Abstract:
An intelligent electronic device ( 100 ) for metering a characteristic of electricity that has a rear opening ( 214 ) and a side opening ( 216 ) in a housing of the device for accepting a connector of an expansion module through one or the other opening. The device can be configured with an integrated display module ( 120 ) that protrudes through a panel of an enclosure, and in this configuration, the expansion module connects to the device through the rear opening of the housing. The device can also be configured to be mounted on a DIN rail, and in this configuration, the expansion module connects through the side opening of the housing. The same module can be used in either configuration, without requiring that different versions of the module be made for the different configurations and without having to mount the device in an awkward orientation that makes it difficult to access external connections around the housing.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is the U.S. National Phase Application under 35 U.S.C. §371 of International Application No. PCT/US2012/057910, filed Sep. 28, 2012. This prior application is incorporated by reference herein in its entirety. 
     FIELD OF THE INVENTION 
     The present disclosure relates generally to intelligent electronic devices (IEDs), and more particularly, to power meters configured for attaching expansion modules on the side or the rear of the base IED unit. 
     BACKGROUND 
     A basic functionality of a power meter is to measure one or more characteristics of electricity, such as current or voltage. A power meter can be attached to a DIN rail or mounted through a cutout to a door of an electrical panel enclosure for power monitoring equipment. A power meter can conventionally include connectors accessible from a rear of the housing for making connections to the power meter, including power supply, I/O, voltage inputs, current inputs, and communications. In addition, certain base power meter units include an expansion connector accessible through the housing of the base unit for connecting expansion modules that enhance or supplement the standard functionality of the power meter. These expansion modules have a separate housing from the base power meter unit and are connected to the expansion connector through the housing of the base power meter unit. When the base power meter unit has a DIN 96 format, the expansion modules are connected to the back of the power meter unit when it is installed through a door panel. However, when an end-user wishes to install the same power meter unit on a DIN rail and leave open the option for future expansion, the base unit must be rotated on its side 90 degrees to allow expansion modules to be compatible with the DIN rail. As a result, the connectors are rotated on their side, and the safety and informational labels on the housing of the base unit are also rotated on the side, making it difficult to access to the connectors with a screwdriver, for example, or to read the labels. 
     What is needed is a new solution that does not require the base power meter unit to be rotated when mounted to a DIN rail or through a door panel yet allows the connectors to be easily accessible and the safety and informational text on the labels on the housing of the base unit to be readable right-side up regardless of how the base unit is installed. 
     SUMMARY 
     According to an aspect of the present disclosure, an intelligent electronic device (IED) for measuring a characteristic of electricity is disclosed. The IED includes: a housing of a base unit having a front, a rear, and a first side opposite a second side connected to the front and to the back, the housing defining an interior volume and including therein a sensor configured to sense a characteristic of electricity, the rear of the housing including a rear opening through which a first connector is accessed when present in the housing, the first connector for connecting to a corresponding connector of an expansion module of a type when mounted to the base unit, and the first side of the housing including a side opening through which a second connector is accessed when present in the housing, the second connector for connecting to the corresponding connector of the expansion module of the same type when mounted to the base unit. 
     The front can include a DIN slot configured to engage a DIN rail. The IED can further include a cover positioned on the rear to completely cover the rear opening. The front can include a display connector configured to receive a corresponding connector of a display module that has a display module housing and a video display device. The front can further include at least one display mount configured to secure the display module to the base unit, causing the display connector to mechanically and electrically couple to the corresponding connector of the display module. 
     A label can be affixed to the first side to completely cover the side opening. The housing can include a top opposite a bottom, and wherein the rear opening is located a first distance from the first side and a second distance from the top. The side opening can be located the first distance from the rear and the second distance from the top, such that the corresponding connector of the expansion module, when connected to the base unit, connects to the second connector through the side opening in a side configuration or to the first connection through the rear opening in a rear configuration. 
     The expansion module can be rotated in two directions about two different axes to switch between being connected to the first side and to the rear of the base unit. The IED can further include a backplane in the housing proximate the rear of the base unit. The backplane can include the first electrical connector having a female receptacle that is positioned to coincide with the rear opening. The backplane can include the second electrical connector having a female receptacle that is positioned to coincide with the side opening. 
     An overall height and an overall width dimension of the expansion module does not have to exceed a corresponding overall height and overall width dimension of the base unit or an overall depth and overall height dimension of the base unit. The housing can include at least two pieces, where each of the side opening and the rear opening spans across the at least two pieces of the housing. 
     The housing can include a top opposite a bottom, and the IED can further include connectors accessible from the top and the bottom of the housing. The connectors can include one or more of a current input connector for receiving one or more current inputs carrying a current sensed by the sensor, a voltage input connector for receiving one or more voltage inputs providing a voltage sensed by the sensor, a data connector for receiving input and output signals between the device and an external system external to the device, a power supply connector supplying power signals for powering electronic components of the device including, or a communications connector configured to carry communication signals to a remote monitoring and control system or to another device. The IED can be a meter device. 
     The first and second connectors can be of the same type and have the same or different mating arrangement. The side opening and the rear opening can have the same dimensions. 
     The corresponding connector of the expansion module, when the expansion module is mounted to the base unit, can be configured to be connected to either the first connector through the side opening or to the second connector through the rear opening. 
     According to another aspect of the present disclosure, a method of assembling an intelligent electronic device (IED) for measuring a characteristic of electricity is disclosed. The method includes the steps of: providing a first housing having a back opening in a back of the first housing and a second housing having a side opening in a side of the second housing; selecting the first housing or the second housing based on an installation configuration of the IED, the installation configuration being selected from the group consisting of (a) installing the meter device through a panel and (b) mounting the IED to a DIN rail along a second side opposite the side through which the side opening is provided; and responsive to the selecting, installing a sensor module into the selected housing to form the IED, the sensor module including a sensor configured to sense a characteristic of electricity. 
     The method can further include: in either order, rotating an expansion module about a first axis extending between a top and a bottom of the IED and rotating the expansion module about a second axis extending between opposite sides of the IED, so as to permit the expansion module to be connected to the sensor module through the back opening or through the side opening. 
     The method can further include rotating an expansion module about at least one axis so as to permit the expansion module to be connected to the sensor module through the back opening or through the side opening following the rotation. 
     The foregoing and additional aspects of the present disclosure will be apparent to those of ordinary skill in the art in view of the detailed description of various aspects, which are made with reference to the drawings, a brief description of which is provided next. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other advantages of the present disclosure will become apparent upon reading the following detailed description and upon reference to the drawings. 
         FIG. 1  is a functional block diagram of an intelligent electronic device (IED) having a housing that can accept a separately housed expansion module along at least two distinct surfaces of the housing; 
         FIG. 2  is a perspective rear view of an intelligent electronic device, such as the IED shown in  FIG. 1 , having an integrated display module and an opening in a rear of its housing for accepting a connector from an expansion module; 
         FIG. 3  is a perspective rear view of a DIN-mounted IED, such as the IED shown in  FIG. 1 , having an opening in a side of its housing for accepting the same connector from the same expansion module; 
         FIG. 4  is a perspective rear view of part of an IED, such as the IED shown in  FIG. 2  or  FIG. 3 , showing a rear opening and a side opening with labels in exploded view that can be placed over the respective openings depending on the configuration of the IED; 
         FIG. 5  is an exploded perspective front view of the IED shown in  FIG. 2  showing how the display module is installed through a panel door of an enclosure; 
         FIG. 6  is an exploded view of various components that can be selected for the IED in different configurations; and 
         FIG. 7  illustrates a sequence of how an expansion module can be rotated twice about two axes to change its connection between the rear of the housing of the IED and its side. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a functional block diagram of an intelligent electronic device (IED)  100 , such as a meter device, is shown. The meter device includes a base unit  102  and one or more expansion modules  104   a ,  104   b ,  104   c ,  104   d  (generally designated as  104 ). The base unit  102  includes a sensor  106 , which can include one or more sensors each configured to sense a characteristic of electricity, such as current or voltage. The base unit  102  further includes a controller  110 . The electronic components in the base unit  102  can be provided on one or more printed circuit boards or backplanes. The controller  110  is coupled to a number of interfaces that allow communication with various systems external to the base unit  102 . For example, the controller  110  can be coupled to a communications interface  108  that is coupled to a power monitoring and control system  130  that is external and remote from the IED  100 . The communications interface  108  can include an electrical port, such as an RS485 port, for receiving an RS485 plug connector. The controller  110  is coupled to a first connector interface  112  and optionally to a second connector interface  114 . The first connector interface  112  can include a first connector, such as described below in connection with  FIG. 2 . The second connector interface  114  can include a second connector, such as described below in connection with  FIG. 2 . A connector interface, as used herein, can be an opening dimensioned to receive a connector or plug therethrough. Alternately, a connector interface can include a connector or a plug (such as of the male or female type) or an outlet or a port. Connectors of the same “type” as used herein can have the same or different mating arrangement (e.g., both can be male or both can be female or one can be male and the other female and still be of the same “type”) and the same or different orientation (e.g., right-angle orientation or straight orientation). The term “type” can encompass the number of pins and the form factor of the connector. Alternately, the connectors of the same “type” can have the same trade designation or nomenclature as used and understood by those of ordinary skill in the art to which the present disclosure pertains, such as “USB,” “DB-25,” or “RJ45,” to name a few examples. Likewise, any of the expansion modules  104  can be of the same type and used in either orientation as disclosed herein. By the same type, it is meant that the expansion module  104  has the same physical form factor and optionally the same functionality. 
     The controller  110  can also be coupled to a display interface  116  that can include a display port or connector for receiving a corresponding display connector or plug  118  from an integrated display module  120 . The integrated display module  120  includes at least one display mount configured to secure the integrated display module  120  to the base unit  102 . By “integrated” it is meant that the display module  120  is attached to the base unit  102  through the connectors  118 ,  120  and the display mount(s) and thereby forms an integrated piece. 
     The base unit  102  can be configured to be mounted on a DIN rail, such as shown in  FIG. 3 , or through a cutout  280  in a door panel  282 , such as shown in  FIG. 5 . For convenience, the former configuration shall be referred to herein as a DIN-mounted configuration, whereas the latter configuration shall be referred to herein as an integrated configuration (integrated referring to the integrated display module  120  that can be attached to the base unit  102 ). When the base unit  102  is configured in the DIN-mounted configuration, the controller  110  can be coupled to a remote display interface  122 , which is operatively coupled to a remote display unit  124  (shown in  FIG. 1 ). The remote display unit  124  is external to and remote from the base unit  102  and can display information from the base unit, such as information relating to the characteristic of electricity sensed by the sensor  106 . Any of the interfaces  108 ,  112 ,  114 ,  116 ,  122  can include a connector, a plug, a port, and can be configured to receive a corresponding connector, port, or plug from an external unit that is electrically coupled to the interface  108 ,  112 ,  114 ,  116 ,  122 . 
     The base unit  102  includes a housing, designated generally by 200, that is formed of one or more pieces  200   a ,  200   b ,  200   c  as shown in  FIG. 2 . The housing has a front  202 , a rear (or back)  204 , and a first side  206  opposite a second side  208 . The first and second sides  206 ,  208  are each connected to the front  202  and to the back  204 . The housing  200  defines an interior volume  210  (shown in  FIG. 5 ), which houses the sensor  106  configured to sense a characteristic of electricity, such as current or voltage. The rear (or back)  204  includes a rear opening (or back opening)  212  (shown in  FIG. 2 ) through which a first connector  214  of a type is accessed when present in the housing  200 . By “when present in the housing  200 ” it is meant that in some configurations, the first connector  214  is not present in the housing  200 , but the rear opening  212  is still provided. The first side  206  of the housing includes a side opening  216  through which a second connector  218  of the same type as the first connector  214  is accessed when present in the housing  200  (shown in  FIG. 3 ). As noted above, the housing  200  includes both the rear opening  212  and the side opening  216  (shown in  FIG. 4 ). Note that the side opening  216  can be formed in the second side  208  instead of in the first side  206 . Although the housing  200  example shown as illustrated is formed of three pieces  200   a ,  200   b ,  200   c , the housing  200  can alternately be formed from fewer or more pieces. The number of pieces of the housing is not a salient feature of aspects of the present disclosure. In the illustrated example, the side opening  216  and the rear opening  212  each spans across two pieces  200   a ,  200   b  of the housing  200  of the base unit  102 . 
     As mentioned above, there are two different configurations of the base unit  102  shown in the drawings: a DIN-mounted configuration shown in  FIG. 3 , and an integrated configuration shown in  FIG. 2 . The base unit is generally designated as  102 , and the DIN-mounted configured base unit is designated as  102   a , whereas the integrated configured base unit is designated as  102   b . Otherwise like reference numbers refer to like elements in the figures. Note that in the DIN-mounted configuration, the base unit  102   a  includes the second connector  218  and lacks a first connector  212  (see  FIG. 3 ), but in the integrated configuration, the base unit includes the first connector  212  but lacks the second connector  218  (see  FIG. 2 ). Alternately, in both configurations, both connectors  212 ,  218  can be present (e.g.,  FIG. 1 ). In both configurations, both rear and side openings  212 ,  216  are present in the housing  200  ( FIGS. 4, 6, 7 ). 
     As shown in  FIG. 3 , in the DIN-mounted configured base unit  102   a , the front  202   a  includes a DIN slot  220  configured to engage a DIN rail  222 . An optional cover, such as a label  224 , is affixed to or positioned on the rear  204  of the base unit  102   a  to completely cover the rear opening  212 . 
     As shown in  FIGS. 2 and 6 , in the integrated configured base unit  102   b , the front  202  includes a display connector  230  configured to receive a corresponding connector  232  of a display module  120  that has a display module housing  236  and a video display device  234 . The front  202  further includes at least one display mount  238  configured to secure the display module  102  to the base unit  102   b , causing the display connector  230  to mechanically and electrically couple to the corresponding connector  232  of the display module  102 . An optional label  240  is affixed to the first side  206  to completely cover the side opening  216 . As mentioned above, in the integrated configuration, the base unit  102   b  can lack the second connector  218  that is present in the DM-configured base unit  102   a.    
     The housing includes a top  242  opposite a bottom  244 . Note that the terms “front,” rear” or “back,” “side,” “top,” and “bottom” are not necessarily indicative of their orientation relative to gravity or earth but rather to differentiate the different surfaces of the housing from one another for ease of discussion. In some implementations, some or all of the adjacent surface pairs that form the housing of the base unit  102   a  or  102   b  (e.g., rear and either side, front and either side, top and either side, bottom and either side) can be perpendicular to one another. As shown in  FIG. 2 , the rear opening  212  is located a first distance d 1  from the first side  206  and a second distance d 2  from the top  242 . These measurements can be taken from the center of the rear opening  212 . The side opening  216  is located the first distance d 1  from the rear  204  and the second distance d 2  from the top  242 , such that a connector  250  of an expansion module  104 , when connected to the base unit  102 , connects to the second connector  218  through the side opening  216  in the DIN-mounted configuration or to the first connector  214  through the rear opening  212  in the integrated configuration. 
     The expansion module  104  is rotated in two directions about two different axes A, B to switch between being connected to the first side  206  and to the rear  204  of the base unit  102 , as can be seen in  FIG. 7 . The first axis A is taken through a center of the base unit  102  extending from the top  242  to the bottom  244  of the base unit  102 . The second axis B is taken through the expansion module  104 , when oriented and positioned to connect to the first connector  214  at the rear  204  of the base unit  102   b , along a line that extends through a center of the base unit  102  extending from the front  202  to the rear  204 . Starting from the integrated configuration where the expansion module  104  is positioned at the rear  204  of the base unit  102  (labeled as the reference number  104   a , though in  FIG. 4 , these reference numbers  104   a,b,c,d  refer to different orientations of the same expansion module  104 ), the expansion module  104  is rotated 90 degrees about axis A (compare orientation  104   a  with  104   c ), and rotated 180 degrees about axis B (in either order) (compare orientation  104   c  with  104   d ) to orient the expansion module  104  to connect to the first side  206  of the base unit  102 , all without rotating or turning the base unit  102 . Unlike in the prior art, the base unit  102  of the present disclosure can remain in the same orientation and position regardless of whether it is configured for DIN-rail mounting or through a door panel  282  with an integrated display  120 , and still allow one or more expansion modules  104  to be connected in a manner that permits the various interfaces to external components and systems to be readily accessible from the top  242  and bottom  244  of the housing  102 . 
     The housing  200  houses a backplane, generally designated as  246  in  FIG. 6 , proximate the rear  204  of the base unit  102 . The backplane  246   b  includes an electrical connector  248  having a female receptacle  250  that is positioned to coincide with the rear opening  212  when the backplane  246   b  is installed in the integrated base unit  102   b . The backplane  246   a  includes an electrical connector  252  (of the same type as the electrical connector  248 ) having a female receptacle  254  that is positioned to coincide with the side opening  216 . 
     An overall height H 1  and an overall width W 1  dimension (labeled in  FIG. 7 ) of the expansion module  104  does not exceed a corresponding overall height H 2  and overall width W 2  (labeled in  FIG. 2 ) dimension of the base unit  102  or an overall depth D (labeled in  FIG. 4 ) and overall height dimension H 2  (labeled in  FIG. 2 ) of the base unit  102 . 
     The base unit  102  has one or more connectors  260 ,  262 ,  264 ,  266 ,  268 ,  270 ,  272  accessible from the top  242  and the bottom  244  of the housing  200 , such as shown in  FIG. 3 . The connectors  260 ,  262 ,  264 ,  266 ,  268 ,  270 ,  272  including one or more of a current input connector for receiving one or more current inputs carrying a current sensed by the sensor, a voltage input connector for receiving one or more voltage inputs providing a voltage sensed by the sensor, a data connector for receiving input and output signals between the meter device and an external system external to the meter device, a power supply connector supplying power signals for powering electronic components of the meter device including, or a communications connector configured to carry communication signals to a remote monitoring and control system or to another meter device like the IED  100 . These connectors  260 ,  262 ,  264 ,  266 ,  268 ,  270 ,  272  can correspond to any of the interfaces  108 ,  112 ,  114 ,  116 ,  122  shown in  FIG. 1 . 
     Advantageously, the two different connector placements, either via the side opening  216  or the rear opening  212 , allow the reuse of the same body or housing  200  in multiple configurations, such as the DIN-mounted ( FIG. 3 ) and integrated configurations ( FIG. 2 ). Note that the aspects illustrated and described herein can be extended to more than two different connector placements for attaching expansion modules  104 , such as three or four, on different surfaces of the base unit  102  of the IED  100 . An IED  100  with six surfaces allows for up to six distinct connections on each of the six surfaces. Installation is significantly simplified, particularly in installations involving multiple configurations, reducing the installation time by the end-user. The labels  224 ,  240  can include safety or other information and can be affixed on the housing  200  so that any text or graphics will be right-side up with respect to a standing human observer when the IED  100  is installed in either configuration. The connectors to external components and systems, such as the connectors  260 ,  262 ,  264 ,  266 ,  268 ,  270 ,  272  can be easily accessed from a rear of the housing  200  in both configurations. Expansion modules  104  can be readily added to the rear  204  or to the side, such as the first side  206 , of the IED  100  by two simple rotations of the expansion module  104  and without requiring any rotation of the housing  200  (as seen in  FIG. 7 ). The electronic components inside the housing, with the exception of the connectors  214 ,  218 , can be reused in both configurations without having to design different internal circuits for different configurations. To keep costs low, the manufacturer can provide two different versions of the IED  100 , one with the connector  214  only and one with the connector  218  only. Alternately, the manufacturer of the IED  100  can provide both connectors  214 ,  218  in both configurations, allowing the customer to purchase the same IED  100  for either configuration without requiring the manufacturer to make two versions of the IED  100 . The same expansion modules  104  can be used in either configuration and can be stacked on behind another for infinite expansion of the standard capabilities of the IED. 
     While particular aspects and implementations of the present disclosure have been illustrated and described, it is to be understood that the present disclosure is not limited to the precise construction and compositions disclosed herein and that various modifications, changes, and variations are not only contemplated but also apparent from the foregoing descriptions without departing from the scope of the present disclosure as defined in the appended claims.