System and method for monitoring the status of one or more components of an electrical machine

Abstract

Example brush holder assemblies of an electric machine are disclosed. An example brush holder assembly of an electric machine includes a carbon brush including an upper surface and a lower surface opposite the upper surface. The brush holder assembly also includes one or more lead wires extending out of the carbon brush at an insertion point on the upper surface and a first cavity extending into the carbon brush from the upper surface at a location spaced away from the insertion point of the one or more lead wires and unobstructed by the one or more lead wires.

Description

<DP=1>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²SYSTEM AND METHOD FOR MONITORING THE STATUS OF ONE OR²MORE COMPONENTS OF AN ELECTRICAL MACHINE² CROSS-REFERENCE TO RELATED APPLICATIONS²This application claims the benefit of priority under 35 U.S.C. 119 to U.S. ²Provisional Application Serial No. 62 / 866,176, filed June 25, 2019, and to ²U.S. ²Provisional Application Serial No. 62 / 741,152, filed October 4, 2018, the ²entirety of ²which are incorporated herein by reference.² TECHNICAL FIELD²The disclosure generally relates to monitoring systems for monitoring brushes²and brush holder assemblies that may be used in electrical devices and / or slip ²ring²assemblies. More specifically, the disclosure relates to monitoring apparatus,²assemblies, systems and methods of monitoring the wear of a brush in a brush ²holder²assembly and / or the condition of a slip ring of an electrical device using a ²sensor.²BACKGROUND²A purpose of a brush in an electrical device is to pass electrical current ²from a²stationary contact to a moving contact surface, or vice versa. Brushes and ²brush²holders may be used in electrical devices such as electrical generators, ²electrical ²motors, and / or slip ring assemblies, or sliding connection applications, for ²example, ²slip ring assemblies on a rotating machine such as a rotating crane or a ²linear sliding ²connection on a monorail. Brushes in many electrical devices are blocks or ²other² structures made of conductive material, such as graphite, carbon graphite,²electrographite, metal graphite, or the like, that are adapted for contact ²with a ²conductive surface or surfaces to pass electrical current. Electrically ²conductive leads ²or shunts extend from the brush to provide an electrical pathway to and / or ²from the ²brush from another conductive member.²In some designs, a brush box type brush holder, or other type of brush holder,²may be used to support a brush in contact with a moving contact surface of an ²electrical device during operation. The brush and brush box may be designed ²such ²that the brush can slide within the brush box to provide for continuing ²contact ²between the brush and the moving contact surface contacted by the brush. ²During²operation an anomalous and / or threshold condition may occur, which may be²1²<DP=2>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²indicative that one or more components of the electrical device may need to be ²²replaced, one or more components of the electrical device may require ²inspection or ²attention, and / or maintenance may need to be performed. For example, an ²anomalous ²and / or threshold condition may indicate that one or more of a brush, brush ²holder,²spring, shunt, commutator, collector ring, and / or other component may need to ²be²replaced, one or more of a brush, brush holder, spring, shunt, commutator, ²collector ²ring, and / or other component may need to be inspected, and / or maintenance may ²need ²to be performed. It would be advantageous to monitor one or more components of ²an ²electrical device in order to observe the occurrence of an anomalous and / or ²threshold² condition. Furthermore, it would be advantageous to alert an operator and / or²technician of the occurrence of an anomalous and / or threshold condition and / or ²²schedule technician intervention.²SUMMARY² The disclosure is directed to monitoring apparatus, assemblies, systems and²methods of monitoring the wear of a brush in a brush holder assembly and / or ²the ²condition of a slip ring of an electrical device using a sensor.²An example brush holder assembly of an electric machine includes a carbon ²brush including an upper surface and a lower surface opposite the upper ²surface. The²brush holder assembly also includes one or more lead wires extending out of ²the²carbon brush at an insertion point on the upper surface and a first cavity ²extending ²into the carbon brush from the upper surface at a location spaced away from ²the ²insertion point of the one or more lead wires and unobstructed by the one or ²more lead ²wires.² Alternatively or additionally, further comprising a spacer coupled to the²carbon brush, the spacer including a first projection configured to releasably ²engage ²within the first cavity.²Alternatively or additionally, further comprising a wear state monitor coupled ²²to the spacer, wherein the wear state monitor is designed to measure an ²angular²displacement of the wear state monitor as the wear state monitor rotates.²Alternatively or additionally, wherein the brush further includes a length ²measured from the upper surface to the lower surface, wherein the length is ²diminished from an initial length as the lower surface of the carbon brush ²wears away²2²<DP=3>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²during use and wherein the measured angular displacement of the wear state ²monitor ²correlates to the diminished length of the carbon brush.²Alternatively or additionally, wherein engagement of the first projection in ²the ²first cavity of the carbon brush is configured to retain the spacer in a fixed² relationship with the carbon brush.²Alternatively or additionally, wherein the first projection extends away from ²a²bottom surface of the spacer.²Alternatively or additionally, wherein the first cavity includes a channel²extending along the upper surface of the carbon brush, and wherein the first ²projection² .. is configured to mate with and insert into the channel.²Alternatively or additionally, wherein the first cavity includes a first ²tapered²surface, and wherein the first projection includes a second tapered surface ²designed to²mate with the first tapered surface of the first cavity.²Alternatively or additionally, wherein the carbon brush further comprises a²second cavity extending into the carbon brush from the upper surface at a ²location²spaced away from the insertion point of the one or more lead wires and ²unobstructed ²by the one or more lead wires, wherein the second cavity is spaced away from ²the first ²cavity.²Alternatively or additionally, wherein the spacer further comprises a second² projection configured to releasably engage within the second cavity.²Alternatively or additionally, wherein the first projection and the second ²projection are designed to engage the carbon brush simultaneously, and wherein ²the ²engagement of the first projection and the second projection with the first ²and second ²cavities of the carbon brush is configured to retain the spacer in a fixed ²relationship² with the carbon brush.²Alternatively or additionally, wherein both the first projection and the ²second ²projection extend away from a bottom surface of the spacer.²Alternatively or additionally, wherein the shape of both the first projection ²and ²the second projection is designed to mate with the first cavity and the second ²cavity.² Another example system for monitoring the wear state of a carbon brush²includes a brush holder assembly. The brush holder assembly includes a carbon ²brush ²including an upper surface, a lower surface opposite the upper surface, and a ²length ²measured from the upper surface to the lower surface, wherein the length is ²diminished from an initial length as the lower surface of the carbon brush ²wears away²3²<DP=4>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²during use. The brush holder assembly also includes a spring having a first ²end and a ²second end, and a coiled portion. Further, the brush holder assembly includes ²a wear ²state monitor positioned within the coiled portion of the spring, the wear ²state monitor ²including a sensor, wherein the sensor is configured to measure an angular² displacement of the wear state monitor as the wear state monitor rotates.²Additionally, the brush assembly further includes a spacer positioned between ²the ²coiled portion of the spring and the upper surface of the carbon brush, the ²spacer ²including a first projection extending away from a bottom surface of the ²spacer, ²wherein the carbon brush includes a first cavity extending into the carbon ²brush from²the upper surface, and wherein the first cavity receives the first projection ²therein.²Alternatively or additionally, further comprising a lead wire having a first ²end ²and a second end extending away from the first end, wherein the first end ²extends into ²the carbon brush at an insertion point at the upper surface of the carbon ²brush and ²spaced away from the first cavity.² Alternatively or additionally, wherein engagement of the first projection²within the first cavity is configured to retain the spacer in a fixed ²relationship with the ²carbon brush.²Alternatively or additionally, wherein the measured angular displacement of ²the wear state monitor correlates to an amount of diminution in the length of ²the² carbon brush.²Alternatively or additionally, wherein the first cavity includes a channel²extending along the upper surface of the carbon brush, and wherein the first ²projection²is configured to mate with and insert into the channel.²Alternatively or additionally, wherein the first cavity includes a tapered²surface, and wherein the first projection includes a tapered surface designed ²to mate²with the tapered surface of the first cavity.²Alternatively or additionally, wherein the carbon brush further comprises a ²second cavity extending into the carbon brush from the upper surface of the ²carbon ²brush, wherein the second cavity is spaced away from the first cavity.² Alternatively or additionally, wherein the spacer further comprises a second²projection extending into the second cavity.²Alternatively or additionally, wherein the first projection and the second ²projection are designed to engage the carbon brush simultaneously, and wherein ²the²4²<DP=5>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²engagement of the first projection and the second projection with the carbon ²brush is ²configured to retain the spacer in a fixed relationship with the carbon brush. ²²Alternatively or additionally, wherein both the first projection and the ²second ²projection extend away from a bottom surface of the spacer.² Alternatively or additionally, wherein the bottom surface of the spacer is²juxtaposed with the upper surface of the carbon brush when the first and ²second ²projections are positioned in the first and second cavities.²Another example assembly for a brush holder assembly of an electrical device ²includes a carbon brush including an upper surface, a lower surface opposite ²the upper²surface, and a length measured from the upper surface to the lower surface. ²The ²brush assembly also includes one or more lead wires extending out of the ²carbon ²brush at an insertion point on the upper surface and first and second cavities ²extending ²into the carbon brush from the upper surface at a location spaced away from ²the ²insertion point of the one or more lead wires and unobstructed by the one or ²more lead² wires. Further, the brush assembly includes a spacer having first and second²projections extending from a lower surface of the spacer wherein the first and ²second ²projections are configured to be inserted into the first and second cavities ²when the ²lower surface of the spacer is juxtaposed with the upper surface of the carbon ²brush. ²The above summary of some embodiments, aspects, and / or examples is not ² intended to describe each embodiment or every implementation of the present ²disclosure. The figures and the detailed description which follows more ²particularly ²exemplify these embodiments.²BRIEF DESCRIPTION OF THE DRAWINGS² The aspects of the disclosure may be more completely understood in²consideration of the following detailed description of various embodiments in ²connection with the accompanying drawings, in which:²FIG. 1 shows an illustrative view of an exemplary brush monitoring system ²positioned adjacent a component of an electrical machine;² FIG. 2 shows an example wear state monitor and spring positioned adjacent a²spacer on a brush;²FIG. 3 shows an exploded view of the wear state monitor components and ²associated spring shown in FIG. 2;²FIG. 4A is a perspective view of an exemplary carbon brush;²5²<DP=6>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²FIG. 4B is a top view of the carbon brush of FIG. 4A; ²FIG. 4C is a bottom view of the carbon brush of FIG. 4A; ²FIG. 4D is a front view of the carbon brush of FIG. 4A; ²FIG. 4E is a rear view of the carbon brush of FIG. 4A;² FIG. 4F is a side view of the carbon brush of FIG. 4A;²FIG. 4G is a side view of the carbon brush of FIG. 4A opposite the side shown ²in FIG. 4F;²FIG. 5 illustrates the spacer of the wear state monitor shown in FIG. 3 ²aligned ²with the carbon brush shown in FIG. 4A;² FIG. 6 illustrates another example spacer aligned with another example carbon²brush;²FIG. 7 illustrates a perspective view of the spacer and carbon brush shown in²FIG. 6;²FIG. 8 illustrates another example spacer aligned with another example carbon² brush;²FIG. 9 illustrates a perspective view of the spacer and carbon brush shown in ²FIG. 8;²FIG. 10 illustrates another example spacer aligned with another example ²carbon brush;²FIG. 11 illustrates a perspective view of the spacer and carbon brush shown in²FIG. 10;²FIG. 12 shows an end view of the wear state monitor and spring shown in²FIG. 3;²FIG. 13 shows a side view of the wear state monitor and spring shown in FIG.² 3;²FIG. 14 shows an exploded view of the wear state monitor shown in FIG. 3; ²FIGS. 15 and 16 show side views of an illustrative brush holder assembly at a ²first wear state and a second wear state.²While the aspects of the disclosure are amenable to various modifications and²alternative forms, specifics thereof have been shown by way of example in the ²drawings and will be described in detail. It should be understood, however, ²that the ²intention is not to limit aspects of the disclosure to the particular ²embodiments ²described. On the contrary, the intention is to cover all modifications, ²equivalents, ²and alternatives falling within the spirit and scope of the disclosure.²6²<DP=7>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²DETAILED DESCRIPTION²For the following defined terms, these definitions shall be applied, unless a²different definition is given in the claims or elsewhere in this ²specification.² All numeric values are herein assumed to be modified by the term "about",²whether or not explicitly indicated. The term "about" generally refers to a ²range of ²numbers that one of skill in the art would consider equivalent to the recited ²value (i.e., ²having the same function or result). In many instances, the term "about" may ²be ²indicative as including numbers that are rounded to the nearest significant ²figure.² The recitation of numerical ranges by endpoints includes all numbers within²that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).²Although some suitable dimensions, ranges and / or values pertaining to various ²components, features and / or specifications are disclosed, one of skill in the ²art, incited ²by the present disclosure, would understand desired dimensions, ranges and / or ²values²may deviate from those expressly disclosed.²As used in this specification and the appended claims, the singular forms "a", ²²"an", and "the" include plural referents unless the content clearly dictates ²otherwise. ²As used in this specification and the appended claims, the term "or" is ²generally ²employed in its sense including "and / or" unless the content clearly dictates ²otherwise.² The following detailed description should be read with reference to the²drawings in which similar elements in different drawings are numbered the ²same. ²The detailed description and the drawings, which are not necessarily to scale, ²depict ²illustrative embodiments and are not intended to limit the scope of the ²disclosure. ²The illustrative embodiments depicted are intended only as exemplary. Selected²features of any illustrative embodiment may be incorporated into an additional²embodiment unless clearly stated to the contrary.²FIG. 1 illustrates an exemplary brush monitoring system 100 that may include ²a brush holder assembly 110, a site monitor 120 and / or a remote monitoring ²site 140 ²including a remote monitoring device 150, 160. In some cases, the brush holder²assembly 110 may substantially resemble a brush holder assembly as described ²in²U.S. Patent No. 7,034,430, entitled "BRUSH HOLDER APPARATUS, BRUSH ²ASSEMBLY, AND METHOD", which is herein incorporated by reference in its ²entirety. However, the illustrative brush monitoring system 100 may be ²amenable to²7²<DP=8>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²any of various brush holder assembly configurations. Thus, the intention is ²that the ²illustrative brush monitoring system 100 may be used in conjunction with any ²desired ²brush holder assembly configurations of an electrical device, such as an ²industrial ²electrical generator. For example, the illustrative brush monitoring system ²100 may²be used with brush holder assemblies, brush holders and / or brushes disclosed ²in U.S.²Patent Nos. 6,731,042; 5,753,992; 5,621,262; 5,463,264; 5,397,952; and ²5,256,925; ²each of which is incorporated herein by reference.²FIG. 1 illustrates a brush 24 including a first end surface 34 and a second ²end ²surface 35 and a length extending therebetween. The second end surface 35 may ²be²in electrical contact with a conductive surface 12 of a rotating component 15 ²of an²electrical machine (e.g., a collector ring, a slip ring, or a commutator) and ²conduct ²electrical current therefrom. Further, FIG. 1 illustrates that, in some ²examples, one or ²more sides of the brush 24 may be surrounded by a brush holder 22 (e.g., a ²brush ²box), whereby the brush holder 22 may include a plurality of guiding surfaces ²for²guiding linear or longitudinal movement of the brush 24 toward the conductive ²surface 12 of the rotating component 15. In other words, the brush 24 may ²translate ²linearly within an aperture defined by the plurality of guiding surfaces of ²the brush ²holder 22 as the brush 24 wears. In some embodiments it is contemplated that ²the ²brush holder 22 may not take on the form of a box, but may include one or a ²plurality²of guiding surfaces, such as channels, posts or columns, abutting and / or ²encompassing²one or more sides of the brush 24 and / or extending into or through the brush ²24, or a ²portion thereof, for guiding linear or longitudinal movement of the brush 24.²FIG. 1 further illustrates that the brush holder 22 may be secured to a ²mounting beam 26 configured and adapted to be mounted to another structure, ²such as²a mounting block 70. The brush holder assembly 110 may be configured to place ²the²brush 24 in contact with the conductive surface 12, such as the surface of the ²rotating ²component 15 of the electrical machine. The brush 24 may extend from the lower ²²edge of the brush holder 22 such that the second end surface 35 of the brush ²24 ²engages the conductive surface 12. The mounting beam 26 may include an over-² center engagement mechanism, a slotted or channeled engagement mechanism for ²sliding engagement, or other mechanism for easily engaging and disengaging the ²²brush 24 from a conductive surface 12. In other embodiments, the brush holder ²assembly 110 may include a brush holder 22 rigidly mounted to another ²structure ²holding the brush holder 22 stationary, or mounted to another structure in any ²desired²8²<DP=9>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²arrangement. For example, in some embodiments the brush holder 22 may be ²bolted ²or welded to a stationary structure. Some such brush holders are disclosed in ²U.S. ²Patent Nos. 6,731,042; 5,753,992; 5,621,262; 5,463,264; 5,397,952; and ²5,256,925; ²which are incorporated herein by reference.² As shown in FIG. 1, the mounting beam 26 may include an upper beam²member 27 and a lower beam member 28 hingedly or pivotedly coupled to one ²another. When the upper beam member 27 and the lower beam member 28 are ²aligned with one another (e.g., the longitudinal axis of the upper beam member ²27 is ²parallel with the longitudinal axis of the lower beam member 28), the brush ²holder 22²to may be ²considered to be in an engaged, or locked, position such that the brush 24 may²be contiguous with or in contact with the conductive surface 12. When the ²upper ²beam member 27 is tilted from the lower beam member 28 (e.g., the longitudinal ²axis ²of the upper beam member 27 is oblique to the longitudinal axis of the lower ²beam ²member 28), the brush holder 22 may be considered to be in a disengaged, or²unlocked, position such that the brush 24 may be non-contiguous with, spaced ²from,²or otherwise not in direct electrical contact with the conductive surface 12. ²The ²mounting beam 26 may be removably coupled to the mounting block 70 during ²operation. In some embodiments, the mounting beam 26 may slidably engage with, ²²interlock with, or otherwise be removably coupled to the mounting block 70. ²The²mounting block 70 may be coupled to, secured to, or otherwise extend from ²another²structure which maintains the mounting block 70 stationary with respect to ²(i.e., a ²fixed distance from) the conductive surface 12, for example.²In some embodiments, a handle 21 may be attached to the brush holder 22 to ²facilitate engagement and disengagement of the brush 24 from the conductive ²surface²12. For example, the handle 21 may be attached to the upper beam member 27 ²such²that movement of the handle 21 actuates (e.g., pivots, slides, releases) the ²upper beam ²member 27 relative to the lower beam member 28. The handle 21 may be a ²removable handle or the handle 21 may be permanently attached to the upper ²beam ²member 27 or another portion of the brush holder 22.² FIG. 1 further illustrates that the brush holder assembly 110 may include a²wear state monitor 50 and a spacer 30. The spacer 30 may be attached to the ²first end ²surface 34 of the brush 24. Additionally, FIG. 1 illustrates that the wear ²state monitor ²50 may be coupled to a spring 29. In some examples, a portion of the spring 29 ²may ²be coiled around a portion of the wear state monitor 50, with an elongate ²portion of²9²<DP=10>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²the spring extending from the coiled portion. Further detailed discussion of ²the wear ²state monitor 50, the spacer 30 and the spring 29 follows below.²In some examples the wear state monitor 50 may include one or more sensors ²which collect and / or measure a variety of parameters corresponding to the ²"wear²state" of the brush 24. For example, the wear state monitor 50 may include one ²or²more sensors which measure and / or communicate the extent to which the brush 24 ²²wears away while in contact with the conductive surface 12 of the rotating ²component ²15. In some examples, the sensor(s) may also measure the vibration and / or ²temperature of the brush holder assembly 110 (including individual components²to thereof) ²and / or the brush 24, and / or electrical current passing through the brush 24,²for instance.²In some cases, the wear state monitor 50 may be positioned adjacent to a ²surface of a component of the brush holder assembly 110, different than the ²spring 29. ²For example, the wear state monitor 50 may be positioned on or adjacent to the ²brush² holder 22, the lower beam member 28, the upper beam member 27 and / or on or ²adjacent to the handle 21 of the brush holder assembly 110. In some cases, the ²wear ²state monitor 50 may be permanently and / or removably incorporated into a ²portion of ²the handle 21 or other component of the brush holder assembly 110. In some ²examples, the wear state monitor 50 may be free from the spring 29.² As described above, in some examples the wear state monitor 50 may be²mounted adjacent a surface of the spring 29 or otherwise within the spring 29, ²such as ²within a coiled portion of the spring 29. The spring 29 may include a constant ²force ²spring, which provides tension to the brush 24, the wear state monitor 50 or ²both the ²brush 24 and the wear state monitor 50 to bias the brush 24 toward and in ²contact with²the conductive surface 12 of the rotating component 15. In other words, the ²spring 29²may include a coiled portion designed to provide a force to engage the brush ²24 with a ²rotating component of an electrical machine, such as a slip ring, a ²commutator, and ²the like.²In some examples, the spring 29 may be attached to a portion of the brush²holder 22 and / or the mounting beam 26 of the brush holder assembly 110. In ²some²instances, a first end 32 of the spring 29 may be removably coupled to the ²brush ²holder and / or the mounting beam 26 with an elongate portion of the spring 29 ²extending along a side surface of the brush 24, between the brush 24 and the ²mounting beam 26. Thus, in some embodiments, an elongate portion of the spring ²29²<DP=11>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²may extend along one side surface of the brush 24 between the brush 24 and the ²²mounting beam 26 of the brush holder assembly 110 up to the coiled portion of ²the ²spring 29 positioned above the upper surface 34 of the brush 24. The opposite, ²second ²end 33 of the spring 29 may be located at the interior of the coiled portion ²of the² spring 29.²In some cases, the wear state monitor 50 may also include one or more ²indicators 55 (e.g., one or more light emitting diodes (LEDs), a speaker, or a ²²combination of LEDs and / or speakers) for communicating wear state information ²to a ²user. In some instances, the wear state monitor 50 may be capable of ²communicating²information about the wear state of the brush 24 and / or the rotating component ²15 to a²user via the indicators 55. In some cases, the wear state monitor 50 may be ²capable of ²receiving messages from an external device, such as the site monitor 120 ²and / or a ²programming device located at the same site or at a remote location (e.g., a ²computer ²150, a tablet 160, a smart phone, etc.). The messages may include commands, ²such as²commands to send wear state information about the brush 24 and / or the rotating ²²component 15, or commands for modifying information used by the wear state ²monitor 50. For example, a user may desire to modify one or more thresholds ²used to ²determine the wear state information of the brush 24 and / or the rotating ²component ²15, and / or to reprogram the wear state monitor 50 by downloading instructions, ²tables² and / or the like.²As described above, in some examples the wear state monitor 50 may measure ²and / or collect information regarding the wear state of the brush 24. In ²particular, the ²wear state monitor 50 may be designed to measure and collect information ²regarding ²the extent to which the second end surface 35 of the brush 24 contacting the².. conductive surface 12 has worn away (i.e., the amount of diminution in ²length of the²brush 24 at some time from its initial length when installed in the brush ²holder ²assembly 110). It can be appreciated that as the second end surface of the ²brush 24 ²maintains contact with the rotating component 15, the second end surface 35 of ²the ²brush 24 may wear away, thereby shortening the overall length of the brush 24.² As described above, the spring 29 may apply a force to the brush 24 which is²directed linearly along the aperture defined by the brush holder 22. Further, ²as the ²brush 24 decreases in length within the brush holder 22, the wear state ²monitor 50 ²may rotate within the coil of the spring 29 while the axis of rotation of the ²wear state ²monitor 50 translates linearly with linear translation of the brush 24 toward ²the²11²<DP=12>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²conductive surface 12 of the rotating component 15. Additionally, a sensor may ²be ²positioned within the wear state monitor 50 and may measure and collect data ²representing the extent (e.g., total angular distance and / or total arc length) ²of rotation ²of the wear state monitor 50 from its initial position when the brush 24 was ²installed²in the brush holder assembly 110, or any other duration desired. It can be ²appreciated²that the amount of rotation measured by the sensor (positioned within the wear ²state ²monitor 50) may be equivalent, proportional, or otherwise representative of ²the linear ²or longitudinal movement of the brush 24 as it translates (e.g., shortens) ²within the ²brush holder 22, and thus equivalent, proportional, or otherwise ²representative of the² amount of diminution of the brush 24 from its initial length.²In some cases, the sensor may associate the rotation of the wear state monitor ²²50 with a wear state of the brush 24 and / or a wear state of the conductive ²surface 12 ²and / or the rotating component 15. The value (e.g., amount of rotation of the ²wear ²state monitor 50) measured by the sensor may correspond to the position of the ²first²end of the brush 24 relative to the conductive surface 12 of the rotating ²component 15.²In some cases, the value measured by the sensor may correspond to a value ²obtained ²over any desired time interval or duration of wear of the brush 24. It can be ²appreciated that the value (e.g., amount of rotation of the wear state monitor ²50 from ²its initial position) may be compared to one or more predetermined threshold ²values²to determine a wear state of the brush 24 and / or other diagnostic information ²about²the machine.²For example, in some cases the wear state monitor 50 (including the sensor ²positioned therein) may be configured to monitor a vibration of the brush 24. ²Vibration of the brush 24 may be due to one or more imperfections, wear or ²other²deformation of the rotating component 15 of the electrical machine. For ²example, a²slip ring may deform or may wear unevenly to cause one or more portions of the ²slip ²ring to be out of round. As the brush 24 encounters these defects at one or ²more ²positions during a revolution of the rotating component 15, the defects may ²cause the ²brush 24 to vibrate at a rate corresponding to the rotation speed and / or the ²number of²defects at the conductive surface 12 of the rotating component 15 (e.g., a ²slip ring, a²commutator, etc.). In some examples, the transient angular displacement of the ²wear ²state monitor 50 may correspond and / or correlate to a threshold change in ²vibration or ²other deformation of the rotating component 15 of the electrical machine. As ²used ²herein, "transient angular displacement" means momentary change in the ²rotational²12²<DP=13>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²orientation of the wear state monitor 50 in an oscillating fashion. Therefore, ²in some ²examples, information corresponding to the transient angular displacement ²(which ²may correspond to a threshold change in vibration) of the wear state monitor ²50 may ²be collected and transmitted to the site monitor 120 to determine if the brush ²24 is² experiencing excessive vibration.²Similarly, it can be appreciated that the sensor positioned within the wear ²state ²monitor 50 (or a separate temperature sensor) may measure and collect ²information ²associated with a temperature of the brush 24, other components of the ²electrical ²machine and / or the ambient air temperature surrounding the brush holder ²assembly²110. Further, the collected temperature values may be monitored and / or ²compared to²one or more predetermined temperature thresholds, whereby the temperature ²thresholds may trigger the sensor to send a signal to the site monitor 120 ²indicative of ²the need for inspection and / or maintenance to be performed on one or more ²components of the electrical machine. For example, in some instances, the²temperature threshold may be set to trigger a signal when the measured ²temperature²exceeds a threshold temperature, such as a threshold temperature of 125 ²degrees ²Celsius. In other words, when the temperature sensor measures a temperature ²(e.g., ²ambient air temperature, temperature of a component of the electrical machine, ²etc.) ²greater than 125 degrees Celsius, it may send a signal to the site monitor 120 ²alerting²personnel of the need for inspection and / or maintenance to be performed on one ²or²more components of the electrical machine. In other instances, the threshold ²temperature may be set in a range of 100 degrees Celsius to 140 degrees ²Celsius, in a ²range of 110 degrees Celsius to 130 degrees Celsius, or in a range of 120 ²degrees ²Celsius to 130 degrees Celsius, for example.² In some cases, the site monitor 120 may be positioned near the electrical²machine to monitor the wear state of one or more brush holder assemblies 110 ²and / or ²the wear state of the slip ring or other rotating component of the electrical ²machine. ²The site monitor 120 may be capable of monitoring the wear states of the brush ²24 of ²the brush holder assembly 110. In some cases, the site monitor 120 may be ²capable of²monitoring the movement of the brushes 24 of two or more brush holder ²assemblies²110 associated with one or more electrical machines. For example, the site ²monitor ²120 may be communicatively coupled to one or more, or a plurality of wear ²state ²monitors 50 associated with a particular electrical machine, such as the wear ²state ²monitor 50 of the brush holder assembly 110 via a communication link 115 ²(e.g., a²13²<DP=14>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²wireless link). The site monitor 120 may be configured to receive processed ²data ²and / or raw data providing information about the wear state of the brush 24 ²and / or the ²rotating component 15. For example, the site monitor 120 may receive ²information ²about a value received from the sensor corresponding to the amount of rotation ²of the²wear state monitor 50 from its initial position at some temporal occasion ²after the²brush 24 has been installed on the electrical machine. However, in other ²examples, ²the site monitor 120 may receive information about a value obtained by the ²sensor and ²a comparison between the value and one or more predetermined thresholds. In ²some ²cases, the communication link 115 may include a radio frequency (RF)² communication link, an audio-based communication link (e.g., an ultrasonic ²communication link), and / or an optical communication link (e.g., an infrared ²(IR) ²communication link, a visible light communication link, etc.). In some cases, ²the site ²monitor 120 may be configured to predict or determine an estimated projection ²of a ²condition of the brush 24 into the future.² In some examples, the wear state monitor 50 may be configured to²communicate the wear state information about the brush 24 to the site monitor ²120 ²using a predetermined schedule (e.g., once per hour or hourly, once per day or ²daily, ²once per week or weekly, twice per week, etc.). In some examples, the wear ²state ²monitor 50 may provide the wear state information about the brush 24 and / or ²the²rotating component 15 of the electrical machine to the site monitor 120 in ²response to²a command received from the site monitor 120 and / or the remote monitoring ²device ²150, 160. Additionally, the site monitor 120 may be programmed to receive wear ²²state information about the brush 24 at predetermined intervals. In some ²cases, the ²predetermined intervals may be fixed at a particular value (e.g., once per ²hour or²hourly, once per day or daily, once per week or weekly, twice per week, etc.) ²and in²other cases, the intervals may change after a particular wear state has been ²reached. ²For example, the site monitor 120 may be configured to receive wear state ²information from the wear state monitor 50 at a first time interval, such as ²once per ²day, until one or more brushes 24 and / or the rotating component 15 reach a ²wear state²approaching the replacement wear state. At that point, the wear state monitor ²50 may²sample the wear state information from the brush 24 at a second shorter time ²interval, ²such as hourly. Thus, the wear state information from the wear state monitor ²50 may ²be communicated to the site monitor 120 at first frequency until the brush 24 ²reaches²14²<DP=15>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²a first wear state, and thereafter, the wear state information may be ²communicated to ²the site monitor 120 at a second frequency greater than the first frequency.²The site monitor 120 may output an indication of the condition and / or ²projected condition of the brush 24. In some cases, the indication may be ²configured²to alert an operator, technician and / or other personnel that the brush 24 ²and / or the²rotating component 15 are sufficiently worn and / or needs to be replaced, the ²brush 24 ²and / or the rotating component 15 are damaged, failure has occurred or is ²imminent, or ²other maintenance or inspection may need to be performed. In some embodiments, ²²the indication may be used for scheduling maintenance or inspection, sending² personnel to perform maintenance or inspection, ordering and / or scheduling ²distribution / delivery of a replacement brush or other part, routing ²maintenance ²personnel and / or product delivery to a specified location, or arranging for ²other ²notification and / or scheduling tasks be performed.²The brush monitoring system 100 may also be used to identify and / or notify² other key maintenance, failure of the brush holder assembly 110 and / or other²anomalous conditions. For example, incidents of excess heating, arcing or ²excess ²vibration, which may indicate a need to perform maintenance and / or disrupt ²operation ²of the electrical equipment, may be identified and / or assessed by one or more ²components of the brush monitoring system 100. The wear state monitor 50, the ²site²monitor 120 and / or the remote monitoring device 150, 160 may carry out an ²appropriate response to respond to an identified anomalous condition in an ²attempt to ²rectify the anomalous condition. In some cases, an operator may carry out an ²appropriate response to respond to an anomalous condition identified with the ²brush ²monitoring system 100 in an attempt to rectify the anomalous condition.² In some cases, the site monitor 120 may be communicatively coupled by a²wireless link 125 and / or wired link 127 to a network 130. The site monitor 120 ²may ²be capable of communicating information about the wear state of one or more ²brushes ²24 to a remote monitoring device 150, 160 at a remote monitoring site 140 via ²the ²network 130 and one or more wired 137 and / or wireless 135 communication links.²The wired link 127, 137 and / or wireless link 125, 135 communication links may ²be²configured to operate using one or more standardized communication protocols ²(e.g., ²Ethernet, Ethernet / IP, BACnet, Modbus, LonWorks, etc.), or proprietary ²communication protocols. Examples of a remote monitoring system are described ²in ²U.S. Patent No. 7,705,744, entitled "MONITORING SYSTEMS AND METHODS²<DP=16>²CA 03114764 2021-03-29²WO 2020 / 072806 ²PCT / US2019 / 054549²FOR MONITORING THE CONDITION OF ONE OR MORE COMPONENTS OF ²AN ELECTRICAL DEVICE", U.S. Patent No. 8,618,943, entitled "BRUSH ²HOLDER ASSEMBLY MONITORING APPARATUS, ASSEMBLY, SYSTEM ²AND METHOD", and U.S. Patent No. 9,252,643, entitled "SYSTEM AND² METHOD FOR MONITORING THE STATUS OF ONE OR MORE ²COMPONENTS OF AN ELECTRICAL MACHINE", which are herein incorporated ²by reference in their entirety. The remote monitoring site 140 may include one ²or ²more remote monitors, such as a personal computer 160, a workstation, a ²laptop, a ²tablet 150, a smart phone or the like, for collecting data and / or analyzing ²data²to received from one or more user sites.²The remote monitoring devices and / or site monitor 120 may be integrated into ²a maintenance program for a brush holder assembly 110, such that the site ²monitor ²120 may be configured to monitor at least a condition of one or more ²components of ²the brush holder assembly 110. To do so, the remote monitors and / or the site ²monitor²120 may be configured to identify each brush holder assembly 110 on a ²particular²machine or at a particular site and / or store an installation date and any ²servicing dates ²for each brush holder assembly 110 and / or components thereof, such as the ²installation date of a brush 24 in the brush holder assembly 110. In some ²examples, ²the wear state monitor 50 (or other sensor of the brush holder assembly 110) ²may²output a signal to the site monitor 120 indicating that a brush 24 or other ²component²of the electrical machine has been removed and / or replaced, and / or an ²indication that ²a new brush 24 has been installed. Component replacement information may be ²collected and monitored by the wear state monitor 50, one or more sensors of ²the ²brush assembly 110 and / or the site monitor 120.² In some cases, one or more parameters received from the wear state monitor²50 associated with a brush holder assembly 110 may be monitored over time to ²determine trending information about a brush 24 and / or a rotating component 15 ²of ²the electrical machine. For example, the site monitor 120 and / or the remote ²monitors ²may determine trend information, that may include an average lifetime for a ²brush 24²installed in a particular brush holder assembly 110 and / or for a particular ²installation²position on an electrical machine. The site monitor 120 and / or the remote ²monitors ²may be configured to store information about the position of a brush 24 when ²the ²brush 24 and / or brush holder assembly 110 is first installed on an electrical ²machine. ²By monitoring the final position and / or replacement date of a brush 24 along ²with the²16²<DP=17>²CA 03114764 2021-03-29²WO 2020 / 072806 ²PCT / US2019 / 054549²initial position and / or installation date each time a brush 24 is replaced and ²a new ²brush 24 is installed in the brush holder assembly 110, information may be ²gathered ²about a wear state of the rotating component 15. For example, a slip ring, or ²other ²rotating component of the electrical machine, may have an initial outer ²diameter² measurement. Over time, with wear including normal wear and / or due to ²environmental conditions (e.g., humidity, temperature, contaminants including ²abrasives, etc.) a wear state associated with the thickness and / or outer ²diameter of the ²rotating component 15 may be measured and / or predicted. In some cases, ²preventative measures to improve the lifetime of the brush 24 and / or the ²rotating²to component 15 may be obtained by analysis of the information received ²from the one²or more wear state monitors 50. For example, a user may be advised to adjust ²one or ²more environmental conditions for a space near the electrical machine, such as ²a ²temperature, a humidity level and / or a contaminant level.²FIG. 2 illustrates the wear state monitor 50, spring 29 and spacer 30 shown in²FIG. 1, positioned above an upper surface of a carbon brush 24. FIG. 3 ²illustrates an²exploded perspective view of the wear state monitor 50, spring 29 and spacer ²30 as ²described above in FIG. 2. For clarity, FIG. 3 illustrates the wear state ²monitor 50, ²spring 29 and spacer 30 after having been rotated 180 degrees as compared with ²their ²orientation depicted in FIG. 1 and FIG. 2.²As illustrated in FIG. 2 in some examples the wear state monitor 50 and spring²29 may be nested within the spacer 30, such as within a concave cradle of the ²spacer ²30. The spacer 30 may be positioned between the coiled portion of the spring ²29 and ²the upper or first end surface 34 of the carbon brush 24. In some instances, ²the spacer²may be attached to the first end surface 34 of the brush 24 such that the ²spacer 30²25 moves with the brush 24.²For example, as shown in FIG. 3 and FIG. 5, the spacer 30 may include one or ²more projections 38 extending from a bottom surface of the spacer 30 which are ²²designed to engage one or more cavities (e.g., bores) 39 extending into the ²brush 24 ²from the first end surface 34 (shown in FIG. 1 and FIG. 4A) of the brush 24. ²As²30 illustrated by the dashed lines in FIG. 5, each of the projections ²38 may extend into a²corresponding cavity 39 located within the first end surface 34 of the brush ²24. It can ²be appreciated that engagement of each of the projections 38 within their ²respective ²cavity 39 may function to secure the spacer 30 to the brush 24 in a fixed ²relationship.²17²<DP=18>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²Further, each of the cavities 39 may be spaced away from one or more of the ²lead wires 62. For example, each of the lead wires 62 may extend into the ²brush 24 ²from the upper surface 34 of the carbon brush 24 at an insertion point along ²the first ²end surface 34 of the brush 24. For instance, the ends of the lead wires 62 ²may be²fixed within bore holes of the brush 24. As shown in FIG. 3 and FIG. 5, the ²cavities²39 may be spaced away (along the upper surface 34 of the brush 24) from the ²insertion locations of the lead wires 62. Thus, the cavities 39 are distinct ²from and not ²intended for receiving ends of the lead wires 62 therein. FIG. 4A is a ²perspective ²view further illustrating the position and arrangement of the cavities 39 ²extending into² the brush 24, while FIGS. 4B-4G illustrate additional views of the brush 24.²Further, it can be appreciated that the projections 38 shown in FIG. 3 and ²FIG. ²5 may permit the spacer 30 to be releasably attached to the brush 24. In other ²words, ²inserting the projections 38 into the cavities 39 may attach the spacer 30 to ²the brush ²24 with the bottom surface of the spacer 30 juxtaposed with the upper surface ²34 of²the brush 24. However, as discussed above, the spacer 30 (including each of ²the²projections 38) may be removed from the brush 24 after being attached thereto. ²In ²other words, the projections 38 may be designed to be inserted into (e.g., ²slide into) or ²removed from (e.g., slide out of) each of their respective cavities 39 through ²manual ²manipulation of the spacer 30 relative to the brush 24 without damaging either ²the²spacer 30 or the brush 24, and / or without breaking an adhesive bond or other ²interface²therebetween. In some instances, the projections 38 may frictionally engage ²the ²sidewall of the cavities 39 when inserted therein, but be readily removed ²therefrom ²with a manual extraction force applied to the spacer 30 without damaging ²either the ²spacer 30 or the brush 24.² Additionally, FIG. 3 and FIG. 5 illustrate each of the projections 38 may²include a particular shape which may be designed to mate with the shape of ²each of ²the cavities 39. For example, both the projections 38 and the cavities 39 may ²include ²a geometric cross-sectional shape (e.g., square, pentagon, hexagon, etc.) ²which allows ²each of the projections 38 to fit snugly within its mating cavity 39.² FIG. 6 and FIG. 7 illustrate front and perspective views, respectively, of²another example spacer 130 and brush 124 (including lead wires 162). It can be ²²appreciated that the spacer 130, brush 124 and lead wires 162 (attached to the ²first end ²surface 134 of the brush 124) may be similar in form and function to the ²spacer 30, ²brush 24 and lead wires 62 described above.²18²<DP=19>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²Similarly to that described above, the spacer 130 may include one or more ²projections 138 extending from a bottom surface of the spacer 130 which are ²designed ²to engage cavities (e.g., bores) 139 extending into the brush 124 from the ²first end ²surface 134 (shown in FIG. 6 and FIG. 7) of the brush 124. As illustrated by ²the²dashed lines in FIG. 6, each of the projections 138 may extend into a ²corresponding²cavity 139 located within the first end surface 134 of the brush 124. It can ²be ²appreciated that engagement of each of the projections 138 within their ²respective ²cavity 139 may function to secure the spacer 130 to the brush 124 in a fixed ²relationship.² Further, each of the cavities 139 may be spaced away from one or more of the²lead wires 162. For example, each of the lead wires 162 may extend into the ²brush ²124 from the upper surface 134 of the carbon brush 124 at an insertion point ²along the ²first end surface 134 of the brush 124. For instance, the ends of the lead ²wires 162 ²may be fixed within bore holes of the brush 124. As shown in FIG. 6 and FIG. ²7, the²cavities 139 may be spaced away (along the upper surface 134 of the brush 124) ²from²the insertion locations of the lead wires 162. Thus, the cavities 139 are ²distinct from ²and not intended for receiving ends of the lead wires 162 therein.²Further, it can be appreciated that the projections 138 shown in FIG. 6 and ²FIG. 7 may permit the spacer 130 to be releasably attached to the brush 124. ²In other²words, inserting the projections 138 into the cavities 139 may attach the ²spacer 130 to²the brush 124 with the bottom surface of the spacer 130 juxtaposed with the ²upper ²surface 134 of the brush 124. However, as discussed above, the spacer 130 ²(including ²each of the projections 138) may be removed from the brush 124 after being ²attached ²thereto. In other words, the projections 138 may be designed to be inserted ²into (e.g.,²slide into) or removed from (e.g., slide out of) each of their respective ²cavities 139²through manual manipulation of the spacer 130 relative to the brush 124 ²without ²damaging either the spacer 130 or the brush 124, and / or without breaking an ²adhesive ²bond or other interface therebetween. In some instances, the projections 138 ²may ²frictionally engage the sidewall of the cavities 139 when inserted therein, ²but be²readily removed therefrom with a manual extraction force applied to the spacer ²130²without damaging either the spacer 130 or the brush 124.²Additionally, FIG. 6 and FIG. 7 illustrate that each of the projections 138 ²may ²include a particular shape which may be designed to mate with the shape of ²each of ²the cavities 139. For example, each of the projections 138 shown in FIG. 6 and ²FIG.²19²<DP=20>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²7 may be generally shaped as a "cone", e.g., conical or frusta-conical, ²(whereby the ²cone-shaped projection 138 extends away from the bottom surface of the spacer ²130). ²As shown in FIG. 6 and FIG. 7, each of the projections 138 may be wider along ²the ²bottom surface of the spacer 130 and taper to a narrower tip. Likewise, each ²of the²cavities 139 may be generally conical or frusta-conical, with a larger cross-²section at²the upper surface 134, tapering to a smaller cross-section toward the base of ²the ²cavities 139 within the brush 124. The generally coned-shaped projections 138 ²may ²allow each of the projections 138 to fit snugly within its mating cavity 139.²FIG. 8 and FIG. 9 illustrate front and perspective views, respectively, of²another example spacer 230 and brush 224 (including lead wires 262). It can be²appreciated that the spacer 230, brush 224 and lead wires 262 (attached to the ²first end ²surface 234 of the brush 224) may be similar in form and function to the ²spacer 30, ²brush 24 and lead wires 62 described above.²Similarly to that described above, the spacer 230 may include a projection 238²extending from a bottom surface of the spacer 230 which is designed to engage ²a²cavity (e.g., channel) 239 extending into the brush 224 from the first end ²surface 234 ²(shown in FIG. 8 and FIG. 9) of the brush 224. As illustrated by the dashed ²lines in ²FIG. 8, the projection 238 may extend into a corresponding cavity 239 located ²within ²the first end surface 234 of the brush 224. It can be appreciated that ²engagement of²the projection 238 within its respective cavity 239 may function to secure the ²spacer²230 to the brush 224 in a fixed relationship.²Further, the cavity 239 may be spaced away from one or more of the lead ²wires 262. For example, each of the lead wires 262 may extend into the brush ²224 ²from the upper surface 234 of the carbon brush 224 at an insertion point along ²the first²end surface 234 of the brush 224. For instance, the ends of the lead wires 262 ²may be²fixed within bore holes of the brush 224. As shown in FIG. 8 and FIG. 9, the ²cavity ²239 may be spaced away (along the upper surface 234 of the brush 224) from the ²²insertion locations of the lead wires 262. Thus, the cavity 239 is distinct ²from and not ²intended for receiving ends of the lead wires 262 therein.²Further, it can be appreciated that the projection 238 shown in FIG. 8 and ²FIG.²9 may permit the spacer 230 to be releasably attached to the brush 224. In ²other ²words, inserting the projection 238 into the cavity 239 may attach the spacer ²230 to ²the brush 224 with the bottom surface of the spacer 230 juxtaposed with the ²upper ²surface 234 of the brush 224. However, as discussed above, the spacer 230 ²(including²<DP=21>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²the projection 238) may be removed from the brush 224 after being attached ²thereto. ²In other words, the projection 238 may be designed to be inserted into (e.g., ²slide into) ²or removed from (e.g., slide out of) the cavity 239 through manual ²manipulation of ²the spacer 230 relative to the brush 224 without damaging either the spacer ²230 or the²brush 224, and / or without breaking an adhesive bond or other interface ²therebetween.²In some instances, the projection 238 may frictionally engage the sidewall of ²the ²cavity 239 when inserted therein, but be readily removed therefrom with a ²manual ²extraction force applied to the spacer 230 without damaging either the spacer ²230 or ²the brush 224.²Additionally, FIG. 8 and FIG. 9 illustrate that the projection 238 may include ²a²particular shape which may be designed to mate with the shape of the cavity ²239. For ²example, the projection 238 shown in FIG. 8 and FIG. 9 may be generally shaped ²as a ²"spine" extending both across and away from the bottom surface of the spacer ²130. ²As shown in FIG. 8 and FIG. 9, the projection 238 may resemble a rectangular ²spine²extending from the front face of the brush 224 to the back face of the brush ²224. The²spine 238 may be designed to fit snugly within its mating channel 239.²FIG. 10 and FIG. 11 illustrate front and perspective views, respectively, of ²another example spacer 330 and brush 324 (including lead wires 362). It can be ²²appreciated that the spacer 330, brush 324 and lead wires 362 (attached to the ²first end²surface 334 of the brush 324) may be similar in form and function to the ²spacer 30,²brush 24 and lead wires 62 described above.²Similarly to that described above, the spacer 330 may include a projection 338 ²²extending from a bottom surface of the spacer 330 which is designed to engage ²a ²cavity 339 extending into the brush 324 from the first end surface 334 (shown ²in FIG.²10 and FIG. 11) of the brush 324. As illustrated by the dashed lines in FIG. ²10, the²projection 338 may extend into a corresponding cavity 339 located within the ²first end ²surface 334 of the brush 324. It can be appreciated that engagement of the ²projection ²338 within its respective cavity 339 may function to secure the spacer 330 to ²the ²brush 324 in a fixed relationship.² Further, the cavity 339 may be spaced away from one or more of the lead²wires 362. For example, each of the lead wires 362 may extend into the brush ²324 ²from the upper surface 334 of the carbon brush 324 at an insertion point along ²the first ²end surface 334 of the brush 324. For instance, the ends of the lead wires 362 ²may be ²fixed within bore holes of the brush 324. As shown in FIG. 10 and FIG. 11, the ²cavity²21²<DP=22>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²339 may be spaced away (along the upper surface 334 of the brush 324) from the ²²insertion locations of the lead wires 362. Thus, the cavity 339 is distinct ²from and not ²intended for receiving ends of the lead wires 362 therein.²Further, it can be appreciated that the projection 338 shown in FIG. 10 and²FIG. 11 may permit the spacer 330 to be releasably attached to the brush 324. ²In²other words, inserting the projection 338 into the cavity 339 may attach the ²spacer ²330 to the brush 324 with the bottom surface of the spacer 330 juxtaposed with ²the ²upper surface 334 of the brush 324. However, as discussed above, the spacer ²330 ²(including the projection 338) may be removed from the brush 324 after being²attached thereto. In other words, the projection 338 may be designed to be ²inserted²into (e.g., slide into) or removed from (e.g., slide out of) the cavity 339 ²through ²manual manipulation of the spacer 330 relative to the brush 324 without ²damaging ²either the spacer 330 or the brush 324, and / or without breaking an adhesive ²bond or ²other interface therebetween. In some instances, the projection 338 may ²frictionally²engage the sidewall of the cavity 339 when inserted therein, but be readily ²removed²therefrom with a manual extraction force applied to the spacer 330 without ²damaging ²either the spacer 330 or the brush 324.²Additionally, FIG. 10 and FIG. 11 illustrate that the projection 338 may ²include a particular shape which may be designed to mate with the shape of the ²cavity²339. For example, the projection 338 shown in FIG. 10 and FIG. 11 may include ²one²or more tapered sides which extend away from the bottom surface of the spacer ²330. ²Tapered sides of the projection 338 may be juxtaposed with the tapered sides ²of the ²cavity 339 when matingly engaged therein. The projection 338 may be designed ²to ²fit snugly within its mating cavity 339.² The wear state monitor 50 may include a first end region 40, a second end²region 42 and a medial region 43 (see FIG. 3 and FIG. 12) extending ²therebetween. ²The medial region 43 may be generally cylindrical, or other such shape ²designed to ²facilitate integration into a brush holder assembly 110 or other mounting ²location ²within the brush holder assembly 110. In some instances, the medial region 43 ²may²have a cylindrical circumferential surface. Each of the first end region 40 ²and the²second end region 42 may extend radially outward from the circumferential ²surface of ²the medial region 43, thereby creating a groove or recessed area (further ²illustrated in ²FIG. 3 and FIG. 12) in which the coiled portion of the spring 29 may be ²positioned ²between the first end region 40 and the second end region 42.²22²<DP=23>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²As discussed above, the medial portion 43 of the wear state monitor 50 may be ²designed to be captured within the coiled portion of the spring 29. In other ²words, a ²portion of the spring 29 (i.e., the coiled portion) may be coiled (e.g., ²wrapped) around ²the medial region 43 of the wear state monitor 50. As shown in FIG. 12, the ²first end²region 40 and the second end region 42 may provide a shoulder on opposing ²sides of²the coiled portion of the spring 29 to ensure that the spring 29 does not slip ²out of the ²groove defined between the first end region 40 and the second end region 42. ²It can ²be appreciated that the first end region 40 and / or the second end region 42 ²may be ²removable, or otherwise configurable, to allow the wear state monitor 50 to be² mounted within a coiled portion of different sized springs. For example, the²removable and / or configurable first end region 40 and / or second end region 42, ²may ²allow the wear state monitor 50 to be mounted within a coiled portion of a ²spring ²having a first width and a first coil diameter and / or a spring having a second ²different ²width and / or a second different coil diameter.² As discussed above, a sensor may be positioned within the wear state monitor²50 and may measure and collect data representing a current rotational position ²of the ²wear state monitor 50 which can be used to determine the extent (e.g., total ²angular ²distance and / or total arc length) of rotation of the wear state monitor 50 ²from its initial ²position whereby the amount of rotation measured by the sensor (positioned ²within²the wear state monitor 50) may be equivalent, proportional, or otherwise ²representative of the linear or longitudinal movement of the brush 24 (shown ²in FIG. ²1) as it translates (e.g., shortens) within the brush holder 22 (shown in FIG. ²1). In ²particular, the sensor positioned within the wear state monitor 50 may be ²designed to ²detect the absolute angular position of the sensor relative to a permanent ²magnet²positioned adjacent the sensor. For example, FIG. 2 illustrates a magnet 14 ²attached²to the spacer 30, or otherwise incorporated with the spacer 30. While FIG. 2 ²illustrates the magnet 14 approximately aligned with the central axis of the ²wear state ²monitor 50, it is contemplated that the magnet 14 may be positioned along ²other ²portions of the wear state monitor 50 and / or along other elements of the brush ²holder²assembly 110. FIG. 3 illustrates that, in some examples, the medial region 43 ²of the²wear state monitor 50 may include an engagement feature such as a tab, ²shoulder or ²an opening, (not shown in FIG. 2) which may be used to facilitate a connection ²with ²or engagement with the second end 33 of the spring 29 located on the interior ²of the²coiled portion of the spring 29. For ²example, FIG. 3 illustrates a boss (e.g.,²23²<DP=24>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²protrusion) 16 extending away from the outer surface of the medial region 43. ²The ²boss 14 may have a shape configured to mate with a corresponding opening 18 of ²the ²spring 29 proximate the second end 33 of the spring 29. The opening 18 may ²have a ²shape corresponding to a cross-sectional shape of the boss 16. For example, ²the boss²16 may have a circular cross-sectional shape designed to mate with a circular ²shape of²the opening 18. However, while FIG. 3 illustrates the boss 16 and the opening ²18 ²having a circular shape, other shapes are contemplated. For example, the boss ²16 and ²the opening 18 may include square, ovular, rectangular, star, triangular, or ²any other ²geometric shape. It can be appreciated that engagement of the boss 16 with the²opening 18 may rotationally fix the wear state monitor 50 with the coiled ²portion of²the spring 29 such that rotational movement (e.g., coiling) of the coiled ²portion of the ²spring 29 correspondingly rotates the wear state monitor 50 an equal amount.²In other embodiments, the outer surface of the medial region 43 may include a ²shoulder or raised edge configured to engage the second end 33 of the spring ²29 when²the coiled portion of the spring 29 is coiled around the medial region 43. In ²some²instances, the second end 33 of the spring 29 may be trapped underneath the ²layers of ²the coiled spring 29 wound thereover, which may apply a radially inward ²compressive ²force on the second end 33 of the spring 29 to maintain the second end 33 of ²the ²spring 29 against the surface of the medial region 43, ensuring the second end ²33 of² the spring 29 remains rigidly fixed to the wear state monitor 50.²FIG. 3 further illustrates that the first end of the spring 32 may be folded ²back ²on itself to form a tab, wherein the tab is designed to be removably coupled ²to the ²brush holder and / or the mounting beam 26 (shown in FIG. 1). In other words, ²the tab ²19 may be designed to engaged (e.g., be inserted into) a portion of the brush ²holder²and / or the mounting beam 26.²As illustrated in FIG. 3, the spacer 30 may include one or more arcuate ²surfaces 36 defining a concave cradle designed to mate with the ²circumferential ²profile of the wear state monitor 50. In other words, the spacer 30 may ²include one or ²more concave surfaces 36 having a radius of curvature that substantially ²matches the²radius of curvature of the outer surface of the wear state monitor 50. Thus, a ²portion²of the wear state monitor 50 may be positioned in the concave cradle of the ²spacer 30. ²The spacer 30 may be positioned between the coiled portion of the spring 29 ²and the ²upper surface of the brush 24 to space the coiled portion of the spring 29 ²away from ²the brush 24.²24²<DP=25>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²Additionally, FIG. 3 illustrates that the spacer 30 may include a projection ²34 ²designed to engage the second end region 42 of the wear state monitor 50. It ²can be ²appreciated that the second end region 42 may include a recess (not shown) ²which is ²designed to mate with the projection 34 and permit rotational movement of the ²wear²state monitor 50 about a rotational axis aligned with the central axis of the ²projection²34. The engagement of the projection 34 within the recess of the second end ²portion ²may provide additional securement between the wear state monitor 50 and the ²spacer ²30 while permitting rotational movement therebetween. Thus, it can be ²appreciated ²the projection 34 may cooperate with the arcuate surfaces 36 of the concave ²cradle to²permit the wear state monitor 50 to rotate (as described above) when engaged ²with the²spacer 30.²FIG. 12 illustrates an end view of the wear state monitor 50 including the ²first ²end region 40, the second end region 42 and the medial region 43 extending ²therebetween. As discussed above, FIG. 12 illustrates the outer peripheral ²surfaces of²both the first end region 40 and the second end region 42 extending radially ²outward²beyond the cylindrical circumferential surface of the medial region 43. As ²described ²above, the inner surfaces of each of the first end region 40, the second end ²region 42 ²and the circumferential surface of medial region 43 may define a groove in ²which the ²spring 29 may be positioned, with the inner surfaces of the first and second ²end² regions 40, 42 forming shoulders.²FIG. 13 shows a side view of the wear state monitor 50 and the spring 29 ²described above. FIG. 13 illustrates that spring 29 may include an elongate ²portion ²extending away from the wear state monitor 50 whereby the first end 32 of the ²spring ²29 extends past the outer circumferential surface of the wear state monitor ²50. As²noted above, the first end 32 of the spring 29 (including tab 19 described ²above) may²be removably coupled to the brush holder and / or the mounting beam 26 with the ²elongate portion of the spring 29 extending along a side surface of the brush ²24, ²between the brush 24 and the mounting beam 26. Additionally, FIG. 13 ²illustrates ²spring 29 wrapping around the medial region 43 of the wear state monitor 50. ²For²example, the dashed line represents the spring 29 wrapping around the medial ²region²43 of the wear state monitor 50, whereby the second end 33 of the spring 29 is ²²coupled to or otherwise in contact with the wear state monitor 50, such as via ²the boss ²16 and opening 18 connection, as described above with respect to FIG. 3.²<DP=26>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²FIG. 14 illustrates an exploded view of the wear state monitor 50 described ²above. As illustrated in FIG. 14, the wear state monitor 50 may include an ²exterior ²housing 52. The exterior housing 52 may include an inner cavity 54. The cavity ²54 ²may be configured to contain one or more internal components of the wear state²monitor 50. The wear state monitor 50 may also include a housing lid 60 ²configured²to mate with the exterior housing 52. In other words, the lid 60 may be ²designed to be ²rigidly attached to the exterior housing 52. In other instances, the exterior ²housing 52 ²may be adhesively bonded or snap fit to the lid 60 to secure the exterior ²housing 52 ²and the lid 60 together. Further, the lid 60 may include an aperture 71 ²extending² through the entire wall thickness of the lid 60.²Additionally, the wear state monitor 50 may include a button 59. In some ²instances, the button 59 may be a Viton button. The button 59 may be utilized ²to pair ²the wear state monitor 50 to another device via a Bluetooth connection, for ²example. ²Further, it can be appreciated that a portion of the button 59 may be designed ²to²project through the aperture 71 of the lid 60, thereby making the button 59 ²accessible²to depress and pair the wear state monitor 50 to another device via a ²Bluetooth ²connection. When the exterior housing 52 is engaged with the lid 60 and the ²button ²59, the cavity 54 created by the combination of the exterior housing 52, the ²lid 60 and ²the button 59 may be sealed to the outside environment.² In other instances the housing 52 may include a first housing section and a²second housing section separable from one another to expose an interior cavity ²of the ²wear state monitor 50 housing the internal components of the wear state ²monitor 50. ²In some instances, the first housing section and the second housing section ²may be ²hingedly connected (e.g., connected in a "clam shell" configuration), or ²otherwise²movable relative to one another. In such cases, when the wear state monitor 50 ²is²located within the coiled portion of the spring 29 (e.g., a helical spring), ²the force ²provided by the spring 29 may facilitate a compression connection or snap fit ²connection for engaging the first housing section with the second housing ²section of ²the wear state monitor 50. In other instances, the first housing section may ²be²adhesively bonded or snap fit to the second housing section to secure the ²first and²second housing sections together.²FIG. 14 further illustrates that the wear state monitor 50 may further include ²a ²power source 53 (e.g., one or more batteries, capacitors, or both) and a ²sensor 56 (it is²26²<DP=27>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²noted that the sensor 56 may correspond to the sensor described above with ²respect to ²FIG. 1). The power source 53 may be rechargeable and / or replaceable.²In some instances, the sensor 56 may be referred to as an angular sensor 56 ²and / or a magnetic encoder 56. As discussed above, the sensor 56 may produce a²signal corresponding to the rotation (e.g., the absolute angular position) of ²the wear²state monitor 50 relative to the stationary magnet 14 described above with ²respect to ²FIG. 2. For example, the sensor 56 may be able to sense a change in the ²magnetic ²field created by the magnet 14, thus determining a rotational orientation of ²the wear ²state monitor 50. The signals provided by the sensor 56 corresponding to the²rotational orientation of the wear state monitor 50 may be compared to ²determine an²angular displacement of the wear state monitor 50 between two temporal ²occasions, ²such as between an angular position of the wear state monitor 50 when the ²brush 24 is ²installed in the brush holder assembly 110 and some later time when the brush ²24 has ²worn. These signals (corresponding to the angular displacement and / or ²rotational²orientation of the wear state monitor 50) may be communicated to the site ²monitor²120 via a variety of communication methods. In some instances, the sensor 56 ²may ²additionally include an accelerometer configured to sense dynamic vibration of ²the ²brush 24 in the brush holder 22. For example, the sensor 56, in addition to ²sensing ²angular displacement and / or rotational orientation of the wear state monitor ²50, may²sense transient angular displacement of the wear state monitor 50 ²corresponding to²dynamic vibration of the brush 24.²Additionally, in some cases, the power source 53 and / or sensor 56 may be ²located within the cavity 54 of the wear state monitor 50, such that the power ²source ²53 and / or the sensor 56 may be integrated with the wear state monitor 50. ²Further, it²can be appreciated that when the exterior housing 52 is engaged with the lid ²60 and²the second button member 59, both the power source 53 and the sensor 56 may be ²²sealed within the cavity 54 formed by the combination of the exterior housing ²52, the ²lid 60 and the second button member 59..²Additionally, FIG. 14 illustrates that the wear state monitor 50 may include a²first foam insulation member 61a and a second foam insulation member 61b. In ²some²instances, each of the first foam insulation member 61a and the second foam ²insulation member 61b may be formed from silicone. Other materials may be ²utilized ²to form the first foam insulation member 61a and / or the second foam insulation ²²member 61b. Further, the first foam insulation member 61a and the second foam²27²<DP=28>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²insulation member 61b may be utilized to insulate the power supply 53 when ²positioned within the cavity 54. In other words, when positioned inside the ²cavity 54, ²the power supply 53 may be disposed between the first foam insulation member ²61a ²and the second foam insulation member 61b.² The power source 53 of the wear state monitor 50 may be used to supply²power to one or more components of the wear state monitor 50, such as the ²sensor 56, ²to facilitate the measurement and generation of a value representative of the ²angular ²displacement or rotation of the wear state monitor 50 (which is proportional ²to the ²diminution in length of the brush 24 during use, as described above). In other ²words,²to as the wear ²state monitor 50 rotates in response to the diminution in length of the²brush 24 as the brush 24 wears, the sensor 56 may sense, measure and collect ²the ²information (e.g., data) of the amount of rotation or angular displacement of ²the wear ²state monitor 50, which is proportional to or otherwise correlates to the ²amount of ²diminution in length of the brush 24. The wear state monitor 50 rotates about ²an axis²of rotation passing through the center of the wear state monitor 50. The axis ²of²rotation is a fixed distance from the second end 34 of the carbon brush 24 as ²the wear ²state monitor 50 rotates, and thus the axis of rotation translates with the ²brush 24 as ²the brush 24 wears and diminishes in length.²For example, in some instances, the sensor 56 may obtain values²corresponding to a first position of the brush 24, at a first temporal ²occasion To, such²as an initial position of the brush 24 when the brush 24 has been placed on ²the ²electrical device and having approximately no wear. In other words, the sensor ²56 ²may be used to sense the angular position of the wear state monitor 50 at the ²initial ²temporal occasion To. The sensor 56 may obtain values corresponding to a ²position²of the brush 24 at a later temporal occasion Ti after the brush has been worn ²a first²amount. In other words, the sensor 56 may be used to sense the angular ²position of ²the wear state monitor 50 at the temporal occasion Ti. The sensor 56 may ²obtain ²additional values corresponding to a further positions of the brush 24 at ²later temporal ²occasions Tz, T3, T4, etc. after the brush has been worn an additional amount. ²In other²words, the sensor 56 may be used to sense the angular position of the wear ²state²monitor 50 at the further temporal occasions Tz, T3, T4, etc. The angular ²displacement ²of the wear state monitor 50 between each temporal occasion may be used to ²determine the diminution in length of the brush 24, and thus the current wear ²state of ²the brush 24 and / or project when the brush 24 will diminish in length to a ²threshold²28²<DP=29>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²amount at a future time. In some instances the threshold amount may correspond ²to a ²brush length approximating when the brush 24 has a predetermined amount of ²wear ²(e.g., approaching the replacement threshold, maximum allowable wear, etc.). ²Additionally, in some cases, the sensor 56 may be configured to sense a first²threshold value corresponding to a first wear state of the brush 24 and a ²second²threshold value different from the first threshold value corresponding to a ²second ²wear state of the brush 24. For example, the first threshold value may include ²the ²total rotation amount or angular displacement of the wear state monitor 50 ²indicative ²of a wear state where the brush 24 should be replaced within a predetermined ²time²period (e.g., within a week). The second threshold value may correspond to a ²total²rotation amount or angular displacement of the wear state monitor 50 ²indicative of a ²wear state requiring the brush 24 to be replaced as soon as possible.²FIGS. 15 and 16 illustrate side views of the brush holder assembly 110 shown ²in FIG. 1, at different temporal occasions representing different identifiable ²wear²states of the brush 24. For simplicity purposes, the spacer 30 (shown in FIG. ²1) has²been removed from FIGS. 15 and 16. Additionally, FIGS. 15 and 16 illustrate ²the ²brush holder assembly 110 including the brush holder 22 secured to the ²mounting ²beam 26, whereby the mounting beam 26 is configured to be removably mounted to ²²the mounting block 70. Further, FIGS. 15 and 16 show the mounting beam 26² including the upper beam member 27 and the lower beam member 28 pivotally ²coupled to one another in the engaged position, as described above with ²respective to ²FIG. 1. FIG. 15 and FIG. 16 further illustrate the brush holder assembly 110 ²including a handle 21 and the conductive wires 62 attached to both the brush ²24 and ²extending therefrom.² As discussed above and illustrated in FIGS. 15 and 16, an end region of the²spring 29 may be coiled around a portion (e.g., the medial region) of the wear ²state ²monitor 50 while the elongate portion of the spring 29 extends along a side ²surface of ²the brush 24 with the first end 32 of the spring 29 coupled to the mounting ²beam 26. ²Further, while not visible in FIGS. 15 and 16, a sensor and / or power supply ²may be²positioned within an interior space (e.g., a cavity) within the wear state ²monitor 50 (as²described above).²FIG. 15 illustrates a first configuration (e.g., an initial wear state) of the ²brush ²24 at an initial temporal occasion To, such as when the brush 24 of the brush ²holder ²assembly 110 is first installed on an electrical machine. FIG. 15 illustrates ²the brush²29²<DP=30>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²24 positioned within the brush holder 22 (as described above with respect to ²FIG. 1), ²with the lower surface of the brush 24 engaged with the conductive surface 12 ²of the ²rotating component 15. Additionally, FIG. 15 shows that the first end surface ²34 of ²the brush 24 is positioned a distance Xi from the end of the brush holder 22 ²nearest²the handle 21 at an initial position at the initial temporal occasion To. It ²can be²appreciated that when the brush holder assembly 110 is in an engaged position, ²the ²spring 29 may apply a force to the first end surface 34 of the brush 24 to ²engage the ²brush 24 with the conductive surface 12 of the rotating component 15.²For illustrative purposes, FIG. 15 includes a "rotation marker" 64 placed on²io the wear state monitor 50. For simplicity, the rotation marker 64 has ²been placed on²the wear state monitor 50 at approximately the "twelve 'o clock" position, but ²could ²be placed at any desired location. The rotation marker 64 need not be a visual ²marker, ²although it is possible to include a visual marker. The rotation marker 64 may ²be ²representative of a positional signal provided by the sensor 56of a rotational² orientation of the wear state monitor 50.²FIG. 16 illustrates a second configuration (e.g., a second wear state) of the ²brush 24 at a later temporal occasion Ti, such as after the brush 24 has ²engaged the ²conductive surface 12 of the rotating component 15 over a period of time and ²diminished in length. As described above, the spring 29 may continue to exert ²a force²on the first end surface 34 of the brush 24 as the brush 24 wears away against ²the²conductive surface 12 of the rotating component 15. For example, FIG. 16 ²illustrates ²the first end surface 34 of the brush 24 positioned a distance X2 from end of ²the brush ²holder 22 nearest the handle. It can be appreciated that the difference ²between ²distance "X2" and distance "Xi" shown in FIG. 15, represents the amount of²diminution in length of the brush 24 (i.e., how much the brush 24 has ²shortened in²length).²Additionally, as described above, as the brush 24 translates within the brush ²holder 22, the wear state monitor 50 may rotate in proportion to the length of ²²shortening of the brush 24. The rotation or angular displacement 0 of the wear ²state²monitor 50 between the initial rotational position of the wear state monitor ²50 at To²and the rotational position of the wear state monitor 50 at Ti is illustrated ²in FIG. 16. ²Additionally, FIG. 16 shows the rotation position marker 64 in a second ²position, ²further representing the rotation or angular displacement of the wear state ²monitor 50.²<DP=31>²CA 03114764 2021-03-29²WO 2020 / 072806 ² PCT / US2019 / 054549²It is noted that the rotational axis of the wear state monitor 50 remains at a ²fixed ²distance from the upper surface of the brush 24 throughout the wear of the ²brush 24. ²As described above, as the wear state monitor 50 rotates in response to the ²shortening of the brush 24 (e.g., the wearing of the second end surface 35 of ²the brush²24), the sensor 56 may measure and collect information relating to the ²rotation or²angular displacement of the wear state monitor 50. Further, this information ²relating ²to the rotation or angular displacement of the wear state monitor 50 may be ²analyzed ²to determine an amount of diminution in length of the brush 24, a current wear ²state ²of the brush 24, a wear rate of the brush 24, and / or predict a future wear ²state of the²brush 24 at a future time. Such information and / or data regarding the state of ²the²brush 24 may be communicated to the site monitoring device 120 and / or a remote ²²monitoring device 140. The remote monitoring device 140 may be located at the ²same and / or at a different geographical location from the geographical ²location of the ²electrical machine and the site monitoring device 120.² In some cases, the wear state monitor 50, the site monitor 120 and / or the²remote monitoring device 140 may include a processor capable of processing ²instructions for predicting a life expectancy of the brush 24 and / or the ²rotating ²component 15 of the electrical machine. In some cases, the processor may be ²capable ²of processing instructions for identifying the wear state of the carbon brush ²and / or²identifying the wear state of the rotating electrical component (e.g., a slip ²ring, a²commutator, etc.) of the electrical device.²Those skilled in the art will recognize that aspects of the present disclosure ²²may be manifested in a variety of forms other than the specific embodiments ²described and contemplated herein. Accordingly, departure in form and detail ²may be²made without departing from the scope and spirit of the present disclosure as²described in the appended claims.²31²

Claims

<DP=1>²CA 03114764 2021-03-29²WO 2020 / 072806 ²PCT / US2019 / 054549²CLAIMS²What is claimed is:²1. An assembly for a brush holder assembly of an electric machine, ²comprising:²a carbon brush including an upper surface and a lower surface opposite the ²upper surface,²one or more lead wires extending out of the carbon brush at an insertion point ²²on the upper surface;²a first cavity extending into the carbon brush from the upper surface at a²location spaced away from the insertion point of the one or more lead wires ²and ²unobstructed by the one or more lead wires.²2. The assembly of claim 1, further comprising a spacer coupled to the ²carbon brush, the spacer including a first projection configured to releasably ²engage ²within the first cavity.²3. The assembly of claim 2, further comprising a wear state monitor ²coupled to the spacer, wherein the wear state monitor is designed to measure ²an²angular displacement of the wear state monitor as the wear state monitor ²rotates.²4. The assembly of claim 3, wherein the brush further includes a length ²measured from the upper surface to the lower surface, wherein the length is ²diminished from an initial length as the lower surface of the carbon brush ²wears away ²during use and wherein the measured angular displacement of the wear state ²monitor ²correlates to the diminished length of the carbon brush.²5. The assembly of claim 2, wherein engagement of the first projection in ²the first cavity of the carbon brush is configured to retain the spacer in a ²fixed ²relationship with the carbon brush.²6. The assembly of claim 5, wherein the first projection extends away ²from a bottom surface of the spacer.²32²<DP=2>²CA 03114764 2021-03-29²WO 2020 / 072806 ²PCT / US2019 / 054549²7. The assembly of claim 6, wherein the first cavity includes a channel ²extending along the upper surface of the carbon brush, and wherein the first ²projection ²is configured to mate with and insert into the channel.²8. The assembly of claim 7, wherein the first cavity includes a first²tapered surface, and wherein the first projection includes a second tapered ²surface ²designed to mate with the first tapered surface of the first cavity.²9. The assembly of claim 2, wherein the carbon brush further comprises a ²second cavity extending into the carbon brush from the upper surface at a ²location ²spaced away from the insertion point of the one or more lead wires and ²unobstructed ²by the one or more lead wires, wherein the second cavity is spaced away from ²the first ²cavity.²10. The assembly of claim 9, wherein the spacer further comprises a ²second projection configured to releasably engage within the second cavity.²11. The assembly of claim 10, wherein the first projection and the second ²projection are designed to engage the carbon brush simultaneously, and wherein ²the ²engagement of the first projection and the second projection with the first ²and second ²cavities of the carbon brush is configured to retain the spacer in a fixed ²relationship ²with the carbon brush.²12. The assembly of claim 11, wherein both the first projection and the ²second projection extend away from a bottom surface of the spacer.²13. The assembly of claim 12, wherein the shape of both the first ²projection and the second projection is designed to mate with the first cavity ²and the ²second cavity.²14. A system for monitoring the wear state of a carbon brush, comprising: ²a brush holder assembly, the brush holder assembly including:²33²<DP=3>²CA 03114764 2021-03-29²WO 2020 / 072806 ²PCT / US2019 / 054549²a carbon brush including an upper surface, a lower surface opposite the ²upper surface, and a length measured from the upper surface to the lower ²surface,²wherein the length is diminished from an initial length as the lower surface ²of ²the carbon brush wears away during use;²a spring having a first end and a second end, and a coiled portion;²a wear state monitor positioned within the coiled portion of the spring, ²the wear state monitor including a sensor, wherein the sensor is configured to ²²measure an angular displacement of the wear state monitor as the wear state ²monitor rotates;²a spacer positioned between the coiled portion of the spring and the ²upper surface of the carbon brush, the spacer including a first projection ²extending away from a bottom surface of the spacer;²wherein the carbon brush includes a first cavity extending into the ²carbon brush from the upper surface, and wherein the first cavity receives the ²²first projection therein.²15. The system of claim 14, further comprising a lead wire having a first ²end and a second end extending away from the first end, wherein the first end ²extends ²into the carbon brush at an insertion point at the upper surface of the carbon ²brush and ²spaced away from the first cavity.²16. The system of claim 14, wherein engagement of the first projection ²within the first cavity is configured to retain the spacer in a fixed ²relationship with the ²carbon brush.²17. The system of claim 16, wherein the measured angular displacement of²the wear state monitor correlates to an amount of diminution in the length of ²the ²carbon brush.²18. The system of claim 14, wherein the first cavity includes a channel ²extending along the upper surface of the carbon brush, and wherein the first ²projection ²is configured to mate with and insert into the channel.²34²<DP=4>²CA 03114764 2021-03-29²WO 2020 / 072806 ²PCT / US2019 / 054549²19. The system of claim 14, wherein the first cavity includes a tapered ²surface, and wherein the first projection includes a tapered surface designed ²to mate ²with the tapered surface of the first cavity.²20. The system of claim 15, wherein the carbon brush further comprises a ²second cavity extending into the carbon brush from the upper surface of the ²carbon ²brush, wherein the second cavity is spaced away from the first cavity.²21. The system of claim 20, wherein the spacer further comprises a second ²projection extending into the second cavity.²22. The system of claim 21, wherein the first projection and the second ²projection are designed to engage the carbon brush simultaneously, and wherein ²the ²engagement of the first projection and the second projection with the carbon ²brush is ²configured to retain the spacer in a fixed relationship with the carbon brush.²23. The system of claim 22, wherein both the first projection and the ²second projection extend away from a bottom surface of the spacer.²24. The system of claim 23, wherein the bottom surface of the spacer is ²juxtaposed with the upper surface of the carbon brush when the first and ²second ²projections are positioned in the first and second cavities.²25. An assembly for a brush holder assembly of an electrical device, ²comprising:²a carbon brush including an upper surface, a lower surface opposite the upper ²surface, and a length measured from the upper surface to the lower surface;²one or more lead wires extending out of the carbon brush at an insertion point ²²on the upper surface;²first and second cavities extending into the carbon brush from the upper²surface at a location spaced away from the insertion point of the one or more ²lead ²wires and unobstructed by the one or more lead wires; and²a spacer having first and second projections extending from a lower surface of ²²the spacer;²<DP=5>²CA 03114764 2021-03-29²WO 2020 / 072806 ²PCT / US2019 / 054549²wherein the first and second projections are configured to be inserted into ²the ²first and second cavities when the lower surface of the spacer is juxtaposed ²with the ²upper surface of the carbon brush.²36²