Customized Process Variable Transmitters with Sealed Electronics

Abstract

The process variable transmitter (102) includes a process variable sensor (110) and an electromagnetic interference (EMI) protection circuit (182) coupled to the process variable sensor (110). The process variable transmitter (102) also includes an enclosed module (104) that encloses the EMI protection circuit (182) and electrical connectors (132, 134, 136) coupled to the EMI protection circuit (182) within the enclosed module (104). The electrical connectors (132, 134, 136) are configurable from outside the enclosed module (104) such that the electronic components of the EMI protection circuit (182) are connected in a configuration that provides transient protection.

Description

[Background technology]

[0001] In the process control industry, process transmitters are often installed in or near corrosive / hazardous environments. Therefore, in some process transmitter constructions, to simplify approval requirements, the transmitter electronics are housed in a hermetically sealed package with flying leads as the customer interface. To achieve the hermetic package, a limited number of electrical signals are passed through a sealed header interface.

[0002] Industrial process transmitters are typically offered with a standard or transient protection option that provides additional protection against lightning and other unintended surges, but also requires additional transient suppression electronics that must be protected from environmental conditions. Summary of the Invention [Problem to be solved by the invention]

[0003] The disclosed embodiments provide a process variable transmitter design where one common sealed module can provide both standard and transient protection options by routing the signal from the sealed header to the output connector during final assembly, thereby overcoming some hazardous location approval hurdles and providing late stage customization capabilities, thus reducing module inventory. [Means for solving the problem]

[0004] In one embodiment, a process variable transmitter is provided that includes a process variable sensor and an electromagnetic interference (EMI) protection circuit coupled to the process variable sensor. The process variable transmitter also includes an enclosed module that encloses the EMI protection circuit and an electrical connector coupled to the EMI protection circuit within the enclosed module. The electrical connector is configurable from outside the enclosed module to connect electronic components of the EMI protection circuit in a configuration that provides transient protection.

[0005] In another embodiment, a method is provided that includes enclosing an electromagnetic interference (EMI) protection circuit coupled to a process variable sensor in an enclosed module having an electrical connector extending to an exterior thereof, and connecting electronic components of the EMI protection circuit from an exterior of the enclosed module through the electrical connector in a configuration that provides transient protection.

[0006] In yet another embodiment, a process variable transmitter is provided. The process variable transmitter includes a process variable sensor and an electromagnetic interference (EMI) protection circuit coupled to the process variable sensor. The process variable transmitter also includes an hermetic module that encloses the EMI protection circuit. The hermetic module has a first end including a feedthrough body and a plurality of feedthrough pins that extend through the feedthrough body and are hermetically sealed relative to the feedthrough body. The feedthrough pins are coupled to the EMI protection circuit within the hermetic module and are configurable from outside the hermetic module such that electronic components of the EMI protection circuit are connected in a configuration that provides transient protection.

[0007] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. The claimed subject matter is not limited to implementations that solve any or all of the disadvantages noted in the Background. [Brief description of the drawings]

[0008] [Figure 1] 1 is a partial cross-sectional view of an example of a process control system including a pressure transmitter in which embodiments of the present disclosure may be utilized. [Diagram 2] FIG. 2 is a simplified block diagram of the pressure transmitter of FIG. 1. [Diagram 3]FIG. 1 is a schematic diagram illustrating an electrical configuration in which components for transient protection or electromagnetic interference (EMI) protection are external to the enclosed module of the process transmitter. [Figure 4] 1 shows an enclosed module containing EMI protection circuitry and an output assembly that does not include EMI protection components. [Diagram 5] FIG. 1 is a schematic diagram illustrating an enclosed module-output assembly configuration with an additional feedthrough routed to electrical ground to enable transient protection according to one embodiment. [Figure 6] FIG. 13 is a schematic diagram showing an enclosed module-output assembly configuration with additional feedthroughs routed back to their respective lines for units without transient protection. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments of the present invention will be described in more detail with reference to the accompanying drawings. Elements identified with the same or similar reference characters shall refer to the same or similar elements. For clarity of the drawings, some elements may not be shown in each figure. Various embodiments of the present disclosure may be implemented in many different forms and should not be construed as being limited to the specific embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art.

[0010] FIELD OF THE DISCLOSURE Embodiments of the present disclosure relate generally to customizing process variable transmitters with sealed electronics. More specifically, embodiments of the present disclosure provide a common sealed module that can be reconfigured after assembly to provide standard or transient protection options while meeting hazardous location approval requirements. Before providing details regarding different embodiments, an exemplary process control system including a process transmitter is described below.

[0011] FIGURE 1 illustrates an example process control system that may incorporate certain embodiments disclosed herein. The process control system illustrated in FIGURE 1 is for illustrative purposes only. Embodiments of the present disclosure are not limited to a particular process control system such as the process control system illustrated in FIGURE 1. Embodiments of the present disclosure are illustratively implemented in many different types of process control systems.

[0012] Figure 1 is a schematic, partial cross-sectional view of an example process control system 100 including a process variable transmitter (e.g., a pressure transmitter) 102 in which embodiments of the present disclosure can be utilized. Figure 2 is a simplified block diagram of the transmitter 102 of Figure 1. The system 100 can be used in the processing of materials (e.g., process media) to convert the materials from a less valuable state into more valuable and useful products, such as petroleum, chemicals, paper, food, etc. For example, the system 100 can be used in facilities that perform sanitary or other types of industrial processes.

[0013] The pressure transmitter 102 may include a housing 104 that may be coupled to an industrial process 106 via a process coupling 108. The housing 104 and the process coupling 108 may be formed of stainless steel or other suitable materials. The transmitter 102 includes a pressure sensor assembly 110 including a pressure sensor 112 and a measurement circuit 114 within the housing 104. The measurement circuit 114 may include processing / computational circuitry, communication circuitry, and electromagnetic interference (EMI) protection circuitry. In the transmitter 102, a first end 116 of the housing 104 surrounds and contacts an exterior surface of a feedthrough body 118 for electrical connection, as further described below, and is hermetically sealed to the feedthrough body 118 by brazing, welding, or other suitable technique. Similarly, a second end 120 of the housing 104 is hermetically sealed using any suitable technique to create a sealed chamber in which the pressure sensor assembly 110 and the measurement circuit 114 are housed.

[0014] The process coupling 108 may be connected to a pipe 121 that is connected to the process 106 and contains a process material (e.g., fluid) at a pressure P that is measured by a pressure sensor 112. The pressure P is communicated to the pressure sensor 112 through a fluid path 122. The pressure sensor 112 includes a sensor element having an electrical parameter indicative of the applied pressure P. A measurement circuit 114 may detect and process the electrical parameter of the sensor element through suitable electrical connections 124 to determine a value of the sensed pressure P. The measured pressure value and other information form the measurement circuit 114 is communicated to an external computerized control unit 126 in a remotely located control room 127 via suitable output electrical connections 128 and a process control loop 130 as shown in FIG.

[0015] As best seen in FIG. 2, the output electrical connection 128 has three electrical connectors (e.g., wires), including a first active connector 132, a second active connector 134, and an electrical ground connector 136. More or fewer connectors may be used. First ends of the connectors 132, 134, 136 are coupled to feedthrough pins 138, 140, 142, respectively, which pass through the feedthrough body 118 and are sealed to the feedthrough body 118 by a sealant, such as glass or ceramic. For example, the pin 142 passes through an opening 144 in the feedthrough body 118 and is sealed to the feedthrough body 118 by a cylindrical seal layer 156 made of glass. Second ends of the wires 132, 134, 136 may be connected to bond pads on a printed circuit board of the transmitter measurement circuit 114, for example. The feedthrough body 118 and the feedthrough pins 138, 140, 142 may be referred to herein as headers.

[0016] As shown in FIGS. 1-2, the transmitter 102 includes an output assembly 158 that is removably coupleable to the housing 104. The output assembly 158 includes a housing 160, an output interface 162, and flying leads 164, 166, 168 coupled to the output interface 162. The output interface 162 and the portions of the flying leads 164, 166, 168 within the housing 160 are encapsulated with any suitable material 170. When the output assembly 158 is coupled to the housing 104 as shown in FIG. 1, the flying leads 164, 166, 168 are electrically connected to the output interface 162 and the connectors 132, 134, 136 via the respective feedthrough pins 138, 140, 142. The flying lead 168 is connected to electrical ground, and the flying leads 164 and 166 are connected to the process control loop 130.

[0017] Communications between the control unit 126, or another external computing device, and the pressure transmitter 102 may occur via the control loop 130 according to conventional analog and / or digital communication protocols. In some embodiments, the two-wire control loop 130 includes a 4-20 milliamp control loop, and the measured pressure value may be represented by the level of loop current flowing through the two-wire control loop 130. An exemplary digital communication protocol includes modulation of a digital signal into an analog current level on the two-wire control loop 130, such as according to the HART® communication standard. Other purely digital techniques may also be used, including FieldBus and Profibus communication protocols.

[0018] In some embodiments, wireless communication between the transmitter 102 and the control unit 130 may also be provided. Exemplary wireless versions of the process control loop 130 include, for example, a wireless mesh network protocol such as WirelessHART® (IEC 62591) or ISA 100.11a (IEC 62734), or another wireless communication protocol such as WiFi, LoRa, Sigfox, BLE, or any other suitable protocol.

[0019] Power can be provided to the pressure transmitter 102 from any suitable power source. For example, the pressure transmitter 102 may be powered entirely by the current flowing through the control loop 130. Alternatively, one or more power sources, such as an internal battery or an external battery, can be utilized to power the pressure transmitter 102. Alternatively, a generator (e.g., solar panels, wind turbines, etc.) can be used to power the pressure transmitter and / or charge the power source used by the pressure transmitter 102.

[0020] It is desirable to manufacture a sealed module (e.g., housing 104 with internal components shown in FIGS. 1 and 2) for an industrial process variable transmitter (e.g., pressure transmitter 102 of FIGS. 1 and 2) in one location and allow later customization of standard or transient protection options at a different final assembly site. One technique to achieve this is to place the components providing the transient protection on a printed circuit assembly (PCA) that is external to the sealed module. If this approach is utilized for the process transmitter 102 of FIGS. 1 and 2, the output interface 162 would include a PCA, where the PCA provides the connection between the sealed module 104 and the flying leads 164, 166, 168 for the customer interface. The assembly of the PCA and flying leads 164, 166, 168 is immersed in an encapsulant 170 to meet hazardous location approval requirements.

[0021] 3 is a schematic diagram illustrating an electrical structure 180 in which components for transient protection are external to the enclosed module 104A of the process transmitter. The enclosed module 104A includes a first active electrical connector 132A, a second active electrical connector 134A, and an electrical ground connector 136A. For simplicity, other circuits and components within the enclosed module 104A (such as the sensor assembly 110 of FIG. 1) are not shown. An output assembly 158A, which is removably coupleable to the enclosed module 104A, includes an EMI protection circuit 182 that electrically connects to the connectors 132A, 134A, and 136A via electrical connectors 132B, 134B, and 136B, respectively. The EMI protection circuit 182 includes capacitors C1 and C2, transient voltage suppression (TVS) diodes D1 and D2, gas-filled discharge tube GT1, and resistors R1 and R2. As shown in FIG. 3, a first capacitor C1 is connected between the active electrical connector 132B and the electrical ground connector 136B, and a second capacitor C2 is connected between the active electrical connector 134B and the electrical ground connector 136B. Each capacitor C1, C2 has a capacitance value of 1500 picofarads (pF), or other suitable capacitance value. The capacitors C1 and C2 delay voltage or current changes in the circuit 182 due to induced transients. The TVS diodes D1 and D2 are bidirectional TVS diodes, represented in one embodiment by two opposing avalanche diodes connected in series with each other. The first TVS diode D1 is connected between the active electrical connector 132B and the electrical ground connector 136B, and the second TVS diode D2 is connected between the active electrical connector 134B and the electrical ground connector 136B. Each TVS diode D1, D2 may have a standoff or breakdown voltage of 70 volts (V), or other suitable breakdown voltage value. TVS diodes D1 and D2 operate by blocking excess current when the induced voltage exceeds their breakdown voltage. When the overvoltage is removed, TVS diodes D1 and D2 automatically reset.The gas discharge tube GT1 is a three-electrode gas discharge tube with a first electrode 1 connected to the active electrical connector 132B, a second electrode 2 connected to the electrical ground connector 136B, and a third electrode 3 connected to the active electrical connector 134B. The three electrodes 1, 2, and 3 allow a single gas discharge tube GT1 to be used to protect the circuit 182. When a voltage exceeding its rated breakdown voltage is applied to the gas discharge tube GT1, the gas in the gas discharge tube GT1 ionizes and becomes conductive, eventually reaching an impulse discharge ignition voltage. At this point, the gas discharge tube GT1 is in a fully on state, and a low arc voltage is maintained regardless of the discharge current. Once the transient has passed, the gas discharge tube GT1 is reset to a non-conductive state. The gas discharge tube GT1 may have an impulse discharge ignition voltage value of 90V, or other suitable impulse discharge ignition voltage value.

[0022] Resistors R1 and R2 are included in the EMI protection circuit 182 to provide protection from when a transient is first induced until the gas-filled discharge tube GT1 reaches its impulse firing voltage. In the embodiment of FIG. 2, resistor R1 is connected in series with the active electrical connector 132B, and resistor R2 is connected in series with the active electrical connector 134B. Resistors R1 and R2 may be wirewound, axial, or the like, and may have any suitable resistance value. As shown in connection with FIGS. 1 and 2 above, the PCA including the EMI protection circuit 182 and the flying wires 164, 166, 168 assembly is immersed in an encapsulant 170 to meet hazardous location approval requirements.

[0023] It may also be desirable to utilize additional protection types in the transmitter design, such as Ex mb (sealed to provide a high level of safety) or Ex eb (explosion-proof to "Enhanced Safety for Zone 1" standards). However, there are additional safety requirements that make them difficult to obtain approval. For example, components that are considered to be at risk for ignition, such as capacitors (e.g., C1 and C2 in Figure 3), gas-filled discharge tubes (e.g., GT1 in Figure 3) and resistors (e.g., R1 and R2 in Figure 3), must be immersed in cemented joints that have passed high pressure hydrostatic tests before and after long-term thermal aging.

[0024] In one instance, testing found that the output assembly and header interface did not meet the approval criteria for additional protection types such as Ex mb or Ex eb due to water ingress at the output assembly and header interface during high pressure testing.

[0025] One technique for meeting the approval requirements for additional protection types involves moving all electrical components for transient protection (e.g., EMI protection circuit 182) into a sealed module. This simplifies the approval process for the output assembly 158, which only includes an assembly of flying wires 164, 166, 168 immersed in the encapsulant 170, and allows a straightforward approach to meeting the approval requirements. However, the number of sealed modules is doubled due to the use of two versions of the sealed module, a standard protection version and a transient protection version. Figure 4 shows a sealed module 104B that includes an EMI protection circuit 182 and an output assembly 158B that does not include EMI protection components. For clarity, the assembly of flying wires 164, 166, 168 is not shown in Figure 4. The sealed module for the standard option is not shown.

[0026] To address the issues of complexity, cost and early customization associated with having two different versions of a sealed module, an alternative solution is provided, which is described below in conjunction with Figures 5 and 6.

[0027] The embodiments of the present disclosure described herein in connection with Figures 5 and 6 provide a structure where the electronics in a sealed package are reconfigurable after assembly while still meeting hazardous location approval requirements. Late stage customization of standard and transient outputs is selected at the hub during final assembly. The cost, complexity and logistics issues associated with the structure previously described in connection with Figure 4 are avoided. Also, Safety Zone 1 approval is simplified since no parts are located within the enclosed area of ​​the output assembly.

[0028] Similar to the structure of Figure 4, the structures shown in Figures 5 and 6 move the electronics into a sealed module. However, the connections to the protection diodes D1 and D2, and the gas-filled discharge tube GT1, are brought outside the hermetic package using additional feedthroughs on the existing header. Late-stage customization is achieved by attaching different wire interface boards during final assembly.

[0029] FIG. 5 is a schematic diagram illustrating a first enclosed module 104C-output assembly 158C configuration with additional feedthroughs 184 and 186 routed to ground to provide transient protection according to one embodiment. As seen in FIG. 5, the enclosed module 104C includes an EMI protection circuit 182 having transient protection elements with additional feedthroughs 184 and 186 connected thereto. More specifically, the feedthrough 184 is connected to a first TVS diode D1, and the feedthrough 186 is connected to both a second TVS diode D2 and a gas-filled discharge tube GT1. The output assembly 158C includes a wire interface board 188A including connectors (e.g., traces) 190, 192, 194, 196, and 198. The trace 190 connects to the active flying lead 164, the trace 192 connects to the active flying lead 166, and the trace 194 connects to the ground flying lead 168. The traces 196 and 198 are connected to the ground trace 194. When the output assembly 158C is coupled to the enclosed module 104C, the traces 190, 192, 194, 196, and 198 are connected to the feedthroughs 138, 140, 142, 184, and 186, respectively. As seen in FIG. 5, in this connection configuration, the first TVS diode D1 is connected between the active electrical connector 132A and electrical ground via the trace 196, and the second TVS diode D2 is connected between the active electrical connector 134A and electrical ground via the trace 198. Also, the second electrode 2 of the gas-filled discharge tube GT1 is connected to electrical ground via the trace 198. Therefore, this connection configuration provides transient protection.

[0030] 6 is a schematic diagram showing a second enclosed module 104C-output assembly 158C configuration with additional feedthroughs 184 and 186 routed back to respective lines 132A and 134A for units without transient protection. In the wire interface board 188B of FIG. 6, trace 196 is routed to trace 190, which is electrically connected to active electrical connector 132A through feedthrough 138. Similarly, trace 198 is routed to trace 192, which is electrically connected to active electrical connector 134A through feedthrough 140. Thus, no transient protection is provided in this configuration. Except for the routing without transient protection, the remainder of the circuit of FIG. 6 is similar to the circuit of FIG. 5.

[0031] This structure shown in Figures 5 and 6 allows the same sealed module to be used for units with and without transient protection. Customization can be done at the hub, for example after a few weeks as would have been done with the structure of Figure 4. The additional cost of installing additional modules and the increased annual cost of maintaining those modules is avoided. It should be noted that instead of using different wire interface boards 188A and 188B for the two different connection configurations, a single wire interface board with one or more switches to switch between these two configurations can be used.

[0032] The approval process is also streamlined. Because the concept of an Enhanced Safety Zone 1 approval is to reduce the risk of heat and sparks, the use of many common electrical components is not permitted. By removing the electrical components from the sealed conduit entry area, approval can be conducted seamlessly and easily.

[0033] This approach gives the end user the flexibility to install the device either as fireproof or for added safety. The electronics are not affected by humidity as all electronics have been moved into a sealed package. Customization is possible at a very late stage. The user can configure the device at the time of commissioning. The device can be reconfigured even after some time in the customer's possession. For example, a customer can reconfigure the device in the field several years after the initial commissioning.

[0034] The structure of the embodiment can be extended to include other functions, for example: a. the unit can be configured to communicate using HART, Fieldbus or Modbus protocols; b. The unit is configurable for standard or low power output protocols.

[0035] 7 is a simplified flow diagram of an embodiment of a method 200. At 202, an electromagnetic interference (EMI) protection circuit coupled to a process variable sensor is enclosed in an enclosed module having an electrical connector extending to the exterior. At 204, electronic components of the EMI protection circuit are connected from the exterior of the enclosed module through the electrical connector in a configuration that provides transient protection.

[0036] Although embodiments of the present invention have been described with reference to preferred embodiments, workers skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the invention.

Claims

1. A process variable sensor; an electromagnetic interference (EMI) protection circuit coupled to the process variable sensor; a sealed module that seals the EMI protection circuit; an electrical connector coupled to the EMI protection circuit within the sealed module and configurable from outside the sealed module such that electronic components of the EMI protection circuit are connected in a configuration that provides transient protection; 1. A process variable transmitter comprising:

2. 2. The process variable transmitter of claim 1, wherein the electrical connector coupled to the EMI protection circuit within the sealed module is configurable from outside the sealed module to connect the electronic components of the EMI protection circuit in a standard configuration without the transient protection.

3. the electrical connector comprises a first electrical connector electrically coupled to a first electronic component of the electrical components of the EMI protection circuit; the first electronic component is further coupled to an active electrical conductor; 3. The process variable transmitter of claim 2.

4. 4. The process variable transmitter of claim 3, wherein the first electrical connector is matable to an electrical ground connector external to the enclosed module such that the first electronic component can provide the transient protection.

5. 4. The process variable transmitter of claim 3, wherein the first electrical connector is matable to the active conductor from outside the enclosed module such that the first electronic component is unable to provide the transient protection.

6. a feedthrough body at a first end of the sealed module; the electrical connector includes a plurality of feedthrough pins extending through the feedthrough body and sealed relative to the feedthrough body; The feedthrough pin is a first active conductor feedthrough pin and a second active conductor feedthrough pin that allow electrical coupling between a first active conductor and a second active conductor that are inside the enclosed module and a first active conductor and a second active conductor that are outside the enclosed module; an electrical ground feedthrough pin that allows electrical coupling between an electrical ground connector inside the sealed module and an electrical ground connector outside the sealed module; a first additional feedthrough pin and a second additional feedthrough pin coupled to different ones of the electronic components of the EMI protection circuit, each of the different ones of the electronic components being further coupled to the first active conductor or the second active conductor in the enclosed module; Equipped with 10. The process variable transmitter of claim 1.

7. 7. The process variable transmitter of claim 6, wherein the first additional feedthrough pin and the second additional feedthrough pin are coupled to the electrical ground connector that is external to the sealed module to enable the transient protection from outside the sealed module.

8. Disabling the transient protection. the first additional feedthrough pin is coupled to the first active conductor that is external to the enclosed module; the second additional feedthrough pin is coupled to the second active conductor that is external to the enclosed module; 7. The process variable transmitter of claim 6.

9. 7. The process variable transmitter of claim 6, wherein the electronic components comprise first and second transient voltage suppression (TVS) diodes and a gas filled discharge tube.

10. the first TVS diode is coupled to the first active conductor in the hermetic module and is coupled to the first additional feedthrough pin in the hermetic module; the second TVS diode is coupled to the second active conductor in the hermetic module and is coupled to the second additional feedthrough pin in the hermetic module; the gas-filled discharge tube is coupled to the first active conductor and the second active conductor in the sealed module, and is coupled to the second additional feedthrough pin in the sealed module; 10. The process variable transmitter of claim 9.

11. Encapsulating an electromagnetic interference (EMI) protection circuit coupled to the process variable sensor in a sealed module having an electrical connector extending to the exterior; connecting electronic components of the EMI protection circuitry from outside the sealed module through the electrical connector in a configuration that provides transient protection; The method includes:

12. 12. The method of claim 11, further comprising connecting the electronic components of the EMI protection circuit from outside the enclosed module through the electrical connector in a standard configuration without the transient protection.

13. electrically coupling a first one of the electrical connectors to a first electronic component of the electrical components of the EMI protection circuit; the first electronic component is further coupled to an active electrical conductor; The method of claim 12.

14. 14. The method of claim 13, further comprising: coupling the first electrical connector to an electrical ground connector external to the enclosed module so as to provide the transient protection by the first electronic component.

15. 14. The method of claim 13, further comprising: electrically coupling the first electrical connector to the active electrical conductor from outside the enclosed module such that the first electronic component is unable to provide the transient protection.

16. A process variable sensor; an electromagnetic interference (EMI) protection circuit coupled to the process variable sensor; an encapsulation module encapsulating the EMI protection circuit, the encapsulation module having a first end including a feedthrough body and a plurality of feedthrough pins extending through the feedthrough body and encapsulated relative to the feedthrough body; 1. A process variable transmitter comprising: the feedthrough pins are coupled to the EMI protection circuitry within the hermetic module and are configurable from outside the hermetic module such that electronic components of the EMI protection circuitry are connected in a configuration that provides transient protection. Process variable transmitter.

17. The plurality of feedthrough pins include a first active conductor feedthrough pin and a second active conductor feedthrough pin that allow electrical coupling between a first active conductor and a second active conductor that are inside the enclosed module and a first active conductor and a second active conductor that are outside the enclosed module; an electrical ground feedthrough pin that allows electrical coupling between an electrical ground connector inside the sealed module and an electrical ground connector outside the sealed module; a first additional feedthrough pin and a second additional feedthrough pin coupled to different ones of the electronic components of the EMI protection circuit, each of the different ones of the electronic components being further coupled to the first active conductor or the second active conductor in the enclosed module; 20. The process variable transmitter of claim 16, comprising:

18. 20. The process variable transmitter of claim 17, wherein the first additional feedthrough pin and the second additional feedthrough pin are coupled to the electrical ground connector that is external to the sealed module to enable the transient protection from outside the sealed module.

19. Disabling the transient protection. the first additional feedthrough pin is coupled to the first active conductor that is external to the enclosed module; the second additional feedthrough pin is coupled to the second active conductor that is external to the enclosed module; 20. The process variable transmitter of claim 17.

20. the electronic component comprises first and second transient voltage suppression (TVS) diodes and a gas-filled discharge tube; the first TVS diode is coupled to the first active conductor in the hermetic module and is coupled to the first additional feedthrough pin in the hermetic module; the second TVS diode is coupled to the second active conductor in the hermetic module and is coupled to the second additional feedthrough pin in the hermetic module; the gas-filled discharge tube is coupled to the first active conductor and the second active conductor in the sealed module and is coupled to the second additional feedthrough pin in the sealed module; 20. The process variable transmitter of claim 17.

Images