THERMAL EXTENSION STRUCTURES FOR MONITORING BUS BAR TERMINATIONS

Abstract

An electrical system comprising an equipment enclosure configured to hold one or more DC power bus bars therein. The system also comprises one or more thermal extension structures. Each thermal extension structure is connected to one or more of the bus bars. Each thermal extension structure has a projection element whose thermal state reflects an electrical connectivity of the one or more DC power bus bars that the thermal extension structure is connected to. The projection element is viewable from a location outside of the equipment enclosure.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser. No. 61/308,215, filed on Feb. 25, 2010, to Edward C. Fontana, et al. entitled, “POWER DISTRIBUTION PLATFORM;” Provisional Application Ser. No. 61/287,322, filed on Dec. 17, 2009, to Roy Davis, et al. entitled, “HYBRID ARCHITECTURE FOR DC POWER PLANTS;” and Provisional Application Ser. No. 61/287,057, to filed on Dec. 16, 2009 to Edward C. Fontana, et al. entitled, “A FLOOR MOUNTED DC POWER DISTRIBUTION SYSTEM,” which are all commonly assigned with this application and incorporated herein by reference in their entirety.

TECHNICAL FIELD

This application is directed, in general, to electrical systems and, more specifically, to a thermal extension of the system, and, methods of using the thermal extension to monitor bus bar terminations of the system.

BACKGROUND

This section introduces aspects that may be helpful to facilitating a better understanding of the inventions. Accordingly, the statements of this section are to be read in this light. The statements of this section are not to be understood as admissions about what is in the prior art or what is not in the prior art.

Telecommunication sites are evolving into large data centers, making extensive use of many similar configurations of server equipment. The Green Grid consortium has suggested that 48VDC is the most efficient and cost effective way to power such equipment, and, provide the highest availability and reliability of reserve power in case of utility grid failure.

There is a long-felt need to more efficiently install and distribute reliable DC power to server equipment at reduced labor and material costs.

SUMMARY

One embodiment provides an electrical system. The system comprises an equipment enclosure configured to hold one or more DC power bus bars therein. The system also comprises one or more thermal extension structures, each thermal extension structure connected to one or more of the bus bars. Each thermal extension structure has a projection element whose thermal state reflects an electrical connectivity of the one or more bus bars that the thermal extension structure is connected to. The projection element is viewable from a location outside of the equipment enclosure.

Another embodiment provides a method of measuring the electrical connectivity of the one or more DC power bus bars of the above-described electrical system. The method comprises passing a direct current through at least one of the bus bars and measuring the thermal state of the projection element.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the disclosure are better understood from the following detailed description, when read with the accompanying FIGUREs. Corresponding or like numbers or characters indicate corresponding or like structures. Various features may not be drawn to scale and may be arbitrarily increased or reduced in size for clarity of discussion. Reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

FIG. 1 shows a perspective view of an example embodiment of an electrical system of the disclosure;

FIG. 2 shows a plan view of the example system of FIG. 1 through view line 2-2 in FIG. 1;

FIG. 3a presents a cross-sectional view of an example system corresponding to view 3a-3a in FIG. 2;

FIG. 3b presents a cross-sectional view of an example system corresponding to view 3b-3b in FIG. 2; and

FIG. 4 presents a flow diagram of an example embodiment of a method measuring the electrical connectivity of a bus bar of an electrical system of the disclosure, such as any of the example systems depicted in FIGS. 1-3b.

DETAILED DESCRIPTION

The following merely illustrate principles of the invention. Those skilled in the art will appreciate the ability to devise various arrangements which, although not explicitly described or shown herein, embody the principles of the invention and are included within its scope. Furthermore, all examples and conditional language recited herein are principally intended expressly to be only for pedagogical purposes to aid in understanding the principles of the invention and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to specifically disclosed embodiments and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass equivalents thereof. Additionally, the term, “or,” as used herein, refers to a non-exclusive or, unless otherwise indicated. Also, the various embodiments described herein are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments.

DC distribution and installation practices can use multiple DC bus bars held inside of an enclosing structure. The bus bars can be interconnected to each other, or to other electrical components (e.g., server equipment) of the electrical system, using terminations. The terminations, however, can loosen and thereby negatively impact the reliable delivery of DC power distribution by compromising the electrical connectivity of the bus bars to other bus bars or electrical components of the system. Therefore, to ensure the reliable delivery of power through the bus bars, it is desirable to periodically inspect the terminations and refasten the termination if the termination has loosened.

When a bus bar is powered, terminations that work loose produce heat, and this heat can be identified using thermal imaging technology deployed outside of the enclosure. However, assembly and electrical connectivity efficiency constraints may not allow the actual termination to be viewable from outside of the enclosure. This, in turn, can increase the labor costs for performing the appropriate inspection and maintenance of the terminations and bus bars. As part of the present disclosure, it was discovered that thermal extensions can be fastened to bus bars such that the thermal state of the bus bar, and hence its electrical connectivity, can be more readily assessed from outside of the enclosure.

One embodiment of the disclosure is an electrical system. FIG. 1 shows a perspective view of an example embodiment of the electrical system 100. FIG. 2 shows a plan view of the system 100 through view line 2-2 in FIG. 1. FIG. 3a presents a cross-sectional view of an example system corresponding to view 3a-3a in FIG. 2 and FIG. 3b presents a cross-sectional view of an example system corresponding to view 3b-3b in FIG. 2.

In some preferred embodiments, the electrical system 100 is a power distribution system. However, the electrical system could be, or include, other electrical systems that have bus bars and terminations, which can loosen, and thereby compromise the electrical connectivity of the bus bar.

The system 100 comprises an equipment enclosure 105 configured to hold one or more DC power bus bars 110 therein. The system 100 also comprises one or more thermal extension structure 115, each being connected to one of the bus bars 110. Each of the thermal extension structures 115 have a projection element 117 whose thermal state reflects an electrical connectivity of the bus bars 110 that the thermal extension structure 115 is connected to. The projection element 117 is viewable from a location 120 outside of the equipment enclosure 105,

The equipment enclosure 105 can be, or include, a cabinet 122 and/or power distribution platform 124. For example, the equipment enclosure 105 can include a platform 124 and at least one cabinet 122, the platform 124 being coupled to an end of the cabinet 122. For example, the platform 124 can hold the DC power bus bars 110 and thermal extension structures 115 therein. For example, the cabinet 122 can hold electronic component modules 126 that are electrically coupled to the bus bars 110 via feed connections 127 (e.g., wires). The platform 124 can further include other structures such as receptacles 128 for over-current current protection devices 130, power tap bus bars 132, and electrical connection bus bars 134, spacer bus bars 305 (FIGS. 3a and 3b) and cabinet connection contacts 136.

Additional examples of cabinets or platforms configurations and other components suitable for embodiments of the electrical system 100 are provided in the above-identified provisional patent applications, as well as the following non-provisional patent applications: U.S. patent application Ser. No. ______ to Edward Fontana, Paul Smith and William England entitled, “A platform for a power distribution system”; U.S. patent application Ser. No. _______ to Edward Fontana, Paul Smith, William England and Richard Hock, entitled, “Stack of bus bars for a power distribution system”; U.S. patent application Ser. No. ______ to Edward Fontana, Paul Smith and William England, entitled, “A cabinet for a power distribution system”; U.S. patent application Ser. No. ______ to Edward Fontana, Paul Smith and Roy Davis entitled, “A cabinet for a high current power distribution system,” all of which are incorporated herein in their entirety.

The DC power bus bar 110 can be composed of any electrically conductive material and configured to have physical dimensions that preferably is suitable for carrying high direct currents (e.g., 80 Amps or greater in some cases). Individual bus bars 110 can be configured to deliver a direct current to at least one electronic component module 126 (e.g., telecommunication server equipment), over-current current protection devices 130, power tap bus bars 132 or electrical connection bus bars 134 of the system 100, or, to transfer the direct current to another DC power bus bar 110 of the system 100.

In some embodiments, as shown in FIG. 2, the location 120 outside of the equipment enclosure 105 can be a pre-designated monitoring site, such as an equipment aisle, situated outside of an outer perimeter 210 of the equipment enclosure 105 (e.g., the outer surfaces of the cabinet and/or platform). For example, the location 120 can be adjacent to an opening 140 in the equipment enclosure 105 that allows an unobstructed view of the projection element 117. In some preferred embodiments, the location 120 is situated such that the enclosure perimeter 210 does not need to be breached in order for the projection element 117 to be viewed. In other cases, however, a covering, door or wall panel of the equipment enclosure 105 can be opened or removed to provide the opening 140 through which the view of the projection element 117 from the location 120 is attained.

The term termination 145, as used herein, refers to any connecting structure that can attach the bus bar 110 to another bus bar or the other above-mentioned components of the system 100. Examples of terminations 145 include threaded fasteners such as bolt or threaded rod, and in some cases, includes a capping structure, such as a nut that screws onto the bolt or rod. Other types of terminations 145 that could be used would be apparent to one skilled in the art based upon the present disclosure.

In some preferred embodiments of the system 100, such as shown in FIG. 3a, the thermal extension structure 115 is connected to a termination 145 of one or more the bus bars 110 (e.g., a stack of bus bars 110). In some cases, connecting the thermal extension structure 115 directly to the termination 145 can advantageously provide a more sensitive indicator of a temperature change in the termination 145 than provided by a indirect connection.

In some cases, such as shown in FIG. 3b, the thermal extension structure 115 is connected to another electrical component of the system 100 that in turn is connected to the termination 145, and, the thermal extension structure 115 is located in a vicinity of the termination 145. For example as shown in FIG. 3b, the thermal extension structure can be connected to a power tap bus bar 132 of the system 100. The power tap bus bar 132 in turn can be connected to a termination 145 that is connected to one or more of the DC power bus bars 110.

Connecting the thermal extension structure 115 directly to the other electrical component (e.g., power tap bus bar 132) instead of directly to the termination 145 can be advantageous in situations where the projection element 117 would not otherwise be viewable from one of the locations 120, or, where there is insufficient space available in the enclosure 105 to accommodate a direct connection to the termination 145.

In such embodiments, the distance 220 separating the thermal extension structure 115 from the termination 145 can depend on a number of system-specific factors, such as the magnitude of temperature change in the termination 145 when loose, the heat transfer coefficients of the bus bar 110, the thermal extension structure 115, the termination 145 and the other electrical component, and, the sensitivity of heat measuring equipment (e.g., a heat imaging devices) deployed to monitor temperature changes in the projection element 117. For example, in some cases the thermal extension structure 115 can be separated from the termination 145 on the bus bar 110 by a distance 220 (FIG. 2) in a range from about 0.1 to 1 foot.

In some embodiments, the thermal extension structure 115 can be a continuous part of one of the DC power bus bars 110. For instance, one or more of the bus bars 110 can be formed, e.g., via a molding or machining step, so as to have a thermal extension structure that is an integral part of the material that the bar 110 is composed of. For instance, an end of one or more bus bar 110 can be formed to have an extension portion that corresponds to the thermal extension 115.

As shown in FIGS. 1-3b, some embodiments of the thermal extension structure 115 can advantageously include a mounting element 150 configured to facilitate attachment of the thermal extension structure 115 to a termination 145 or other electrical component of the system 100. In some embodiments, the projection element 117 and the mounting element 150 can be composed of the same continuous piece of material that was molded or machined into the desired shape of the elements 117, 150. As shown in FIG. 3a, some embodiments of the mounting element 150 are, or include, an opening 315 through which a portion of the termination 145 can pass. For instance, as shown in FIG. 3a, a bolt termination 145 can pass through an opening 315 of a mounting element 150 and through a termination hole 320 of at least one of the DC power bus bars 110 to thereby connect the thermal extension structure 115 to the bus bar 110. For example, the mounting element 150 can be configured as a rectangular plate, a washer or washer lock with an extension structure that corresponds to the projection element 117.

Other example embodiments of the mounting element 150 include clamps such as spring-loaded or screw-tightened clamps. For example, in some embodiments, where the thermal extension structure 115 is connected to another electrical component such as a power tap bus bar 132, the mounting element 150 can be or include a clamp that attaches, e.g., to the power tap bus bar 132. Still other embodiments of the mounting element 150 would be apparent to one skilled in the art based upon the present disclosure.

As further illustrated in FIGS. 1-3b, in some embodiments of the thermal extension structure 115, the projection element 117 extends to an outside surface 155 of the equipment enclosure 105. For example, as illustrated in FIG. 3b, the projection element 117 can be configured as a rod that extends from the mounting element 150 to the outside surface 155 of the platform 124 such that an end 330 of the mounting element 150 is substantially parallel with the outside surface 155. In such embodiments, the outside surface 155 of the equipment enclosure 105 can further includes an opening 335 through which the projection element's end 330 can extend to.

In other embodiments, however, the projection element 117 can be located inside of the equipment enclosure 105. In such embodiments, for instance, the outside surface 155 of the equipment enclosure 105 can again include an opening 337 through which a surface 340 of the projection element 117 can be viewed. In such embodiments, for instance, the projection element 117 can be configured such that the surface 340 of the element 117 is viewable from the location 120 outside of the equipment enclosure 105. For example, to facilitate making the surface 340 viewable from the location 120, the projection element 117 can have an oblique or perpendicular angle 345 with respect to a surface 350 of the component (e.g., a power tap bus bar 132 in FIG. 3a, or a bus bar 110) that the thermal extension structure 115 is connected to.

In some embodiments, the thermal state of the projection element 117 is signified by a temperature of the projection element 117. For instance, when it becomes loose, the termination 145 heats up and heat is transferred to the connected thermal extension structure 115, resulting in a temperature increase of the projection element 117, thereby signifying a change in thermal state. In various embodiments, the absolute temperature, or, a change in temperature, of the projection element 117 could be used as the thermal state indicator that, in turn, is indicative of a loss in the electrical connectivity of the DC power bus bar 110 to which the loose termination 145 is connected to. In other embodiments, the thermal state can be signified by a relative temperature of one projection element 117 (e.g., the projection element 117 shown in FIG. 3a) compared to a second projection element 117 (e.g., the projection element 117 shown in FIG. 3b) of a second thermal extension structure 115 that is connected to a second different bus bar 110 of the system 100. If one or more terminations 145 associated with the first bus bar 110 are loose and the terminations 145 associated with the second bus bar 110 are not loose, then thermal extension structure 115 that is connected to a first bus bar 110 will have a different thermal state (e.g., higher temperature) than the thermal extension structure 115 that is connected to a second bus bar 110.

The thermal state of the projection element 117 can be measured in a number of different fashions. For instance, and shown in FIG. 2, in some embodiments, the system 100 further includes including a heat imaging device 225 to provide a rapid and non-contact indicator of the thermal state of the element 117. The use of a heat imaging device 225 can help avoid electrocution hazards in cases where, e.g., the thermal extension 115 is electrically conductive and un-insulated. Examples of suitable heat imaging devices 225 include thermal imaging goggles or thermal imaging cameras. Some embodiments of the heat imaging device 225 can be configured to detect, and present in a heat image, the thermal state of the projection element 117. For instance, the thermal state of the projection element 117 can be presented as thermal image that highlights an elevated temperature, or changes in temperature, of a projection element 117 connected to a DC power bus bar 110 that has non-optimal electrical connectivity, e.g., due to a loose termination 145.

In other embodiments, to assess the thermal state of the projection element 117, the system 100 can further include a non-contact infrared thermometer 230 such as a laser-guided infrared thermometer. The use of a non-contact thermometer 230 can also help avoid electrocution hazards in cases similar to the heat imaging devices 225. The use of a non-contact thermometer 230 can also facilitate assessing the thermal state of the protection element 117 in cases where the element 117 is located deep inside of the enclosure 105 (e.g., such as shown in FIG. 3a).

In still other cases, however, the thermal state of the projection element 117 could be assessed using a contact temperature sensor, such as a resistance thermometer, or simply an inspector's finger to feel the heat or estimate the temperature of the element 117 in cases where the projection element 117 extends to the enclosure's outside surface 155.

In some embodiments, the thermal extension 115 can be composed of a material that is thermally conductive and electrically insulating. Having the thermal extension 115 composed of such material can help avoid electrocution hazards, e.g., when the projection element 117 extends to the enclosure's outside surface 155. Examples of such materials include ceramic material such as silica or electrically conductive heat conductors (e.g., metal particles) embedded in an insulating matrix such as rubbers or non-conducting plastics (e.g., polyester or polyvinyl plastics). In some cases, the entire thermal extension 115 can be composed of the thermally conductive and electrically insulating material. In other cases only the projection element 117 is composed of the thermally conductive and electrically insulating material. In still other cases, the thermal extension structure 115 can include an electrically conductive metal core (e.g., aluminum) that is coated with an electrically insulating layer such as a rubber or non-conducting plastics, paint or tape layer.

Another embodiment of the disclosure is a method of measuring the electrical connectivity of a DC power bus bar 110 of the electrical system 100. For example, the method can be performed on any of the systems 100 and use any of the components discussed in the context of FIGS. 1-3 herein.

FIG. 4 presents a flow diagram of an example embodiment of selected steps in the method 400 of measuring the DC power bus bar's 110 electrical connectivity. With continuing reference to FIGS. 1-3b, the method 400 comprises a step 405 of passing a direct current (e.g., 80 Amps or higher) through the DC power bus bar 110, and, a step 410 of measuring the thermal state of the projection element 117.

Some preferred embodiments of measuring the thermal state in step 410 can include a step 415 of measuring black-body radiation emitted by the projection element 117. For instance, the heat imaging device 225 or non-contact infrared thermometer 230 can be used to measure infrared radiation emitted by the projection element 117 as part of step 415.

Some embodiments of the method 400 further include a step 420 comparing the thermal state of the projection element 117 to a database to determine if the desired direct current is reliably passing through the bus bar 110. For instance, the database can include a collection of multiple measurements of a target direct current through the DC power bus bar 110 and a average or range of temperatures (or proxy for temperature) for the projection element 117, e.g., over a period of known normal operation of the system 100. The method 400 can include an alerting step 425 when an un-acceptable direct current is passing through the bus bar 110, if, in decision step 430, the thermal state is determined to be outside of an accepted thermal range (e.g., a measure temperature or temperature proxy exceed the average, or range, of a target temperature) provided by the database.

Although the embodiments have been described in detail, those of ordinary skill in the art should understand that they could make various changes, substitutions and alterations herein without departing from the scope of the disclosure.

Claims

1. An electrical system, comprising:

an equipment enclosure configured to hold one or more DC power bus bars therein; and

one or more thermal extension structures, each thermal extension structure connected to one or more of the bus bars, and each of the thermal extension structures having a projection element whose thermal state reflects an electrical connectivity of the one or more bus bars that the thermal extension structure is connected to, wherein the projection element is viewable from a location outside of the equipment enclosure.

2. The system of claim 1, wherein the electrical system is a power distribution system.

3. The system of claim 1, wherein the thermal extension structure is connected to a termination of the one or more DC power bus bars.

4. The system of claim 1, wherein the thermal extension structure is connected to an electrical component of the system that is connected to a termination of the one or more DC power bus bars and the thermal extension structure is located in a vicinity of the termination.

5. The system of claim 1, wherein the thermal extension structure is a continuous part of one of the DC power bus bars.

6. The system of claim 5, wherein the thermal extension structure includes a mounting element, the mounting element having an opening therein and a termination that passes through a termination hole of at least one of the DC power bus bars also passes through the opening thereby connecting the thermal extension to the DC power bus bar.

7. The system of claim 1, wherein the projection element extends to an outside surface of the equipment enclosure.

8. The system of claim 1, wherein the projection element is located inside of the equipment enclosure and includes a surface that is viewable from the location.

9. The system of claim 1, wherein an outside surface of the equipment enclosure further includes an opening through which the projection element can be viewed.

10. The system of claim 1, wherein the projection element has an oblique or perpendicular angle with respect to a mounting surface that the thermal extension structure is connected to.

11. The system of claim 1, wherein the equipment enclosure includes a platform and at least one cabinet, the platform being coupled to an end of the cabinet, the platform holding the DC power bus bars and the thermal extension structures therein, and, the cabinet holding electronic component modules that are electrically coupled to the one or more DC power bus bars.

12. The system of claim 1, wherein the thermal state of the projection element is signified by a temperature of the projection element.

13. The system of claim 1, wherein the thermal state of the projection element is signified by a relative temperature of the projection element as compared to a second projection element of a second thermal extension structure that is connected to a second DC power bus bar of the system.

14. The system of claim 1, further including a heat imaging device configured to detect the thermal state of the projection element.

15. The system of claim 1, further including a non-contact infrared thermometer configured to detect the thermal state of the projection element.

16. The power distribution system of claim 1, wherein the thermal extension structure is composed of a material that is thermally conductive and electrically insulating.

17. The power distribution system of claim 1, wherein the thermal extension structure includes an electrically conductive metal core that is coated with an electrically insulating layer.

18. A method of measuring the electrical connectivity of the one or more DC power bus bars of the electrical system of claim 1, comprising:

passing a direct current through at least one of the DC power bus bars; and

measuring the thermal state of the projection element.

19. The method of claim 18, wherein measuring the thermal state of the projection element includes measuring black-body radiation emitted by the projection element.

20. The method of claim 18, further including comparing the thermal state to a database to determine if the desired direct current is reliably passing through the bus bar.