Smart Conduit Plug

Abstract

The smart conduit plug (80, 180, 300, 400) includes a plug body (100, 302) having an externally threaded region (101, 330) and a diameter and thread pitch for engaging the conduit port (28). At least one electrical component (108, 208, 228, 308, 328) is attached to the plug body (100, 302) and configured to electrically couple to the field device (14) and provide an indication to the field device (14).

Description

[Background technology]

[0001] A field device is a device that can be coupled to a process, such as a manufacturing or refining process, to support the process by providing one or more functions for measuring and controlling parameters related to the process. Field devices are so named because they can be mounted in the field. The "field" is generally an external area within a process facility that may be subject to climatological extremes, vibrations, humidity changes, electromagnetic or radio frequency interference, or other environmental challenges. Thus, the rugged physical packaging of such field devices provides the ability to operate in the "field" for extended periods of time (such as years) at a time.

[0002] Field devices, such as process variable transmitters, are used in the process control and monitoring industry to remotely sense process variables. Field devices, such as actuators, are used by the process control industry to remotely control physical parameters of a process, such as flow rate, temperature, etc. A controller may then send control information to field devices, such as actuators, to modify the parameters of the process. For example, information about the pressure of a process fluid may be sent to a control room and used to control a process, such as an oil refinery.

[0003] One environment in which field devices are particularly useful is process control and monitoring. In such environments, process fluids such as petrochemicals, slurries, and pharmaceutical compounds may be processed and transported to various locations within a processing facility. However, process control and monitoring environments present challenges for many devices in that the environment itself may contain flammable or highly explosive gases. Therefore, in some such environments, it is important that electronic devices used within the environment be housed in explosion-proof enclosures. If so housed, even if the device's circuitry contains electrical components with surface temperatures high enough to generate a spark or ignite the environment, the resulting ignition is completely contained within the enclosure and cannot escape into the surrounding environment. This is important to ensure the safety of the process control equipment and the workers within it.

[0004] An example of an explosion-proof rating is ATEX certification to Ex-d standards EN60079-0 and EN60079-1 for potentially explosive atmospheres. Explosion-proof housings are typically relatively bulky to provide sufficient mechanical robustness to contain an internal explosion without rupturing. Such enclosures are typically very robust metal enclosures designed to withstand explosion pressures. These enclosures often include conduit ports for coupling process wiring to the device. If not all of the conduit ports on a field device are required for process wiring, the unused conduit ports must be plugged with conduit plugs. Summary of the Invention

[0005] The smart conduit plug includes a plug body having an externally threaded region and a diameter and thread pitch for engaging the conduit port, and at least one electrical component is mounted to the plug body and configured to electrically couple to the field device and provide instructions to the field device. [Brief explanation of the drawings]

[0006] [Figure 1]1 is a schematic diagram of a field device in which embodiments described herein are particularly useful. [Figure 2] FIG. 1 is a cross-sectional view of a smart conduit plug in accordance with one embodiment of the present invention. [Figure 3] FIG. 1 is a perspective view of a smart conduit plug in accordance with one embodiment of the present invention. [Figure 4] FIG. 10 is a cross-sectional view of a smart conduit plug according to another embodiment of the present invention. [Figure 5] FIG. 10 is a perspective view of a smart conduit plug according to another embodiment of the present invention. [Figure 6] FIG. 10 is a cross-sectional view of a smart conduit plug according to another embodiment of the present invention. [Figure 7] FIG. 10 is a perspective view of a smart conduit plug according to another embodiment of the present invention. [Figure 8] FIG. 10 is a schematic perspective view of a smart conduit plug according to another embodiment of the present invention. [Figure 9] FIG. 10 is a schematic cross-sectional view of a smart conduit plug according to another embodiment of the present invention. [Figure 10] FIG. 2 is a schematic perspective view of a shroud of a smart conduit plug in accordance with an embodiment of the present invention. [Figure 11] FIG. 2 is an elevation view of a smart conduit plug attached to a field device in accordance with one embodiment of the present invention. [Figure 12] FIG. 10 is a schematic diagram of different alert colors (shown as different shades of gray) for a smart conduit plug in accordance with one embodiment of the present invention. [Figure 13A] FIG. 1 is a block diagram of a smart conduit plug according to an embodiment of the present invention. [Figure 13B] FIG. 1 is a block diagram of a smart conduit plug according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0007] One challenge with field devices is sometimes being able to determine whether the field device is operating as expected. In many applications, field devices are installed in the field and connected to process and control systems without any kind of feedback that the device is on, powered, functioning, connected, communicating, and / or measuring on-scale values. Field devices with LCD screens provide an equipment technician with at least some visual feedback that the field device is powered and functional, but field devices without LCD displays do not provide such local feedback to the equipment technician.

[0008] The embodiments described herein provide a smart conduit plug that provides an indication of field device status using the form factor (e.g., diameter, thread pitch, etc.) of a standard conduit plug with some electronics and a glass viewing window. The smart conduit plug is electrically coupled to a field device terminal block. In one particularly simple embodiment, an LED simply turns on when the field device is receiving power. In another example, the smart conduit plug uses an integrated circuit configured to drive the LED state based on the field device analog output. For example, the integrated circuit may cause the LED to display blue if normal and red if the field device is in a high alarm state. More advanced embodiments include providing a small microcontroller to expand the number of indicated states. The microcontroller that drives the LED may be located on the smart conduit plug's printed circuit board or may be located on the field device terminal block PCA. Some example functions that the smart conduit plug can indicate include, but are not limited to, power-on state, on and normal operation (process variable within limits), alarm, fault, field device health, and no power.

[0009] Figure 1 is a schematic diagram of a field device in which embodiments described herein are particularly useful. Figure 1 generally illustrates a process measurement environment 10. Process piping 12 contains a fluid under pressure and is coupled to a process measurement system 14 for measuring the process pressure. The process measurement system 14 includes impulse piping 16 connected to the process piping 12. The impulse piping 16 is connected to a process pressure transmitter 20. A primary element 22, such as an orifice plate, venturi tube, or flow nozzle, contacts the process fluid at a location within the process piping 12 between the tubes of the impulse piping 16. The primary element 22 induces a pressure change in the fluid as it flows through the primary element 22.

[0010] Transmitter 20 is a process measurement device that receives the process pressure through impulse piping 16, senses the differential process pressure, and converts it into a standardized transmitted signal representing flow that is a function of the differential process pressure.

[0011] Process loop 24 provides both power signals and bidirectional communications from a control room (not shown) to transmitter 20 and may be configured according to several process communication protocols. In the illustrated example, process loop 24 is a two-wire loop. The two-wire loop is used to carry all power and all communications to and from transmitter 20 during normal operation with a 4-20 mA signal. In another exemplary configuration, loop 24 is a wireless connection in which data may be transmitted or received wirelessly in either a point-to-point configuration, a mesh network, or other configuration.

[0012] 1, transmitter 20 includes an electronics housing 26 that includes an internally threaded opening 28 for receiving conduit for protecting the wiring of process loop 24. Typically, electronics housing 26 includes a pair of such internally threaded openings 28.

[0013] 2 and 3 are cross-sectional and perspective views of a smart conduit plug 80 according to one embodiment of the present invention. In the illustrated embodiment, a conduit plug body 100 includes a male threaded region 101 configured to thread into opening 28 (shown in FIG. 1 ). Conduit plug body 100 is welded to a metal-glass header 102 at welds 104. A printed circuit board 106 is disposed within conduit plug body 100 and may be attached thereto in any suitable manner, including with plastic, solder, and / or epoxy. In embodiments where maintaining the explosion-proof rating of the field device housing is not necessary, conduit plug body 100 and header body 104 may be formed solely from plastic. As shown in FIG. 3 , the smart conduit plug still includes wrench flats 107 of a standard conduit plug for installation within the field device housing. As shown in FIG. 2 , one or more LEDs 108 are disposed on printed circuit board 106 and oriented to provide illumination through glass 110. A pair of wires 112 extend from the printed circuit board 106 through holes 109 to field device wiring, such as a field device terminal block in the field device's electronics housing (eg, electronics housing 26 shown in FIG. 1).

[0014] 4 and 5 are cross-sectional and perspective views of a smart conduit plug 180 according to another embodiment of the present invention. As shown, the conduit plug 180 may include multiple wrench flats. Furthermore, in the illustrated embodiment, an LED 208 having a metal cap 220 and a glass header 222 is provided as a subassembly with solder pins 224 extending from the glass header 222 to the printed circuit board 206. The metal cap 220 is then welded or brazed to the metal conduit plug body at interface 226. The LED 208 is configured to direct light through the glass 210 to provide one or more visual indications to the field device. As shown in FIG. 4 , a component or logic chip 228 is disposed on a surface 230 of the printed circuit board 206. The component 228 may include a simple integrated circuit that drives the state of the LED 208 based on the field device state. Furthermore, the logic chip / component 228 may also include a small microcontroller configured to provide additional indications to the field device. While chips / components 228 are shown only on surface 230, it is expressly contemplated that additional components may be located on the opposite side of printed circuit board 206. Wiring or connectors 212 extend from printed circuit board 206 to field device wiring, such as a terminal block (not shown). Printed circuit board 206 may be attached to conduit plug body 200 in any suitable manner, including, but not limited to, epoxy, solder, or mechanically (e.g., using clips). Note that in embodiments simply requiring an LED to turn off the analog power supply of the field device, printed circuit board 206 may be omitted.

[0015] 6 and 7 are cross-sectional and perspective views of a smart conduit plug 300 according to another embodiment of the present invention. As shown in FIG. 6, the smart conduit plug 300 includes a conduit plug body 302 having an external threaded portion 330, a chamber 332, and multiple wrench flats. The smart conduit plug 300 uses a potting design with an O-ring 334 between the conduit plug body 302 and a glass tube 336. Potting 338 mounts the glass tube 336 within the chamber 332 and directs illumination from the LED 308 to an exterior region 337. The potting 338 is dispensed within the chamber 332 and forms an environmental seal with the O-ring 336. Potting is required along the length of the glass tube 336 to provide an adequate flame-resistant seal. The printed circuit board 306 is attached to the conduit plug body 302 in any suitable manner, including via epoxy, solder (depending on material selection), or via ultrasonic welding or resin or potting 338 attached to the conduit plug body 302 and held in place. 6, one or more LEDs 308 are disposed on the printed circuit board 306 and configured to generate light in the direction of the glass tube 336. One or more electrical components 328 are disposed on the opposite side of the printed circuit board 306 from the LEDs 308. A plurality of wires or connectors 312 extend from the printed circuit board 306 to field device wiring (not shown).

[0016] While the foregoing embodiments generally provide LEDs to provide indications for a field device, it is expressly contemplated that embodiments may include additional components on the printed circuit board to provide additional functionality. For example, a humidity sensor on the printed circuit board may be used to detect humidity within the field device housing, and the visual indication provided by one or more LEDs may include an indication of the moisture level within the field device housing. In another example, an alarm may be activated if the moisture content increases significantly, a condition that would typically lead to a malfunction, for example. In yet another example, a vibration sensor / accelerometer may be mounted on the smart conduit plug's printed circuit board to provide a warning if the field device, and therefore its installation point, is experiencing significant vibration. In another example, an early-warning wet / corrosive terminal block detector may be provided to detect and provide an indication of a wet / corrosive terminal block. Furthermore, while instructions are described for driving one or more LEDs to display different colors, it is expressly contemplated that one or more LEDs may also communicate visual information via a flashing code in place of or in combination with changing colors.

[0017] Additional functionality that may be included in the smart plug according to the various embodiments described above includes providing audio indications within the field device to indicate status and / or communicate alarms. An RF antenna may be located within the smart conduit plug to provide an RF path through the glass within an otherwise sealed metal field device housing. The RF antenna may be configured for any suitable RF communication, but in one particular embodiment, it is a Bluetooth Low Energy (BLE) antenna. In yet another embodiment, a small LCD is mounted on the smart conduit plug's printed circuit board and is visible through the glass. The small LCD may also include a backlight to improve visibility and / or provide additional visual indications (e.g., via color or flashing codes).

[0018] 8 and 9 are schematic perspective and cross-sectional views of a smart conduit plug according to another embodiment of the present invention. Smart conduit plug 400 includes a housing 402 preferably formed from two portions 404, 406 that mate with each other at interface 408 to provide an explosion-proof housing. Such engagement may be via threaded engagement, slip fit, welding, press fit, and / or heat shrinking. Housing 402 also includes external NPT threads 410 configured to thread into the conduit of a field device. A hex bolt 412 is attached to threads 410 such that a technician can threadably engage NPT threads 410 with the conduit of field device 28 using a wrench or other suitable tool.

[0019] As shown in FIG. 9 , the smart conduit plug 400 includes at least one printed circuit board 414, which may include any or all of the circuit components described above. The printed circuit board 414 includes at least one LED that provides an indication of the status of a device, a process, or any combination thereof. In one particular example, the LED is mounted to the center of the circular circuit board 414 and positioned to view a window 416. In the example shown in FIG. 9 , a shroud 418 is interposed between the printed circuit board 414 and the window 416. The shroud 418 includes an opening aligned with the position of the LED so that illumination from the LED can pass through the opening in the shroud 418 and out of the window 416. However, other elements of the circuit board 414 are hidden from view through the window 416.

[0020] FIG. 10 is a schematic perspective view of a shroud of a smart conduit plug in accordance with one embodiment of the present invention. The shroud 418 generally includes a circular platform 420 with a number of standoffs 422 extending downwardly therefrom. The standoffs 422 help provide proper spacing between the circular platform 420 and the printed circuit board 414 (shown in FIG. 9). FIG. 10 shows a centrally located opening 424 in the circular platform 420 that allows illumination from a centrally located LED. However, in embodiments where the LED is not located in the center of the printed circuit board, the opening 424 is located in a different position so that the LED can still illuminate. In the illustrated example, the circular platform 420 includes an opaque surface to prevent light from passing through. In some embodiments, the circular platform itself may be opaque.

[0021] As shown in FIG. 10 , the shroud 418 may include additional features. One such feature may be the shape of the shroud 418. For example, the shroud 418 may be provided with a concave shape to enhance LED visibility. Additionally, the shroud 418 may have or include a metalized surface to provide reflectivity and improve visibility. The shroud 418 may be designed to surround and / or protect the printed circuit board 414 (shown in FIG. 9 ). The shroud 418 may include one or more mechanical features for physically attaching to the printed circuit board 414. For example, the shroud 418 may include snap features for snapping onto and retaining the printed circuit board 414. Additionally or alternatively, the shroud 418 may include one or more mechanical features for installing and retaining itself within the housing 402. For example, the shroud 418 may include snap features for installing and retaining the shroud 418 in the housing 402. Additionally, the shroud 418 may include an overmold for environmental protection as well as protection against high vibrations.

[0022] 11 is an elevation view of a smart conduit plug 400 attached to a field device 440 according to one embodiment of the present invention. As shown in FIG. 11, the smart conduit plug 400 is attached to a field device 440 and has a centrally located LED 442 that shows through a window 416 in the smart conduit plug 400.

[0023] 12 is a schematic diagram of different alert colors (shown as different shades of gray) for a smart conduit plug in accordance with one embodiment of the present invention. In the illustrated example, when the system is in region 470, the LED color may indicate nominal operation, such as by illuminating green. If the system is slightly above or below the nominal range, as indicated by regions 472 and 474, respectively, an appropriate alert, such as a saturation alert, may be generated by illuminating the LED blue. If the system progresses further into either regions 476 and 478, an alert may be indicated by illuminating the LED red. Certainly, other color schemes may be used, as well as incorporating LED blink and / or flash codes indicating particular device or process states.

[0024] 13A and 13B are block diagrams of a smart conduit plug according to embodiments of the present invention. FIG. 13A is a block diagram of a smart conduit plug 500A according to one embodiment of the present invention. The plug 500A includes an LED 504 disposed within a conduit plug body 502. The LED 504 is mounted within the conduit plug body 502 to direct illumination 506 through a window 516. The LED 504 is coupled to an LED driver circuit 508, which includes appropriate circuit components for powering the LED 504. Examples of such components include a current-limiting resistor, a selectable switch capable of reversing the polarity of the voltage applied to the LED 504 (e.g., to change the color of a multi-color LED), or a flashing circuit configured to flash the LED to provide additional information (such as a process warning or field device status alarm), and / or a buck and boost converter configured to draw power from the field device loop without affecting the device's operation or output. The LED driver circuit is typically operably coupled to a field device (not shown) by coupling wires 508, 510 to appropriate terminals on a terminal block of the field device.

[0025] 13B is a block diagram of a smart conduit plug 500B according to one embodiment of the present invention. The plug 500B includes an LED 504 disposed within a conduit housing 512. The LED 504 is mounted within the housing 512 to direct illumination 506 through a window 516. The LED 504 is coupled to an LED driver circuit 508, which includes appropriate circuit components for powering the LED 504. In the smart conduit plug 500B, the LED driver circuit 508 is coupled to or included within a controller 520. The controller 520 may include any suitable circuitry or logic capable of executing a series of program steps or instructions to perform one or more functions for the smart conduit plug 500B. The controller 520 may be a microprocessor, microcontroller, application specific integrated circuit (ASIC), field programmable gate array (FPGA), or any other suitable device. In the illustrated embodiment, the controller 520 is coupled to additional circuitry / sensors 522. The additional circuit sensors 522 represent several additional components that can be used alone or in combination with any of the other circuit / sensor components listed below.

[0026] The additional circuitry / sensors 522 may include sensors configured to sense some characteristic associated with a field device, a process, or a combination thereof. Such sensors may include temperature sensors, pressure sensors, moisture sensors, vibration sensors, emf interference sensors, and / or gas sensors. The controller 522 includes appropriate internal logic for measuring the electrical characteristics (e.g., resistance, voltage, etc.) of the sensors and calculating parameters for the measured characteristics. The controller 522 may then drive the LED 502 to provide an indication of the measured characteristic.

[0027] The additional circuitry / sensors 522 may also include a user display, such as an LED display, an LCD display, or an electronic ink display. The controller 520 may drive the display to provide a visual output for a process condition, a field device condition, or a combination thereof. Furthermore, in embodiments in which the additional circuitry 522 includes one or more sensors and a display, the display may provide information regarding the sensed characteristic.

[0028] The additional circuits / sensors 522 may also include wireless communication circuitry to enable the controller 520 to communicate with remote devices and / or the field device itself. The wireless communication circuitry may be configured to communicate according to Bluetooth (such as Bluetooth Low Energy - BLE), Wifi (IEEE 802.11), Cellular (such as GPRS or TDMA), RFID, satellite communication, etc.

[0029] The additional circuitry / sensors 522 may also include current measurement circuitry configured to measure the current consumed by the field device. By measuring the current consumed by the field device, the smart conduit plug 500B may receive process variable information (i.e., via a 4-20 mA current loop), which may be provided locally via a display and / or remotely via wireless communication. This current consumption may be tracked over time by the controller 520 to provide an indication of the health of the field device.

[0030] The additional circuits / sensors 522 may also include energy harvesting circuitry. Such circuitry may include photovoltaic arrays (e.g., solar cells), kinetic energy harvesters that convert mechanical energy such as vibration into electricity, and thermoelectric harvesters such as Peltier elements or thermocouples. In some embodiments, the harvesting circuitry may provide all the electrical energy necessary to power the smart conduit plug.

[0031] The additional circuitry / sensors 522 may also include one or more user input buttons. These buttons can be used for a variety of purposes. For example, the user input buttons can wake the smart conduit plug from a low-power state and provide that information. This can be particularly useful in very low-power applications where the smart conduit plug must rely on a very limited power budget, such as when operating solely from harvested energy from the environment. In another example, the user input buttons can enable the smart conduit plug to transition between multiple different states or provide different types of information. In yet another example, the user input buttons can enable a user to cause the smart conduit plug to perform some activity or affect a connected field device without having to open the field device cover. Such activities can include resetting the field device, causing the field device to enter a diagnostic state, causing the field device to enter a commissioning state, or any other suitable change.

[0032] The additional circuitry / sensor 522 may also include an energy storage device such as a battery or a capacitor. In embodiments in which the energy storage device is a battery, the device may be a primary battery (i.e., non-rechargeable) or a secondary battery (rechargeable).

Claims

1. a plug body having an externally threaded region, the plug body having a diameter and thread pitch for engaging a conduit port of a field device; at least one electrical component attached to the plug body and configured to electrically couple to a field device and provide instructions to the field device; A smart conduit plug comprising:

2. The smart conduit plug, wherein the at least one electrical component includes a light emitting diode.

3. The smart conduit plug of claim 2 , wherein the indication is selected from the group consisting of power status, normal operation, an alarm condition, a fault, and field device health.

4. The smart conduit plug of claim 1 , wherein the smart conduit plug is configured to maintain an explosion-proof rating of the field device when the smart conduit plug is coupled to the conduit port of the field device.

5. 10. The smart conduit plug of claim 1, further comprising at least one sensor disposed on a printed circuit board of the smart conduit plug, the at least one sensor configured to sense a condition for the field device, and the indication provided by the smart conduit plug is based on the sensed condition.

6. The smart conduit plug of claim 5 , wherein the sensor is a moisture sensor.

7. The smart conduit plug of claim 5 , wherein the sensor is a vibration sensor.

8. The smart conduit plug of claim 1 , wherein the at least one electrical component is configured to provide the instruction as an audio instruction.

9. The smart conduit plug of claim 1 , wherein the at least one component includes an RF antenna.

10. The smart conduit plug of claim 1 , wherein the at least one component includes an LCD display.

11. a housing having an externally threaded region, the externally threaded region having a diameter and thread pitch for engaging a conduit port of a field device; at least one electrical component mounted within the housing and configured to electrically couple to the field device and provide instructions to the field device; A conduit plug comprising:

12. 12. The conduit plug of claim 11, wherein the housing is formed from two sections that thread together.

13. The conduit plug of claim 12 , wherein the housing is explosion-proof.

14. 12. The conduit plug of claim 11, further comprising a glass window through which the indication for the field device is visible.

15. The conduit plug of claim 14 , wherein the at least one electrical component includes an LED.

16. 16. The conduit plug of claim 15, further comprising a shroud disposed within the housing and interposed between the LED and the glass window.

17. 17. The conduit plug of claim 16, wherein the shroud is circular and includes an opening aligned with the LED to allow illumination of the LED to pass through the shroud to the window.

18. 20. The conduit plug of claim 17, wherein the shroud includes a plurality of standoffs for providing spacing between the shroud and a printed circuit board on which the at least one electrical component is mounted.

19. The conduit plug of claim 11 , further comprising a controller operably couplable to the field device, the controller configured to generate the instructions to the field device.

20. 20. The conduit plug of claim 19, further comprising a sensor disposed within the housing and coupled to the controller.

21. 20. The conduit plug of claim 19, further comprising at least one additional circuit disposed within the housing and coupled to the controller.

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