Seal strip wear monitoring system and assembly thereof

Abstract

The seal strip and wear monitoring system includes a seal strip having a top surface; and a wear monitoring system including a sensing portion including a plurality of electrical traces, each of the plurality of electrical traces having a top portion generally parallel to and disposed at a predetermined depth from the top surface of the seal strip, where the depth of the top portion of each trace is different from the depth of the top portions of other electrical traces; and a signal processing portion electrically connected to the plurality of electrical traces, the signal processing portion including circuitry configured to detect electrical signals from the plurality of traces and to determine when the top portion of a trace has been damaged.

Description

[Technical Field]

[0001] Related Applications This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63 / 481,835, filed January 27, 2023, the disclosure of which is incorporated herein by reference in its entirety.

[0002] The present invention is directed generally to papermaking, and more specifically to suction rolls and equipment within papermaking machines. [Background technology]

[0003] The papermaking process inherently requires the removal of moisture at many stages in the production process. Typically, paper pulp (a slurry of water and wood and other fibers) is placed on top of a felt (in the form of a wide belt) which acts as a carrier for the wet pulp before the actual sheet of paper is formed. The felt is used to transport the pulp through the wet section of the paper machine until enough moisture has been removed from the pulp so that a paper sheet can be processed without the additional support of the felt.

[0004] Very commonly in the wet end of a paper machine, initial water removal is accomplished using a suction roll (either a couch, pickup, or press suction roll) in the press section, used in combination with an aligned, opposing, non-perforated standard press roll (or Yankee dryer in tissue machines). The felt pulp carrier is pressed between these two rolls.

[0005] The primary components of the suction roll 10 include a hollow shell 12 (FIG. 1) made of stainless steel, bronze, or other metal, containing tens of thousands of holes drilled in a predetermined pattern radially around the circumference of the roll. The size of these holes (ranging from less than 1 / 8 inch to nearly 1 / 4 inch) is designed for the specific paper material being processed. These holes form "vents" for moisture removal. These vents can typically range from approximately 20 to 45 percent of the roll's effective surface area. The suction roll shell is driven by a drive system that rotates the shell around a fixed core called the suction box.

[0006] The suction box 20 (FIG. 2) can be thought of as a conventional rectangular box with an open top and ports on the ends, bottom, or sides. The ends of the box (specifically, the drive end) typically contain a pilot bearing, whose inner raceway is a pilot bushing or bearing that slip-fits against a journal on the suction box, and whose outer raceway presses against a rotating shell. The suction box 20 is connected to a suction source (e.g., a vacuum pump). An exemplary suction box and shell are shown in U.S. Pat. No. 6,358,370 to Huttunen, the disclosure of which is incorporated herein in its entirety.

[0007] To utilize the holes in the shell, a vacuum zone 30 must be created inside the suction roll shell using these ports, in the zone directly below the paper pulp being processed. This is accomplished by the suction box 20 using slotted holders 32 that hold seals along the long axis of the suction box on both sides. Figure 2 shows the slotted holders 32, and Figures 3 and 4 show two types of seals 34 and 34' in the form of strips (hereinafter "seal strips"). In addition to these long seals, the short ends (called the tending and drive ends) have two short seals (called end deckles) that allow for some axial adjustment needed to accommodate various sheet widths.

[0008] The seal strips 34 and 34' are typically made of rubberized polymerized graphite and are held in substantial contact with the inner surface of the shell 12 during operation (see FIGS. 3 and 4). A constant vacuum is drawn between the seal strips 34 and 34', allowing a vacuum zone 30 to form under the sheet 40 passing over the roll 10. The seal strips 34 and 34' are biased upward toward the suction roll shell 12 by a load tube 42, a sealed hose that runs under the entire length of the seal strips 34 and 34'. Pressure within the load tube 42 expands the load tube 42 (like air in a balloon) and lifts the seal strips 34 and 34' toward the inner surface of the shell 12. This effect, along with the assistance of the system vacuum from the suction box 20 and the laminar flow of lubricating water described above, forms a seal between the end of the seal strip 34 and the inside of the shell 12.

[0009] In actual applications, in a properly functioning suction roll, the sealing strips 34 and 34' never come into direct contact with the inside of the suction roll shell 12. If the sealing strips 34 and 34' were to contact the shell 12, they would wear and quickly lose their sealing ability. To eliminate or significantly reduce this wear and to provide a seal, water is applied along the length of the sealing strips 34 and 34' in a lubrication shower formed by water flowing through spray nozzles 24 (see FIG. 2). This shower keeps the sealing strips 34 and 34' lubricated by a laminar flow of water between the sealing surfaces and the inner surface of the shell 12.

[0010] The amount of water used for lubrication should be properly metered so that just the right amount of lubricant is applied to keep the seal strips 34 and 34' lubricated, but not so much that it causes problems for the pulp being processed or wastes water. Additionally, process water used in paper mills can contain chemicals and also significant particulates that can clog the lubrication shower nozzles 24 during normal operation. These nozzles 24 are located inside the rotating shell 12 and are therefore not visible to the paper machine operator. Summary of the Invention [Problem to be solved by the invention]

[0011]

[0003] The seal strip is typically replaced periodically after a certain amount of wear occurs. However, because the seal strip inside the suction roll is not visible to the papermaking equipment operator or anyone who chooses to view the seal strip, many conditions inside the suction roll during operation, including the extent of seal strip wear, are unknown. Therefore, a reliable method of detecting seal strip wear may be desired to alert the papermaking equipment operator that maintenance of the equipment is required before a failure occurs. [Means for solving the problem]

[0012] In a first aspect, an embodiment of the present invention is directed to a seal strip and a wear monitoring system, the system including a seal strip having an upper surface and a wear monitoring system, the wear monitoring system including a sensing portion including a plurality of electrical traces, each of the plurality of electrical traces including a top portion disposed at a predetermined depth from the upper surface of the seal strip, where the depth of the top portion of each trace is different from the depth of the top portions of the other electrical traces, and a signal processing portion electrically connected to the plurality of electrical traces, the signal processing portion including circuitry configured to detect electrical signals from the plurality of traces and to determine when the top portion of a trace has been damaged.

[0013] In a second aspect, an embodiment of the present invention is directed to a sealing strip monitoring system including: a sealing strip having a top surface; a printed circuit board (PCB) having first and second fingers and a main panel; a wear monitoring system; and a temperature monitoring system at least partially mounted to the PCB. The wear monitoring system includes a sensing portion including a plurality of electrical traces, each of the plurality of electrical traces having a top generally parallel to the top surface of the sealing strip and disposed at a predetermined depth from the top surface of the sealing strip, where the depth of the top of each trace is different from the depth of the top of each other electrical trace, where the top of the plurality of electrical traces is disposed on the first finger; and a signal processing portion electrically connected to the plurality of electrical traces, the signal processing portion being mounted to the main panel of the PCB and including circuitry configured to detect electrical signals from the plurality of traces and to determine when the top of a trace has been damaged. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a perspective end view of a typical paper machine suction roll. [Figure 2] FIG. 2 is an enlarged perspective end view of the vicinity of the suction box of a typical suction roll. [Figure 3] FIG. 3 is an end view of the suction box area and sealing strip of a conventional suction roll. [Figure 4] FIG. 4 is an end view of the suction box area and seal strip of another conventional suction roll. [Figure 5] FIG. 5 is a schematic side view of a seal strip and wear monitoring system in accordance with an embodiment of the present invention. [Figure 6] FIG. 6 is a schematic diagram of the wear monitoring system of FIG. [Figure 7A] 7A is a serial perspective view illustrating the structure of the sensing portion of the wear monitoring system of FIG. [Figure 7B] 7B is a serial perspective view illustrating the structure of the sensing portion of the wear monitoring system of FIG. [Figure 7C] 7C is a serial perspective view illustrating the structure of the sensing portion of the wear monitoring system of FIG. [Figure 8] FIG. 8 is a perspective view of the electronic components of the wear monitoring system of FIG. [Figure 9] FIG. 9 is a schematic diagram of a wear monitoring system in accordance with an alternative embodiment of the present invention. [Figure 10] FIG. 10 is a schematic diagram of a wear monitoring system in accordance with an alternative embodiment of the present invention. [Figure 11] FIG. 11 is a plan view of a seal strip monitoring system in accordance with an embodiment of the present invention. [Figure 12A] 12A is a serial perspective view illustrating the structure of the seal strip monitoring system of FIG. [Figure 12B] 12B is a serial perspective view illustrating the structure of the seal strip monitoring system of FIG. [Figure 12C] 12C is a serial perspective view illustrating the structure of the seal strip monitoring system of FIG. [Figure 12D] 12D is a serial perspective view illustrating the structure of the seal strip monitoring system of FIG. [Figure 13] FIG. 13 is a schematic diagram of a wear monitoring system according to a further embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention will be described in more detail below, illustrating embodiments of the invention. However, the present invention may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, like reference numerals refer to like elements. The thickness and dimensions of some elements may be exaggerated for clarity.

[0016] Additionally, spatially relative terms, such as "under," "below," "lower," "over," "upper," etc., may be used herein to describe the relationship of one or more elements or features to one or more other elements or features, as shown in the figures. It will be understood that spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures were turned over, an element described as "under" or "beneath" another element or feature would then be oriented "over" the other element or feature. Thus, the exemplary term "under" can encompass both an orientation of "over" and "under." The device may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein would be interpreted accordingly.

[0017] Well-known functions or constructions may not be described in detail for the sake of brevity and / or clarity.

[0018] Referring now to the drawings, a seal strip 100 and associated wear monitoring system 120 are shown in FIGS. 5-8. Except for the housing for the wear monitoring system 120, described below, the seal strip 100 is generally similar to the conventional design described above. The seal strip 100 is elongated and of generally constant cross-section. The seal strip 100 resides in a channel-shaped holder and is supported by a load tube against its lower surface 105. The load cell urges the seal strip 100 upward (i.e., toward the shell of the suction roll) so that its upper surface 106 faces the shell and contributes to the seal, and is formed of a polymer material, such as rubber (which may be filled with a filler, such as graphite).

[0019] 5, a wear monitoring system 120 is shown incorporated within the seal strip 100. The wear monitoring system 120 includes a sensing portion 122, a signal processing portion 124, and a cable 126 connecting the sensing portion 122 to the signal processing portion 124. The seal strip 100 includes a channel 108 on its underside through which the cable 110 is routed between adjacent wear monitoring systems 120. A cap 128 also surrounds the upper end of the sensing portion 122 and is flush with the upper surface 106 of the seal strip 100.

[0020] 6, the sensing portion 122 typically includes a printed circuit board (PCB) 123 having traces 130 (discussed in more detail below). The signal processing portion 124 typically includes a PCB 125 having processing components (discussed in more detail below). Also, although shown as separate PCBs herein, the sensing portion 122 and the signal processing portion 124 may be formed on the same PCB (see, for example, system 420 shown in FIGS. 11-12D below).

[0021] Referring now to Figure 6, a wear monitoring system 120 is shown schematically. The sensing portion 122 shown at the top of Figure 6 comprises a plurality of electrical traces 130 on a PCB 123. As can be seen in Figure 6, the plurality of traces 130 are laid out on the PCB 123 as a series of generally U-shaped lines, with the upper horizontal "runs" 132 (the tops of each trace 130) of each trace 130 being spaced a fixed distance apart, such that the upper runs 132 are spaced apart from one another (in some embodiments, they may be evenly or regularly spaced apart, for example, 1 / 32 inch in this example), and each at a different "depth" (i.e., distance from the upper surface 106 of the sealing strip 100). One of the vertical runs 134 of each trace 130 is connected (through cable 126) to a switch 140 on PCB 125 of signal processing section 124, and the other of the vertical runs 136 of each trace 130 is connected (also through cable 126) to an individual capacitor 142 mounted on PCB 125. (It should be understood that in some embodiments, capacitors 142 may be mounted on or near multiple traces 130 themselves.)

[0022] 6, the signal processing section 124 also includes a microcontroller 146, a power supply 148, and a communication driver 150. The switch 140 is connected to the microcontroller 146 both directly and through parallel charge / discharge resistors 152a, 152b and a sampling buffer 153. The microcontroller 146 is connected to the power supply 148 and to the communication driver 150. Both the power supply 148 and the communication driver 150 are connected to a data and power bus 154. All of the capacitors 142 are also connected in parallel and to ground.

[0023] The wear monitoring system 120 operates by repeatedly sampling each trace 123 and its corresponding capacitor 142. When a direct connection is made between the charging resistor 152a and the capacitor 142, the capacitor 142 begins to charge. This relationship can be understood as the following equation:

number

number

[0024] 6, the time constant τ is 1 ms when capacitor 142 is a 10 nF capacitor, charging resistor 152a is 100 KΩ, and the supply voltage is 5 V. Based on the knowledge that a capacitor typically reaches steady state (approximately 99% of its maximum charge) after 5 τ, it can be calculated that the voltage on capacitor 142 should be approximately 4.97 V after 5 ms. If the measured voltage across capacitor 142 being sampled is within a threshold (e.g., within 10%) of this value, it can be assumed that the connection between capacitor 142 and charging resistor 152a is intact.

[0025] It should also be appreciated that in some embodiments, the discharge rate may be defined by the following formula:

number

[0026] As the seal strip 100 is used, it undergoes wear. When the top surface 106 of the seal strip 100 wears to the extent that the material of the seal strip 100 above the furthest, farthest trace 130a (i.e., the trace whose run 132 is closest to the top surface of the seal strip 100, see FIG. 6 ) wears away, the trace 130a also wears away. Wear on the trace 130a destroys the connection between its corresponding capacitor 142a and charging resistor 152a. Thus, when the switch 140 samples the connection to the capacitor 142a, the measured voltage is outside the acceptable range, thereby indicating that the trace 130a has been damaged and, therefore, that the wear on the seal strip 100 has reached the depth of the trace 130a.

[0027] As seal strip 100 continues to wear, top surface 106 wears away until it reaches run 132 of the next-furthest trace 130b. As trace 130b continues to wear, its connection to its corresponding capacitor 142b is broken. That broken connection is detected when switch 140 attempts to connect to capacitor 142b. This process can continue either (a) until all of the traces 130 are broken, or (b) until a user chooses to replace the worn seal strip 100 when a certain wear depth is reached.

[0028] 7A-7C show an exemplary configuration and structure of the sensing unit 122. As shown in FIG. 7A, the PCB 123 includes a plurality of traces 130 and a plurality of contact pads 131 for connecting the plurality of traces 130 to the signal processing unit 124 via a cable 126. FIG. 7B illustrates the application of a cap 128 that serves to insulate and protect the plurality of traces 130. FIG. 7C shows that any space between the cap 128 and the PCB 123 may be filled with a potting compound 129, and also shows that the cable 126 is attached to the plurality of contact pads 131.

[0029] FIG. 8 illustrates an exemplary configuration of the signal processing unit 124. As shown in FIG. 8, the capacitor 142 is mounted to the PCB 125, as is the control circuitry (i.e., the microcontroller 146, the power supply 148, and the communication driver 150). FIG. 8 shows the cable 126 attached to contact pads (not shown) at one end of the PCB 125. Connectors 160 are also mounted near either end of the PCB 125 to allow the system 120 to be "daisy-chained" to other systems 120 along the length of the sealing strip 100, thereby forming an overall assembly capable of providing a full-length wear profile for the sealing strip 100.

[0030] An alternative embodiment of a wear monitoring system is illustrated in FIG. 9 and is generally designated 220. Wear monitoring system 220 is similar to wear monitoring system 120 in that it includes a sensing portion 222 mounted on PCB 223 having traces 230 and a signal processing portion 224 mounted on PCB 225, with the sensing portion 222 and signal processing portion 224 connected by cable 226. However, rather than a capacitor, wear monitoring system 220 relies on a plurality of resistors 242 connected to traces 230 of sensing portion 222. These resistors are connected in parallel to ground and to each other. The detection circuitry mounted on signal processing portion 224 is also slightly different, with switch 240 connected directly to microcontroller 246 and to resistor 252, which is connected to voltage supply 247 on one end and to microcontroller 246 via sampling buffer 253 on the other end.

[0031] When switch 240 connects resistor 252 to one of resistors 242, the relationship can be defined as:

number

[0032] In the system 220 illustrated in FIG. 9, when the supply voltage is 5V, the plurality of resistors 242 is 10 kΩ, and the resistor 252 is also 10 kΩ, the output voltage V out is half the supply voltage, or 2.5V.

[0033] As described above, as seal strip 200 wears during use, it will eventually reach and damage run 232 of the farthest trace 230a. When switch 240 connects resistor 242a with charging resistor 252, the voltage should be approximately 2.5V. If this measurement changes by more than a certain threshold (e.g., 10%), system 220 recognizes that such a measurement indicates that seal strip 200 has worn to the depth of run 232 of trace 230a.

[0034] The voltage reading can be either 0 V, indicating a short circuit, or 5 V, indicating an open circuit. An open circuit indicates that no current is passing through trace 230 a, while a short circuit indicates that electrical trace 230 a is in contact with an external element, such as lubricating water. Either event indicates that seal strip 200 has worn down to the level of trace 230 a.

[0035] As with the wear monitoring system 120, the process is repeated with other traces 230 until all traces 130 are destroyed or until the user chooses to replace the worn seal strip 100 when a certain wear depth is reached.

[0036] Another embodiment of a wear monitoring system is shown in FIG. 10 and is broadly designated 320. In this system, multiple traces 330 of a sensing portion 322 are generally L-shaped. The multiple traces 330 are connected in parallel by a common trace 331, which in turn connects to a signal processing portion 324. A resistor 341 is also located on the common trace 331 between each pair of adjacent traces. Resistors 342 connected to each trace 330 are located on a PCB 323 of the sensing portion 322. In this embodiment, the multiple resistors 342 vary in strength. The multiple resistors 342 are connected in parallel to each other by traces 343 connecting to the traces 331.

[0037] The signal processing section 324 does not have a switch; instead, common trace 331 is connected directly to microcontroller 346 via trace 357. A constant current source 355 is also connected to trace 357.

[0038] The system 320 operates according to Ohm's law (voltage = current x resistance). For multiple resistors 341 connected in series, the resistance is:

number

[0039] where Rt is the total resistance and Rn is the resistance of an individual resistor. For multiple resistors 342 connected in parallel, the resistance is calculated as follows:

[0040]

number

[0041] Therefore, since the current is constant, a change in the measured voltage indicates a change in the resistance of the system, which occurs when trace 330 is damaged by wear on seal strip 300.

[0042] 10, when the traces 330 are all intact, a voltage of approximately 10 V is read by the microcontroller 346. As the sealing strip 300 wears, an increase of approximately 1 V is detected for each trace 330.

[0043] Those skilled in the art will appreciate that although voltage and current signals are monitored in the embodiments described above, in other embodiments a combination of voltage and current signals may be detected and used.

[0044] 11 illustrates another wear monitoring system, broadly designated 420. The wear monitoring system 420 is mounted on a single PCB 423 (i.e., both the sensing portion 422 and the signal processing portion 424 are located on the same PCB 423). As such, there is no cable like cable 126; instead, multiple traces 430 connect directly to the components of the signal processing portion 424. The PCB 423 is flexible, thereby allowing it to bend so that the fingers 421, to which the sensing portion 422 is attached, can be oriented generally perpendicular to a main portion 427 of the PCB 423. Any of the wear monitoring systems 120, 220, and 320 described above may be mounted on the PCB 423.

[0045] In this embodiment, temperature monitoring system 470 is also mounted to PCB 423. Temperature monitoring system 470 may take many forms, including those described in U.S. Provisional Patent Application No. 63 / 375,587, filed September 14, 2022, the disclosure of which is incorporated herein by reference in its entirety. Sensing portion 472 of temperature monitoring system 470 is mounted to fingers 471 of PCB 423, and signal processing components of temperature monitoring system 470 are mounted to main portion 427 of PCB 423. Wear monitoring system 420 and temperature monitoring system 470 together form an overall seal strip monitoring system 480.

[0046] The installation of the seal strip monitoring system 480 is illustrated in FIGS. 12A-12D. FIG. 12A illustrates the underside of the seal strip 400, with the channel 408 formed and holes 409 and 410 drilled perpendicular to the channel 408. FIG. 12B illustrates the system 480 installed in the seal strip 400, with the fingers 421 and 471 inserted into the holes 409 and 410 to deploy the sensing portions 422 and 472, and the main portion 427 of the PCB 423 attached to the channel 408 itself. FIG. 12C illustrates the connection of a cable 490 to the PCB 423 to enable the aforementioned "daisy-chaining" of the system 480 along the length of the seal strip 400. FIG. 12D illustrates that a potting compound 492 (e.g., elastomeric silicone) has been applied to fill the channel 408.

[0047] It should also be noted that any of the sealing strips discussed herein may use different components to perform different functions. For example, the load tubes may be replaced with other components (e.g., springs, resilient pads, etc.) that bias the sealing strip toward the shell of the suction roll. The sealing strip holders may take on a variety of configurations. Other variations may also be used.

[0048] Another variation of a wear monitoring system is shown in FIG. 13 and is generally designated 520. Sensing portion 522 includes a plurality of traces 530. The plurality of traces 530 differs from those shown in wear monitoring systems 120, 220, 320, and 420 in that (a) the plurality of traces 530 describe arcuate paths at their upper end portions and (b) the tops 531 of the plurality of traces 530 are spaced apart from one another in a non-uniform manner. More specifically, a first distance between the tops of the upper traces (e.g., traces 530a and 530b) is much smaller than a second distance between the lower traces 530 (e.g., traces 530g and 530h). In the embodiment shown in FIG. 13, intermediate traces 530 (traces 530c, 530d, 530e, and 530f) are spaced apart by one or more distances that are different from both the first distance and the second distance. In other words, the distance between the top ends of adjacent traces 530 increases with distance from the top surface of the sealing strip 500, although in some cases the distance from the top end of one trace 530 to the top end of its adjacent trace 530 may be the same (e.g., (i) the distance between trace 530a and trace 530b, and (ii) the distance between trace 530b and trace 530c may be the same).

[0049] Also, in the illustrated embodiment, the traces shown with solid lines (i.e., 530a, 530c, 530e, and 530g) are located on one side of the PCB, and the traces shown with dashed lines (i.e., 530b, 530d, 530f, and 530h) are located on the other side of the PCB, which can help keep traces that are close to each other separated.

[0050] Those skilled in the art will appreciate that the sensing portion 522 of the wear monitoring system 520 may be connected to a signal processing portion similar to any of the signal processing portions 124, 224 or 324 in terms of resistor and / or capacitor locations.

[0051] This arrangement of the traces 530 may provide the user with some flexibility for use. By locating the tops of the traces 530 close to the surface of the sealing strip, the user can detect early wear with great accuracy. The user may choose to act immediately upon the detection of wear (e.g., by replacing the sealing strip 500). In contrast, if early wear is less of a concern to the user, more widely spaced traces 530 located further from the top surface may provide a "fail-safe" level of detection where more wear is acceptable.

[0052] The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. While exemplary embodiments of the present invention have been described, those skilled in the art will readily appreciate that many modifications can be made therein without substantially departing from the novel teachings and advantages of the present invention. Accordingly, all such modifications are intended to be included within the scope of the present invention as set forth in the claims. The present invention is defined by the appended claims, with equivalents of the claims to be included therein.

Claims

1. 1. A seal strip and wear monitoring system, comprising: a seal strip having an upper surface; and Wear Monitoring System It is equipped with the wear monitoring system comprising: a sensing portion comprising a plurality of electrical traces, each of the plurality of electrical traces including a top portion disposed at a predetermined depth from an upper surface of the sealing strip, wherein the depth of the top portion of each trace is different from the depth of the top portion of the other electrical traces; and a signal processor electrically connected to the plurality of electrical traces, the signal processor comprising circuitry configured to detect electrical signals from the plurality of traces and to determine when a top of a trace has been damaged; Equipped with 5. The seal strip and wear monitoring system.

2. 10. The system of claim 1, wherein the signal processing section comprises a plurality of capacitors, each connected to a respective electrical trace.

3. 10. The system of claim 1, wherein the signal processing section comprises a plurality of resistors, each connected to a respective electrical trace.

4. The system of claim 3 , wherein each of the plurality of resistors has the same resistance value.

5. The system of claim 3 , wherein each of the plurality of resistors has a different resistance value.

6. The system of claim 1 , wherein the detected electrical signal is a voltage signal.

7. The system of claim 1 , wherein the detected electrical signal is a current signal.

8. The system of claim 1 , wherein the tops of the plurality of electrical traces are regularly spaced from one another.

9. The system of claim 1 , wherein the tops of the plurality of electrical traces are non-uniformly spaced from one another.

10. The system of any one of claims 1 to 9, wherein the sensing portion and the signal processing portion are located on a common printed circuit board (PCB).

11. The system of claim 10 further comprising a temperature sensing system disposed on the common PCB.

12. 11. The system of claim 10, wherein the tops of the plurality of electrical traces are disposed on fingers of the common PCB, the circuit is disposed on a main portion of the PCB, and the fingers are generally perpendicular to a plane defined by the main portion.

13. The system of claim 1 , wherein each top is generally parallel to each of the other tops.

14. The system of claim 1 , wherein each top portion is arcuate.

15. 1. A seal strip monitoring system, comprising: a sealing strip having an upper surface; a printed circuit board (PCB) having first and second fingers and a main panel; a wear monitoring system; and a temperature monitoring system at least partially attached to said PCB; It is equipped with the wear monitoring system comprising: a sensing portion comprising a plurality of electrical traces, each of the plurality of electrical traces having a top that is generally parallel to and disposed at a predetermined depth from the top surface of the sealing strip, wherein the depth of the top of each trace is different from the depth of the tops of other electrical traces; and wherein the tops of the plurality of electrical traces are disposed on the first finger; a signal processing unit electrically connected to the plurality of electrical traces, the signal processing unit being mounted on the main panel of the PCB and comprising circuitry configured to detect electrical signals from the plurality of traces and to determine when a top of a trace has been damaged. The seal strip monitoring system comprises:

16. The seal strip monitoring system of claim 15 , wherein the first and second fingers are positioned generally parallel to the main portion of the PCB.

17. The seal strip monitoring system of claim 15 , wherein the temperature monitoring system is at least partially attached to the second finger.

18. The seal strip monitoring system of claim 15 , wherein the tops of the plurality of electrical traces are regularly spaced apart from one another.

19. The seal strip monitoring system of claim 15 , wherein the tops of the plurality of electrical traces are non-uniformly spaced from one another.

20. The seal strip monitoring system of claim 15 , wherein each top portion is arcuate.

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