, the LED segments250may be arranged into three lines252, each of the lines252displaying data for one of the three phases of the electrical system101. In this arrangement, the LED segments250may also be used to display text (e.g., for displaying menu options of the meter100or indicating error messages).

The indicators134of the user interface130, as implemented in the illustrated embodiment, include a plurality of LEDs254. The plurality of LEDs254may be grouped in any appropriate manner. For example, some of the LEDs254may be grouped together to form a status bar256for indicating a relative quantity (e.g., % load). Others of the LEDs254may indicate which of the various parameters (e.g., Volts, Amps, watthours, reactive power, etc.) measured or calculated by the meter100is currently being displayed by the display132, or indicate information about the parameter being displayed, such as the units of measurement (i.e., kilo or mega), or whether the value displayed is a minimum, maximum, programmable limit, etc. A watthour pulse258may also be included.

The user controls136of the user interface module130include a plurality of buttons260for allowing the user to navigate menus, set meter preferences, select which measurements to view, etc. Of course, the buttons260may include any appropriate buttons for these purposes, including a “menu” button, navigation arrow buttons, a “select” button, and any other buttons necessary to control the meter100. In addition to, or instead of, the buttons260, the user controls136may also comprise a touch screen integrated with the display132, such as when the display132is an LCD display. In the illustrated embodiment, the user controls136are multi-functional push-buttons, which buttons' functions may be programmed according to the particular commands being entered, or according to the options being displayed on the front panel display132.

Referring now toFIG. 6, the user interface module130may be arranged in any suitable fashion. In the depicted embodiment, the display132is disposed in the center of a face133of the meter100. The plurality of LEDs254comprising the indicators134of the user interface130, are disposed on the left and right sides of the display132. For example, the group of LEDs254comprising the status bar256is disposed along the lower left of the display132. A group of LEDs262is disposed along the upper left of the display132to indicate whether the values on the display are indicative of a reading type (e.g., a minimum, a maximum, % total harmonic distortion, etc.), whether the meter100is in a programming mode, etc. The infrared communication device146is disposed to the left of the display132, between the status bar256and the LEDs262. A third group of LEDs264is disposed along the upper right of the display132to designate the parameter displayed on the display132(e.g., Volts, Amps, Wh, etc.). A fourth group of LEDs266, including the Watthour pulse258, is disposed along the lower right of the display132. The fourth group of LEDs266indicates the scaling factor of the information displayed on the display132(e.g., kilo, mega, etc.). Of course, the indicators134need not be separate from the display132. Instead, the display132could display the data and/or information indicated by the indicators134where, for example, the display132is an LCD display with sufficient resolution and size to show all of the desired information. In the depicted embodiment, the buttons260comprising the user controls136are disposed along the top and bottom of the face133of the meter100, above and below the display132. However, the indicators134and user controls136need not be arranged as described here, but may be arranged in any manner according to the desire of the manufacturer.

As described above, each of the processing module120, the user interface module130and the infrared communication device146of the communications module140are disposed on the motherboard210. With reference toFIG. 7, the motherboard210has two planar surfaces (or faces) including the first planar surface or face133and a second planar surface or face135. In the illustrated embodiment, the user interface module130and the infrared communication device146are disposed on the first face133of the motherboard210. The processing module120is disposed on the second face135of the motherboard210, as are the plurality of connectors214,216, and218. By utilizing surface mount technology, embedded electrical connections (not shown) in the motherboard PCB210serve to connect the user interface130, and its attendant support circuitry, to the processing module120. When disposed in the housing105, the first surface133of the motherboard210will face the cover or opening107and the second surface135of the motherboard210, including connectors214,216and218, will face the rear portion of the housing toward openings109. In this manner, the single motherboard PCB210may be placed at the front of the meter100, eliminating the need to have a separate PCB for the user interface module130, and the attendant connectors for interfacing the user interface module130to the processing module120. This necessarily reduces the size of the meter100, as well as the cost and complexity of assembling the meter100.

A digital electrical power and energy meter that integrates a primary processing module and a user interface module onto a single printed circuit board has been described. The meter of the present disclosure utilizes surface mount technology to reduce overall meter size, assembly time, and cost. Furthermore, by using surface mount techniques instead of conventional thru-hole techniques, the meter of the present disclosure will realize the following advantages: fewer or no holes are required to be drilled through abrasive boards; small errors in component placement are corrected automatically (e.g, the surface tension of the molten solder pulls the component into alignment with the solder pads); components can be fitted to both sides of the printed circuit board; lower lead resistance and inductance leading to better performance for high frequency parts; better mechanical performance under shake and vibration conditions and fewer unwanted RF signal effects in SMT parts when compared to leaded parts, yielding better predictability of component characteristics.

Although the disclosure herein has been described with reference to particular illustrative embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present disclosure. Therefore, numerous modifications may be made to the illustrative embodiments and other arrangements may be devised without departing from the spirit and scope of the present disclosure, which is defined by the appended claims.