Patent Publication Number: US-11644341-B2

Title: Intelligent electronic device with hot swappable battery

Description:
PRIORITY 
     This application a continuation application of U.S. Application Ser. No. 16/391,723 filed Apr. 23, 2019, now U.S. Pat. No. 10,739,162, which is a continuation application of U.S. application Ser. No. 15/869,595 filed Jan. 12, 2018, now U.S. Pat. No. 10,274,340 which is a continuation application of U.S. application Ser. No. 15/056,537 filed Feb. 29, 2016, now U.S. Pat. No. 9,897,461, which claims priority to U.S. Provisional Patent Application No. 62/126,049 filed Feb. 27, 2015, entitled “INTELLIGENT ELECTRONIC DEVICE”, the contents of which are hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     Field 
     The present disclosure relates generally to intelligent electronic devices (IEDs). 
     Description of the Related Art 
     Monitoring of electrical energy by consumers and providers of electric power is a fundamental function within any electric power distribution system. Electrical energy may be monitored for purposes of usage, equipment performance and power quality. Electrical parameters that may be monitored include volts, amps, watts, vars, power factor, harmonics, kilowatt hours, kilovar hours and any other power related measurement parameters. Typically, measurement of the voltage and current at a location within the electric power distribution system may be used to determine the electrical parameters for electrical energy flowing through that location. 
     Devices that perform monitoring of electrical energy may be electromechanical devices, such as, for example, a residential billing meter or may be an intelligent electronic device (“IED”). Intelligent electronic devices typically include some form of a processor. In general, the processor is capable of using the measured voltage and current to derive the measurement parameters. The processor operates based on a software configuration. A typical consumer or supplier of electrical energy may have many intelligent electronic devices installed and operating throughout their operations. IEDs may be positioned along the supplier&#39;s distribution path or within a customer&#39;s internal distribution system. IEDs include revenue electric watt-hour meters, protection relays, programmable logic controllers, remote terminal units, fault recorders and other devices used to monitor and/or control electrical power distribution and consumption IEDs are widely available that make use of memory and microprocessors to provide increased versatility and additional functionality. Such functionality includes the ability to communicate with remote computing systems, either via a direct connection, e.g., a modem, a wireless connection or a network. IEDs also include legacy mechanical or electromechanical devices that have been retrofitted with appropriate hardware and/or software allowing integration with the power management system. 
     Typically, an IED is associated with a particular load or set of loads that are drawing electrical power from the power distribution system. The IED may also be capable of receiving data from or controlling its associated load. Depending on the type of IED and the type of load it may be associated with, the IED implements a power management function that is able to respond to a power management command and/or generate power management data. Power management functions include measuring power consumption, controlling power distribution such as a relay function, monitoring power quality, measuring power parameters such as phasor components, voltage or current, controlling power generation facilities, computing revenue, controlling electrical power flow and load shedding, or combinations thereof. 
     SUMMARY 
     An intelligent electronic device (IED) is provided. 
     According to one aspect of the present disclosure, an intelligent electrical device (IED) includes an input base module sub-assembly including base having a plurality of apertures, a first, second, and third current input blade disposed in a respective aperture and a corresponding fourth, fifth, and sixth input current blade disposed in a respective aperture; a metering sub-assembly including a first, second, and third current plate disposed on a first surface of the metering sub-assembly and a corresponding fourth, fifth, and sixth current plate disposed on a second surface of the metering sub-assembly opposite to the first surface, the first current plate coupled to the first current input blade, the second current plate coupled to the second current input blade, the third current plate hingedly coupled to the third current input blade, the fourth current plate coupled to the fourth current input blade, the fifth current plate coupled to the fifth current input blade, and the sixth current plate hingedly coupled to the sixth current input blade, wherein the input base module sub-assembly can be pivoted about the third current plate and third current input blade and the sixth current plate and sixth current input blade to achieve an open position and a closed position relative to the metering sub-assembly; and at least one current sensor that senses current provided to a respective current input blade. 
     In one aspect, a combined width of the first, second, and third current plates substantially covers the first surface of the metering sub-assembly and a combined width of the fourth, fifth, and sixth current plates substantially covers the second surface of the metering sub-assembly. 
     In another aspect, the metering sub-assembly includes a bezel that supports a display. 
     In a further aspect, the IED includes a battery backup circuit for a real-time clock, wherein a removable battery is hot-swappable. 
     In yet another aspect, a battery detection is configured to detect if a removable battery is coupled to a battery receptacle and if the removable battery is holding a predetermined charge. 
     In another aspect, at least one voltage input blade is coupled to a filter/suppression module of the input base module sub-assembly. 
     In a further aspect, at least one spring contact is disposed on a surface of the filter/suppression module, wherein the at least one spring contact is coupled to at least one voltage input blade. 
     In yet another aspect, the metering sub-assembly includes at least one slot that is accessible when the metering sub-assembly is in an open position relative to the input base module sub-assembly, the at least one slot configured to receive a card to add functionality and/or communication capability to the IED. 
     According to another aspect of the present disclosure, a device for filtering sensed voltage and providing power to an intelligent electronic device is provided including at least one contact pad coupled to at least one voltage input, the at least one voltage input senses at least one voltage phase of an electrical distribution system; at least one current limiter coupled to the at least one contact pad; at least one suppressor coupled to the current limiter; and at least one rectifier coupled to the at least one current limiter and at least one suppressor. The filtering device provides full surge suppression at transient voltage conditions, i.e., the filtering device snubs transient voltage events that traditionally damage conventional meters and thus improves reliability of meters/IEDs utilizing the filtering device of the present disclosure. 
     In one aspect, the filtering device includes varistors for suppressing phase-to-phase voltage transients, while a clamping device suppresses phase-to-earth voltage transients. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other objects, features and advantages of the present disclosure will be apparent from a consideration of the following Detailed Description considered in conjunction with the drawing Figures, in which: 
         FIG.  1    is a block diagram of an intelligent electronic device (IED), according to an embodiment of the present disclosure. 
         FIG.  2    is a perspective view of an intelligent electronic device (IED) in accordance with an embodiment of the present disclosure. 
         FIGS.  2 A- 2 D  illustrate exemplary form factors for an intelligent electronic device (IED) in accordance with embodiments of the present disclosure. 
         FIG.  3    is a perspective view of the IED shown in  FIG.  2    with a cover removed in accordance with an embodiment of the present disclosure. 
         FIG.  4    is an exploded view of the IED shown in  FIG.  2    in accordance with an embodiment of the present disclosure. 
         FIG.  5    is a perspective view of the IED shown in  FIG.  2    with an outer housing removed in accordance with an embodiment of the present disclosure. 
         FIG.  6    is a top side view of the IED shown in  FIG.  5    in accordance with an embodiment of the present disclosure. 
         FIG.  7    is a left side view of the IED shown in  FIG.  5    in accordance with an embodiment of the present disclosure. 
         FIG.  8    is a bottom side view of the IED shown in  FIG.  5    in accordance with an embodiment of the present disclosure. 
         FIG.  9    is a right side view of the IED shown in  FIG.  5    in accordance with an embodiment of the present disclosure. 
         FIG.  10    is another exploded view of the IED shown in  FIG.  2    in accordance with an embodiment of the present disclosure. 
         FIG.  11    is an exploded view of a metering sub-assembly shown in  FIG.  10    in accordance with an embodiment of the present disclosure. 
         FIG.  12    is a perspective view of the IED illustrating current bars installed in accordance with an embodiment of the present disclosure. 
         FIG.  13 A  is a perspective view of an IED illustrating a current wrap configuration in accordance with an embodiment of the present disclosure. 
         FIG.  13 B  is a perspective front of a current plate holder in accordance with an embodiment of the present disclosure. 
         FIG.  13 C  is a front view of the current plate holder shown in  FIG.  13 B . 
         FIG.  14    is a perspective view of the IED shown in  FIG.  13 A  with a current holder plate installed in accordance with an embodiment of the present disclosure. 
         FIG.  15    is a partial perspective view of the IED shown in  FIG.  3    with a battery door removed in accordance with an embodiment of the present disclosure. 
         FIG.  16    is a partial perspective view of the IED shown in  FIG.  3    with a battery drawer removed in accordance with an embodiment of the present disclosure. 
         FIG.  17 A  is an exploded view of an input base module sub-assembly shown in  FIG.  10    in accordance with an embodiment of the present disclosure. 
         FIG.  17 B  is a front perspective view of a base in accordance with an embodiment of the present disclosure. 
         FIG.  17 C  is a rear perspective view of a base in accordance with an embodiment of the present disclosure. 
         FIG.  18    is a partial cross section of the input base module sub-assembly in accordance with an embodiment of the present disclosure. 
         FIG.  19    illustrates a voltage terminal contacting an input filter board in accordance with an embodiment of the present disclosure. 
         FIG.  20 A  is a perspective view of the input base module sub-assembly in accordance with an embodiment of the present disclosure. 
         FIGS.  20 B and  20 C  illustrate a front perspective view and a rear perspective view of a filter box cover in accordance with an embodiment of the present disclosure. 
         FIG.  21    is a side perspective view of the input base module sub-assembly in accordance with an embodiment of the present disclosure. 
         FIG.  22    is a rear left perspective view of the IED shown in  FIG.  2    in accordance with an embodiment of the present disclosure. 
         FIG.  23 A  is a perspective view of the IED shown in  FIG.  5    hinged open in accordance with an embodiment of the present disclosure. 
         FIG.  23 B  illustrates a patch cable in accordance with an embodiment of the present disclosure. 
         FIG.  23 C  is a front view of a connector of the patch cable shown in  FIG.  23 B . 
         FIG.  23 D  is a side view of the connector shown in  FIG.  23 C . 
         FIG.  23 E  illustrates a patch cable in accordance with another embodiment of the present disclosure. 
         FIG.  24    is a top side view of the IED shown in  FIG.  23    in accordance with an embodiment of the present disclosure. 
         FIG.  25    is a side elevational view of the IED shown in  FIG.  23    in accordance with an embodiment of the present disclosure. 
         FIG.  26    illustrates the IED shown in  FIG.  23    with various input/output cards removed in accordance with an embodiment of the present disclosure. 
         FIG.  27 A  illustrates a top surface of a filter board in accordance with an embodiment of the present disclosure. 
         FIG.  27 B  illustrates a bottom surface of a filter board in accordance with an embodiment of the present disclosure. 
         FIG.  28    illustrates a filter board assembly in accordance with an embodiment of the present disclosure. 
         FIG.  29    is an electrical schematic diagram of a filter/suppression circuit in accordance with an embodiment of the present disclosure. 
         FIG.  30    is an electrical schematic diagram of a battery backup circuit for a real-time clock (RTC) in accordance with an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure will be described herein below with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail. The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any configuration or design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other configurations or designs. Herein, the phrase “coupled” is defined to mean directly connected to or indirectly connected with through one or more intermediate components. Such intermediate components may include both hardware and software based components. 
     It is further noted that, unless indicated otherwise, all functions described herein may be performed in either hardware or software, or some combination thereof. In one embodiment, however, the functions are performed by at least one processor, such as a computer or an electronic data processor, digital signal processor or embedded micro-controller, in accordance with code, such as computer program code, software, and/or integrated circuits that are coded to perform such functions, unless indicated otherwise. 
     It should be appreciated that the present disclosure can be implemented in numerous ways, including as a process, an apparatus, a system, a device, a method, or a computer readable medium such as a computer readable storage medium or a computer network where program instructions are sent over optical or electronic communication links. 
     As used herein, intelligent electronic devices (“IEDs”) can be any device that senses electrical parameters and computes data including, but not limited to, Programmable Logic Controllers (“PLC&#39;s”), Remote Terminal Units (“RTU&#39;s”), electric power meters, panel meters, protective relays, fault recorders, phase measurement units, serial switches, smart input/output devices and other devices which are coupled with power distribution networks to manage and control the distribution and consumption of electrical power. A meter is a device that records and measures power events, power quality, current, voltage waveforms, harmonics, transients and other power disturbances. Revenue accurate meters (“revenue meter”) relate to revenue accuracy electrical power metering devices with the ability to detect, monitor, report, quantify and communicate power quality information about the power that they are metering. 
       FIG.  1    is a block diagram of an intelligent electronic device (IED)  10  for monitoring and determining power usage and power quality for any metered point within a power distribution system and for providing a data transfer system for faster and more accurate processing of revenue and waveform analysis. 
     The IED  10  of  FIG.  1    includes a plurality of sensors  12  coupled to various phases A, B, C and neutral N of an electrical distribution system  11 , a plurality of analog-to-digital (A/D) converters  14 , including inputs coupled to the sensor  12  outputs, a power supply  16 , a volatile memory  18 , a non-volatile memory  20 , a multimedia user interface  22 , and a processing system that includes at least one of a central processing unit (CPU)  50  (or host processor) and one or more digital signal processors, two of which are shown, i.e., DSP 1   60  and DSP 2   70 . The IED  10  also includes a Field Programmable Gate Array  80  which performs a number of functions, including, but not limited to, acting as a communications gateway for routing data between the various processors  50 ,  60 ,  70 , receiving data from the A/D converters  14 , performing transient detection and capture and performing memory decoding for CPU  50  and the DSP processor  60 . In one embodiment, the FPGA  80  is internally comprised of two dual port memories to facilitate the various functions. It is to be appreciated that the various components shown in  FIG.  1    are contained within housing  90 . Exemplary housings will be described below in relation to  FIGS.  2  and  2 A- 2 D . 
     The plurality of sensors  12  sense electrical parameters, e.g., voltage and current, on incoming lines, (i.e., phase A, phase B, phase C, neutral N), from an electrical power distribution system  11  e.g., an electrical circuit. In one embodiment, the sensors  12  may include current transformers and potential/voltage transformers, wherein one current transformer and one voltage transformer may be coupled to each phase of the incoming power lines. A primary winding of each transformer may be coupled to the incoming power lines and a secondary winding of each transformer may output a voltage representative of the sensed voltage and current. The output of each transformer may be coupled to the A/D converters  14  configured to convert the analog output voltage from the transformer to a digital signal that can be processed by the CPU  50 , DSP 1   60 , DSP 2   70 , FPGA  80  or any combination thereof. 
     A/D converters  14  are respectively configured to convert an analog voltage output to a digital signal that is transmitted to a gate array, such as Field Programmable Gate Array (FPGA)  80 . The digital signal is then transmitted from the FPGA  80  to the CPU  50  and/or one or more DSP processors  60 ,  70  to be processed in a manner to be described below. 
     The CPU  50  or DSP Processors  60 ,  70  are configured to operatively receive digital signals from the A/D converters  14  (see  FIG.  1   ) to perform calculations necessary to determine power usage and to control the overall operations of the IED  10 . In some embodiments, CPU  50 , DSP 1   60 , DSP 2   70  and FPGA  80  may be combined into a single processor, serving the functions of each component. In some embodiments, it is contemplated to use an Erasable Programmable Logic Device (EPLD) or a Complex Programmable Logic Device (CPLD) or any other programmable logic device in place of the FPGA  80 . In some embodiments, the digital samples, which are output from the A/D converters  14 , are sent directly to the CPU  50  or DSP processors  60 ,  70 , effectively bypassing the FPGA  80  as a communications gateway, thus eliminating the need for FPGA  80  in certain embodiments. 
     The power supply  16  provides power to each component of the IED  10 . In one embodiment, the power supply  16  is a transformer with its primary windings coupled to the incoming power distribution lines  11  and having windings to provide a nominal voltage, e.g., 5 VDC, +12 VDC and −12 VDC, at its secondary windings. In other embodiments, power may be supplied from an independent power source to the power supply  16 . For example, power may be supplied from a different electrical circuit or an uninterruptible power supply (UPS). 
     In one embodiment, the power supply  16  may be a switch mode power supply in which the primary AC signal will be converted to a form of DC signal and then switched at high frequency, such as, for example, 100 Khz, and then brought through a transformer to step the primary voltage down to, for example, 5 Volts AC. A rectifier and a regulating circuit may then be used to regulate the voltage and provide a stable DC low voltage output. Other embodiments, such as, but not limited to, linear power supplies or capacitor dividing power supplies are also contemplated to be within the scope of the present disclosure. 
     The multimedia user interface  22  is shown coupled to the CPU  50  in  FIG.  1    for interacting with a user and for communicating events, such as alarms and instructions to the user. The multimedia user interface  22  may include a display  23  for providing visual indications to the user and a front panel interface  21  including indictors, switches and various inputs. The display  23  may be embodied as a touch screen, a liquid crystal display (LCD), a plurality of LED number segments, individual light bulbs or any combination. The display may provide information to the user in the form of alpha-numeric lines, computer-generated graphics, videos, animations, etc. The multimedia user interface  22  further includes a speaker or audible output means for audibly producing instructions, alarms, data, etc. The speaker is coupled to the CPU  50  via a digital-to-analog converter (D/A) for converting digital audio files stored in a memory  18  or non-volatile memory  20  to analog signals playable by the speaker. An exemplary interface is disclosed and described in commonly owned U.S. Pat. No. 8,442,660, entitled “INTELLIGENT ELECTRONIC DEVICE HAVING AUDIBLE AND VISUAL INTERFACE”, which claims priority to expired U.S. Provisional Patent Appl. No. 60/731,006, filed Oct. 28, 2005, the contents of which are hereby incorporated by reference in their entireties. 
     It is to be appreciated that the display and/or user interface  22  of the present disclosure is programmable and may be configured to meet the needs of a specific user and/or utility. An exemplary programmable display and/or user interface  22  is disclosed and described in commonly owned pending U.S. Patent Application Publication No. 2012/0010831, the contents of which are hereby incorporated by reference in its entirety. U.S. Patent Application Publication No. 2012/0010831 provides for defining screens of a display on a revenue based energy meter, an intelligent electronic device, etc. In one embodiment, a method utilizes Modbus registers and defines a programming technique wherein a user can custom make any desired screen for every application based on what a user needs. The programming utilizes Modbus registers maps to allow for the customizable screens. Moreover, the display interface allows for customized labeling to provide notice and information to users as to measured parameters other than electricity that the meter might be accumulating such as steam, water, gas or other type of commodity. 
     The IED  10  will support various file types including but not limited to Microsoft Windows Media Video files (.wmv), Microsoft Photo Story files (.asf), Microsoft Windows Media Audio files (.wma), MP3 audio files (.mp3), JPEG image files (.jpg, .jpeg, .jpe, .jfif), MPEG movie files (.mpeg, .mpg, .mpe, .m1v, .mp2v .mpeg2), Microsoft Recorded TV Show files (.dvr-ms), Microsoft Windows Video files (.avi) and Microsoft Windows Audio files (.wav). 
     An input/output (I/O) interface  25  may be provided for receving inputs generated externally from the IED  10  and for outputing data, e.g., serial data, a contact closure, etc., to other devices. In one embodiment, the I/O interface  25  may include a connector for receiving various cards and/or modules that increase and/or change the functionality of the IED  10 . Such cards and/or module will be further described below. 
     The IED  10  further comprises a volatile memory  18  and a non-volatile memory  20 . In addition to storing audio and/or video files, volatile memory  18  may store the sensed and generated data for further processing and for retrieval when called upon to be displayed at the IED  10  or from a remote location. The volatile memory  18  includes internal storage memory, e.g., random access memory (RAM), and the non-volatile memory  20  includes non-removable and removable memory such as magnetic storage memory; optical storage memory, e.g., the various types of CD and DVD media; solid-state storage memory, e.g., a CompactFlash card, a Memory Stick, SmartMedia card, MultiMediaCard (MMC), SD (Secure Digital) memory; or any other memory storage that exists currently or will exist in the future. By utilizing removable memory, an IED can be easily upgraded as needed. Such memory may be used for storing historical trends, waveform captures, event logs including time-stamps and stored digital samples for later downloading to a client application, web-server or PC application. 
     In a further embodiment, the IED  10  may include a communication device  24 , also know as a network interface, for enabling communications between the IED or meter, and a remote terminal unit, programmable logic controller and other computing devices, microprocessors, a desktop computer, laptop computer, other meter modules, etc. The communication device  24  may be a modem, network interface card (NIC), wireless transceiver, etc. The communication device  24  may perform its functionality by hardwired and/or wireless connectivity. The hardwire connection may include but is not limited to hard wire cabling e.g., parallel or serial cables, RS232, RS485, USB cable, Firewire (1394 connectivity) cables, Ethernet, and the appropriate communication port configuration. The wireless connection may operate under any of the various wireless protocols including but not limited to Bluetooth™ interconnectivity, infrared connectivity, radio transmission connectivity including computer digital signal broadcasting and reception commonly referred to as Wi-Fi or 802.11.X (where x denotes the type of transmission), satellite transmission or any other type of communication protocols, communication architecture or systems currently existing or to be developed for wirelessly transmitting data including spread spectrum 900 MHz, or other frequencies, Zigbee, WiFi, or any mesh enabled wireless communication. 
     The IED  10  may communicate to a server or other computing device such as a client via the communication device  24 . The client may comprise any computing device, such as a server, mainframe, workstation, personal computer, hand held computer, laptop, telephony device, network appliance, other IED, Programmable Logic Controller, Power Meter, Protective Relay etc. The IED  10  may be connected to a communications network, e.g., the Internet, by any means, for example, a hardwired or wireless connection, such as dial-up, hardwired, cable, DSL, satellite, cellular, PCS, wireless transmission (e.g., 802.11a/b/g), etc. It is to be appreciated that the network may be a public or private intranet, an extranet, a local area network (LAN), wide area network (WAN), the Internet or any network that couples a plurality of computers to enable various modes of communication via network messages. Furthermore, the server may communicate using various protocols such as Transmission Control Protocol/Internet Protocol (TCP/IP), File Transfer Protocol (FTP), Hypertext Transfer Protocol (HTTP), etc. and secure protocols such as Hypertext Transfer Protocol Secure (HTTPS), Internet Protocol Security Protocol (IPSec), Point-to-Point Tunneling Protocol (PPTP), Secure Sockets Layer (SSL) Protocol, etc. Communications may also include IP tunneling protocols such as those that allow virtual private networks coupling multiple intranets or extranets together via the Internet. The server may further include a storage medium for storing a database of instructional videos, operating manuals, etc. 
     In an additional embodiment, the IED  10  may also have the capability of not only digitizing waveforms, but storing the waveform and transferring that data upstream to a central computer, e.g., a remote server, when an event occurs such as a voltage surge or sag or a current short circuit. This data may be triggered and captured on an event, stored to memory, e.g., non-volatile RAM, and additionally transferred to a host computer within the existing communication infrastructure either immediately in response to a request from a remote device or computer to receive said data in response to a polled request. The digitized waveform may also allow the CPU  50  to compute other electrical parameters such as harmonics, magnitudes, symmetrical components and phasor analysis. Using the harmonics, the IED  10  may also calculate dangerous heating conditions and can provide harmonic transformer derating based on harmonics found in the current waveform. 
     In a further embodiment, the IED  10  may execute an e-mail client and may send e-mails to the utility or to the customer direct on an occasion that a power quality event occurs. This allows utility companies to dispatch crews to repair the condition. The data generated by the meters are used to diagnose the cause of the condition. The data may be transferred through the infrastructure created by the electrical power distribution system. The email client may utilize a POP3 or other standard mail protocol. A user may program the outgoing mail server and email address into the meter. An exemplary embodiment of said metering is available in U.S. Pat. No. 6,751,563, which all contents thereof are incorporated by reference herein. In the U.S. Pat. No. 6,751,563, at least one processor of the IED or meter is configured to collect the at least one parameter and generate data from the sampled at least one parameter, wherein the at least one processor is configured to act as a server for the IED or meter and is further configured for presenting the collected and generated data in the form of web pages. 
     In a further embodiment, the IED  10  of the present disclosure may communicate data from an internal network to a server, client, computing device, etc. on an external network through a firewall, as disclosed and described in commonly owned U.S. Patent Application Publication No. 2013/0031201, the contents of which are hereby incorporated by reference in its entirety. 
     The techniques of the present disclosure can be used to automatically maintain program data and provide field wide updates upon which IED firmware and/or software can be upgraded. An event command can be issued by a user, on a schedule or by digital communication that may trigger the IED  10  to access a remote server and obtain the new program code. This will ensure that program data will also be maintained allowing the user to be assured that all information is displayed identically on all units. 
     It is to be understood that the present disclosure may be implemented in various forms of hardware, software, firmware, special purpose processors, or a combination thereof. The IED  10  also includes an operating system and micro instruction code. The various processes and functions described herein may either be part of the micro instruction code or part of an application program (or a combination thereof) which is executed via the operating system. 
     It is to be further understood that because some of the constituent system components and method steps depicted in the accompanying figures may be implemented in software, or firmware, the actual connections between the system components (or the process steps) may differ depending upon the manner in which the present disclosure is programmed. Given the teachings of the present disclosure provided herein, one of ordinary skill in the related art will be able to contemplate these and similar implementations or configurations of the present disclosure. 
     Furthermore, it is to be appreciated that the components and devices of the IED  10  of  FIG.  1    may be disposed in various housings depending on the application or environment. 
     Referring to  FIGS.  2  and  3   , the IED of the present disclosure may be configured as a socket meter  100 , also known as a S-base type meter or type S meter. The meter  100  includes a main housing  102  surrounded by a cover  104 . The cover  104  is preferably made of a clear material to expose a display  106  disposed on a bezel  108  of the housing  102 . An interface  110  to access the display and a communication port  112  is also provided and accessible through the cover  104 . The interface  110  may include a switch, for example, to reset values, and/or buttons for entering or confirming input values. The meter  100  further includes a plurality of current terminals and voltage terminals (not shown) disposed on the backside of the meter extending through a base  114 , the details of which will be described below. The terminals are designed to mate with matching jaws of a detachable meter-mounting device, such as a revenue meter socket. The socket is hard wired to the electrical circuit and is not meant to be removed. To install an S-base meter, the utility need only plug in the meter into the socket. Once installed, a socket-sealing ring (not shown) is used as a seal between the meter housing  102  and/or cover  104  and the meter socket to prevent removal of the meter and to indicate tampering with the meter. 
     In a further embodiment, the IED  100  of  FIG.  2    may be disposed in a switchboard or draw-out type housing  116  as shown in  FIGS.  2 A and  2 B , where  FIG.  2 A  is a front view and  FIG.  2 B  is a rear view. The switchboard enclosure  116  usually features a cover  118  with a transparent face  120  to allow the meter display  106  to be read and the user interface  110  to be interacted with by the user. The cover  118  also has a sealing mechanism (not shown) to prevent unauthorized access to the meter. A rear surface  122  of the switchboard enclosure  116  provides connections for voltage and current inputs  124  and for various communication interfaces  126 . Although not shown, the meter disposed in the switchboard enclosure  116  may be mounted on a draw-out chassis which is removable from the switchboard enclosure  116 . The draw-out chassis interconnects the meter electronics with the electrical circuit. The draw-out chassis contains electrical connections which mate with matching connectors  124 ,  126  disposed on the rear surface  122  of the enclosure  116  when the chassis is slid into place. Exemplary housings, enclosures and/or cases are shown and described in commonly owned U.S. Design Pat. Nos. D706,659, D706,660, D708,082 and D708,533. 
     In yet another embodiment, the IED  100  of  FIG.  2    may be disposed in a A-base or type A housing as shown in  FIGS.  2 C and  2 D . A-base meters  128  feature bottom connected terminals  130  on the bottom side of the meter housing  132 . These terminals  130  are typically screw terminals for receiving the conductors of the electric circuit (not shown). A-base meters  128  further include a meter cover  134 , meter body  136 , a display  138  and input/output means  140 . Further, the meter cover  134  includes an input/output interface  142 . The cover  134  encloses the meter electronics  144  and the display  138 . The cover  134  has a sealing mechanism (not shown) which prevents unauthorized tampering with the meter electronics. 
     It is to be appreciated that other housings and mounting schemes, e.g., circuit breaker mounted, are contemplated to be within the scope of the present disclosure. 
     Referring to  FIGS.  3 ,  4  and  10   , housing  102  includes an upper clam shell half  150  and a lower clam shell half  152 . The upper clam shell half  150  and lower clam shell half  152  are secured to each other via a plurality of screws  149 . Each of the upper clam shell half  150  and the lower clam shell half  152  include a plurality of louvers  200  to allow heat to escape. In one embodiment, the upper clam shell half  150  and lower clam shell half  152  each include a shiny or reflective finish, e.g., a chrome finish, on an outer surface to reflect sunlight in outdoor applications to avoid heating up the internal components of the IED  100 . In one embodiment, the reflective finish is applied to the upper clam shell half  150  and lower clam shell half  152  as a first sticker  151  and a second sticker  153 , as shown in  FIGS.  3  and  10   . Internal to the housing  102 , the IED  100  includes a metering sub-assembly  154  and an input base module sub-assembly  156 , the details of which will be described below. As shown in  FIG.  4   , the metering sub-assembly  154  is hinged to the input base module sub-assembly  156 . When in an open position, various cables, connectors, and input/output cards/modules are exposed, as will be described below. 
     Referring to  FIGS.  5 - 9   , various views of the IED  100  are illustrated with the housing  102  removed. The metering sub-assembly  154  is hinged to the input base module sub-assembly  156  via current plates  158 ,  160 ,  162 ,  164 ,  166 ,  168  and current input blades  170 ,  172 ,  174 ,  176 ,  178 ,  180  respectively. Each current plate is coupled to a respective current input blade via spring loaded screw. For example, current plate  158  is coupled to current input  170  via screw  182 , current plate  160  is coupled to current input  172  via screw  184 , current plate  162  is coupled to current input  174  via screw  186 , current plate  164  is coupled to current input  176  via screw  188 , current plate  166  is coupled to current input  178  via screw  190  and current plate  168  is coupled to current input  180  via screw  192 . The current input path for each combination of current plates and current inputs is completed by a current bar  194 ,  196 ,  198 . For example, when the IED is coupled to a three phase system, the current input path for phase A flows through current input  170  to current plate  158  through current bar  194  through current plate  164  and through current input  176 . The current input path for phase B flows through current input  172  to current plate  160  through current bar  196  through current plate  166  and through current input  178 . The current input path for phase C flows through current input  174  to current plate  162  through current bar  198  through current plate  168  and through current input  180 . It is to be appreciated that the current bars  194 ,  196 ,  198  pass through current sensing circuits disposed within metering sub-assembly  154 , the details of which will be described below. Additionally, the current inputs, current plates and current bars may be made of highly electrically conductive material such as copper, however, other materials may be used. 
     It is further to be appreciated that the current plates  158 ,  160 ,  162 ,  164 ,  166 ,  168  are relatively wide to have increased surface area. The increased surface area allows high current to pass through. Additionally, the large surface area of the current plates  158 ,  160 ,  162 ,  164 ,  166 ,  168  act as a heat sink drawing heat generated internal to the metering sub-assembly  154  and dissipating such heat through ventilation slots or louvers  200  disposed on the housing  102 . In certain embodiments, the delta T, i.e., temperature change, of the heat drawn away and dissipated by the current plates is approximately 10 degrees F. As best shown in  FIGS.  4  and  10   , the louvers  200  are positioned on a respective calm shell half  150 ,  152  to approximately align over respective current plates to allow heat to dissipate through the louvers  200 . To facilitate drawing heat away from the internal electronic components of the metering sub-assembly  154 , current plates  158 ,  160 ,  162 ,  164 ,  166 ,  168  are disposed on at least one surface of an inner housing  206  of the metering sub-assembly  154 . For example, referring to  FIG.  5   , current plate  160  includes at least a first aperture  146  and at least a second aperture  148 , where the first and second apertures  146 ,  148  align and secure the current plate  160  via alignment post  155  and locking tab  157 . Although not specifically pointed out, each current plate includes at least one first aperture for receiving an alignment post and at least one second aperture for receiving a securing or locking tab, e.g., a mushroom tab. As can be seen in  FIGS.  5 ,  6  and  8   , the combined widths of current plates  158 ,  160 ,  162  substantially cover a first surface  145 , or top surface, of the inner housing, while current plates  164 ,  166 ,  168  substantially cover a second surface  147 , or bottom surface. Also, it is to be appreciated that, in one embodiment, housing  206  of metering sub-assembly  154  also includes louvers  201  to further aid in the dissipation of heat generated by the IED Generally, the current plates are aligned over the louvers  201  to draw heat from the inside of the housing  206 . 
       FIG.  10    is another exploded view of the IED shown in  FIG.  2    in accordance with an embodiment of the present disclosure. The upper clam shell half  150  and lower clam shell half  152  of the housing  102  are illustrated. The metering sub-assembly  154  and an input base module sub-assembly  156  are shown spaced apart from each other. 
     Referring to  FIG.  11   , an exploded view of the metering sub-assembly  154  is illustrated. The metering sub-assembly  154  includes an upper inner case  202  and lower inner case  204  to collectively form an inner housing  206 . The upper inner case  202  and lower inner case  204  are coupled together, for example, by screws  205 . A back plate  208  is disposed on a rear portion of the inner housing  206 . A DSP board assembly  210  is disposed on a front portion  207  of the inner housing  206 . The DSP board assembly  210  includes the display  106  and at least one processor on a rear surface thereof. In one embodiment, the display  106  may be a touch sensitive display or user interface as disclosed and described in commonly owned U.S. Patent Application Publication No. 2014/0180613, the contents of which are hereby incorporated by reference in its entirety. In one embodiment, a user may interact with the display  106  by directly touching a surface of the display  106 . In another embodiment, a user may interact with the display  106  while the cover  104  is disposed over the IED  100  by touching a portion of the cover  104  that is approximately aligned over the display  106 . 
     A VIP board assembly  212  is disposed in the inner housing  206  perpendicular to the DSP board assembly  210  and electrically coupled thereto. The VIP board assembly  212  includes a plurality of current sensors  214  disposed thereon. The current sensors  214  are positioned on the VIP board assembly  212  to accept the current bars  194 ,  196 ,  198  through a respective center of the current sensors  214  when the current bars  194 ,  196 ,  198  are disposed in apertures  216  of the upper inner case  202 . A similar current sensing technique is described in commonly owned U.S. Pat. No. 7,271,996, the contents of which are hereby incorporated by reference in its entirety. 
     Referring to  FIG.  12   , the current bars  194 ,  196 ,  198  are shown disposed in apertures  216  of the upper inner case  202 . As described above, the current input path for each combination of current plates and current inputs is completed by a current bar  194 ,  196 ,  198 . For example, when the IED is coupled to a three phase system, the current input path for phase C flows through current input  174  to current plate  162  through current bar  198  through current plate  168  and through current input  180 . Each current rod is coupled to a respective current plate via a plurality of fasteners, such as washers/clips and nuts. Referring to  FIGS.  10  and  12   , current bar  198  is threaded on each end. A first washer or clip  161  and first nut  163  is coupled to first end  165  of current bar  198 . An aperture  167  of current plate  186  is disposed over the first end  165  of current bar  198  and secured by second washer or clip  169  and second nut  171 . Similarly, a third washer or clip  173  and third nut  175  is coupled to second end  177  of current bar  198 . An aperture  179  of current plate  168  is disposed over the second end  177  of current bar  198  and secured by fourth washer or clip  169  and fourth nut  171 . Current bars  194 ,  196  are assembled in a similar manner. It is to be appreciated that the current bars  194 ,  196 ,  198  limit movement of the metering sub-assembly  154  in the XYZ coordinate directions and provide structural strength. 
     To achieve more accurate current sensing at lower current ranges, a wire may be used in lieu of the current bars. A wire  181 ,  183 ,  185  is disposed through a respective aperture  216  and wound about the current sensor  214  internal to the metering sub-metering  154  by repeatedly inserting the respective wire through the aperture  216  as shown in  FIG.  13 A . The wire  181 ,  183 ,  185  is wrapped a predetermined number of times, e.g., about ten turns. After the wire is wrapped the predetermined number of turns, each end of the respective wire is coupled to a respective current plate. For example, wire  181  is coupled to current plate  158  on one end and to current plate  164  on the other end; wire  183  is coupled to current plate  160  on one end and to current plate  166  on the other end; and wire  185  is coupled to current plate  162  on one end and to current plate  168  on the other end. 
     In this embodiment, a current plate holder  187  provides structural strength similar to the strength provided by the current bars. A perspective view of the current plate holder  187  is shown in  FIG.  13 B  and a front view of the current plate holder is shown in  FIG.  13 B . A first end  189  of the current plate holder  187  includes apertures or slots  191  that interact with current plates  158 ,  160 ,  162  and a second end  193  of the current plate holder  187  includes apertures or slots  195  that interact with current plates  164 ,  166 ,  168 . As shown in  FIG.  14   , the current plate holder  187  is disposed over the portion of the metering sub-assembly  154  including wires  181 ,  183 ,  185 . The first end  189  of the current plate holder  187  including apertures  191  interact with current plates  158 ,  160 ,  162  and the second end  193  of the current plate holder  187  including apertures  195  interact with current plates  164 ,  166 ,  168 . In one embodiment, the current plate holder  187  snaps onto the current plates, i.e., a portion of the current plate snaps into the apertures or slots  191 ,  195 , however, other configurations are contemplated to be within the scope of the present disclosure. The current plate holder  187  may include apertures  197  to dissappate heat generated by the wires  181 ,  183 ,  185 . 
     Referring back to  FIG.  11   , a RS485/KYZ board assembly  218  is also disposed in the inner housing  206  perpendicular to the DSP board assembly  210  and electrically coupled thereto. It is to be appreciated that the DSP board assembly  210  is configured to accept and be coupled to other boards, for example, input/output boards that are disposed in the inner housing  206  via back plate  208 . Such mounting/coupling techniques are disclosed and described in commonly owned U.S. Pat. No. 8,587,949, the contents of which are hereby incorporated by reference in it entirety. Additionally, a plastic divider sheet  219  is disposed in the inner housing  206  separating the VIP board assembly  214  from other components, for example, the RS485/KYZ board assembly  218  and/or function modules or cards. 
     The DSP board assembly  210  is protected by bezel  108 . In certain embodiments, a sticker  109  having identifying information, instructions, etc., is disposed over the bezel  108 . Buttons  220  extends through apertures  222  in the bezel  108  and contact an input mechanism on a front surface of the DSP board assembly  210 . The DSP board assembly  210  includes a battery receptacle  224  which when a battery is disposed therein provides battery backup to at least one storage device for retaining data upon a power loss and/or battery backup power for a real time clock (RTC) upon a power loss. To access the battery receptacle  224 , the bezel  108  includes a battery aperture or window  226 , as also shown in  FIGS.  11 ,  15  and  16   . The battery aperture  226  is configured to accept a battery drawer  228  that is configured to retain a battery  230  therein. When the battery drawer  228  is disposed in the battery window  226 , a battery door  232  is disposed in the battery window  226  to secure the battery drawer  228 . In one embodiment, the battery drawer  228  and the battery door  232  may be a single, unitary piece, wherein the battery  230  may be removed by removing the battery door  232 . It is to be appreciated that the battery  230  is replaceable or “hot swappable”, that is, battery  230  may be changed without powering down the IED  100  so the IED  100  may remain in service. Additionally, the IED  100  includes a battery detection circuit for determining if the battery is holding a charge and for providing an indication, via the user interface, that the battery needs to be replaced, as will be described in greater detail below. 
     Referring to  FIGS.  17 ,  20 A and  21   , the input base module sub-assembly  156  is illustrated, where  FIG.  17 A  is an exploded view of the input base module sub-assembly  156 ,  FIG.  20 A  is a perspective view of the input base module sub-assembly  156  and  FIG.  21    is a side view of the input base module sub-assembly  156 . 
     The input base module sub-assembly  156  includes generally circular base  114  having a plurality of aperture or slots  234  for receiving current and voltage input blades. The base  114  is shown in further detail in  FIGS.  17 B and  17 C . A plurality of current input blades  170 ,  172 ,  174 ,  176 ,  178 ,  180  are provided. Each current input blade  170 ,  172 ,  174 ,  176 ,  178 ,  180  includes a first end  236  and a second end  238  which are configured in perpendicular planes relative to each other. The first end  236  includes a shoulder tab  240  for providing a stop when at least one gasket is placed over the first end  236 . In one embodiment, a metal gasket  242  is placed over the first end  236  and positioned against the shoulder tab  240 . Additionally, a rubber gasket  244  may be placed over the first end  236  and positioned against the metal gasket  242 . The first end  236  is disposed in an appropriate slot  234  in the base  114 , e.g. a current blade aperture or slot  235 . The current blade is secured to the base by disposing a fixing member  246 , e.g., a cotter pin, in aperture  248  of the first end  236  of the current blade. An exemplary fixing member  246  disposed in aperture  248  is shown in  FIG.  22   . 
     A plurality of voltage input blades  250  are provided for sensing voltage. Each voltage input blade  250  includes a first end  252  and a second end  254 . The second end  254  includes a shoulder tab  256  for providing a stop when at least one gasket is placed over the first end  252 . In one embodiment, a metal gasket  258  is placed over the first end  252  and positioned against the shoulder tab  256 . Additionally, a rubber gasket  260  may be placed over the first end  252  and positioned against the metal gasket  258 . The first end  252  is disposed in an appropriate slot  234  in the base  114 , e.g., voltage blade aperture or slot  237 . The voltage blade  250  is secured to the base by displacing tab  262  from the plane of the blade  250  as to make contact with the base  114 . 
     A filter board  264  is disposed over the voltage input blades  250  and between the second ends  238  of the current input blades. Each voltage input blade  250  includes a contact  266  which is configured to have perpendicular surface with respect to the blade. Once the filter board is positioned on the base  114 , each contact  266  makes contact with an input  276  on a rear surface  278  of the filter board  264 , as shown in  FIGS.  18  and  19   . Referring to  FIG.  19   , each voltage input  276  of the filter board  264  includes a spring contact  280 . By providing a spring contact  280  on the voltage input  276 , no soldering is required between the voltage input  276  and the voltage blade  250  facilitating assembly. Additionally, since soldered is not used to rigidly fix the voltage blade, the filter board and/or voltage blade is less susceptible to being broken during the forces used when installing the IED, for example, into or out of a standard ANSI meter socket. Voltage sensed by each voltage input blade  250  is provided to the filter board  264  which subsequently provides power to other portions of the IED and at least one signal indicative of the voltage sensed via connector  268 , the details of which are described below. It is to be appreciated that connector  268  is coupled to filter board  264  via cable  386 . 
     The filter board  264  is secured to the base  114  via screws or other means  270  coupled to standoffs  272 , e.g., at least four standoffs are shown in  FIG.  17 A . A filter box cover  274  is disposed over the filter board  264 , as shown in  FIGS.  20 A and  21   , to protect the filter board  264  and to route wires and cables from the base  114  to other portions of the IED as will be described below. It is to be appreciated that  FIGS.  20 B and  20 C  show additional views of filter box cover  274  and will be described in greater detail below. 
     Referring to  FIG.  22   , a rear left perspective view of the IED shown in  FIG.  2    in accordance with an embodiment of the present disclosure is provided. As discussed previously, the base  114  includes a plurality of apertures  234  for receiving the current and voltage input blades internally so the current and voltage input blades extend from the rear surface  290  of the base  114 . The base  114  further employs universal quick connectors for coupling wires to the base  114 . For example, as seen in  FIG.  22   , base  114  includes apertures  307 ,  308 ,  310 ,  312 , and  313 , where connector  300  is disposed in aperture  307 , connector  298  is disposed in aperture  308 , connector  296  is disposed in aperture  310 , connector  294  is disposed in aperture  313 , and connector  292  is disposed in aperture  312 . In one embodiment, connectors  292 ,  294 ,  296 ,  298 ,  300  include RJ-45 receptacles and apertures  307 ,  308 ,  310 ,  312 , and  313  are configured to provide access to each receptacle. At least one of the connectors, for example, connector  296 , is employed for RS-485 communications and for an KYZ pulse and is coupled to RS485/KYZ board assembly  218  (via cable  341  and connector  342  as can be seen in  FIG.  4    and will be described in greater detail below). The other connectors  292 ,  294 ,  296 ,  300  can be internally coupled to various communication modules and/or input/output modules disposed in the inner housing  206 . Connector  302  is provided to be coupled to an external, auxiliary power source when the internal components of the IED are not powered via the sensed voltage provided to a respective load being monitored by the IED. Additionally, meter hanger  303  is rotatably coupled to the base  114  via pin  305 . 
     It is to be appreciated that one side of each connector includes a receptacle that can be accessed via a respective aperture of base  114  and the other side of each connector is configured to be coupled to various modules disposed in the inner housing  206  via a cable. For example, referring again to  FIG.  20 A , the rear sides or portions of connectors  292 ,  294 ,  296 ,  298 , and  300  are shown disposed through apertures  312 ,  313 ,  310 ,  308 , and  307  respectively. Connector  292  includes rear portion  293 , connector  294  includes rear portion  295 , connector  296  includes rear portion  340 , connector  298  includes rear portion  299 , and connector  300  includes rear portion  301 . Connectors  292 ,  294 ,  296 ,  300  are coupled to base  114  via an I/O connector frame. Referring to  FIG.  26   , a single I/O connector frame  315  and a double I/O connector frame  317  are shown. In one embodiment, the connectors  292 ,  294 ,  296 ,  300  snap-in to an appropriate apperture of the I/O connector frame, e.g., aperture  319  of the single I/O connector frame  315 . 
     Referring again to  FIG.  22   , it is to be appreciated that base  114  includes rear surface  290  which is offset from surface  304  by edge  306 . Edge  306  allows for routing of cables that are coupled to the various connectors  292 ,  294 ,  296 ,  298 ,  300 , when the IED is disposed in a socket. Furthermore, connector apertures  307 ,  308 ,  310 ,  312 , and  313  include curved surfaces  314 ,  316 ,  318 , where curved surface  314  corresponds to apertures  307  and  308 , curved surface  316  corresponds to aperture  310 , and curved service  318  corresponds to apertures  312  and  313  to allow for a 90 degree radius of a bend for any wire or cable coupled to a respective connector. By providing curved surfaces  314 ,  316 ,  318 , cables coupled to the various connectors  292 ,  294 ,  296 ,  298 ,  300  are less susceptible to damage as opposed to having a sharp or squared edge at the apertures, i.e., the cables may conform to the curved surfaces without having to make abrupt bends. 
     Referring to  FIGS.  23 A,  24  and  25   , a perspective view of the IED  100  hinged open in accordance with an embodiment of the present disclosure is illustrated in  FIG.  23 A , with a top view shown in  FIG.  24    and a side elevational view shown in  FIG.  25   . As described above, the metering sub-assembly  154  is hinged to the input base module sub-assembly  156  via current plates  158 ,  160 ,  162 ,  164 ,  166 ,  168  and current input blades  170 ,  172 ,  174 ,  176 ,  178 ,  180  respectively. Each current plate is coupled to a respective current input blade via a spring loaded, captive screw. By uncoupling at least two corresponding sets of the spring loaded screws, the IED is hingedly opened to expose a front portion of the input base module sub-assembly  156  and a rear portion of the metering sub-assembly  154 . For example, by uncoupling screw  182  and correspond screw  188  and screw  184  and corresponding screw  190 , the metering sub-assembly  154  and the input base module sub-assembly  156  will be hingedly coupled via screw  186  and corresponding screw  192 , i.e., to move the IED  100  to an open position as shown in  FIGS.  23 - 25    and a closed position as shown in  FIGS.  5 - 9   . By employing spring loaded, captive screws  182 ,  184 ,  186 ,  188 ,  190 ,  192 , the screws enable a respective current blade to be disengaged from a respective current input blade, while the screw remains coupled to the respective current plate to prevent loss of the screw. It is to be appreciated that other types of fasteners, in lieu of spring loaded captive screws, may be employed to couple a current plate to a respective current input blade. It is further to be appreciated that each current input blade includes an aperture for receiving or mating with the screws  182 ,  184 ,  196 ,  188 ,  190 ,  192 . For example, current input blade  170  includes aperture  199  for mating with screw  182 . Although not specifically pointed out, each current input blade includes a similar aperture. 
     In the open position, wiring between the metering sub-assembly  154  and the input base module sub-assembly  156  is facilitated. For example, a rear side  340  of connector  296  is exposed on the input base module sub-assembly  156 . In one embodiment, the metering sub-assembly  154  includes a RS-485/KYZ connector  342 , where RS-485/KYZ connector  342  is coupled to a receptacle  347  (shown in  FIG.  26   ) which is coupled to RS-485/KYZ board  218 . RS-485/KYZ connector  342  can then be coupled to the rear side  340  of connector  296 , for example, via a patch cable. It is to be appreciated that patch cable  341  can be seen coupled to connector  342  and rear portion  340  of connector  296  in  FIGS.  4  and  5   . Additionally, the metering sub-assembly  154  includes connector  268  which includes a power input portion  346  and a voltage sensing input portion  348 . Power and voltage sensed is provided by the filter board  264  to connector  268  via cable  386 . It is to be appreciated that cable  386  can be seen coupled to connector  268  in  FIG.  4   . The connector  268  is received by receptacle  344  (most clearly shown in  FIG.  26   ), where receptacle  344  is coupled to the VIP board  212 . 
     The functionality of the IED  100  can be expanded by the addition of function modules or cards disposed in the metering sub-assembly  154  and coupled to the DSP board assembly  210 . Referring to  FIG.  26   , function modules or cards  320 ,  322  are disposed in the metering sub-assembly  154  via apertures or slots  324 ,  326  in the back plate  208 . When the function modules or cards  320 ,  322  are fully seated in the metering sub-assembly  154 , an edge  328 ,  330  of the function modules or cards  320 ,  322  respectively are received by an appropriate connector of the DSP board assembly  210  and is thus coupled thereto. 
     It is to be appreciated that the function modules or cards  320 ,  322  may add functionality to the IED by including additional processing devices, additional memories or a combination thereof that work in cooperation, or independently, with the processing devices of the DSP board assembly  210 . In other embodiments, the function modules or cards  320 ,  322  may expand the input/output (I/O) and/or the communication capabilities of the IED. For example, exemplary I/O modules or cards may include a four channel bi-directional 0-1 mA output card, a four channel 4-20 mA output card, a two relay output/two status input card, a four pulse output/four status input card, etc. or any combination thereof. 
     Exemplary communication cards or modules may include a 100 Base T Ethernet card, an IEC 61850 protocol Ethernet card, a fiber optic communication card, among others. It is to be appreciated that the Ethernet card or module may add at least one of the following capabilities and/or protocols to the IED including, but not limited to, Modbus TCP, DNP 3.0, File Transfer Protocol (FTP), Simple Mail Transfer Protocol (SMTP), SNMP, encryption, IEEE 1588 time sync, etc. It is further to be appreciated that two communication cards or modules may be employed to provide dual Ethernet ports. In one embodiment, the dual Ethernet ports may be configured such that each port is independent and communicatively isolated from the other port. Such a configuration is described in commonly owned U.S. Pat. No. 7,747,733, the contents of which are hereby incorporated by reference in its entirety. In this embodiment, each port has a unique identifier, e.g., an IP address, and may be connected to a different network than the other port. In another embodiment, each port connects to the same network. In this embodiment, each port may have the same identifier, e.g., IP address, wherein one of the two ports acts as an Ethernet switch to facilitate network wiring. 
     It is to be appreciated that the above-mentioned list of cards and/or modules, whether intelligent or passive, is not exhaustive and other types of inputs, outputs and communication protocols are contemplated to be within the scope of the present disclosure. Further exemplary cards and/or modules and techniques for coupling such cards and/or modules to add functionality, capabilities, etc. are disclosed and described in commonly owned U.S. Pat. Nos. 7,184,904 and 7,994,934, the contents of which are hereby incorporated by reference in their entireties. 
     Referring back to  FIG.  23 A , a 100 Base T Ethernet card  332  is shown inserted into slot  324  and a two relay output/two status input card  334  is shown inserted into slot  326 . Card  332  includes a connector  336 , e.g., an RJ-45 receptacle, which may then be coupled via a patch cable to a connector on the base  114 , for example, rear portion  299  of connector  298 . Similarly, card  334  includes a connector  338 , e.g., a crimp connector. It is to be appreciated that the patch cables may be configured with preformed ends to facilitate installation. Referring to  FIGS.  23 B- 23 D , an exemplary patch cable  321  is provided. The patch cable  321  may be configured to include connector  298  on one end of a multiconductor cable  325  and a RJ45 plug  323  on the other end of the cable  325 . In this manner, the RJ45 plug  323  of the patch cable  321  merely needs to be plugged into the connector  336  on card  332  and the connector  298  needs to be mated to the I/O connector frame  317 , e.g., plugged or snapped into. It is further to be appreciated that the RJ45 connector and connector  289  are merely exemplary and other types of plugs, receptacles, connectors, etc. are contemplated to be within the scope of the present disclosure. 
     It is to be appreciated that certain types of cards may be coupled to separate connectors on base  114  for separate input/output communication. For example, in one embodiment, the two relay output/two status input card  334  is configured to be coupled to two different connectors coupled to base  114 . In one embodiment, the top portion of connector  338  may be coupled via a patch cable to a connector on the base  114 , for example, rear portion  301  of connector  300  for input communication and the bottom portion of connector  338  may be coupled via a patch cable to another connector on the base  114 , for example, rear portion  293  of connector  292 . In another embodiment, the patch cable may be configured to include a single connector on one end for interacting with connector  338  of card  334 , while the other end of the patch cable includes two separate connectors, e.g., connector  292  and connector  300 . Such an exemplary patch cable is shown in  FIG.  23 E  as cable  327 . Patch cable  327  includes a single connector  329  for coupling to connector  338  of card  334 . The connector  329  is coupled to a first multiconductor cable  331  terminating with connector  300  and connector  329  is coupled to a second multiconductor cable  333  terminating with connector  292 . Legend  335  indicates an exemplary wiring configuration between connector  329  and connector  292  and legend  337  indicates an exemplary wiring configuration between connector  329  and connector  300 . 
     It is to be appreciated that when no additional function modules or cards are used, a blank plate (not shown) is disposed over slots  332 ,  334 . Furthermore, it is to be appreciated that when no additional function module or cards are used, one or more of connectors  292 ,  294 ,  296 ,  298 , and/or  300  may be removed and blank plates or covers (not shown) may be disposed over apertures  307 ,  308 ,  310 ,  312 , and/or  313 . In one embodiment, the blank plates or covers disposed over apertures  307 ,  308 ,  310 ,  312 , and/or  313  may interact with an aperture of the I/O connector frame to secure the covers to the base  114 . 
     In one embodiment, when one or more of connectors  292 ,  294 ,  296 ,  298 ,  300  is coupled to base  114 , the receptacle of each respective connector that is coupled to base  114  is color coded, where the color of the receptacle (as seen from the rear side of the base  114  as shown in  FIG.  22   ) corresponds to the type of card or module the respective connector is coupled to internally in the IED. In this way, when the IED is in a closed position (i.e., the current plates of metering sub-assembly  154  are each coupled to the current input blades of input base module sub-assembly  156 ) the type of modules and/or cards included in the IED and connected to a respective connector on base  114  is readily discernable by a user without the need to open the IED. A legend including the colors associated with each connector may be included on a surface of the IED. For example, in one embodiment, a legend may be included on sticker  151  disposed on upper clam shell half  150  or on sticker  153  disposed on lower clam shell half  152  (as seen in  FIG.  10   ). The legend may include various colors assigned to the different cards/modules that can be included in the IED. For example, in one embodiment, the legend may have the color white associated with an 100 Base T Ethernet card, the color green associated with an IEC 61850 protocol Ethernet card, the color yellow associated with the four channel bi-directional 0-1 mA output card, the color black associated with the four channel 4-20 mA output card, and the color grey associated with RS-485/KYZ card. It is to be appreciated that the legend may also include colors associated to one of two ports of a card (i.e., input or output) for cards that are connected to two different connectors on base  114 . For example, in one embodiment the legend may have the color pink associated with the input of the four pulse output/four status input card, the color blue with the output of the four pulse output/four status input card, the color brown associated with the input of the two relay output/two status input card (e.g., card  334  in  FIG.  26   ), and the color purple associated with the output of the two relay output/two status input card. It is to be appreciated that the above described color associations are merely exemplary and that any color association can be used to indicate which connector coupled to base  114  is associated to a specific card/module of the IED. 
     Referring to  FIGS.  20 B and  20 C , perspective views of front side  275  and rear side  271  of filter box cover  274  are shown in accordance with the present disclosure. As stated above, filter box cover  274  is configured to protect filter board  264  and to facilitate the routing of wires from connectors coupled to base  114  to other portions of the IED. Filter box cover  274  includes a plurality of clips  284  that enable the filter box cover  274  to be snapped onto the filter board  264 . When filter box cover  274  is coupled to the filter board  264 , filter board  264  is disposed in the interior  277  of filter box cover  274  and is protected. Filter box cover  274  also includes a plurality of louver  282  to facilitate the dissipation of heat generated by filter board  264  and other components of the IED. 
     Additionally, in one embodiment, filter box cover  274  includes apertures  279 ,  286 , and  288 , where apertures  286  and  288  can also be seen in  FIGS.  20 A and  23   . Aperture  279  is configured to provide an opening or path for cable  386  (as seen in  FIGS.  6 ,  12 ,  13 ,  14 , and  24   ) which couples filter board  264  to receptacle  344  when filter board  264  is disposed in the interior of filter box cover  274  and filter box cover  274  is coupled to base  114 . Aperture  286  is configured to receive and pass through a cable coupled to one of rear portion  299  of connector  298  or rear portion  301  of connector  300  and a connector (such as connector  336  or connector  338 ) coupled to a card (such as card  320  or card  322 ) disposed in one of slots  324  and  326 . Aperture  288  is configured to receive and pass through a cable coupled to one of rear portion  295  of connector  296  and rear portion  293  of connector  294  and a connector (such as connector  336  or connector  338 ) coupled to a card (such as card  320  or card  322 ) disposed in one of slots  324  and  326 . 
     As described above, voltage sensed by each voltage input blade  250  is provided to the filter board  264  which subsequently provides power to other portions of the IED and at least one signal indicative of the voltage sensed from the electrical distribution system via cable  286  and connector  268 . Referring to  FIG.  27 A , a top surface  360  of the filter board  264  is illustrated, while  FIG.  27 B  illustrates the bottom surface  278  of the filter board  264 . The bottom surface  278  of the filter board  264  includes at least one contact pad  362 ,  364 ,  366 ,  368  that is coupled to a corresponding voltage input  276 , as shown in  FIGS.  18  and  19   . The sensed voltage is then passed through the various components of the IED to provide a sensed voltage for example, for each phase of an electrical distribution system, and provide power as will be described in relation to  FIG.  29   . 
     The sensed voltage for each phase is provided by a contact point on the top surface  360  of the filter board  264 . Referring to  FIG.  27 A , contact point  370  provides sensed voltage for phase A, contact point  372  provides sensed voltage for phase B, contact point  374  provides sensed voltage for phase C, and contact point  376  provides sensed voltage for neutral. Additionally, power is provided through contact point  378  for DC+, contact point  380  for DC− and contact point  382  for ground. Referring to  FIG.  28   , a filter board assembly  384  includes the filter board  264 , a wiring harness or cable  386  and connector  268 .  FIG.  28    illustrates the wiring between the filter board  264  and connector  268  as indicated by legend  388 . The sensed voltage for each phase and power for various components of the IED are transmitted from the filter board  264  via cable  386  to the VIP board  212 . In certain embodiments, the sensed voltage for each phase may be further transmitted to the DSP board  210  for further processing. It is to be appreciated that the wiring harness or cable  386  may include a twisted pair connection to reduce noise and prevent other interfering signals from being wrongfully coupled to the wiring harness or cable  268 . In other embodiment, the wiring harness or cable  268  may be enclosed by a ferrite bead noise reduction filter to limit an amount of conducted and radiated noise being emitted from the IED. 
     Referring to  FIG.  29   , an electrical schematic diagram of the filter board circuit in accordance with an embodiment of the present disclosure is provided. It is to be appreciated that similar reference numbers and/or labels (e.g., D 1  for diode, R 1  for resistor) shown in  FIG.  29    correspond to reference numbers and/or labels on the filter board  264  shown in  FIGS.  27 A and  27 B . Voltage is sensed, via input voltage blades  250 , and input to the circuit  390  at contact pads  362 ,  364 ,  366 ,  368 . The input voltage initially passes through a current limiting section  392  where a current limiting resistor R 1 , R 2 , R 3 , R 4 , is coupled in series with each voltage input. The output of the current limiting resistors R 1 , R 2 , R 3 , R 4  is transmitted to a rectifier section  394 . A suppressor section  396  is coupled in parallel to the transmission paths between the current limiting section  392  and rectifier section  394 . The suppressor section  396  includes at least one at capacitor and at least one metal oxide varistor (MOV) coupled in parallel with each voltage input path. For example, the voltage input path for phase A  398  includes a series combination of capacitors C 1 , C 14  in parallel with path  398  and one metal oxide varistor MOV 1  coupled in parallel with the path  398 ; the voltage input path for phase B  400  includes a series combination of capacitors C 2 , C 15  in parallel with path  400  and one metal oxide varistor MOV 2  coupled in parallel with the path  400 ; the voltage input path for phase C  402  includes a series combination of capacitors C 3 , C 16  in parallel with path  402  and one metal oxide varistor MOV 3  coupled in parallel with the path  402 ; and the voltage input path for neutral  404  includes a series combination of capacitors C 4 , C 17  in parallel with path  404  and one metal oxide varistor MOV 4  coupled in parallel with the path  404 . Capacitors C 1 -C 4 , C 14 -C 17  are provided for suppressing noise. The metal oxide varistors MOV 1 , MOV 2 , MOV 3 , MOV 4  clamp the input voltage to prevent an over-voltage surge condition between each phase which may result in damage to the rectifier section  394  or other components thereafter. The values of the metal oxide varistors MOV 1 , MOV 2 , MOV 3 , MOV 4  shown in  FIG.  29    are exemplary values and are chosen based on the ratings of the components of the rectifier section  394  and components thereafter. Additionally, a common mode clamping device  406 , e.g., a gas tube, is provided for clamping the voltage between any sensed phase and earth potential. Resistor (R 6 )  407  is provided in series with clamping device  406  to reduce current flow through clamping device  406  thereby extending the useful life of clamping device  406  and other components in the circuit. By employing earth potential as the reference for each phase provides for a safer environment as compared to conventional IEDs or meters that employ neutral as the reference. 
     It is to be appreciated that the current limiting resistors R 1 , R 2 , R 3 , R 4  and resistor R 6   407  limit the amount of current passing through the metal oxide varistors MOV 1 , MOV 2 , MOV 3 , MOV 4  and clamping device  406  to prevent damage to the metal oxide varistors MOV 1 , MOV 2 , MOV 3 , MOV 4  and clamping device  406  and lengthen their lifetime. 
     The rectifier section  394  receives AC voltage as sensed by the voltage input blades and converts the AC voltage to a DC voltage. The DC voltage is then passed to the common mode choke or filter  408 , e.g., an inductor, to prevent electromagnetic interference (EMI) and radio frequency interference (RFI) on the power supply lines. The DC voltage is then passed to buffer  410  for storing energy to be supplied via DC+  378  and DC−  380 . The buffer  410  includes capacitors C 5 , C 6 , C 7 , C 8  and resistors R 5 , R 8 . An additional noise suppression section  412  is optionally provided at the output including capacitors C 9 , C 11 , C 12 , C 13 . 
     In another embodiment, voltage used for supplying power to the various components of the IED may be supplied via an auxiliary power source, e.g., coupled to auxiliary connector  302  as shown in  FIG.  22   . In this embodiment, sensed voltage via pads  362 ,  364 ,  366 ,  368  is provided to the VIP board  212  for determining the respective voltages of the electrical distribution system and components R 1 , R 2 , R 3 , R 4  are removed so the sensed voltage does not pass to the rectifier section  394 . Auxiliary power provided via connector  302  is coupled to contact point  414  (VCMID) and contact point  416  (VNMID) which is then passed to rectifier section  394 . In this embodiment, only portion  418  of suppression section  396  is employed and components C 1 , C 14 , MOV 1 , C 2 , C 15  and MOV 2  may be removed. The remaining circuit operates as described above. 
     It is to be appreciated that the filter board  264  provides full surge supression at transient voltage conditions, i.e., the filter board  264  snubs transient voltage events that traditionally damage conventional meters and thus improves reliability of meters/IEDs utilizing the filter board  264  of the present disclosure. That is, the metal oxide varistors MOV 1 , MOV 2 , MOV 3 , MOV 4  suppress phase-to-phase voltage transients, while the clamping device  406  suppresses phase-to-earth voltage transients. It is further to be appreciated that line surge suppression is not found in revenue meters or revenue IEDs, and therefore, it is envisioned that other forms of line surge suppression may be designed and that such line surge suppression techniques are contemplated to be within the scope of the present disclosure. 
     Referring to  FIG.  30   , an electrical schematic diagram of a battery backup circuit  500  in accordance with an embodiment of the present disclosure is provided. The circuit  500  includes a real-time clock (RTC)  502  that generates a clock signal that may be used by CPU  50  to determine an amount of energy cosumed by a load over a given period of time, e.g., revenue metering. Under normal operating conditions, the RTC  502  is powered via pin  4  (i.e., input VCC), where pin  4  receives a predetermined voltage, e.g., 3.3 volts, from a power supply which may be powered by filter board circuit  390 . Upon a loss of power provided to pin  4  of RTC  502 , a battery  504  provides power to the RTC  502  via pin  16  (i.e., inout VBAT) so the RTC  502  maintains proper time. It is to be appreciated that battery  504  is battery  230  shown in  FIG.  16   . By employing circuit  500  as configured in  FIG.  30   , the battery  504  may be removed and replaced without powering down the IED  100  and/or the RTC  502 , i.e., the IED  100  may remain in service while the battery is being replaced. 
     Additionally, the circuit  500  includes a battery detection circuit, e.g., comparator  506 , that compares a voltage level of battery  504  with a predetermined voltage level, e.g., 3.3 volts, to generate a signal indicating that the battery  504  needs to be replaced. The predetermined voltage is input to pin  5  (i.e., input VCC) of comparator  506 . Pin  3  of the comparator (i.e., input INP) is in parallel with the battery  504 . When the comparator  506  determines that the voltage at pin  3  is below the predetermined voltage applied to pin  5 , the comparator  506  generates a signal  508  (i.e., BATTMONITOR) indicating that the battery  504  needs to be replaced. It is to be appreciated that the comparator  506  may include an offset before generating the signal  508 , i.e., may not generate the signal  508  until the voltage at pin  3  is below the predetermined voltage minus the offset. The replace battery signal  508  may then be transmitted to the CPU  50  which then provides an indication of same on the display  106 . A user may then replace the battery as described above in relation to  FIGS.  15  and  16   . 
     It is to be appreciated that the various features shown and described are interchangeable, that is a feature shown in one embodiment may be incorporated into another embodiment. 
     While non-limiting embodiments are disclosed herein, many variations are possible which remain within the concept and scope of the present disclosure. Such variations would become clear to one of ordinary skill in the art after inspection of the specification, drawings and claims herein. The present disclosure therefore is not to be restricted except within the spirit and scope of the appended claims. 
     Furthermore, although the foregoing text sets forth a detailed description of numerous embodiments, it should be understood that the legal scope of the present disclosure is defined by the words of the claims set forth at the end of this patent. The detailed description is to be construed as exemplary only and does not describe every possible embodiment, as describing every possible embodiment would be impractical, if not impossible. One could implement numerous alternate embodiments, using either current technology or technology developed after the filing date of this patent, which would still fall within the scope of the claims. 
     It should also be understood that, unless a term is expressly defined in this patent using the sentence “As used herein, the term ‘______’ is hereby defined to mean . . . ” or a similar sentence, there is no intent to limit the meaning of that term, either expressly or by implication, beyond its plain or ordinary meaning, and such term should not be interpreted to be limited in scope based on any statement made in any section of this patent (other than the language of the claims). To the extent that any term recited in the claims at the end of this patent is referred to in this patent in a manner consistent with a single meaning, that is done for sake of clarity only so as to not confuse the reader, and it is not intended that such claim term be limited, by implication or otherwise, to that single meaning. Finally, unless a claim element is defined by reciting the word “means” and a function without the recital of any structure, it is not intended that the scope of any claim element be interpreted based on the application of 35 U.S.C. § 112, sixth paragraph.