Thermochromic temperature indication for low pressure connections

Abstract

Indicator labels including thermochromic material are mounted in thermal contact with electrical components in the housing. An observation port in the cover of the housing is juxtaposed with the indicator label so that the thermochromic material indicating the temperature of the component can be visually observed. Each indicator label includes a visible portion located at one end of the arm and a fastening portion located at the other end, the fastening portion being in thermal contact with the component and the thermochromic material being located in the visible portion. The indicator label is composed of a material having a high thermal conductivity to effectively conduct heat toward the visible portion. In a housing where the components are closely together, the arms can be composed of a high resistivity material to avoid short circuits with other components. Alternatively, in a housing where the components are not closely positioned, the arms can be composed of a metallic material.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This international application is based on and claims priority from U.S. patent application serial number 16 / 426,752, filed on May 30, 2019, entitled “THERMOCHROMIC TEMPERATURE INDICATION FOR LOW VOLTAGE CONNECTIONS,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to thermal monitoring of electrical components in enclosures and, more particularly, to color changing materials that change color based on the temperature of the electrical components they contact. Background Art

[0004] Thermal monitoring is an important activity and part of many customers' routine preventive maintenance activities. A common method is to use IR scanning equipment to perform thermal monitoring on a regular basis. Open the electrical cabinet door and scan the equipment with an IR measurement tool to look for hot spots that need attention. Typically, IR scanning requires energizing the electrical device and generating heat, with the possibility of exposing live parts. Summary of the invention

[0005] According to one embodiment described herein, a thermal monitoring system is capable of passive thermal scanning of energized equipment from an observation point outside an electrical enclosure. The system is comprised of one or more indicator tags that contain a thermochromic material that changes color based on the temperature of an electrical component in thermal contact therewith. Each indicator tag includes an arm comprised of a material having a high thermal conductivity. A visible portion of the indicator tag located at one end of the arm includes the thermochromic material. A fastening portion of the indicator tag is located at an opposite end of the arm and in thermal contact with the electrical component within the enclosure. An observation port in the enclosure cover is juxtaposed with the visible portion of the indicator tag so that the color of the thermochromic material, which indicates the temperature of the electrical component, can be visually observed from outside the enclosure.

[0006] Each indicator tag is constructed of a material having a high thermal conductivity to effectively conduct heat from the fastening portion toward the visible portion of the indicator tag where the thermochromic material is located. When the indicator tag is used in an electrical enclosure where components are closely positioned, the arms can be constructed of a high resistivity material to prevent electrical shorts between the electrical component and other nearby electrical components. Alternatively, when the indicator tag is used in an electrical enclosure where components are not closely positioned, the arms can be constructed of a metallic material having a high thermal conductivity to effectively conduct heat from the fastening portion toward the visible portion of the indicator tag where the thermochromic material is located.

[0007] This embodiment enables personnel to quickly check the temperature of current carrying parts at any time without shutting down the equipment. The viewing port or viewing window of the housing enables visual observation of the color of the indicator label from outside the housing without exposure to hazardous live parts.

[0008] Example embodiments of indicator labels include:

[0009] an indicator label including an arm constructed of a material having a high thermal conductivity;

[0010] a visible portion of the indicator label on one end of the arm, the visible portion comprising a thermochromic material; and

[0011] A fastening portion of the indicator tag, located on the end of the arm opposite the visible portion, is in thermal contact with the electrical component, the temperature of the electrical component being indicated by the color of the thermochromic material of the visible portion.

[0012] Example embodiments of indicator labels observable from outside the housing include:

[0013] an indicator label including an arm constructed of a material having a high thermal conductivity;

[0014] a visible portion of the indicator label located on one end of the arm, the visible portion comprising a thermochromic material;

[0015] a fastening portion of the indicator tag on the end of the arm opposite the visible portion, the fastening portion being in thermal contact with an electrical component in the housing, the temperature of the component being indicated by the color of the thermochromic material of the visible portion; and

[0016] A viewing port in the cover of the housing, juxtaposed with the visible portion of the indicator label, enables visual observation of the color of the thermochromic material from the exterior of the housing. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] A more detailed description of the disclosure briefly summarized above can be obtained by reference to various embodiments, some of which are illustrated in the accompanying drawings. Although the drawings illustrate selected embodiments of the disclosure, these drawings are not to be considered limiting of its scope, as the disclosure may admit to other equally effective embodiments.

[0018] Figure 1 is a front view of the enclosure and its viewing port through which the color of the indicator label indicating the temperature of the electrical components within the enclosure can be seen.

[0019] Figure 2 yes Figure 1 Front perspective view of the enclosure with the indicator label viewed through the viewing port indicating the temperature of the electrical components within the enclosure.

[0020] Figure 3Ais a top view of a first embodiment of an indicator label.

[0021] Figure 3B yes Figure 3A A side view of a first embodiment of an indicator label showing it installed on an electrical component.

[0022] Figure 4A is a top view of a second embodiment of an indicator label having a coating of thermochromic material.

[0023] Figure 4B yes Figure 4A A side view of a second embodiment of an indicator label, shown mounted on an electrical component.

[0024] Wherever possible, identical reference numerals have been used to designate identical elements that are common to the figures. However, elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation. DETAILED DESCRIPTION

[0025] According to one embodiment described herein, the temperature of live components within an electrical enclosure can be safely monitored from outside the electrical enclosure through an observation port. The color of the indicator labels can be seen through the observation port, indicating the temperature of the electrical components they are in contact with within the enclosure. The indicator labels include a thermochromic material that changes color depending on the temperature of the electrical components with which they are in thermal contact. Each indicator label includes an arm constructed of a material having a high thermal conductivity. The visible portion of the indicator label located at one end of the arm includes the thermochromic material. The fastening portion of the indicator label is located at the opposite end of the arm and is in thermal contact with the electrical components within the enclosure. The observation port of the enclosure is juxtaposed with the visible portion of the indicator label so that the color of the thermochromic material, which indicates the temperature of the electrical components, can be visually observed from outside the enclosure.

[0026] Figure 1 1 is a front view of the housing 100 and its viewing port 120 through which the color of the indicator label 110 can be seen, which indicates the temperature of the electrical component 114 within the housing. As seen through the viewing port 120 in the housing, each indicator label 110 includes a thermochromic material 112 in thermal contact with the low voltage electrical component 114 in the housing 100. The application of the indicator label 110 for indicating the temperature of the electrical component 114 is for operating voltages that are generally in the range of less than 600 volts. The heat that increases the temperature of the electrical component 114 can be generated by resistive heating within the component, or it can be heat radiated or conducted from other nearby components.

[0027] A viewing port or window 120 in the cover 102 of the enclosure 100 is juxtaposed with the indicator label 110 to enable visual observation of the thermochromic material 112 from the exterior of the enclosure 100, thereby observing the color of the thermochromic material 112 indicating the temperature of the low voltage electrical component 114. A color scale 130 is located on the cover 102 to facilitate correlation of the observed color of the thermochromic material 112. The color scale represents temperatures that are considered to be "cold", "warm", "hot", and "caution" states of the low voltage electrical component 114. For example, a relative scale without actual temperature values ​​may be blue = 0-25%, yellow = 25-50%, orange = 50-75%, red = 75+%, where each value represents a percentage of the thermal limit of the monitored component.

[0028] Depending on the thermochromic material 112, the color change occurs at a specific temperature, which is called the thermochromic transition temperature. When the transition temperature is reached, the color change may occur rapidly. The transition temperature of most inorganic thermochromic materials is higher than the transition temperature of most organic thermochromic materials. In order to monitor the higher temperatures of electrical components, inorganic thermochromic materials may be preferred.

[0029] Figure 2 yes Figure 1 1, a front perspective view of an enclosure 100, with an indicator label 110 seen through a viewing port 120 indicating the temperature of an electrical component 114 within the enclosure. The indicator label 110 includes a thermochromic material 112 in thermal contact with the electrical component 114 in the enclosure 100. The enclosure 100 may be a safety switch, a load center enclosure, an HVAC cabinet, an industrial control panel, an enclosed motor control device, an electrical transformer cabinet, etc. The viewing port 120 is located in a cover 102 of such an enclosure 100, juxtaposed with a visible portion of the indicator label 110 so that the color of the thermochromic material, which indicates the temperature of the electrical component 114, can be visually observed from the exterior of the enclosure 100.

[0030] Figure 3A 1 is a top view of a first embodiment of an indicator tag 110. The indicator tag 110 includes a visible portion 116, which may have a generally circular shape at one end of an arm 118. The visible portion 116 may have other shapes, such as a square, rectangular, or other polygonal shape configured to be sufficiently visible through a viewing port to indicate the temperature of the electrical component. The visible portion 116 includes a thermochromic material 112 that indicates the temperature of the electrical component 114, which may be a thermochromic additive embedded in the composition of the main portion of the visible portion 116. The other end of the arm 118 includes a fastening portion 117, such as a hole in the arm 118, through which a fastener 115 may be passed to fasten the indicator tag 110 to the electrical component 114 for good thermal contact.

[0031] Figure 3B yes Figure 3AA side view of a first embodiment of an indicator tag 110 is shown mounted on an electrical component 114 by a fastener 115 passing through a hole 117. Other forms of fastening may also be used, such as welding or clamping to the component 114 being monitored. The electrical component 114 may be, for example, an electrical lug, busbar, wire, blade, or electrical terminal. When the electrical component 114 is energized, the current flowing through it produces resistive heating. The fastener 115 at the location of the hole 117 forces the underside of the arm 118 against its mounting location on the electrical component 114 to ensure effective heat transfer from the electrical component 114 to the arm 118. The material constituting the arm 118 is selected to have a relatively high thermal conductivity and is selected to effectively conduct heat entering the arm 118 at the location of the hole 117 toward the visible portion 116 of the indicator tag 110 where the thermochromic material 112 is located. When the indicator tag is used in an electrical enclosure where components 114 are closely spaced together, the arm 118 can be constructed of a high resistivity material to avoid inadvertently creating an electrical short between the electrical component 114 and other nearby electrical components. Alternatively, when the indicator tag is used in an electrical enclosure where components 114 are not closely positioned, the arm 118 can be constructed of a metallic material.

[0032] Organic polymer materials such as epoxy resins, polyurethanes, and polyacrylic resins generally have relatively high resistivity, but also generally have relatively low thermal conductivity. However, by introducing inorganic fillers with relatively high thermal conductivity, by introducing embedded thermochromic additives, a composite composition suitable for the arm 118 and visible portion 116 of the indicator tag 110 can be produced.

[0033] Inorganic fillers suitable for organic polymer materials may include aluminum oxide, aluminum nitride, boron nitride, silicon carbide, silicon nitride, and beryllium oxide. These materials have high inherent thermal conductivity and high resistivity, making them suitable for indicator label 110. Other suitable inorganic fillers for organic polymer materials of indicator label 110 may include ceramics, such as silicon dioxide, zinc oxide, silicon carbide, and magnesium oxide, which are standard materials for commercial electric heaters.

[0034] Thermochromic material 112 can be a polymer itself, an embedded thermochromic additive, or an ordered structure of a polymer with an incorporated thermochromic additive and a suitable inorganic filler such as a polymer-glass composite. The color change can be based on the change of light reflection, light absorption or light scattering properties with temperature changes. In some embodiments, thermochromic material 112 can be a thermochromic organic material, in which certain organic dyes made of liquid crystals reversibly change color when their temperature changes. In some embodiments, thermochromic material 112 can be a thermosensitive material with an irreversible color change, which is used to indicate and record the temperature extremes that have occurred in electrical component 114.

[0035] Thermochromic material 112 may be an inorganic thermochromic material that is introduced as an embedded additive to form a composite composition suitable for use with arm 118 and visible portion 116 of indicator tag 110. Transition temperatures of example inorganic thermochromic materials are provided in the technical publication by Jesse H. Day. Thermochromism of Inorganic Compounds, Chem. Rev., 1968, 68(6), pp 649–657. For example, thermochromic inorganic oxides such as vanadium dioxide (VO2) undergo a reversible transformation at a phase transition temperature of 68°C. When the temperature of the material is below the phase transition temperature, it is infrared transparent, and when the temperature is above the phase transition temperature, it is infrared reflecting. Another example of thermochromism caused by phase transition is Ag. 2 HkDJ 4 The color at room temperature is dark red. 2 HkDJ 4 Heating the crystal to 50°C causes a phase change, with the color changing to orange. Further heating of the material to 75°C causes a phase change, with the color changing to black. See Alexander N. Bourque, Investigations of Reversible Thermochromism in Three-Component Systems , PhD thesis, Dalhousie University, Halifax, Nova Scotia, March 2014. Copper iodide is a solid brown-grey substance that turns orange at 60-62°C. Ammonium metavanadate is a white substance that turns brown at 150°C and then black at 170°C. Manganese violet (Mn(NH 4 ) 2 P 2 O 7 ) is a purple substance that turns white at 400°C.

[0036] Thermochromic material 112 may be an organic thermochromic material such as an organic liquid crystal or dye embedded in the bulk of visible portion 116 of indicator tag 110. Heating the material changes the arrangement of the molecules, thereby changing the color of light reflected by the material. However, these organic materials typically degrade at temperatures of about 100°C.

[0037] Figure 4A1 is a top view of a second embodiment of an indicator tag 110 having a coating of a thermochromic material 112, such as an organic thermoplastic or thermosetting coating, on a substrate 113 of a visible portion 116 of the indicator tag 110. The thermochromic material 112 is a coating on the substrate 113 of the visible portion 116 that is at least one of a thermochromic polymer coating, a thermochromic additive embedded in the coating, or an ordered structure of a polymer incorporating a thermochromic additive into the coating. When the indicator tag is used in an electrical enclosure with components 114 spaced closely together, the body of the indicator tag 110 can be a structural insulator, such as mica, which is both a thermally conductive material and an electrically insulating material. The visible portion 116 of the indicator tag 110 can be coated with a thermochromic material 112, such as an epoxy, polyurethane, or polyacrylic resin embedded with an inorganic or organic thermochromic additive. Figure 4B yes Figure 4A FIG. 1 is a side view of a second embodiment of an indicator label 110 showing a coating of an inorganic or organic thermochromic material 112 on a substrate 113 of a visible portion 116 of the indicator label 110 .

[0038] In the foregoing, reference has been made to various embodiments. However, the scope of the present disclosure is not limited to the specifically described embodiments. On the contrary, any combination of the described features and elements, whether or not related to different embodiments, is contemplated to implement and practice the intended embodiments. In addition, although an embodiment may achieve advantages over other possible solutions or prior art, whether a particular advantage is achieved by a given embodiment does not limit the scope of the present disclosure. Therefore, the foregoing aspects, features, embodiments, and advantages are merely illustrative and are not considered elements or limitations of the appended claims unless expressly stated in the claims.

[0039] It should be understood that the above description is intended to be illustrative rather than limiting. After reading and understanding the above description, many other implementation examples are apparent. Although the present disclosure describes specific examples, it should be appreciated that the systems and methods of the present disclosure are not limited to the examples described herein, but can be modified to be implemented within the scope of the attached claims. Therefore, the description and drawings are to be considered illustrative rather than restrictive. Therefore, the scope of the present disclosure should be determined with reference to the attached claims and the full scope of equivalents to which these claims are assigned.

Claims

1. A device comprising: an indicator label including an arm constructed of a material having a high thermal conductivity; a visible portion of the indicator label, located at one end of the arm, the visible portion comprising a thermochromic material; as well as a fastening portion of the indicator tag, located at the end of the arm opposite the visible portion, the fastening portion being in thermal contact with the electrical component, the temperature of the electrical component being indicated by the color of the thermochromic material of the visible portion, The high thermal conductivity of the arms effectively conducts heat from the fastening portion of the indicator tag toward the visible portion where the thermochromic material is located, and the material of the arms also has a high electrical resistivity, preventing electrical shorts between the electrical component and other nearby electrical components.

2. The device according to claim 1, wherein: The thermochromic material is a coating on the substrate of the visible portion, the coating being at least one of a thermochromic polymer coating, a thermochromic additive embedded in the coating, or an ordered structure of a polymer incorporating a thermochromic additive in the coating.

3. The device according to claim 1, wherein: The visible portion includes a thermochromic material as a thermochromic additive embedded in a main body portion of the visible portion.

4. The device according to claim 1, wherein: The thermochromic material is an organic material.

5. The device according to claim 1, wherein: The thermochromic material is a thermoplastic coating on the indicator label.

6. The device according to claim 1, wherein: The thermochromic material produces a color change based on at least one of a change in light reflection, light absorption, or light scattering properties as a function of temperature.

7. The device according to claim 1, wherein: The thermochromic material is a thermochromic organic material in which an organic dye made of liquid crystal reversibly changes color when its temperature changes.

8. The device according to claim 1, wherein: The thermochromic material is a heat-sensitive material with an irreversible color change which indicates and records the temperature extremes that have occurred in the electrical component.

9. The device according to claim 1, wherein: The thermochromic material is an inorganic thermochromic material.

10. The device according to claim 1, wherein: The visible portion has a polygonal shape at one end of the arm, and the opposite end of the arm is mounted on the electrical component.

11. A device comprising: an indicator label including an arm constructed of a material having a high thermal conductivity; a visible portion of the indicator label, located at one end of the arm, the visible portion comprising a thermochromic material; a fastening portion of the indicator tag, located at an end of the arm opposite the visible portion, the fastening portion being in thermal contact with an electrical component in the housing, the temperature of the component being indicated by the color of the thermochromic material of the visible portion; as well as a viewing port in the cover of the housing, juxtaposed with the visible portion of the indicator label, to enable visual observation of the color of the thermochromic material from outside the housing, The high thermal conductivity of the arms effectively conducts heat from the fastening portion of the indicator tag toward the visible portion where the thermochromic material is located, and the material of the arms also has a high electrical resistivity, preventing electrical shorts between the electrical component and other nearby electrical components.

12. The device according to claim 11, wherein The thermochromic material is a coating on the substrate of the visible portion, the coating being at least one of a thermochromic polymer coating, a thermochromic additive embedded in the coating, or an ordered structure of a polymer incorporating a thermochromic additive in the coating.

13. The device according to claim 11, wherein: The visible portion includes a thermochromic material as a thermochromic additive embedded in a main body portion of the visible portion.

14. The device according to claim 11, wherein: The material of the arm is a metal material having high thermal conductivity, which effectively conducts heat from the fastening portion of the indicator label toward the visible portion where the thermochromic material is located.

15. The apparatus according to claim 11, wherein: The thermochromic material is a heat-sensitive material with an irreversible color change which indicates and records the temperature extremes that have occurred in the electrical component.

16. The apparatus according to claim 11, wherein: The enclosure is at least one of a safety switch, a load center enclosure, an HVAC cabinet, an enclosed motor control device, or an electrical transformer cabinet.

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