Intrinsic safety (IS) barrier with associated energy limiting apparatus

A method and apparatus is disclosed that includes first and second hardware components. The first component includes at least one first input configured to receive at least one first data or power signal, at least one voltage clamping circuit configured to limit a voltage of the at least one first data or power signal, and at least one first output configured to provide the at least one voltage-limited first data or power signal. The second component includes at least one second input configured to receive at least one second data or power signal, at least one limiter circuit configured to limit an amount of energy in the at least one second data or power signal, and at least one second output configured to provide the at least one energy-limited second data or power signal.

TECHNICAL FIELD

This disclosure generally relates to electrical safety barriers. More specifically, this disclosure relates to an intrinsic safety (IS) barrier with an associated energy limiting apparatus.

BACKGROUND

Industrial process control and automation systems are often used to automate large and complex industrial processes. These types of systems routinely include various components including sensors, actuators, and controllers. Some of the controllers can receive measurements from the sensors, possibly through connected input/output (I/O) subsystems, and generate control signals for the actuators. Existing process control and automation systems typically have hardware components participating in control and I/O functions that are installed in control rooms and in the field. These hardware components are often used to gather I/O information from the field, transmit that I/O information to the control rooms, perform various control functions, and transmit I/O information back to the field.

In hazardous environments, it may be necessary or desirable to limit and isolate critical I/O functions or other functions using intrinsic safety (IS) barriers. Intrinsic safety barriers implement protection techniques that limit electrical or thermal energy available in the hazardous environments. This helps to ensure safe operation of electrical equipment in the hazardous environments and limits the electrical or thermal energy available for ignition in the hazardous environments. As a particular example, intrinsic safety barriers can be used to limit the electrical or thermal energy available in environments that contain flammable or explosive gasses, liquids, or other materials.

SUMMARY

This disclosure provides an intrinsic safety (IS) barrier with an associated energy limiting apparatus.

In a first embodiment, an apparatus includes a first hardware component and a second hardware component. The first hardware component includes at least one first input configured to receive at least one first data or power signal. The first hardware component also includes at least one voltage clamping circuit configured to limit a voltage of the at least one first data or power signal. The first hardware component further includes at least one first output configured to provide the at least one voltage-limited first data or power signal. The second hardware component includes at least one second input configured to receive at least one second data or power signal, where the at least one second data or power signal comprises or is based on the at least one voltage-limited first data or power signal. The second hardware component also includes at least one limiter circuit configured to limit an amount of energy in the at least one second data or power signal. The second hardware component further includes at least one second output configured to provide the at least one energy-limited second data or power signal.

In a second embodiment, a system includes at least one input/output (I/O) module that includes at least one I/O channel. The system also includes at least one intrinsic safety barrier. Each intrinsic safety barrier includes a first hardware component and a second hardware component. The first hardware component includes at least one first input configured to receive at least one first data or power signal. The first hardware component also includes at least one voltage clamping circuit configured to limit a voltage of the at least one first data or power signal. The first hardware component further includes at least one first output configured to provide the at least one voltage-limited first data or power signal to the at least one I/O module. The second hardware component includes at least one second input configured to receive at least one second data or power signal from the at least one I/O module. The second hardware component also includes at least one limiter circuit configured to limit an amount of energy in the at least one second data or power signal. The second hardware component further includes at least one second output configured to provide the at least one energy-limited second data or power signal.

In a third embodiment, a method includes coupling a first hardware component of an intrinsic safety barrier to a first device. The first hardware component includes at least one first input configured to receive at least one first data or power signal. The first hardware component also includes at least one voltage clamping circuit configured to limit a voltage of the at least one first data or power signal. The first hardware component further includes at least one first output configured to provide the at least one voltage-limited first data or power signal to the first device. The method also includes coupling a second hardware component of the intrinsic safety barrier to the first device. The second hardware component includes at least one second input configured to receive at least one second data or power signal, where the at least one second data or power signal comprises or is based on the at least one voltage-limited first data or power signal. The second hardware component also includes at least one limiter circuit configured to limit an amount of energy in the at least one second data or power signal. The second hardware component further includes at least one second output configured to provide the at least one energy-limited second data or power signal to one or more second devices.

DETAILED DESCRIPTION

As noted above, industrial process control and automation systems typically have hardware components participating in various control and input/output (I/O) functions. In hazardous environments, it may be necessary or desirable to limit and isolate critical I/O functions or other functions using intrinsic safety (IS) barriers, which implement protection techniques that limit electrical or thermal energy available in the hazardous environments. This helps to ensure safe operation of electrical equipment in the hazardous environments and limits the electrical or thermal energy available for ignition in the hazardous environments. In other words, intrinsic safety barriers help to facilitate the use of electrical equipment in hazardous environments by reducing or eliminating the likelihood that the electrical equipment could cause explosions or other problems in the hazardous environments.

Conventional intrinsic safety barriers are often single-channel barriers, meaning each barrier can only be used with a single I/O channel. Conventional intrinsic safety barriers are also often general-purpose barriers, meaning the barriers are typically designed for a wide range of applications in various environments. As a result, a large number of intrinsic safety barriers may be needed in systems having a large number of I/O channels, and these intrinsic safety barriers may occupy a large amount of space. In some cases, a control room could need dedicated cabinets and power supplies just for single-channel intrinsic safety barriers. Moreover, because conventional intrinsic safety barriers are general-purpose components, these conventional barriers are often generic components that need to satisfy a large number of requirements for use in different environments. This can increase the number of components in the intrinsic safety barriers, as well as the size and cost of the intrinsic safety barriers. As a specific example, general-purpose intrinsic safety barriers often undergo rigorous assessments under IEC 60079-xx standards, and a 250V assessment can often force hardware to be designed with high-capacity safety devices with high creepage and clearance. This leads to larger sizes of intrinsic safety barriers, which in turn reduces channel densities in a given cabinet. In addition, because they are general-purpose components, conventional intrinsic safety barriers are often not configurable, so different intrinsic safety barriers are needed for different types of I/O channels.

This disclosure describes approaches for integrating intrinsic safety barriers into specific hardware, where only the desired functionality is packaged with the hardware. As a result, the overall sizes of the integrated intrinsic safety barriers can be reduced, and channel densities can be improved. The intrinsic safety barriers are also implemented using a miniature form factor. Again, the size and cost of the intrinsic safety barriers can be reduced, which can also help to provide improved channel densities. In addition, because the functionality of the intrinsic safety barriers could be limited to only the functionality that is actually needed, the barriers could be easier to design, develop, and certify.

FIG. 1illustrates an example industrial process control and automation system100according to this disclosure. As shown inFIG. 1, the system100includes various components that facilitate production or processing of at least one product or other material. For instance, the system100can be used to facilitate control or monitoring of components in one or multiple industrial plants. Each plant represents one or more processing facilities (or one or more portions thereof), such as one or more manufacturing facilities for producing at least one product or other material. In general, each plant may implement one or more industrial processes and can individually or collectively be referred to as a process system. A process system generally represents any system or portion thereof configured to process one or more products or other materials or energy in different forms in some manner.

In the example shown inFIG. 1, the system100includes one or more sensors102aand one or more actuators102b. The sensors102aand actuators102brepresent components in a process system that may perform any of a wide variety of functions. For example, the sensors102acould measure a wide variety of characteristics in the process system, such as temperature, pressure, or flow rate. Also, the actuators102bcould alter a wide variety of characteristics in the process system. Each of the sensors102aincludes any suitable structure for measuring one or more characteristics in a process system. Each of the actuators102bincludes any suitable structure for operating on or affecting one or more conditions in a process system.

At least one I/O module104is coupled to the sensors102aand actuators102b. The I/O modules104facilitate interactions with the sensors102a, actuators102b, or other field devices. For example, an I/O module104could be used to receive one or more analog inputs (AIs), digital inputs (DIs), digital input sequences of events (DISOEs), pulse accumulator inputs (PIs), or other inputs from one or more field devices. An I/O module104could also be used to provide one or more analog outputs (AOs), digital outputs (DOs), or other outputs to one or more field devices. As described below, the interactions with one or more field devices occur through one or more intrinsic safety barriers. Each I/O module104includes any suitable structure(s) for receiving one or more input signals from or providing one or more output signals to one or more field devices.

The system100also includes various controllers106. The controllers106can be used in the system100to perform various functions in order to control one or more industrial processes. For example, a first set of controllers106may use measurements from one or more sensors102ato control the operation of one or more actuators102b. These controllers106could interact with the sensors102a, actuators102b, and other field devices via the I/O modules104. A second set of controllers106could be used to optimize the control logic or other operations performed by the first set of controllers. A third set of controllers106could be used to perform additional functions. It is also possible that one set of controllers could be in a stand-by or load sharing mode to improve overall availability of the system.

Controllers106are often arranged hierarchically in a system. For example, different controllers106could be used to control individual actuators, collections of actuators forming machines, collections of machines forming units, collections of units forming plants, and collections of plants forming an enterprise. The controllers106in different hierarchical levels can communicate via one or more networks108and associated switches, firewalls, and other components.

Each controller106includes any suitable structure for controlling one or more aspects of an industrial process. At least some of the controllers106could, for example, represent proportional-integral-derivative (PID) controllers or multivariable controllers, such as Robust Multivariable Predictive Control Technology (RMPCT) controllers or other types of controllers implementing model predictive control (MPC) or other advanced predictive control. As a particular example, each controller106could represent a computing device running a real-time operating system, a WINDOWS operating system, or other operating system.

The network108couples the controllers106and other devices in the system100. The network108facilitates the transport of information between components. The network108could represent any suitable network or combination of networks. As particular examples, the network108could represent at least one Ethernet network.

Operator access to and interaction with the controllers106and other components of the system100can occur via various operator stations110. Each operator station110could be used to provide information to an operator and receive information from an operator. For example, each operator station110could provide information identifying a current state of an industrial process to an operator, such as values of various process variables and warnings, alarms, or other states associated with the industrial process. Each operator station110could also receive information affecting how the industrial process is controlled, such as by receiving setpoints for process variables controlled by the controllers106or other information that alters or affects how the controllers106control the industrial process. Each operator station110includes any suitable structure for displaying information to and interacting with an operator.

Multiple operator stations110can be grouped together and used in one or more control rooms112. Each control room112could include any number of operator stations110in any suitable arrangement. In some embodiments, multiple control rooms112can be used to control an industrial plant, such as when each control room112contains operator stations110used to manage a discrete part of the industrial plant.

This represents a brief description of one type of industrial process control and automation system that may be used to manufacture or process one or more materials. Additional details regarding industrial process control and automation systems are well-known in the art and are not needed for an understanding of this disclosure. Also, industrial process control and automation systems are highly configurable and can be configured in any suitable manner according to particular needs.

In particular embodiments, the various controllers106and operator stations110inFIG. 1may represent computing devices. For example, each of the controllers and operator stations could include one or more processing devices, such as one or more microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), or discrete circuitry. Each of the controllers106and operator stations110could also include one or more memories for storing instructions and data used, generated, or collected by the processing device(s), such as a random access memory, read only memory, Flash memory, optical disc, hard drive, or any other suitable volatile or non-volatile storage device(s). Each of the controllers106and operator stations110could further include at least one network interface, such as one or more Ethernet interfaces or wireless transceivers.

In process control and automation systems such as the system100, I/O channels are used to connect controllers (such as the controllers106) and field devices (such as the sensors102aand actuators102b). In general, the I/O modules104or other devices can support I/O channels of various types, including AIs, DIs, DISOEs, PIs, AOs, or DOs. Different I/O channel types are characterized by different inputs, outputs, voltages, currents, and configurations. A universal I/O (UIO) channel is a specialized I/O channel that is reconfigurable to operate as any of multiple I/O channel types. Example types of UIO circuits are shown in U.S. Pat. No. 8,072,098; U.S. Pat. Nos. 8,392,626; 8,656,065; and U.S. Patent Publication No. 2015/0278144 (all of which are hereby incorporated by reference in their entirety). UIO circuits that support UNIVERSAL CHANNEL TECHNOLOGY available from HONEYWELL INTERNATIONAL INC. are also suitable for use.

As described in more detail below, the I/O modules104or other components of the system100can include intrinsic safety (IS) barriers that allow sensors, actuators, or other field devices to be used in hazardous environments or other environments. In this example, the sensors102aand actuators102bare used in a hazardous environment114, which may also be referred to a hazardous location or “HazLoc” area. The intrinsic safety barriers include energy limiting devices and can provide galvanic isolation (GI) for the sensors, actuators, and other field devices. These intrinsic safety barriers can be implemented with improved channel densities, improved or optimized space utilization, and reduced costs. The described approaches can be used with traditional I/O channels, universal I/O channels, or other suitable I/O channels or combinations of I/O channels.

In some embodiments, each I/O module104could support up to sixteen or thirty-two I/O channels and include an intrinsic safety barrier for each I/O channel. However, these numbers are examples only, and other numbers of I/O channels and intrinsic safety barriers could be used. Also, in some embodiments, the I/O module104could still fit within the available space for an I/O module in a cabinet or other structure, even though the I/O module104is used with a large number of intrinsic safety barriers.

The use of intrinsic safety barriers could be supported in any suitable I/O modules104or other devices. For example, in some embodiments, each I/O module104could include only universal digital input, digital output, and/or digital input/output channels along with the intrinsic safety barriers. However, an I/O module104could support any number(s) and type(s) of I/O channels.

Additional details regarding example intrinsic safety barriers are provided below. Note that these details relate to specific implementations of intrinsic safety barriers and that other embodiments of the intrinsic safety barriers could also be used. For example, specific voltages, numbers of I/O modules or I/O channels, numbers of intrinsic safety barriers, and redundancy configurations may be described below, although any other suitable values could be used.

AlthoughFIG. 1illustrates one example of an industrial process control and automation system100, various changes may be made toFIG. 1. For example, the system100could include any number of sensors, actuators, I/O modules, controllers, operator stations, networks, intrinsic safety barriers, and other components. Also, the makeup and arrangement of the system100inFIG. 1is for illustration only. Components could be added, omitted, combined, or placed in any other suitable configuration according to particular needs. Further, particular functions have been described as being performed by particular components of the system100. This is for illustration only. In general, control and automation systems are highly configurable and can be configured in any suitable manner according to particular needs. In addition,FIG. 1illustrates one example operational environment in which one or more intrinsic safety barriers can be used. This functionality can be used in any other suitable system, and the system need not be related to industrial process control and automation.

FIG. 2illustrates an example intrinsic safety barrier200with an associated energy limiting apparatus according to this disclosure. For ease of explanation, the intrinsic safety barrier200may be described as being used in the I/O modules104in the industrial process control and automation system100ofFIG. 1. However, the intrinsic safety barrier200could be used with any suitable devices and in any suitable systems (whether or not those devices and systems relate to industrial process control and automation). Also, note that the intrinsic safety barrier200may be described below in the context of a specific intrinsic safety standard, such as IEC 60079-xx. However, compliance with other intrinsic safety standards is also possible.

According to IEC 60079-11, any signal coming from a safe area is considered as a potential carrier of 250V, which needs to be voltage-clamped and energy-limited before passing to a hazardous location. This 250V assessment is often difficult for barrier certification, which can result in the selection of bulky protection devices that increase the size and cost of the barrier and reduce channel density. To help with these or other issues, the intrinsic safety barrier200inFIG. 2is split into two separate hardware components, namely an isolation module202and IS barrier hardware204. The isolation module202and the IS barrier hardware204are used in conjunction with at least one I/O module206, which could represent any of the I/O modules104ofFIG. 1. Among other things, this division helps to facilitate easier safety assessment of the intrinsic safety barrier200.

The isolation module202operates to clamp power or communication signals from a controller or other subsystem208in a safe area, such as to a voltage that complies with a relevant safety standard (like IEC 60079-xx). In some embodiments, the isolation module202can clamp power or communication signals from 250V to a much lower voltage. Thus, the isolation module202could be assessed for 250V and can optionally have an isolating element. Depending on the implementation, the isolation module202could perform voltage clamping and galvanic isolation for the power and communication signals. In particular embodiments, the isolation module202can perform voltage clamping and galvanic isolation for both serial communication (such as RS485) and DC power (such as 24 VDC) coming from a controller cabinet or other source, although other power or communication signals could be used. Also, in particular embodiments, the isolation module202could be implemented according to suitable guidelines for use in a “zone 0,” “zone 1,” or “zone 2” environment.

As described in more detail below, in some embodiments, one or more voltage clamping circuits210can be used in the isolation module202. Each voltage clamping circuit210could be passive or active. This portion of the intrinsic safety barrier200may require an “ia,” “ib,” “ic,” or other safety assessment since the outputs of the isolation module202are fed to another subsystem that includes the IS barrier hardware204. Each voltage clamping circuit210could therefore undergo an “ia,” “ib,” or “ic” assessment for 250V inputs, as well as for thermal assessment. Galvanic isolation could be provided before or after an active voltage clamp (if used). Each voltage clamping circuit210includes any suitable structure for limiting the voltage of a power signal or at least one communication signal. In some embodiments, resistive elements could be used as a power and current limiting circuit for communication channels or other channels carrying data signals to or from a safe area. Suitable isolation techniques (such as opto, transformer, or capacitive) may be implemented for channels carrying data signals.

Outputs of the isolation module202can be functionally the same as inputs of the isolation module202, but (as far as the safety assessment is concerned) the outputs of the isolation module202are voltage-limited. In some cases, the outputs are voltage-limited to a voltage lower than 250V, although the exact value depends on the design. Subsequent systems connecting to the outputs of the isolation module202would not need go through a 250V or other assessment for IS purposes. This is because the subsequent systems connecting to the outputs of the isolation module202would only receive voltage-clamped signals from the isolation module202.

In some embodiments, multiple instances of the isolation module202could be used, and one or multiple instances of the IS barrier hardware204can be coupled to the outputs of each of the isolation modules202. Also, in some embodiments, each of the isolation modules202could be installed in a safe zone, “zone 0,” “zone 1,” or “zone 2.” Further, in some embodiments, isolation modules202can optionally have a 1:1 redundancy or other redundancy configuration to improve overall system availability. Note that an isolation module202by itself need not be certified as a subsystem; rather, certification may only be needed when the isolation module202is used in combination with the IS barrier hardware204.

The IS barrier hardware204provides energy limiting and isolation circuitry for one or more I/O channels supported by the I/O module(s)206. However, the IS barrier hardware204does not need to be assessed for 250V or other voltage clamping functionality for IS compliance since the inputs to the IS barrier hardware204come through the isolation module202(which does comply with 250V or other assessment outputs). Thus, the inputs to the IS barrier hardware204are already safety-assessed for a lower voltage. The energy limiting and isolation circuitry of the IS barrier hardware204can still be assessed for intrinsic safety, such as per the IEC 60079-11 standard or other suitable standard.

As described in more detail below, in some embodiments, the IS barrier hardware204includes an isolated power supply212, isolators214a-214bfor power and communication signals, and at least one current limiter or other energy-limiting circuit216. The isolated power supply212includes any suitable source of electrical power that provides electrical isolation. For example, the isolated power supply212could include a transformer that operates as an isolating element. Each isolator214a-214bincludes any suitable structure for providing electrical isolation for power or at least one communication signal. For instance, the isolators214a-214bfor power and communication signals could include opto, transformer, or capacitive elements that operate as isolating elements. Each energy-limiting circuit216includes any suitable structure for limiting electrical energy provided from the IS barrier hardware204. As an example, the energy-limiting circuit216could be implemented using resistive elements near the outputs of the IS barrier hardware204.

Multiple instances of the IS barrier hardware204could be interfaced to one isolation module202to help control the overall cost of the intrinsic safety barrier200. However, multiple isolation modules202(each with one or multiple instances of the IS barrier hardware204) could also be used. In specific embodiments, two isolation modules202provide 1:1 redundancy and are coupled to two I/O modules206(which also provide 1:1 redundancy), and one instance of the IS barrier hardware204is coupled to the two I/O modules206. In some embodiments, the isolation modules202, IS barrier hardware204, and I/O modules206can all be installed within the same cabinet or other structure. Note, however, that this is not necessarily required, and the intrinsic safety barrier200could be installed or used in any other suitable manner.

In this type of design approach, intrinsic safety can be provided at a lower cost and smaller space per channel, which can allow for an improved channel density. Moreover, the smaller size of the intrinsic safety barrier200can help with integration within larger devices or systems, as well as with the overall cost for a project. Further, the intrinsic safety barrier200could find use in a large number of hardware devices. In addition, the IS barrier hardware204does not need to go through 250V or other safety assessment, which can provide tremendous advantages for designers with respect to component ratings, sizes, channel densities, and hardware costs. This helps in the development of hardware with high channel densities and lower costs, which is typically not possible with existing third-party solutions.

Note that a number of other features could also be supported by the intrinsic safety barrier200. For example, the isolation module202and the IS barrier hardware204could be packaged as separate subsystems. The intrinsic safety barrier200could support the use of any suitable type(s) and number(s) of I/O channels in any suitable combination, including fixed and universal I/O channels. Each instance of the isolation module202and of the IS barrier hardware204could be independently accessed and replaced while keeping one or more controllers “on process” (meaning the one or more controllers maintain constant control over an industrial process or portion thereof). Each instance of the isolation module202and of the IS barrier hardware204could be approved for live insertion and removal.

There are various ways in which an intrinsic safety barrier200can be packaged and installed along with one or more I/O modules206. For example, one or more intrinsic safety barriers200can be used with an Input/Output Termination Assembly (“IOTA”). The IOTA generally represents a structure through which other components (such as controllers106) communicate with the I/O modules206. The isolation modules202of the intrinsic safety barriers200can be installed in any suitable location(s), such as at or near a power supply of a cabinet. The IS barrier hardware204of the intrinsic safety barriers200can be separate hardware and can also be installed in any suitable location(s), such as on the IOTA.

AlthoughFIG. 2illustrates one example of an intrinsic safety barrier200with an associated energy limiting apparatus, various changes may be made toFIG. 2. For example, the intrinsic safety barrier200could include any suitable number of isolation modules202and IS barrier hardware204and could be used in conjunction with any suitable number of I/O modules206. Also, the intrinsic safety barrier200could be used with any other suitable device(s) and need not be used with an I/O module.

FIG. 3illustrates an example implementation of an isolation module202in the intrinsic safety barrier200ofFIG. 2according to this disclosure. Note that the example implementation of the isolation module202shown inFIG. 3is for illustration only. The isolation module202could be implemented in any other suitable manner without departing from the scope of this disclosure.

As shown inFIG. 3, the isolation module202includes a first input connector302and a first output connector304. The input connector302is configured to receive an input power signal into the isolation module202, and the output connector304is configured to provide a voltage-clamped output power signal from the isolation module202. Each connector302and304includes any suitable structure configured to receive or provide an electrical signal, such as a 24 VDC signal.

The input power signal passes through the input connector302and is received at a fuse306. The fuse306represents a structure configured to break in order to prevent excessive current from flowing further into the isolation module202. An in-rush control circuit308is configured to receive the input power signal through the fuse306and to limit the current passing through the control circuit308, such as when the isolation module202is initially powered-on. The in-rush control circuit308can also perform other functions, such as by providing short-circuit protection and reverse polarity protection.

A voltage limiting circuit310is coupled to the output of the in-rush control circuit308. The voltage limiting circuit310generally operates to prevent an overvoltage condition from propagating to downstream components coupled to the output connector304. For example, the voltage limiting circuit310could selectively create one or more short-circuit or low-resistance paths to ground when an overvoltage condition occurs. In some embodiments, the voltage limiting circuit310can withstand a 250V input and allow a significantly smaller voltage to be passed to the output connector304. The voltage limiting circuit310could also have a rapid response time, such as about 10 s or less. In addition, the voltage limiting circuit310could maintain a suitable temperature during a fault condition. The voltage limiting circuit310includes any suitable structure configured to protect against an overvoltage condition, such as one or more crowbar circuits.

An optional isolated power supply312can be positioned between (i) the in-rush control circuit308and the voltage limiting circuit310and (ii) the output connector304. The isolated power supply312receives the input power signal from the in-rush control circuit308and provides a voltage-clamped output power rail to the output connector304. The isolated power supply312also helps to electrically isolate the in-rush control circuit308and the voltage limiting circuit310from the output connector304. In some embodiments, the isolated power supply312includes a transformer. In particular embodiments, the isolated power supply312is designed to comply with an IEC 60079-xx standard or other similar standard in order to support use in a HazLoc area.

The isolation module202also includes a second input connector314and a second output connector316. The input connector314is configured to receive an input data signal into the isolation module202, and the output connector316is configured to provide a voltage-clamped output data signal from the isolation module202. Each connector314and316includes any suitable structure configured to receive or provide a data signal. Note that in this example, the input data signal is a differential data signal, such as an RS485 signal, so there are positive and negative terminals in the connectors314and316, as well as separate electrical paths for the positive and negative portions of the input data signal. However, this is not required, and a single-ended input data signal could be used here.

The two portions of the input data signal pass through the input connector314and are received at respective fuses318. Each fuse318represents a structure configured to break in order to prevent excessive current from flowing further into the isolation module202. The two portions of the input data signal also pass through respective protection circuits320, each of which is implemented in this example using a resistor. In some embodiments, each protection circuit320can withstand a 250V input.

Two transceivers322and324are used to transmit the two portions of the input data signal across respective signal isolators326. For example, the transceiver322could receive the input data signal from the protection control circuits320, regenerate the input data signal if needed, and transmit the input data signal towards the signal isolators326. The transceiver324could receive signals from the signal isolators326, regenerate the input data signal, and transmit the regenerated input data signal towards the output connector316. Optionally, data can flow in both directions through the isolation module202, and one or both transceivers322and324could be configured to receive a data direction control signal that controls the direction of data transport.

Each transceiver322and324includes any suitable structure for transmitting or receiving a data signal, such as an RS485 or other serial data transceiver. Note that while transceivers are shown here, one transceiver322or324could represent a transmitter and the other transceiver324or322could represent a receiver if data transport occurs in a single direction through the isolation module202. Each signal isolator326includes any suitable structure for electrically isolating a data communication pathway. For example, each signal isolator326could include an opto-isolator that uses a photodiode to convert an electrical signal into light and a photodetector to convert the light back into an electrical signal. However, other isolation techniques (such as transformer or capacitive techniques) could be used here.

For each of the two portions of the input data signal, a respective resistor328and a respective resistor330are positioned on opposite sides of each isolator326. Moreover, a respective resistor332is positioned between the transceiver324and the output connector316. Each resistor328-332could have any suitable resistance.

Multiple parallel diodes334can be coupled to the output of each protection control circuit320. These diodes334help to clamp the voltages that appear at the inputs to the transceiver322. Note that while three parallel diodes334are used here for each input to the transceiver322, any number of diodes334(including a single diode) could be used. Similarly, various diodes336are connected in series and in parallel with each other and are coupled between the inputs to the transceiver322and the output from the in-rush control circuit308. These diodes334-336are used to couple any overvoltage appearing on the signal path to the input of the voltage limiting circuit310. This allows the same voltage limiting circuit310to clamp the overvoltage in the power and signal paths. Note, however, that separate voltage limiting circuits could also be used for the power and signal paths. Note that while each set of diodes336includes three parallel-coupled lines (each line with three series-coupled diodes), any number of diodes336in any suitable arrangement could be used.

In particular embodiments, the components in the isolation module202can be configured for use in a wide temperature range, such as between about −40° C. and +70° C. Also, in particular embodiments, the components in the isolation module202can undergo an “ia” assessment or other suitable assessment. Further, in particular embodiments, a redundant pair of isolation modules202can be used in each of multiple columns of a cabinet. Of course, one or more isolation modules202could be used in any other suitable manner.

AlthoughFIG. 3illustrates one example implementation of an isolation module202in the intrinsic safety barrier200ofFIG. 2, various changes may be made toFIG. 3. For example, while specific components and specific values are provided above, these are examples only, and any other suitable components or values could be used in the isolation module202. Also, if a single-ended input data signal is received, a single path may be used between the input connector314and the output connector316.

FIG. 4illustrates an example implementation of intrinsic safety barrier hardware204in the intrinsic safety barrier200ofFIG. 2according to this disclosure. Note that the example implementation of the IS barrier hardware204shown inFIG. 4is for illustration only. The IS barrier hardware204could be implemented in any other suitable manner without departing from the scope of this disclosure.

As shown inFIG. 4, an input power signal received by the IS barrier hardware204is provided to a hot swap circuit402. The input power signal could be provided from the output connector304of the isolation module202. Alternatively, the input power signal could be provided from an I/O channel, such as one of multiple I/O channels supported by an I/O module206. The hot swap circuit402allows the IS barrier hardware204to be inserted into a powered-on system and limits in-rush current during the insertion. The input power signal from the hot swap circuit402is received at a fuse404. The fuse404represents a structure configured to break in order to prevent excessive current from flowing further into the IS barrier hardware204. An isolated power supply406can be positioned between the fuse404and a power supply line408. The isolated power supply406receives the input power signal from the fuse404and provides a corresponding output power signal over the power supply line408. The isolated power supply406also helps to electrically isolate the fuse404from the power supply line408and could include a transformer.

Multiple Zener diodes410are connected in series and in parallel with each other and are coupled between ground and the input to the isolated power supply406. The Zener diodes410help to clamp the voltage that appears at the input to the isolated power supply406. Note that the use of the Zener diodes410is optional and they may be omitted if power is drawn through the output connector304of the isolation module202. If power is drawn from one of the I/O channels of an I/O module206, the Zener diodes410can be used. Any suitable Zener diodes410could be used here. Note that while the set of Zener diodes410includes three parallel-coupled lines (each line with two series-coupled Zener diodes), any number of Zener diodes410in any suitable arrangement could be used.

The IS barrier hardware204receives an input data signal from an I/O module206or other source. In this example, the input data signal is a differential data signal, such as an RS485 signal, so again there are separate electrical paths for the positive and negative portions of the input data signal. However, this is not required, and a single-ended input data signal could be used here.

The two portions of the input data signal pass through respective resistors412a-412b. Each of the resistors412a-412bcould have any suitable resistance. A set of parallel-coupled diodes414is connected to each of the resistors412a-412band to the input of the isolated power supply406. Note that while three parallel diodes414are used here for each of the resistors412a-412b, any number of diodes414(including a single diode) could be used.

The two portions of the input data signal are provided from the resistors412a-412bto a functional circuit416. The functional circuit416operates to condition the differential data signal for input to a signal isolator418. For example, the functional circuit416could perform level shifting and signal conditioning to prepare the differential data signal for input to the signal isolator418.

The signal isolator418operates to electrically isolate signals being used by the functional circuit416and a functional circuit420. For example, the signal isolator418could receive an incoming signal from the functional circuit416and provide an electrically-isolated replica of the signal to the functional circuit420(or vice versa). As a particular example, the signal isolator418could use one or more transformers to electrically isolate the signals used by the functional circuit416and the functional circuit420. Various resistors422are used on the signal lines between the functional circuit416and the signal isolator418. Also, various resistors424are used on the signal lines between the signal isolator418and the functional circuit420. Each of the resistors422and424could have any suitable resistance.

The functional circuit420processes the incoming data signal from the signal isolator418into a form suitable for transmission out of the intrinsic safety barrier200and to a field device or other destination. For example, the functional circuit420could convert the differential data signal into a single-ended data signal that is output from the functional circuit420. The functional circuit420could also ensure that the single-ended data signal complies with any specified protocol or other guidelines, such as by ensuring that the single-ended data signal has a desired voltage or current level. The functional circuit420could further optionally supply power received from the isolated power supply406to the field device or other destination. In some embodiments, the functional circuit420could represent a digital I/O circuit, although any other suitable circuitry could be used in the functional circuit420.

The output from the functional circuit420passes through a resistor426and multiple diodes428. The resistor426is also coupled to multiple parallel-coupled Zener diodes430. The resistor426could have any suitable resistance. Any suitable diodes428could be used here. Note that while three series-coupled diodes428are used here, any number of diodes428(including a single diode) could be used. Any suitable Zener diodes430could be used here. Note that while three parallel-coupled Zener diodes430are used here, any number of Zener diodes430(including a single diode) could be used. The output from the functional circuit420is provided to a field device or other destination through an output connector432, which could be coupled to any suitable pathway to the destination.

The signal isolator418and the functional circuit420can receive power from the isolated power supply406. In this example, the two sides of the signal isolator418are coupled to the isolated power supply406through resistors434a-434b, respectively. Each of the resistors434a-434bis respectively coupled in series to a Zener diode436a-436b. Each of the resistors434a-434bcould have any suitable resistance. Any suitable Zener diodes436a-436bcould be used here, such as those used to provide a 3.3V reference to the signal isolator418. Also, the functional circuit420is coupled to the isolated power supply406through a resistor438. The resistor438could have any suitable resistance.

It should be noted that the components412a-412b,414-432shown inFIG. 4are used to handle a single I/O channel associated with an I/O module206or other device. These components could be replicated any suitable number of times to support communications over any suitable number of I/O channels. As a particular example, the IS barrier hardware204could include components that support sixteen or thirty-two I/O channels. Moreover, the components416-424are used here specifically to support a digital output channel. The IS barrier hardware204could include other components in place of the components416-424in order to support analog, digital, or other types of input or output channels.

AlthoughFIG. 4illustrates one example implementation of intrinsic safety barrier hardware204in the intrinsic safety barrier200ofFIG. 2, various changes may be made toFIG. 4. For example, while specific components and specific values (like voltages, currents, and powers) are provided above, these are examples only, and any other suitable components or values could be used in the IS barrier hardware204. Also, if a single-ended input data signal is received, a single path may be used between the I/O module input and the output connector432.

FIG. 5illustrates an example method500for using an intrinsic safety barrier with an associated energy limiting apparatus according to this disclosure. For ease of explanation, the method500is described as being performed using the intrinsic safety barrier200ofFIG. 2in the system100ofFIG. 1. However, the method500could be performed using any suitable intrinsic safety barrier designed in accordance with this disclosure, and the intrinsic safety barrier could be used in any suitable system.

As shown inFIG. 5, a first hardware component of an intrinsic safety barrier is coupled to an I/O module or other device at step502, and a second hardware component of the intrinsic safety barrier is coupled to the I/O module or other device at step504. This could include, for example, coupling the isolation module202of the intrinsic safety barrier200to one or more inputs of an I/O module206or other device. This could also include coupling the IS barrier hardware204of the intrinsic safety barrier200to one or more outputs of the I/O module206or other device. Optionally, this could further include coupling the isolation module202of the intrinsic safety barrier200to the IS barrier hardware204of the intrinsic safety barrier200so that the IS barrier hardware204receives a power input from the isolation module202. In some embodiments, this could include coupling redundant isolation modules202and/or redundant IS barrier hardware204to one or more I/O modules206(such as redundant I/O modules206).

One or more voltage clamping circuits of the first hardware component are used to limit the voltage(s) of one or more power or data signals at step506. This could include, for example, one or more voltage clamping circuits210of the isolation module202operating to clamp the voltages in power and data signals transported through the isolation module202and provided to the I/O module206or other device. As a particular example, this could include the components of the isolation module202shown inFIG. 3operating to clamp the voltages in power and data signals transported through the isolation module202and provided to the I/O module206or other device.

One or more limiter circuits of the second hardware component are used to limit the amount(s) of energy contained in the one or more power or data signals at step508. This could include, for example, one or more energy-limiting circuits216of the IS barrier hardware204operating to limit the energy contained in the power and data signals received from the I/O module206or other device and output to a field device or other destination. As a particular example, this could include the components of the IS barrier hardware204shown inFIG. 4operating to limit the energy contained in the power and data signals received from the I/O module206or other device and output to a field device or other destination.

In addition, galvanic isolation is provided using at least one of the first and second hardware components at step510. This could include, for example, the isolation module202or the IS barrier hardware204providing galvanic isolation for the power and data signals being transported through the intrinsic safety barrier200. As particular examples, this could include one or more of the isolated power supply312of the isolation module202and the isolated power supply406of the IS barrier hardware204providing the galvanic isolation for the power and data signals being transported through the intrinsic safety barrier200.

AlthoughFIG. 5illustrates one example of a method500for using an intrinsic safety barrier with an associated energy limiting apparatus, various changes may be made toFIG. 5. For example, while shown as a series of steps, various steps inFIG. 5could overlap, occur in parallel, occur in a different order, or occur any number of times. As a particular example, steps506-510may generally overlap during operation of the intrinsic safety barrier200.