Emergency shut-off control system for target fluid transfer

Abstract

Embodiments of the present disclosure relate to an emergency shut-off control system for target fluid transfer. The emergency cut-off control system comprises: a control unit of a near-end device, which outputs a near-end current to an isolation interlocking unit and receives a near-end current returned by the isolation interlocking unit, and is configured to stop outputting the near-end current in response to detecting that the returned near-end current is greater than a first predetermined current; the isolation interlocking unit is configured to disconnect the first backflow path when the far-end current is smaller than the second preset current, and disconnect the second backflow path when the near-end current is smaller than the third preset current; and the control unit of the remote equipment is configured to output the remote current to the isolation interlocking unit and receive the remote current flowing back through the second backflow path of the isolation interlocking unit. When the backflow current is too large, the emergency cut-off control system can cut off the current loop in time to ensure safety.

Description

Technical Field

[0001] Embodiments of the present disclosure generally relate to the field of emergency shutdown (ESD), and more particularly to an emergency shutdown control system for target fluid transfer. Background Art

[0002] Taking liquefied natural gas (LNG) as an example, during the process of transferring from the ship end to the shore end, if a dangerous situation occurs, the transfer should be stopped immediately to ensure safety. Therefore, when a dangerous situation occurs at the ship end, the equipment at the shore end should be notified to stop the transfer operation; when a dangerous situation occurs at the shore end, the equipment at the ship end should be notified to stop the transfer operation.

[0003] In current equipment for emergency shutdown control, only the signals sent by the equipment at the ship end or the shore end are relied on to perform the shutdown operation. For abnormal situations that occur in other components such as control equipment, timely responses cannot be made, posing potential safety hazards. Summary of the Invention

[0004] In view of the above problems, the present disclosure provides an emergency shutdown control system for target fluid transfer. When the returned current is too large, the emergency shutdown control system can timely cut off the current circuit to ensure safety.

[0005] According to one aspect of the present disclosure, there is provided an emergency shutdown control system for target fluid transfer. Wherein, the target fluid is configured to be transferred between a proximal device and a distal device. The emergency shutdown control system includes: a control unit of the proximal device, configured to output a proximal current to an isolation interlock unit and receive the proximal current returned via the isolation interlock unit, and configured to stop outputting the proximal current in response to detecting that the returned proximal current is greater than a first predetermined current; the isolation interlock unit includes: a first return path for returning the proximal current to the control unit of the proximal device, and a second return path for returning the distal current to the control unit of the distal device. The isolation interlock unit is configured to disconnect the first return path when the distal current is less than a second predetermined current, and disconnect the second return path when the proximal current is less than a third predetermined current; and a control unit of the distal device, configured to output a distal current to the isolation interlock unit and receive the distal current returned via the second return path of the isolation interlock unit.

[0006] In some embodiments, the control unit of the proximal device is further configured to: output a proximal current with a fourth predetermined current value in response to detecting that the emergency cut-off signal from the proximal device indicates a normal state and detecting that the refluxed proximal current is less than or equal to a first predetermined current, and in response to detecting that the emergency cut-off signal indicates a normal state and detecting that the refluxed proximal current is greater than the first predetermined current, first stop outputting the proximal current, connect the first reflux path and the second reflux path within a first predetermined time interval, and output a proximal current with a fifth predetermined current value, where the fourth predetermined current value is greater than the fifth predetermined current value.

[0007] In some embodiments, the control unit of the proximal device is further configured to: output a cut-off control signal to the proximal device in response to detecting that the time during which the refluxed proximal current is less than a predetermined lower limit current lasts longer than a second predetermined time, where the second predetermined time interval is greater than the first predetermined time interval.

[0008] In some embodiments, the control unit of the proximal device is further configured to: stop outputting the proximal current in response to detecting that the emergency cut-off signal indicates a fault state.

[0009] In some embodiments, the control unit of the proximal device includes: a first branch, connected in parallel with a second branch, configured to output a proximal current with a fourth predetermined current value; and a second branch, configured to output a proximal current with a fifth predetermined current value; the control unit of the proximal device is further configured to: disconnect the first branch and the second branch in response to detecting that the emergency cut-off signal indicates a fault state, conduct the first branch and disconnect the second branch in response to detecting that the emergency cut-off signal indicates a normal state and detecting that the refluxed proximal current is less than or equal to the first predetermined current, and in response to detecting that the emergency cut-off signal indicates a normal state and detecting that the refluxed proximal current is greater than the first predetermined current, first disconnect the first branch and the second branch, then conduct the second branch, and connect the first reflux path and the second reflux path.

[0010] In some embodiments, the control unit of the proximal device further includes: a sampling resistor, configured to receive the refluxed proximal current to output a sampling voltage; a first comparator, the non-inverting input terminal of the first comparator is configured to receive the sampling voltage, the inverting input terminal of the first comparator is configured to receive a signal with a first predetermined voltage, where the first predetermined voltage is related to the first predetermined current; and a first MOS transistor, the gate of the first MOS transistor is electrically connected to the output terminal of the first comparator, the source of the first MOS transistor is grounded, and the drain of the first MOS transistor is electrically connected to the control terminals of the first branch and the second branch.

[0011] In some embodiments, the control unit of the proximal device further includes: a second comparator, one input terminal of the second comparator is configured to receive a sampled voltage, and the other input terminal of the second comparator is configured to receive a signal having a second predetermined voltage; and a control device, the control device is configured to output a cut-off control signal to the proximal device in response to detecting that the time for which the output terminal of the second comparator remains in a first state is greater than a first predetermined time, and output control signals to the control terminals of the first branch and the second branch in response to detecting that an emergency cut-off signal from the proximal device indicates a fault state so that the first branch and the second branch are disconnected, the first state corresponding to the proximal current flowing back being less than a predetermined lower limit current.

[0012] In some embodiments, the emergency cut-off control system further includes: an internal loop switch unit, configured to conduct in response to detecting that a test signal is in an effective state, so as to provide a test path for enabling the proximal current to flow back to the control unit of the proximal device; the control unit of the proximal device is further configured to disconnect the connection with the isolation interlock unit in the test mode, and make the test signal in an effective state, and generate a proximal current.

[0013] In some embodiments, the isolation interlock unit includes a first opto-coupler and a second opto-coupler. The first return path at least includes the light-emitting source of the first opto-coupler and the light-receiving device of the second opto-coupler. The light-emitting source of the first opto-coupler is connected in series with the light-receiving device of the second opto-coupler. The second return path at least includes the light-emitting source of the second opto-coupler and the light-receiving device of the first opto-coupler. The light-emitting source of the second opto-coupler is connected in series with the light-receiving device of the first opto-coupler.

[0014] In some embodiments, the isolation interlock unit further includes: a first reset switch, one end of the first reset switch is electrically connected to one end of the light-receiving device of the first opto-coupler, and the other end of the first reset switch is electrically connected to the other end of the light-receiving device of the first opto-coupler; and a second reset switch, one end of the second reset switch is electrically connected to one end of the light-receiving device of the second opto-coupler, and the other end of the second reset switch is electrically connected to the other end of the light-receiving device of the second opto-coupler; the first reset switch and the second reset switch are configured to conduct in response to detecting that a reset signal is in an effective state.

[0015] In some embodiments, the control unit of the distal device is further configured to stop outputting a distal current to the isolation interlock unit in response to at least one of the following: detecting that an emergency cut-off signal from the distal device indicates a fault state; and detecting that the distal current flowing back is greater than a sixth predetermined current; the proximal end is one of the source end and the destination end, and the proximal end is the other of the source end and the destination end.

[0016] In some embodiments, the control unit of the proximal device further includes: a first safety barrier, the input end of the first safety barrier is electrically connected to the output ends of the first branch and the second branch, and the output end of the first safety barrier is configured to output a proximal current; and a second safety barrier, the input end of the second safety barrier is configured to receive the returned proximal current, and the output end of the second safety barrier is electrically connected to the sampling resistor.

[0017] According to an embodiment of the present disclosure, the control unit of the proximal device of the emergency cut-off control system is configured to output a proximal current to the isolation interlock unit and receive the returned proximal current via the isolation interlock unit, and is configured to stop outputting the proximal current in response to detecting that the returned proximal current is greater than a first predetermined current. The isolation interlock unit includes: a first return path for returning the proximal current to the control unit of the proximal device, and a second return path for returning the distal current to the control unit of the distal device. The isolation interlock unit is configured to disconnect the first return path when the distal current is less than a second predetermined current, and disconnect the second return path when the proximal current is less than a third predetermined current; and the control unit of the distal device is configured to output a distal current to the isolation interlock unit and receive the returned distal current via the isolation interlock unit. Therefore, when the returned proximal current is too large (for example, greater than the first predetermined current), the emergency cut-off control system can timely cut off the current loop to avoid potential risks such as fire caused by excessive current, so as to ensure safety.

[0018] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present disclosure, nor is it used to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In combination with the accompanying drawings and referring to the following detailed description, the above and other features, advantages and aspects of the embodiments of the present disclosure will become more obvious. In the drawings, the same or similar reference numerals denote the same or similar elements.

[0020] Figure 1 FIG. shows a block diagram of an emergency cut-off control system for target fluid transmission according to an embodiment of the present disclosure.

[0021] Figure 2 FIG. shows a schematic structural diagram of the control unit of the proximal device according to an embodiment of the present disclosure.

[0022] Figure 3 FIG. shows a schematic structural diagram of the isolation interlock unit according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The exemplary embodiments of the present disclosure will be described below in conjunction with the accompanying drawings. Various details of the embodiments of the present disclosure are included to facilitate understanding, and they should be considered merely exemplary. Therefore, those of ordinary skill in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present disclosure. Similarly, descriptions of well-known functions and structures are omitted in the following description for clarity and conciseness.

[0024] As used herein, the term "including" and its variations mean open inclusion, i.e., "including but not limited to". Unless otherwise stated, the term "or" means "and / or". The term "based on" means "at least partially based on". The terms "an exemplary embodiment" and "an embodiment" mean "at least one exemplary embodiment". The term "another embodiment" means "at least one additional embodiment". The terms "first", "second", etc. may refer to different or the same objects. Other explicit and implicit definitions may also be included hereinafter.

[0025] As described above, in current devices for emergency cut-off control, the cut-off operation is only carried out depending on the signals sent by the devices from the ship end or the shore end. For abnormal situations occurring in other components such as control devices, timely responses cannot be made, posing potential safety hazards.

[0026] To at least partially solve one or more of the above problems and other potential problems, an emergency cut-off control system for target fluid transmission according to an exemplary embodiment of the present disclosure is proposed. Wherein, the target fluid is configured to be transmitted between a proximal device and a distal device. The control unit of the proximal device of the emergency cut-off control system is configured to output a proximal current to the isolation interlock unit and receive the proximal current flowing back via the isolation interlock unit, and is configured to stop outputting the proximal current in response to detecting that the flowing-back proximal current is greater than a first predetermined current. The isolation interlock unit includes: a first return path for enabling the proximal current to flow back to the control unit of the proximal device, and a second return path for enabling the distal current to flow back to the control unit of the distal device. The isolation interlock unit is configured to disconnect the first return path when the distal current is less than a second predetermined current, and disconnect the second return path when the proximal current is less than a third predetermined current; and the control unit of the distal device is configured to output a distal current to the isolation interlock unit and receive the distal current flowing back via the isolation interlock unit. Therefore, when the flowing-back proximal current is too large (e.g., greater than the first predetermined current), the emergency cut-off control system can timely cut off the current circuit to avoid potential risks such as fires caused by excessive current, so as to ensure safety.

[0027] Figure 1A block diagram of an emergency cut-off control system 100 for target fluid transfer according to an embodiment of the present disclosure is shown. Figure 2 A structural diagram of a control unit 102 of a proximal device according to an embodiment of the present disclosure is shown. Figure 3 A structural diagram of an isolation interlock unit 104 according to an embodiment of the present disclosure is shown. The target fluid is configured to be transferred between the proximal device and the distal device. It should be understood that during the process of the target fluid being configured to be transferred between the proximal device and the distal device, it will pass through a hazardous area (or "explosion-proof area") between the proximal device and the distal device. For this hazardous area, explosion-proof measures need to be taken. The emergency cut-off control system 100 includes, for example, a control unit 102 of the proximal device, an isolation interlock unit 104, and a control unit 106 of the distal device. The control unit 102 of the proximal device can be communicatively connected to the proximal device 201, for example, to receive an emergency cut-off signal from the proximal device 201 and send a cut-off control signal to the proximal device 201. The control unit 106 of the distal device can be communicatively connected to the distal device 203, for example, to receive an emergency cut-off signal from the distal device 203 and send a cut-off control signal to the distal device 203. The proximal device 201 is arranged proximally, and the distal device 203 is arranged distally. The target fluid is configured to be transferred between the proximal device 201 and the distal device 203. The proximal end is one of the source end and the destination end, and the distal end is the other of the source end and the destination end. In the scenario of liquefied natural gas transfer between a ship and a shore station, the distal end and the destination end are the ship end and the shore end, the proximal end is, for example, one of the ship or the shore station, and the distal end is, for example, the other of the ship or the shore station. In the scenario of liquefied natural gas transfer between ships, the distal end and the destination end are the first ship and the second ship, the proximal end is, for example, one of the first ship (e.g., the source ship) or the second ship (e.g., the destination ship), and the distal end is, for example, the other of the first ship (e.g., the source ship) or the second ship (e.g., the destination ship). The target fluid is, for example, a liquid such as liquefied natural gas. When the cut-off control signal indicates a cut-off operation, the proximal device 201 stops the relevant transfer operation to ensure safety.

[0028] In the process of implementing the target fluid transfer, taking the proximal device 201 as an example, if the proximal device 201 is operating normally, the proximal device 201 generates an emergency cut-off signal representing the normal state (for example, it can be a high-level state) and transmits it to the control unit 102 of the proximal device. If the proximal device 201 is operating abnormally (or "faulty"), the proximal device 201 generates an emergency cut-off signal representing the faulty state (for example, it can be a low-level state) and transmits it to the control unit 102 of the proximal device. The proximal device 201 can perform a transfer operation on the target fluid. The proximal device 201 is configured with detection devices for temperature, pressure, liquid level, flow rate, etc., for example. When the values detected by the relevant detection devices deviate from the predetermined safety range, the proximal device 201 determines that it is operating abnormally, and thus generates an emergency cut-off signal representing the faulty state.

[0029] Similarly, taking the distal device 203 as an example, if the distal device 203 is operating normally, the distal device 203 generates an emergency cut-off signal representing the normal state (for example, it can be a high-level state) and transmits it to the control unit 106 of the distal device. If the distal device 203 is operating abnormally (or "faulty"), the distal device 203 generates an emergency cut-off signal representing the faulty state (for example, it can be a low-level state) and transmits it to the control unit 106 of the distal device. The distal device 203 can perform a transfer operation on the target fluid. The distal device 203 is configured with detection devices for temperature, pressure, liquid level, flow rate, etc., for example. When the values detected by the relevant detection devices deviate from the predetermined safety range, the distal device 203 determines that it is operating abnormally, and thus generates an emergency cut-off signal representing the faulty state.

[0030] It should be understood that the application scenario of the emergency cut-off control system 100 is not limited to the emergency cut-off during the loading and unloading of the target fluid, but also includes the emergency cut-off protection of various devices during the normal navigation and docking of the ship. The emergency cut-off signals generated by the proximal device 201 and the distal device 203 include, for example, the emergency cut-off signal corresponding to the transfer pump, the emergency cut-off signal corresponding to the high liquid level alarm of the storage, the emergency cut-off signal corresponding to the filling emergency stop, etc., and also include the emergency cut-off signals corresponding to factors such as temperature, pressure, liquid level, ship lateral, and longitudinal inclination parameters exceeding the limit.

[0031] Regarding the control unit 102 of the proximal device, it is communicatively connected to the proximal device 201 and electrically connected to the isolation and interlock unit 104. The control unit 102 of the proximal device is configured to output a proximal current to the isolation and interlock unit 104 and receive the proximal current flowing back via the isolation and interlock unit 104, and is configured to stop outputting the proximal current in response to detecting that the flowing-back proximal current is greater than a first predetermined current.

[0032] The control unit 102 of the proximal device includes at least a proximal output terminal 121 and a proximal input terminal 122. Among them, the proximal output terminal 121 is configured to output a proximal current to the isolation interlock unit 104. The proximal input terminal 122 is configured to receive the proximal current flowing back via the first return path of the isolation interlock unit 104. The control unit 102 of the proximal device is further configured to stop outputting the proximal current to the isolation interlock unit 104 in response to at least one of the following: detecting that the emergency cut-off signal from the proximal device 201 indicates a fault state, and detecting that the flowing-back proximal current is greater than a first predetermined current.

[0033] The control unit 102 of the proximal device is further configured to, for example: output a proximal current with a fourth predetermined current value in response to detecting that the emergency cut-off signal from the proximal device indicates a normal state and detecting that the flowing-back proximal current is less than or equal to the first predetermined current; and in response to detecting that the emergency cut-off signal indicates a normal state and detecting that the flowing-back proximal current is greater than the first predetermined current, first stop outputting the proximal current, then connect the first return path and the second return path within a first predetermined time interval and output a proximal current with a fifth predetermined current value, where the fourth predetermined current value is greater than the fifth predetermined current value. That is to say, corresponding to the situation where the flowing-back proximal current is too large (e.g., greater than the first predetermined current), the emergency cut-off control system 100 can first cut off the output proximal current for protection to avoid risks caused by excessive current. Then, within the first predetermined time interval after stopping the output of the proximal current, the closed loop is restored and a smaller current is output again. Among them, the first predetermined time interval can be reasonably set according to specific circumstances, for example, it is 100 milliseconds. Regarding the first predetermined current, it can be reasonably set according to specific requirements. In some embodiments, the first predetermined current is, for example, 1.5 times the rated value of the proximal current.

[0034] The control unit of the proximal device is further configured to: output a cut-off control signal to the proximal device in response to detecting that the duration for which the refluxed proximal current is less than a predetermined lower limit current is greater than a second predetermined time, and the second predetermined time interval is greater than the first predetermined time interval. That is, in some embodiments, for example, if the closed loop of the control unit of the proximal device is disconnected due to an excessive refluxed proximal current (e.g., greater than the first predetermined current), resulting in the stop of outputting the proximal current, the emergency cut-off control system 100 can actively restore the closed loop within a reasonable predetermined time. Thus, the duration for which the refluxed proximal current is less than the predetermined lower limit current is less than or equal to the second predetermined time. To avoid confusion or causing misoperation of the proximal device 201 (or the distal device 203), this situation can be distinguished from the emergency cut-off scenario where the proximal device 201 (or the distal device 203) generates an emergency cut-off signal indicating a fault state. For example, in response to this situation, the control unit 102 of the proximal device does not generate a cut-off control signal. Thus, the proximal device 201 does not consider, for example, that an emergency cut-off event has occurred in the distal device 203 and does not stop relevant transmission operations, thereby avoiding unnecessary shutdowns and misoperations. For the situation where the duration for which the refluxed proximal current is less than the predetermined lower limit current is greater than the second predetermined time, it is regarded as an emergency cut-off event (outputting an emergency cut-off signal indicating a fault state) occurring in the distal device 203 (or the proximal device 201). Thus, the control unit 102 of the proximal device outputs a cut-off control signal to the terminal device 201 to notify the terminal device 201 to perform cut-off and shutdown operations and stop relevant transmission operations.

[0035] The control unit 102 of the proximal device includes, for example, a control device 123, a first switch unit K1, a first branch, and a second branch. Among them, the first branch is connected in parallel with the second branch. The first branch is configured to output a proximal current with a fourth predetermined current value. The second branch is configured to output a proximal current with a fifth predetermined current value. The control unit of the proximal device is further configured to: disconnect the first branch and the second branch in response to detecting that the emergency cut-off signal indicates a fault state, connect the first branch and disconnect the second branch in response to detecting that the emergency cut-off signal indicates a normal state and detecting that the refluxed proximal current is less than or equal to the first predetermined current, and first disconnect the first branch and the second branch and then connect the second branch in response to detecting that the emergency cut-off signal indicates a normal state and detecting that the refluxed proximal current is greater than the first predetermined current.

[0036] Among them, one end of the first switch unit K1 is electrically connected to the power supply terminal VCC, and the other end of the first switch unit K1 is respectively electrically connected to the first branch and the second branch. The first branch and the second branch are connected in parallel, and the first branch at least includes a first resistor R1. The second branch at least includes a second resistor R2. Among them, the resistance value of the first resistor R1 is less than the resistance value of the second resistor R2. The output ends of the first branch and the second branch are electrically connected to the proximal output end 121.

[0037] The control unit 102 of the proximal device is further configured to: in response to detecting that the emergency cut-off signal represents a fault state, disconnect the first switch unit K1, and in response to detecting that the emergency cut-off signal represents a normal state and detecting that the proximal current flowing back is less than or equal to the first predetermined current, turn on the first switch unit K1 and the first branch, so as to output a proximal current with a fourth predetermined current, and in response to detecting that the emergency cut-off signal represents a normal state and detecting that the proximal current flowing back is greater than the first predetermined current, first disconnect the first switch unit K1, and then turn on the first switch unit K1 and the second branch, so as to output a proximal current with a fifth predetermined current. It should be understood that the fourth predetermined current is greater than the fifth predetermined current.

[0038] In some embodiments, the first switching unit K1 is implemented by, for example, an optocoupler. The positive electrode of the light-emitting source (such as a light-emitting diode) of the first switching unit K1 serves as the control terminal of the first switching unit K1, and the negative electrode of the light-emitting source (such as a light-emitting diode) of the first switching unit K1 is grounded. One end of the light-receiving device of the first switching unit K1 serves as one end of the first switching unit K1 and is electrically connected to the power supply terminal VCC. The other end of the light-receiving device of the first switching unit K1 serves as the other end of the first switching unit K1 and is electrically connected to the first branch and the second branch. In some embodiments, the other end of the light-receiving device of the first switching unit K1 is, for example, electrically connected to the two-way switch KS. The two-way switch KS is electrically connected to the first branch and the second branch. The two-way switch KS is, for example, controlled by a gating signal so that one of the first branch and the second branch is connected to the first switching unit K1. The gating signal can be generated by the control device 123, for example. For example, the first input terminal I1 of the control device 123 (via the fourth resistor R4) is electrically connected to the output terminal of the first comparator U1 to generate a gating signal according to the signal output from the first comparator U1. For example, when the signal output from the first comparator U1 indicates that the sampling voltage output by the sampling resistor RS is higher than the first predetermined voltage (i.e., the proximal current flowing back is greater than the first predetermined current), the control device 123 generates a gating signal for controlling the second branch to be turned on. For example, this gating signal controls the two-way switch KS so that the second branch is connected to the first switching unit K1, while the first branch is disconnected from the first switching unit K1. When the signal output from the first comparator U1 indicates that the sampling voltage output by the sampling resistor RS is less than or equal to the first predetermined voltage (i.e., the proximal current flowing back is less than or equal to the first predetermined current), the control device 123 generates a gating signal for controlling the first branch to be turned on. For example, this gating signal controls the two-way switch KS so that the first branch is connected to the first switching unit K1, while the second branch is disconnected from the first switching unit K1. The control device 123 can include, for example, a PLC (programmable logic controller), a DCS (distributed control system), an MCU (microcontroller), an FPGA (field programmable gate array), etc.

[0039] Among them, the current output by the first branch is related to the resistance value of the first resistor R1. Specifically, the current output by the first branch is restricted by the voltage of the power supply terminal VCC, the conduction voltage drop of the first switching unit K1, and the resistance value of the first resistor R1. For example, the current output by the first branch is the ratio of the difference between the voltage of the power supply terminal VCC and the conduction voltage drop of the first switching unit K1 to the resistance value of the first resistor R1. For example, by reasonably setting the resistance value of the first resistor R1, the current output by the first branch can be made to conform to the fourth predetermined current.

[0040] Similarly, the current output by the second branch is related to the resistance value of the second resistor R2. Specifically, the current output by the second branch is constrained by the voltage of the power supply terminal VCC, the conduction voltage drop of the first switch unit K1, and the resistance value of the second resistor R2. For example, the current output by the second branch is the ratio of the difference between the voltage of the power supply terminal VCC and the conduction voltage drop of the first switch unit K1 to the resistance value of the second resistor R2. For example, by reasonably setting the resistance value of the second resistor R2, the current output by the second branch can be made to conform to the fifth predetermined current.

[0041] The resistance value of the first resistor R1 is less than that of the second resistor R2. Therefore, the fourth predetermined current is greater than the fifth predetermined current.

[0042] The control unit of the proximal device further includes a first comparator U1 and a first MOS transistor Q1. Among them, the non-inverting input terminal of the first comparator U1 is configured to receive a sampling voltage. For example, the non-inverting input terminal of the first comparator U1 is electrically connected to one end of the sampling resistor RS. The inverting input terminal of the first comparator U1 is configured to receive a signal VH having a first predetermined voltage, and the first predetermined voltage is related to the first predetermined current. For example, the first predetermined voltage is the product of the first predetermined current and the resistance value of the sampling resistor RS. The gate of the first MOS transistor Q1 is electrically connected to the output terminal of the first comparator U1, the source of the first MOS transistor Q1 is grounded to GND, and the drain of the first MOS transistor Q1 is electrically connected to the control terminals of the first branch and the second branch. For example, the drain of the first MOS transistor Q1 is electrically connected to the control terminal of the first control unit K1 to control the conduction or disconnection of the first control unit K1.

[0043] The control device 123 is further configured to cause the control unit 102 of the proximal device to stop outputting the proximal current in response to detecting that the emergency cut-off signal from the proximal device 201 indicates a fault state. The first output terminal O1 of the control device 123 is electrically connected to the control terminal of the first switch unit K1 (for example, the positive electrode of the light source of the first switch unit K1). For example, the first output terminal O1 of the control device 123 is electrically connected to the control terminal of the first switch unit K1 via a third resistor R3. It should be understood that the third resistor R3 is a current-limiting resistor. The control device 123 outputs a first switch control signal for controlling the first switch unit K1 via its first output terminal O1.

[0044] The control unit 102 of the proximal device further includes a first safety barrier 124 and a second safety barrier 125. Among them, the input end of the first safety barrier 124 is electrically connected to the output ends of the first branch and the second branch, and the output end of the first safety barrier 124 is configured to be electrically connected to the proximal output end 121 to output proximal current. The input end of the second safety barrier 125 is configured to be electrically connected to the proximal input end 122 to receive the returned proximal current, and the output end of the second safety barrier 125 is electrically connected to one end of the sampling resistor RS to transmit the returned proximal current to the sampling resistor RS. The first safety barrier 124 and the second safety barrier 125 output intrinsically safe currents of 4 to 20 mA (milliamperes) for example.

[0045] The control unit 102 of the proximal device further includes a second comparator U2 for example. Among them, one end of the sampling resistor RS is electrically connected to the proximal input end 122, and the other end of the sampling resistor RS is grounded to GND. One input end of the second comparator U2 is configured to receive the sampling voltage, and the other input end of the second comparator U2 is configured to receive a signal with a second predetermined voltage. For example, the non-inverting input end of the second comparator U2 is electrically connected to one end of the sampling resistor RS, and the inverting input end of the second comparator U2 is configured to receive a signal VL with a second predetermined voltage. The control device 123 is configured to output a cut-off control signal in response to detecting that the output end of the second comparator U2 is in a first state. When the voltage output by the sampling resistor RS is higher than the second predetermined voltage, the output end of the second comparator U2 outputs a high-level signal. When the voltage output by the sampling resistor RS is lower than the second predetermined voltage, the output end of the second comparator U2 outputs a low-level signal. Among them, the second predetermined voltage is set low enough so that when the output end of the second comparator U2 outputs a low-level signal, it can be considered that there is basically no current (less than a predetermined lower limit current) on the sampling resistor RS. Or rather, when there is no current flowing through the sampling resistor RS, that is, when the proximal current returned through the first return path of the isolation interlock unit 104 received by the proximal input end 122 is zero, the output end of the second comparator U2 outputs a low-level signal. In this case, the low-level state of the signal output by the output end of the second comparator U2 (for example, the "first state" corresponding to the signal output by the output end of the second comparator U2) can indicate that the returned proximal current is less than the predetermined lower limit current. That is, the "first state" corresponding to the signal output by the output end of the second comparator U2 corresponds to the returned proximal current being less than the predetermined lower limit current.

[0046] It should be noted that the reason for making the output signal of the second comparator U2 in the "first state", or in other words, making the returned proximal current less than the predetermined lower limit current, may include: (1) an emergency cut-off event occurs in the remote device 203 and an emergency cut-off signal indicating a fault state is output; (2) an emergency cut-off event occurs in the proximal device 201 and an emergency cut-off signal indicating a fault state is output; (3) the control unit of the proximal device stops outputting the proximal current due to the returned proximal current being greater than the first predetermined current; (4) the control unit of the remote device stops outputting the remote current due to the returned remote current being greater than the sixth predetermined current.

[0047] In some embodiments, for the above reason (3) (reason (4) is similar), for example, it is caused by the returned proximal current being too large (e.g., greater than the first predetermined current), resulting in the open-loop of the control unit of the proximal device being disconnected and thus stopping the output of the proximal current. The emergency cut-off control system 100 can actively restore the closed-loop within a reasonable predetermined time, and the returned proximal current is restored to be greater than or equal to the predetermined lower limit current. Correspondingly, the output signal of the second comparator U2 is converted to a "second state" (e.g., high-level state) different from the "first state". Thus, the duration for which the returned proximal current is less than the predetermined lower limit current is less than or equal to the second predetermined time. To avoid confusion or to prevent misoperation of the proximal device 201 (or the remote device 203), this situation can be distinguished from the emergency cut-off situation where the proximal device 201 (or the remote device 203) generates an emergency cut-off signal indicating a fault state. For example, for reason (3), the control unit 102 of the proximal device does not generate a cut-off control signal. Thus, the proximal device 201 does not consider that, for example, an emergency cut-off event has occurred in the remote device 203 and does not stop the relevant transmission operations, thereby avoiding unnecessary shutdowns and misoperations.

[0048] For reason (1) (reason (2) is similar), the time required to rule out the emergency cut-off event is relatively long (greater than the second predetermined time). Therefore, the duration for which the returned proximal current is less than the predetermined lower limit current (or in other words, the output signal of the second comparator U2 is in the "first state") will be greater than the second predetermined time. So, when the duration for which the returned proximal current is less than the predetermined lower limit current (or in other words, the output signal of the second comparator U2 is in the "first state") is greater than the second predetermined time, it is regarded that an emergency cut-off event has occurred in the remote device 203 (or the proximal device 201) (an emergency cut-off signal indicating a fault state is output). Thus, the control unit 102 of the proximal device outputs a cut-off control signal to the end device 201 to notify the end device 201 to perform cut-off and shutdown operations and stop the relevant transmission operations.

[0049] It should be noted that, in some embodiments, the inverting input terminal of the second comparator U2 is configured to receive a sampled voltage, and the non-inverting input terminal of the second comparator U2 is configured to receive a signal having a second predetermined voltage. Then, the polarity of the signal output by the output terminal of the second comparator U2 is opposite to the foregoing.

[0050] Regarding the isolation interlock unit 104, it is configured to at least provide a first return path connecting the proximal output terminal 121 and the proximal input terminal 122, and is configured to be electrically connected to the control unit 106 of the remote device to receive the remote current from the control unit 106 of the remote device, and to disconnect the first return path in response to determining that the remote current is less than a second predetermined current. It should be understood that when the first return path connecting the proximal output terminal 121 and the proximal input terminal 122 is disconnected, the proximal current flowing back through the first return path of the isolation interlock unit received by the proximal input terminal 122 of the control unit 102 of the proximal device is zero.

[0051] The isolation interlock unit 104 is further configured to provide a second return path connecting the remote output terminal 161 and the remote input terminal 162, and to disconnect the second return path in response to determining that the proximal current is less than a third predetermined current.

[0052] In some embodiments, the isolation interlock unit 104 includes a first optocoupler 141 and a second optocoupler 142. It should be understood that an optocoupler includes a light-emitting source and a light-receiving device. When the light-emitting source is not supplied with current and does not emit light, the light-receiving device is not exposed to light and is in an off state. When the light-emitting source is supplied with current and emits light, the light-receiving device is exposed to light and conducts. Among them, the light-emitting source is a light-emitting diode, and the light-receiving device is, for example, a photoresistor, a photodiode, a phototransistor, a photothyristor, etc. The first optocoupler 141 includes, for example, a first light-emitting source 1411 and a first light-receiving device 1412. The second optocoupler 142 includes, for example, a second light-emitting source 1421 and a second light-receiving device 1422.

[0053] The first return path at least includes the light-emitting source of the first optocoupler 141 (such as the first light-emitting source 1411) and the light-receiving device of the second optocoupler 142 (such as the second light-receiving device 1422). Among them, the light-emitting source of the first optocoupler 141 is in series with the light-receiving device of the second optocoupler 142. The second return path at least includes the light-emitting source of the second optocoupler 142 (such as the second light-emitting source 1421) and the light-receiving device of the first optocoupler 141 (such as the first light-receiving device 1412). The light-emitting source of the second optocoupler 142 is in series with the light-receiving device of the first optocoupler 141.

[0054] The first return path also includes, for example, a first light-emitting diode LED1, which is connected in series with the light-emitting source of the first opto-coupler 141 and the light-receiving device of the second opto-coupler 142. It should be understood that when the first return path is conducting and current flows through it, the first light-emitting diode LED1 emits light; when the first return path is disconnected, the first light-emitting diode LED1 does not emit light. Therefore, the state of whether the first light-emitting diode LED1 emits light or not can indicate the on / off state of the first return path.

[0055] Similarly, the second return path also includes, for example, a second light-emitting diode LED2, which is connected in series with the light-emitting source of the second opto-coupler 142 and the light-receiving device of the first opto-coupler 141. It should be understood that when the second return path is conducting and current flows through it, the second light-emitting diode LED2 emits light; when the second return path is disconnected, the second light-emitting diode LED2 does not emit light. Therefore, the state of whether the second light-emitting diode LED2 emits light or not can indicate the on / off state of the second return path.

[0056] In some embodiments, the positive electrode of the light-emitting source (such as a light-emitting diode) of the first opto-coupler 141 is electrically connected to the proximal output terminal 121, the negative electrode of the light-emitting source of the first opto-coupler 141 is electrically connected to one end of the light-receiving device of the second opto-coupler 142, one end of the light-receiving device of the first opto-coupler 141 is electrically connected to the distal output terminal 161, the other end of the light-receiving device of the first opto-coupler 141 is electrically connected to the positive electrode of the light-emitting source of the second opto-coupler 142, and the negative electrode of the light-emitting source of the second opto-coupler 142 is electrically connected to the distal input terminal 162.

[0057] The isolation interlock unit 104 also includes, for example, a first reset switch KR1 and a second reset switch KR2. One end of the first reset switch KR1 is electrically connected to one end of the light-receiving device of the first opto-coupler 141, and the other end of the first reset switch KR1 is electrically connected to the other end of the light-receiving device of the first opto-coupler 141. That is, the first reset switch KR1 is connected in parallel with the light-receiving device of the first opto-coupler 141. One end of the second reset switch KR2 is electrically connected to one end of the light-receiving device of the second opto-coupler 142, and the other end of the second reset switch KR2 is electrically connected to the other end of the light-receiving device of the second opto-coupler 142. The first reset switch KR1 and the second reset switch KR2 are configured to conduct in response to detecting that the reset signal is in an effective state.

[0058] In some embodiments, the reset signal is generated by a reset button. For example, both the first reset switch KR1 and the second reset switch KR2 are controlled by the reset button. When the reset button is pressed, both the first reset switch KR1 and the second reset switch KR2 conduct; when the reset button is released, both the first reset switch KR1 and the second reset switch KR2 disconnect.

[0059] In some embodiments, the reset signal is generated by the control device 123. For example, both the first reset switch KR1 and the second reset switch KR2 are controlled by the control device 123. When the control device 123 generates a reset signal in an active state (such as a high-level state), both the first reset switch KR1 and the second reset switch KR2 are turned on; when the control device 123 generates a reset signal in an inactive state (such as a low-level state), both the first reset switch KR1 and the second reset switch KR2 are turned off.

[0060] It should be noted that inside the isolation interlock unit 104, two optocouplers are connected together in a mutually connected manner, effectively isolating the signal (proximal current) on the control unit 102 side of the proximal device and the signal (distal current) on the control unit 106 side of the distal device through the optical medium. At the same time, its high-speed response interlock mechanism can be utilized to ensure that when either the control unit 102 of the proximal device or the control unit 106 of the distal device responds to an emergency cut-off signal indicating a fault, the other side of the control unit 102 of the proximal device and the control unit 106 of the distal device synchronizes quickly, resulting in a very small response difference time between the two sides of the control unit 102 of the proximal device and the control unit 106 of the distal device, and greatly ensuring the quickness and consistency of the signal responses on both sides of the control unit 102 of the proximal device and the control unit 106 of the distal device. Based on the design of the isolation interlock unit 104, the emergency cut-off control system 100 of the embodiments of the present disclosure can be provided with a reset button during normal use or self-test function testing. When either side of the control unit 102 of the proximal device and the control unit 106 of the distal device responds to an emergency cut-off signal indicating a fault state, the current loop can be reset by manually operating the reset button.

[0061] In some embodiments, the light-emitting source in the optocoupler is a light-emitting diode, and the light-receiving device is a MOSFET (metal-oxide-semiconductor field-effect transistor). For example, refer to Figure 3As shown, the LEDs of the two optocouplers in the isolation interlock unit 104 are connected to the pins of the corresponding MOSFETs. When the system is operating normally, the LEDs of both optocouplers are operating normally, meaning the MOSFETs are in the on state. Accordingly, the LED indicators (LED1 and LED2) on both sides illuminate, indicating that both the local device 201 and the remote device 203 are operating normally, and the emergency shutdown signal issued indicates normal operation. When either the control unit 102 of the local device or the control unit 106 of the remote device enters an ESD emergency stop state (e.g., receives an emergency shutdown signal indicating a fault state), a short circuit occurs in the current loop. This causes the LED on the corresponding side of the optocoupler to enter a fault state (e.g., no current flows, no light is emitted), which in turn causes the MOSFET on the opposite side to disconnect. This in turn causes the LED of the optocoupler on the opposite side to enter a fault state (e.g., no current flows, no light is emitted), and the MOSFET on the local side is disconnected. Consequently, both MOSFETs are disconnected, triggering an ESD emergency stop response on both sides and achieving interlocking. After the problems on both sides are checked, the isolation interlock unit 104 can be reset to release the locked state.

[0062] The remote device control unit 106 is communicatively connected to the remote device 203 and electrically connected to the isolation interlock unit 104. The remote device control unit 106 includes at least a remote output terminal 161 and a remote input terminal 162. The remote output terminal 161 is configured to output a remote current to the isolation interlock unit 104, and the remote input terminal 162 is configured to receive the remote current flowing back through the second return path of the isolation interlock unit 104. The remote device control unit 106 is further configured to stop supplying the remote current to the isolation interlock unit in response to at least one of the following: detecting that the emergency shutdown signal from the remote device 203 indicates a fault state, and detecting that the flowing remote current is greater than a sixth predetermined current.

[0063] The control unit 106 of the remote device is also configured to: in response to detecting that the emergency shut-off signal represents a normal state and detecting that the remote current flowing back is less than or equal to the sixth predetermined current, output a remote current having a seventh predetermined current; and in response to detecting that the emergency shut-off signal represents a normal state and detecting that the remote current flowing back is greater than the first predetermined current, first stop outputting the remote current to the isolation interlock unit 104, and then output a remote current having an eighth predetermined current and connect at least the second return path, the seventh predetermined current being greater than the eighth predetermined current.

[0064] In some embodiments, the control unit 102 of the near-end device and the control unit 106 of the far-end device have the same or similar structure, which will not be described in detail here.

[0065] It should be noted that after initialization, both the proximal device 201 and the distal device 203 enter the normal working state. The proximal device 201 transmits an emergency cut-off signal indicating the normal state to the control unit 102 of the proximal device. When the control device 123 detects that the emergency cut-off signal from the proximal device 201 indicates the normal state, the control device 123 outputs a first switch control signal (such as a high-level signal) corresponding to the normal state via its first output terminal O1. Then, the light source of the first switch unit K1 emits light, so that the light receiver of the first switch unit K1 is turned on, that is, a conduction is established between one end and the other end of the first switch unit K1.

[0066] Moreover, at this time, the first branch is conducted, and then a proximal current with a fourth predetermined current is output. The first safety barrier 124 receives the proximal current with the fourth predetermined current from the first branch and outputs a proximal current with the fourth predetermined current at its output terminal. For example, the initial state of the gating signal output by the control device 123 corresponds to a state in which the first branch is conducted.

[0067] It should be noted that after initialization, the isolation interlock unit 104 is in the reset state. For example, both the first reset switch KR1 and the second reset switch KR2 are conducted. Then, the proximal current output by the control unit 102 of the proximal device flows back to the proximal input terminal 122 of the control unit 102 of the proximal device via the isolation interlock unit 104. The light source of the first optocoupler 141 of the isolation interlock unit 104 emits light, making the light receiver of the first optocoupler 141 turned on. Similarly, the distal current output by the control unit 106 of the distal device flows back to the distal input terminal 162 of the control unit 106 of the distal device via the isolation interlock unit 104. The light source of the second optocoupler 142 of the isolation interlock unit 104 emits light, making the light receiver of the second optocoupler 142 turned on. Then, the first reset switch KR1 and the second reset switch KR2 can be disconnected.

[0068] Since the proximal current normally flows back to the control unit 102 of the proximal device via the isolation interlock unit 104 and the proximal current flowing back is within the normal range, the signals output by the first comparator U1 and the second comparator U2 both indicate that the proximal current flowing back is within the normal range. Correspondingly, the states of the first switch unit K1 and the gating switch KS are maintained.

[0069] If the proximal current flowing back through the isolation interlock unit 104 is greater than the first predetermined current, the first comparator U1 outputs a high-level signal. Then, the first MOS transistor Q1 is turned on, and the control terminal of the first switch unit K1 is pulled down to a low level. Thus, the light source of the first switch unit K1 does not emit light, and the light receiver of the first switch unit K1 is disconnected, that is, the first switch unit K1 is disconnected. As a result, both the first branch and the second branch are disconnected, and the control unit 102 of the proximal device stops outputting the proximal current to the isolation interlock unit 104. Therefore, no current flows through the light source of the first optocoupler 141 of the isolation interlock unit 104 (the proximal current is less than the third predetermined current), and it no longer emits light, causing the light receiver of the first optocoupler 141 of the isolation interlock unit 104 to be disconnected, that is, the second return path is disconnected. That is, when the proximal current is less than the third predetermined current, the second return path is disconnected.

[0070] After the second return path is disconnected, the connection between the distal output terminal 161 and the distal input terminal 162 of the control unit 106 of the distal device is disconnected, and the control unit 106 of the distal device cannot form a closed loop, and the control unit 106 of the distal device cannot continue to form a distal current. Therefore, no current flows through the light source of the second optocoupler 142 of the isolation interlock unit 104 (the distal current is less than the second predetermined current), and it no longer emits light, causing the light receiver of the second optocoupler 142 of the isolation interlock unit 104 to be disconnected, that is, the first return path is disconnected. That is, when the distal current is less than the second predetermined current, the first return path is disconnected. If any one of the first return path and the second return path is disconnected, it will cause the other one of the first return path and the second return path to also be disconnected. Therefore, it is called "interlock".

[0071] Therefore, for the emergency cut-off control system 100 according to the embodiment of the present disclosure, when the flowing-back proximal current is too large (greater than the first predetermined current), the current loop is disconnected, thereby effectively avoiding dangerous situations (such as fires) caused by excessive current.

[0072] It should be noted that when the control device 123 receives, via its first input terminal I1, a signal from the first comparator U1 indicating that the proximal current flowing back is greater than the first predetermined current (i.e., the signal output by the first comparator U1), it can be determined that the reason for disconnecting the current loop at this time is excessive current, rather than a fault state indicated by an emergency cut-off signal. Therefore, based on the signal from the first comparator U1 indicating that the proximal current flowing back is greater than the first predetermined current, the control device 123 generates a corresponding gating signal to control the two-way switch KS, such that the second branch is conducted with the first switch unit K1, while the first branch is disconnected from the first switch unit K1. Moreover, the control device 123 outputs, via its first output terminal O1, a first switch control signal in a high-level state to the first switch unit K1, causing the first switch unit K1 to conduct. The control device 123 also generates a reset signal to reset the isolation interlock unit 104, that is, to connect the first return path and the second return path. As a result, the control unit 102 of the proximal device re-forms a closed loop, and the control unit 106 of the distal device re-forms a closed loop.

[0073] It can be seen that for the emergency cut-off control system 100 according to the embodiments of the present disclosure, when the proximal current flowing back is excessive (greater than the first predetermined current), in addition to disconnecting the current loop to effectively avoid a dangerous situation caused by excessive current, it can also adaptively adjust the generated proximal current (e.g., reduce the proximal current), and re-close the current loop to resume the transmission of emergency cut-off related signals between the proximal and the distal ends.

[0074] It should be understood that after the current loop of the control unit 102 of the proximal device is disconnected (the first switch unit K1 is disconnected and the first return path is disconnected), the signal output by the output terminal of the first comparator U1 returns to a low level, and the first MOS transistor Q1 enters a cut-off (disconnected) state.

[0075] For example, in the emergency cut-off control system 100, the control unit 102 of the proximal device provides a proximal current in the range of 4 to 20 mA, and the power supply terminal VCC uses a voltage of 24 V (volts). Appropriate resistors are configured and combined with the input terminal of the safety barrier such that when the current loop is closed, a suitable proximal current is generated, for example, a proximal current of 15 mA. It should be understood that when the current loop of the control unit 102 of the proximal device is disconnected, the proximal current is zero. When the emergency cut-off related signal received by the control unit 102 of the proximal device from the proximal device 201 indicates a normal state, the current loop of the control unit 102 of the proximal device can be maintained in a closed state; when the emergency cut-off related signal received by the control unit 102 of the proximal device from the proximal device 201 indicates a normal state, the current loop of the control unit 102 of the proximal device is disconnected.

[0076] The 15 mA proximal current of the control unit 102 of the proximal device flows through the first return path of the isolation interlock unit 104. On the one hand, it returns to the control unit 102 of the proximal device. On the other hand, it can maintain the second return path in a conducting state, providing a necessary condition for maintaining a closed current loop for the control unit 106 of the distal device. The returned proximal current is collected by the sampling resistor R6 and converted into a sampling voltage. Then, the second comparator U2 is used to determine whether the emergency cut-off related signal indicates a normal state or a fault state. For example, the value of the second predetermined voltage corresponding to the signal VL is set to 10 mA * R6. When the returned proximal current is greater than 10 mA, the sampling voltage output by the sampling resistor R6 is greater than the second predetermined voltage, and the second comparator U2 outputs a high-level signal, indicating that the control unit 102 of the proximal device does not detect the emergency cut-off related signal indicating a fault state. At this time, the control device 123 determines that the detected output terminal of the second comparator does not belong to the first state (such as a low-level state), and the control device 123 does not output a cut-off control signal to the proximal device. Conversely, if the returned proximal current is less than 10 mA, the sampling voltage output by the sampling resistor R6 is less than the second predetermined voltage, and the second comparator U2 outputs a low-level signal, indicating that the control unit 102 of the proximal device detects the emergency cut-off related signal indicating a fault state. At this time, the control device 123 determines that the detected output terminal of the second comparator is the first state, and the control device 123 outputs a cut-off control signal to the proximal device.

[0077] In addition, the sampling voltage output by the sampling resistor R6 is also transmitted to the first comparator U1 to determine whether the returned proximal current is greater than the first predetermined current. This is to prevent damage to the circuit unit due to an excessive returned proximal current or an excessive loop transmission current exceeding the explosion point. When the returned proximal current is excessive (greater than the first predetermined current), the sampling voltage output by the sampling resistor R6 is greater than the first predetermined voltage, and the first comparator U1 outputs a high-level signal. The high-level signal output by the first comparator U1, on the one hand, drives the first MOS transistor Q1 to conduct, so that the first switch unit K1 of the control unit 102 of the proximal device is in an open state, closing the transmission of the proximal current. On the other hand, it also notifies the control device 123 of the occurrence of a current overlimit event via the second input terminal I1 of the control device 123, so that the control device 123 processes it according to the current overlimit mode. The related processing of the current overlimit mode, for example, includes first disconnecting the first branch and the second branch, then making the second branch conduct, and resetting the isolation interlock unit 104 (connecting the first return path and the second return path).

[0078] If a fault occurs on the proximal device 201 side, the proximal device 201 transmits an emergency cut-off signal indicating the fault state to the control unit 102 of the proximal device. In response to detecting that the emergency cut-off signal from the proximal device 201 indicates a fault state, the control unit 102 of the proximal device stops outputting proximal current to the isolation interlock unit 104. For example, in response to detecting that the emergency cut-off signal from the proximal device 201 indicates a fault state, the control device 123 generates a first switch control signal for disconnecting the first switch unit K1. Thus, both the first branch and the second branch are disconnected, and the control unit 102 of the proximal device stops outputting proximal current to the isolation interlock unit 104. As a result, no current flows through the light-emitting source of the first optocoupler 141 of the isolation interlock unit 104 (the proximal current is less than the third predetermined current), and it no longer emits light, causing the light-receiving device of the first optocoupler 141 of the isolation interlock unit 104 to be disconnected, that is, the second return path is disconnected. That is, the second return path is disconnected when the proximal current is less than the third predetermined current.

[0079] After the second return path is disconnected, the distal output terminal 161 and the distal input terminal 162 of the control unit 106 of the distal device are disconnected, and the control unit 106 of the distal device cannot form a closed loop, and the control unit 106 of the distal device cannot continue to form distal current. As a result, no current flows through the light-emitting source of the second optocoupler 142 of the isolation interlock unit 104 (the distal current is less than the second predetermined current), and it no longer emits light, causing the light-receiving device of the second optocoupler 142 of the isolation interlock unit 104 to be disconnected, that is, the first return path is disconnected. That is, the first return path is disconnected when the distal current is less than the second predetermined current.

[0080] Similarly, if a fault occurs on the distal device 203 side, the distal device 203 transmits an emergency cut-off signal indicating the fault state to the control unit 106 of the distal device. In response to detecting that the emergency cut-off signal from the distal device 203 indicates a fault state, the control unit 106 of the distal device stops outputting distal current to the isolation interlock unit 104. For example, in response to detecting that the emergency cut-off signal from the distal device 203 indicates a fault state, the control device 123 generates a first switch control signal for disconnecting the first switch unit K1. Thus, both the first branch and the second branch are disconnected, and the control unit 106 of the distal device stops outputting proximal current to the isolation interlock unit 104. As a result, no current flows through the light-emitting source of the second optocoupler 142 of the isolation interlock unit 104 (the distal current is less than the second predetermined current), and it no longer emits light, causing the light-receiving device of the second optocoupler 142 of the isolation interlock unit 104 to be disconnected, that is, the first return path is disconnected. That is, the first return path is disconnected when the distal current is less than the second predetermined current.

[0081] It should be understood that the second predetermined current and the third predetermined current are, for example, current values such that the light-emitting source (such as a light-emitting diode) of the opto-coupler is not sufficient to emit light. The third predetermined current is a reference value for the proximal current, and the second predetermined current is a reference value for the distal current. The predetermined lower limit current is a reference value for the proximal current that flows back. Regarding the predetermined lower limit current, it can be reasonably set according to requirements. There is no necessary constraint relationship between the predetermined lower limit current and the third predetermined current (or the second predetermined current). The predetermined lower limit current is not necessarily equal to the third predetermined current (or the second predetermined current). In some embodiments, the predetermined lower limit current is equal to the third predetermined current (or the second predetermined current). In some embodiments, the predetermined lower limit current is greater than the third predetermined current (or the second predetermined current). In some embodiments, the predetermined lower limit current is less than the third predetermined current (or the second predetermined current).

[0082] After the first return path is disconnected, the connection between the proximal output terminal 121 and the proximal input terminal 122 of the control unit 102 of the proximal device is disconnected. The control unit 102 of the proximal device cannot form a closed loop, and the control unit 102 of the proximal device cannot continue to form a proximal current. As a result, no current flows through the light-emitting source of the first opto-coupler 141 of the isolation interlock unit 104 (the proximal current is less than the third predetermined current), and it no longer emits light, causing the light-receiving device of the first opto-coupler 141 of the isolation interlock unit 104 to be disconnected, that is, the second return path is disconnected. That is, when the proximal current is less than the third predetermined current, the second return path is disconnected.

[0083] Regarding the working mechanism at the control unit 106 of the distal device, reference can be made to the control unit 102 of the proximal device, and details are not described here again.

[0084] Between the control unit 102 of the proximal device and the isolation interlock unit 104, and between the control unit 106 of the distal device and the isolation interlock unit 104, they are electrically connected by cables that comply with the SIGGTO (International Gas Carrier and Terminal Operators Association) standard, for example.

[0085] The emergency cut-off control system 100 also includes, for example, an internal loop switch unit 126, which is configured to turn on in response to detecting that the test signal is in an effective state, so as to provide a test path for enabling the proximal current to flow back to the control unit 102 of the proximal device. The control unit 102 of the proximal device is also configured to disconnect from the isolation interlock unit 104 in the test mode, and make the test signal in an effective state, and generate a proximal current. The internal loop switch unit 126 is connected, for example, between the proximal output terminal 121 and the proximal input terminal 122. The internal loop switch unit 126 can be implemented by an optocoupler. The control terminal of the internal loop switch unit 126 (for example, the positive electrode of the light-emitting source of the optocoupler) is electrically connected to the second output terminal O2 of the control device 123 via the fifth resistor R5. The control device 123 outputs a test signal via its second output terminal O2 to control the internal loop switch unit 126 to turn off or on.

[0086] For example, before connecting the control unit 102 of the proximal device to the isolation interlock unit 104 and connecting the isolation interlock unit 104 to the control unit 106 of the distal device, a self-test can be first performed inside the control unit 102 (or the control unit 106 of the distal device) of the proximal device. Or after the foregoing connection has been completed, for example, after the system has been running for a period of time, a self-test can also be performed inside the control unit 102 (or the control unit 106 of the distal device) of the proximal device. In the test mode, the control unit 102 of the proximal device disconnects from the isolation interlock unit 104, and makes the test signal in an effective state, and generates a proximal current. For example, the control device 123 outputs a test signal in a first state via its second output terminal O2 to control the internal loop switch unit 126 to turn on. The control device 123 controls the first switch unit K1 to turn on, and controls the gating switch KS to make the first branch turn on. At this time, the control unit 102 of the proximal device receives an emergency cut-off signal indicating a normal state from the proximal device 201. Then, the control device 123 determines whether the control unit 102 of the proximal device is operating normally according to the signal output by the first comparator U1 and the signal output by the second comparator U2. For example, if the signal output by the first comparator U1 indicates that the returned proximal current is less than or equal to the first predetermined current, and the signal output by the second comparator U2 indicates that the returned proximal current is greater than or equal to the third predetermined current, it indicates that the internal self-test of the control unit 102 of the proximal device is successful and the control unit 102 of the proximal device is operating normally. Otherwise, it indicates that the control unit 102 of the proximal device is operating abnormally.

[0087] When the emergency cut-off control system 100 has not been operated for a long time, it first performs self-check. After the self-check is normal, it can be put into use. In the loop self-check mode, the emergency cut-off control system 100 can be tested by pressing the test button KT corresponding to the control unit 102 of the proximal device. The test button KT is, for example, a normally closed switch. When the test button KT is pressed, the switch is disconnected, and the path for the proximal device 201 to transmit the emergency cut-off signal to the control unit 102 of the proximal device is cut off. Then, the control unit 102 of the proximal device detects that the emergency cut-off signal from the proximal device indicates a fault state. Thus, the emergency cut-off control system 100 enters the ESD emergency stop alarm mode. Among them, the isolation interlock unit 104 enters the interlock state, that is, both the first return path and the second return path are disconnected. For the specific working principle, refer to the previous text and will not be elaborated here. Through the interlock mechanism of the isolation interlock unit 104, the current loop of the control unit 106 of the remote device is disconnected, so that no remote current can be formed in the control unit 106 of the remote device. Correspondingly, the control unit 106 of the remote device generates a cut-off control signal and transmits it to the remote device 203. Thus, the emergency cut-off signal indicating the fault state simulated during the test is substantially transmitted to the remote device 203 via the emergency cut-off control system 100, so that both the proximal and distal ends are in the ESD emergency stop mode, indicating that the test is normal.

[0088] After the test is completed, the isolation interlock unit 104 can be made to enter the reset state by using a reset signal, that is, a state in which both the first return path and the second return path are conducting.

[0089] In addition, the emergency cut-off control system 100 is also provided with a prohibit button KF, for example. The function of the prohibit button KF is that when the emergency cut-off control system 100 is in normal operation, if personnel need to enter the dangerous area, through the function of the prohibit button KF, the emergency cut-off control system 100 can be made to temporarily not respond to the emergency cut-off signal indicating the fault state. For example, when personnel enter the dangerous area, it will actually cause the proximal device 201 or the remote device 203 to send an emergency cut-off signal indicating the fault state. To ensure that the ESD system does not enter the alarm state under the condition of ensuring safe operation, the prohibit button can be pressed. The prohibit button KF is, for example, a normally open switch. When the prohibit button KF is pressed, it becomes a closed (conducting) state. For example, it can ensure that the proximal ESD is always in a loop-closed state, and the ESD system is artificially prohibited.

[0090] The embodiments of the present disclosure have been described above. The above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The choice of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to technologies in the market, or to enable other ordinary skill in the art to understand the embodiments disclosed herein.

[0091] The above are only optional embodiments of the present disclosure and are not used to limit the present disclosure. For those skilled in the art, the present disclosure may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included within the protection scope of the present disclosure.

Claims

1. An emergency cut-off control system for target fluid transmission, where the target fluid is configured to be transmitted between a proximal device and a distal device, characterized in that, The emergency cut-off control system includes: A control unit of the proximal device, configured to output a proximal current to the isolation interlock unit and receive the proximal current flowing back via the isolation interlock unit, and configured to stop outputting the proximal current in response to detecting that the flowing-back proximal current is greater than a first predetermined current; The isolation interlock unit includes: a first return path for enabling the proximal current to flow back to the control unit of the proximal device, and a second return path for enabling the distal current to flow back to the control unit of the distal device. The isolation interlock unit is configured to disconnect the first return path when the distal current is less than a second predetermined current, and disconnect the second return path when the proximal current is less than a third predetermined current; and A control unit of the distal device, configured to output a distal current to the isolation interlock unit and receive the distal current flowing back via the isolation interlock unit.

2. The emergency cut-off control system according to claim 1, characterized in that, The control unit of the proximal device is further configured to: output a proximal current with a fourth predetermined current value in response to detecting that the emergency cut-off signal from the proximal device indicates a normal state and detecting that the flowing-back proximal current is less than or equal to the first predetermined current, and in response to detecting that the emergency cut-off signal indicates a normal state and detecting that the flowing-back proximal current is greater than the first predetermined current, first stop outputting the proximal current, and then connect the first return path and the second return path and output a proximal current with a fifth predetermined current value within a first predetermined time interval, where the fourth predetermined current value is greater than the fifth predetermined current value.

3. The emergency cut-off control system according to claim 2, characterized in that, The control unit of the proximal device is further configured to: output a cut-off control signal to the proximal device in response to detecting that the time during which the flowing-back proximal current is less than a predetermined lower limit current lasts longer than a second predetermined time, and the second predetermined time interval is greater than the first predetermined time interval.

4. The emergency cut-off control system according to claim 3, wherein, The control unit of the proximal device is further configured to: stop outputting the proximal current in response to detecting that the emergency cut-off signal indicates a fault state.

5. The emergency cut-off control system according to claim 4, characterized in that The control unit of the proximal device includes: A first branch, connected in parallel with the second branch, configured to output a proximal current with a fourth predetermined current value; and A second branch, configured to output a proximal current with a fifth predetermined current value; The control unit of the proximal device is further configured to: disconnect the first branch and the second branch in response to detecting that the emergency cut-off signal indicates a fault state, conduct the first branch and disconnect the second branch in response to detecting that the emergency cut-off signal indicates a normal state and detecting that the flowing-back proximal current is less than or equal to the first predetermined current, and in response to detecting that the emergency cut-off signal indicates a normal state and detecting that the flowing-back proximal current is greater than the first predetermined current, first disconnect the first branch and the second branch, then conduct the second branch, and connect the first return path and the second return path.

6. The emergency cut-off control system according to claim 5, characterized in that, The control unit of the proximal device further includes: A sampling resistor, configured to receive the flowing-back proximal current to output a sampling voltage; A first comparator, the non-inverting input terminal of the first comparator is configured to receive a sampled voltage, and the inverting input terminal of the first comparator is configured to receive a signal having a first predetermined voltage, and the first predetermined voltage is related to a first predetermined current; and A first MOS transistor, the gate of the first MOS transistor is electrically connected to the output terminal of the first comparator, the source of the first MOS transistor is grounded, and the drain of the first MOS transistor is electrically connected to the control terminals of the first branch and the second branch.

7. The emergency cut-off control system according to claim 6, wherein The control unit of the proximal device further includes: A second comparator, one input terminal of the second comparator is configured to receive a sampled voltage, and the other input terminal of the second comparator is configured to receive a signal having a second predetermined voltage; and A control device, the control device is configured to output a cut-off control signal to the proximal device in response to detecting that the time for which the output terminal of the second comparator remains in a first state is greater than a first predetermined time, and output a control signal to the control terminals of the first branch and the second branch in response to detecting an emergency cut-off signal from the proximal device indicating a fault state so that the first branch and the second branch are disconnected, and the first state corresponds to the proximal current flowing back being less than a predetermined lower limit current.

8. The emergency cut-off control system according to claim 1, characterized in that It further includes: An internal loop switch unit, configured to conduct in response to detecting that the test signal is in an effective state, so as to provide a test path for enabling the proximal current to flow back to the control unit of the proximal device; The control unit of the proximal device is further configured to disconnect the connection with the isolation interlock unit in the test mode, and make the test signal in an effective state, and generate a proximal current.

9. The emergency cut-off control system according to claim 1, characterized in that The isolation interlock unit includes a first opto-coupler and a second opto-coupler. The first return path at least includes the light-emitting source of the first opto-coupler and the light-receiving device of the second opto-coupler. The light-emitting source of the first opto-coupler is connected in series with the light-receiving device of the second opto-coupler. The second return path at least includes the light-emitting source of the second opto-coupler and the light-receiving device of the first opto-coupler. The light-emitting source of the second opto-coupler is connected in series with the light-receiving device of the first opto-coupler.

10. The emergency cut-off control system according to claim 8, wherein, The isolation interlock unit further includes: A first reset switch, one end of the first reset switch is electrically connected to one end of the light-receiving device of the first opto-coupler, and the other end of the first reset switch is electrically connected to the other end of the light-receiving device of the first opto-coupler; and A second reset switch, one end of the second reset switch is electrically connected to one end of the light-receiving device of the second opto-coupler, and the other end of the second reset switch is electrically connected to the other end of the light-receiving device of the second opto-coupler; The first reset switch and the second reset switch are configured to conduct in response to detecting that the reset signal is in an effective state.

11. The emergency cut-off control system according to claim 1, characterized in that, The control unit of the distal device is further configured to stop outputting the distal current to the isolation interlock unit in response to at least one of the following: Detecting an emergency cut-off signal from the distal device indicating a fault state; And Detecting that the distal current flowing back is greater than a sixth predetermined current; The proximal end is one of the source end and the destination end, and the proximal end is the other of the source end and the destination end.

12. The emergency cut-off control system according to claim 5, characterized in that, The control unit of the proximal device further includes: The first safety barrier, the input end of the first safety barrier is electrically connected to the output ends of the first branch and the second branch, and the output end of the first safety barrier is configured to output a proximal current; and The second safety barrier, the input end of the second safety barrier is configured to receive the refluxed proximal current, and the output end of the second safety barrier is electrically connected to the sampling resistor.

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