Marine environment protected cathode service performance monitoring and alarm device

Abstract

The present invention provides a marine environment protected cathode service performance monitoring and alarm device, comprising a sampling resistor, a voltage sampling device, a temperature sensor, a control module and an alarm, wherein the sampling resistor is used to be connected in series between a sacrificial anode and a protected cathode, and the voltage sampling device is connected in parallel with two ends of the sampling resistor; the temperature sensor is arranged close to the sampling resistor, and the temperature sensor is used to detect the temperature T of the surrounding environment of the sampling resistor; the voltage sampling device and the temperature sensor are both connected to the control module with an electrical signal, and the control module is connected with the alarm signal; the control module is used to calculate the actual resistance value R of the sampling resistor according to the temperature value measured by the temperature sensor, and calculate the protection current I according to the actual resistance value R of the sampling resistor, and compare the protection current I with the critical current value I when pitting occurs on the protected cathode min The size of the signal is compared to control whether the alarm will send out an alarm message.

Description

Technical Field

[0001] The invention relates to the technical field of cathode protection and anti-corrosion, in particular to a device for monitoring and alarming the service performance of a cathode protected in a marine environment. Background Art

[0002] In recent years, with the advancement of my country's marine engineering technology, there are more and more marine engineering equipment such as offshore platforms, submarine pipelines, and marine steel piles. However, these marine engineering equipment are prone to corrosion due to being in harsh marine environments for a long time. Therefore, the anti-corrosion of marine engineering equipment has been a research hotspot for a long time.

[0003] Cathodic protection technology is an effective means of corrosion control. Cathodic protection technology is divided into sacrificial anode protection technology (i.e. sacrificial anode cathodic protection method) and impressed current protection technology. Among them, sacrificial anode protection technology is to connect the protected metal (i.e. the protected cathode) with another metal or alloy with lower electrode potential (i.e. sacrificial anode), so that the metal or alloy with lower potential is consumed as the anode first, and the protected metal obtains the cathode current and is protected.

[0004] When the sacrificial anode is being consumed, a current, i.e., the protective current, will be generated between the protected cathode and the sacrificial anode. When pitting (also known as hole corrosion) occurs on the protected cathode, the protective current will increase. Therefore, by monitoring the magnitude of the protective current, it is possible to determine whether the protected cathode is corroded. In order to monitor the magnitude of the protective current, a high-precision sampling resistor is generally connected in series between the protected cathode and the sacrificial anode, and the voltage across the sampling resistor (i.e., voltage division) is measured through a voltage sampling device. The magnitude of the protective current is obtained by calculating the ratio of the voltage across the sampling resistor to the resistance value of the sampling resistor.

[0005] Since the sampling resistor is in a marine environment, the temperature of the external environment varies greatly, and the change in ambient temperature will have a great impact on the actual resistance value of the sampling resistor, thereby affecting the accuracy of the calculated protection current (currently the rated resistance value of the sampling resistor is generally used to calculate the protection current), and cannot truly reflect the corrosion state of the protected cathode. Summary of the invention

[0006] The purpose of the present invention is to provide a marine environment protected cathode service performance monitoring and alarm device, which can calculate the actual resistance value of the sampling resistor according to the change of the ambient temperature, so as to obtain an accurate protection current value, thereby avoiding the problem of inaccurate measured protection current due to inaccurate resistance value of the sampling resistor when the external ambient temperature changes.

[0007] The present invention provides a marine environment protected cathode service performance monitoring and alarm device, which is used to detect a protection current I generated between a sacrificial anode and a protected cathode, wherein the sacrificial anode is electrically connected to the protected cathode; the marine environment protected cathode service performance monitoring and alarm device comprises a sampling resistor, a voltage sampling device, a temperature sensor, a control module and an alarm, wherein the sampling resistor is used to be connected in series between the sacrificial anode and the protected cathode, the voltage sampling device is connected in parallel with both ends of the sampling resistor, and the voltage sampling device is used to detect a voltage U across both ends of the sampling resistor; the temperature sensor is arranged close to the sampling resistor, and the temperature sensor is not in contact with the sampling resistor, and the temperature sensor is used to detect a temperature T of an environment surrounding the sampling resistor; the voltage sampling device and the temperature sensor are both electrically connected to the control module, and the control module is signal connected to the alarm; the control module is used to calculate an actual resistance R of the sampling resistor according to a temperature value measured by the temperature sensor, and calculate the protection current I according to the actual resistance R of the sampling resistor, and compare the protection current I with a critical current value I when pitting occurs on the protected cathode min The size of the signal is compared to control whether the alarm device issues an alarm message.

[0008] In one achievable manner, the method for calculating the actual resistance R of the sampling resistor includes:

[0009] Using the temperature sensor to detect the temperature T of the surrounding environment of the sampling resistor;

[0010] When |TT R |<M, the actual resistance of the sampling resistor R=Ra; wherein Ra is the rated resistance of the sampling resistor, and T R The rated temperature corresponding to the rated resistance of the sampling resistor is measured, and M is the temperature deviation;

[0011] When |TT R |≥M, the actual resistance of the sampling resistor R=Rb; wherein, Rb=(a0+3.2*10 -6 )+(a1-1.6*10 -6 )*(TT R )+(a2-0.5*10 -6 )*(TT R ) 2 ; a0, a1 and a2 are temperature difference coefficients.

[0012] In one achievable manner, the T R is 20°C and the M is 4°C.

[0013] In one achievable manner, the method for calculating the actual resistance R of the sampling resistor includes:

[0014] A data mapping table related to the actual resistance value R of the sampling resistor and the ambient temperature is pre-set in the control module;

[0015] The temperature sensor is used to detect the temperature T of the surrounding environment of the sampling resistor, and the actual resistance value R of the corresponding sampling resistor is obtained by querying the data mapping table.

[0016] In an achievable manner, when the protection current I is less than the critical current value I when pitting occurs in the protected cathode min When the protection current I is greater than or equal to the critical current value I when pitting occurs in the protected cathode, the alarm does not send out an alarm message; when the protection current I is greater than or equal to the critical current value I when pitting occurs in the protected cathode min When the alarm is triggered, the alarm device sends out corresponding alarm information.

[0017] In one achievable manner, the sampling resistor is used to be arranged in seawater, the temperature sensor is used to be arranged in seawater close to the sampling resistor, and the temperature sensor is used to detect the temperature of the seawater around the sampling resistor.

[0018] In one achievable manner, the marine environment protected cathode service performance monitoring and alarm device further includes a sealed box, the sampling resistor and the temperature sensor are both disposed in the box, and the temperature sensor is used to detect the temperature inside the box.

[0019] In one achievable manner, the sampling resistor has a rated resistance less than or equal to 2.5*10 -6 A small resistance resistor of Ω.

[0020] In one practicable manner, the marine environment protected cathode service performance monitoring and alarm device further comprises a communication module, the communication module is electrically connected to the control module, and the communication module is wirelessly connected to the alarm.

[0021] In an achievable manner, the number of the temperature sensor is one; or, the number of the temperature sensors is multiple, and the multiple temperature sensors are arranged at intervals around the outer periphery of the sampling resistor.

[0022] The marine environment protected cathode service performance monitoring and alarm device provided by the present invention is provided with a temperature sensor, and the temperature sensor is used to detect the temperature T of the surrounding environment of the sampling resistor. The control module calculates the actual resistance value R of the sampling resistor according to the temperature value measured by the temperature sensor, and then calculates the protection current I according to the actual resistance value R of the sampling resistor, and compares the protection current I with the critical current value I when pitting occurs in the protected cathode.min The size of the sample resistor is compared to control whether the alarm will send out an alarm message. The marine environment protected cathode service performance monitoring alarm device can calculate the actual resistance value of the sampling resistor according to the change of the ambient temperature, so as to obtain an accurate protection current value, avoiding the problem of inaccurate protection current I measured due to inaccurate resistance value of the sampling resistor when the external ambient temperature changes, improving the control accuracy of the system, and being able to accurately feedback whether the protected cathode is corroded. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the connection relationship between the sampling resistor, the sacrificial anode, the protected cathode and the voltage sampling device in an embodiment of the present invention.

[0024] Figure 2 Schematic diagram of the relative position relationship between the temperature sensor and the sampling resistor in an embodiment of the present invention.

[0025] Figure 3 It is a structural block diagram of a device for monitoring and alarming the service performance of a cathode protected in a marine environment in an embodiment of the present invention.

[0026] Figure 4 Schematic diagram of the relative position relationship between the temperature sensor and the sampling resistor in another embodiment of the present invention.

[0027] Figure 5 Schematic diagram of the relative position relationship between the temperature sensor and the sampling resistor in another embodiment of the present invention.

[0028] Figure 6 It is a schematic diagram of the working process of the device for monitoring and alarming the service performance of the protected cathode in the marine environment in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0030] The terms "first", "second", "third", "fourth" and the like (if any) in the description and claims of the present invention are used to distinguish similar objects and are not necessarily used to describe a particular sequence or order.

[0031] The directional words such as up, down, left, right, front, back, top, bottom, etc. (if any) involved in the specification and claims of the present invention are defined by the positions of the structures in the drawings and the positions of the structures relative to each other, and are only for the clarity and convenience of expressing the technical solution. It should be understood that the use of directional words should not limit the scope of protection claimed in this application.

[0032] like Figures 1 to 3As shown, an embodiment of the present invention provides a marine environment protected cathode service performance monitoring and alarm device, which is used to detect the protection current I generated between the sacrificial anode 91 and the protected cathode 92, and the sacrificial anode 91 is electrically connected to the protected cathode 92. The protected cathode 92 can be marine engineering equipment such as an offshore platform, a submarine pipeline, and an offshore steel pile, and the protected cathode 92 is at least partially located in the seawater, and the sacrificial anode 91 is arranged in the seawater. The protected cathode 92 and the sacrificial anode 91 form a primary battery circuit through the seawater environment, so when the sacrificial anode 91 is consumed, a current, that is, the protection current I, will be generated between the protected cathode 92 and the sacrificial anode 91.

[0033] The marine environment protected cathode service performance monitoring and alarm device includes a sampling resistor 1, a voltage sampling device 2, a temperature sensor 3, a control module 4 and an alarm 5. The sampling resistor 1 is used to be connected in series between the sacrificial anode 91 and the protected cathode 92, the voltage sampling device 2 is connected in parallel with both ends of the sampling resistor 1 (that is, the first end of the voltage sampling device 2 is connected to the first end of the sampling resistor 1, and the second end of the voltage sampling device 2 is connected to the second end of the sampling resistor 1), and the voltage sampling device 2 is used to detect the voltage U across the two ends of the sampling resistor 1 (that is, the voltage division of the sampling resistor 1). The temperature sensor 3 is set close to the sampling resistor 1, and the temperature sensor 3 does not contact the sampling resistor 1 (to avoid affecting the resistance value of the sampling resistor 1), and the temperature sensor 3 is used to detect the temperature T of the environment around the sampling resistor 1.

[0034] The voltage sampling device 2 and the temperature sensor 3 are both electrically connected to the control module 4, and the control module 4 is signal-connected to the alarm 5; the control module 4 is used to calculate the actual resistance R of the sampling resistor 1 according to the temperature value measured by the temperature sensor 3, and calculate the protection current I according to the actual resistance R of the sampling resistor 1, and compare the protection current I with the critical current value I when pitting occurs on the protected cathode 92 min (The critical current value I min The size of the voltage can be obtained through engineering simulation test) and compared to control whether the alarm device 5 sends out an alarm message.

[0035] Specifically, according to actual engineering experience, when pitting (also known as pitting) occurs on the protected cathode 92, the protection current I will increase; therefore, when pitting is about to occur on the protected cathode 92, there is a critical current value I between the protected cathode 92 and the sacrificial anode 91. min (i.e., the minimum current value at which pitting will occur in the protected cathode 92), the critical current value I min It can be obtained through engineering simulation test. By monitoring the size of protection current I and comparing the protection current I with the critical current value I min By making a comparison, it is possible to determine whether corrosion occurs to the protected cathode, and to control the alarm device 5 to issue an alarm message according to the determination result.

[0036] The marine environment protected cathode service performance monitoring and alarm device provided by the embodiment of the present invention is provided with a temperature sensor 3, and the temperature sensor 3 is used to detect the temperature T of the surrounding environment of the sampling resistor 1. The control module 4 calculates the actual resistance R of the sampling resistor 1 according to the temperature value measured by the temperature sensor 3, and then calculates the protection current I according to the actual resistance R of the sampling resistor 1, and compares the protection current I with the critical current value I when pitting occurs on the protected cathode 92. min The size of the sampling resistor 1 is compared to control whether the alarm device 5 issues an alarm message. The marine environment protected cathode service performance monitoring and alarm device can calculate the actual resistance value of the sampling resistor 1 according to the change of the ambient temperature, so as to obtain an accurate protection current value, thereby avoiding the problem of inaccurate protection current I measured due to inaccurate resistance value of the sampling resistor 1 when the external ambient temperature changes, improving the control accuracy of the system, and being able to accurately feedback whether the protected cathode 92 is corroded.

[0037] As an embodiment, when the protection current I is less than the critical current value I when pitting occurs in the protected cathode 92 min When the protection current I is greater than or equal to the critical current value I when pitting occurs in the protected cathode 92, the protection current I is greater than or equal to the critical current value I when pitting occurs in the protected cathode 92. min When the protected cathode 92 is considered to have been pitted or is about to be pitted, the control module 4 controls the alarm 5 to issue a corresponding alarm message.

[0038] As an implementation manner, a method for calculating the actual resistance R of the sampling resistor 1 includes:

[0039] The temperature sensor 3 is used to detect the temperature T of the surrounding environment of the sampling resistor 1;

[0040] When |TT R |<M, the actual resistance of the sampling resistor 1 is R=Ra; where Ra is the rated resistance of the sampling resistor 1, T R The rated temperature corresponding to the rated resistance value of the sampling resistor 1 (i.e., the rated resistance value of the sampling resistor 1 is at the rated temperature T R Ra and T measured under R It is related to the selected model of sampling resistor 1), M is the temperature deviation. That is, when the temperature T of the surrounding environment of sampling resistor 1 is different from the rated temperature T R When the difference between them is small, the rated resistance Ra of the sampling resistor 1 can be regarded as its actual resistance R;

[0041] When |TT R |≥M, the actual resistance value of the sampling resistor 1 is R=Rb; wherein, Rb=(a0+3.2*10 -6 )+(a1-1.6*10-6 )*(TT R )+(a2-0.5*10 -6 )*(TT R ) 2 ; a0, a1 and a2 are all temperature difference coefficients. That is, when the temperature T of the surrounding environment of the sampling resistor 1 is different from the rated temperature T R When the difference between them is large, the actual resistance value R of the sampling resistor 1 is greatly different from its rated resistance value Ra, so it is necessary to calculate the value of R by the above Rb calculation formula to reduce the error.

[0042] The calculation formula of Rb is obtained by using the Chebyshev approximation method combined with engineering simulation data, which can reduce the influence of ambient temperature on the calculation of the resistance value of the sampling resistor 1. Among them, the above a0, a1 and a2 can be calculated through actual engineering simulation data, for example: two or more sets of correlation data of Rb and T are measured through experiments, and then substituted into the above Rb calculation formula for calculation, and the values ​​of a0, a1 and a2 can be obtained.

[0043] As an implementation mode, the above T R is 20℃, the above M is 4℃, that is:

[0044] When |T-20|<4, the actual resistance value of the sampling resistor 1 is R=Ra;

[0045] When |T-20|≥4, the actual resistance value of the sampling resistor 1 is R=Rb; Rb=(a0+3.2*10 -6 )+(a1-1.6*10 -6 )*(T-20)+(a2-0.5*10 -6 )*(T-20) 2 .

[0046] Of course, in other embodiments, T R and M may also be other values ​​and can be adjusted according to actual conditions.

[0047] As another implementation, a method for calculating the actual resistance R of the sampling resistor 1 includes:

[0048] A data mapping table related to the actual resistance value R of the sampling resistor 1 and the ambient temperature is pre-set in the control module 4 (for example, the corresponding data of R and temperature in the temperature range of 0-40° C.);

[0049] The temperature sensor 3 is used to detect the temperature T of the surrounding environment of the sampling resistor 1, and the actual resistance R of the corresponding sampling resistor 1 is obtained by querying the data mapping table. Compared with the above formula calculation method, the table query method has a more accurate calculation result, but a large amount of data needs to be measured in advance.

[0050] As an implementation manner, the data mapping table may be, for example (taking the corresponding data relationship between R and T in the temperature range of 0-40° C. as an example; of course, in other embodiments, the temperature range may be narrowed or expanded as required):

[0051]

[0052] As an implementation method, the sampling resistor 1 has a rated resistance less than or equal to 2.5*10 -6 A small resistance of Ω is used, thereby minimizing the influence of the sampling resistor 1 on the protection current I, and avoiding the protection current I being reduced due to the excessive resistance of the sampling resistor 1, thereby affecting the protection effect of the protected cathode 92.

[0053] like Figure 2 As shown, as an implementation mode, the sampling resistor 1 is used to be set in seawater, the temperature sensor 3 is used to be set in seawater near the sampling resistor 1, and the temperature sensor 3 is used to detect the seawater temperature around the sampling resistor 1, that is, the sampling resistor 1 and the temperature sensor 3 are both exposed to seawater. This setting method is relatively simple, but it requires the sampling resistor 1 and the temperature sensor 3 to have good corrosion resistance and other properties. At the same time, the temperature sensor 3 can be set downstream or top flow in the seawater, avoiding the side flow setting, so as to reduce the impact force of the seawater on the temperature sensor 3 and ensure its stability.

[0054] like Figure 4 As shown, as another embodiment, the marine environment protected cathode service performance monitoring and alarm device further includes a sealed box 7, in which the sampling resistor 1 and the temperature sensor 3 are both arranged, and the temperature sensor 3 is used to detect the temperature inside the box 7. Since the sampling resistor 1 and the temperature sensor 3 are both arranged in the sealed box 7, the seawater corrosion and the attachment of marine microorganisms to the sampling resistor 1 and the temperature sensor 3 can be reduced, thereby improving their detection accuracy and extending their service life.

[0055] like Figure 2 As shown, as an implementation manner, the number of the temperature sensor 3 is one.

[0056] like Figure 5 As shown, as another embodiment, the number of temperature sensors 3 is multiple (two are shown in the figure, but more can be set in practice), and multiple temperature sensors 3 are arranged at intervals around the outer periphery of the sampling resistor 1, and multiple temperature sensors 3 are all connected to the control module 4 by electrical signals. By setting multiple temperature sensors 3, the problem of failure to read data due to failure of one of the temperature sensors 3 can be avoided, and the accuracy of temperature detection can be improved (for example, the average value of the readings of several temperature sensors 3 is taken); this setting method can be used for key monitoring and protection objects.

[0057] like Figure 3 As shown, as an embodiment, the marine environment protected cathode service performance monitoring and alarm device also includes a communication module 6, the communication module 6 is electrically connected to the control module 4, and the communication module 6 is wirelessly connected to the alarm 5, that is, the control module 4 is wirelessly connected to the alarm 5 through the communication module 6.

[0058] Specifically, since the alarm 5 is generally arranged in a monitoring room on land, by providing the communication module 6, the alarm signal can be remotely transmitted to the alarm 5, thereby realizing the function of remote monitoring.

[0059] As an implementation mode, the alarm 5 includes a display screen (not shown) for displaying alarm information, and the control module 4 is wirelessly connected to the display screen via the communication module 6. Of course, the alarm 5 can also be an audible and visual alarm device.

[0060] like Figure 3 As shown, as an embodiment, the marine environment protected cathode service performance monitoring and alarm device also includes an industrial tablet computer 8. The control module 4 is wirelessly connected to the industrial tablet computer 8 through the communication module 6. The user can view, modify, and store monitoring data and set values ​​through the industrial tablet computer 8.

[0061] like Figure 6 As shown, as an implementation method, the working process of the marine environment protected cathode service performance monitoring and alarm device is as follows:

[0062] 1. Use the voltage sampling device 2 to detect the voltage U across the sampling resistor 1, and use the temperature sensor 3 to detect the temperature T of the surrounding environment of the sampling resistor 1;

[0063] 2. According to the ambient temperature T detected by the temperature sensor 3, the actual resistance value R of the sampling resistor 1 is calculated by the above formula method or table lookup method;

[0064] 3. Calculate the protection current I according to the formula U / R, and then compare the protection current I with the critical current value I min If the protection current I is less than the critical current value I min , the alarm 5 does not issue an alarm message; if the protection current I is greater than or equal to the critical current value I min , the alarm 5 sends out corresponding alarm information.

[0065] The marine environment protected cathode service performance monitoring and alarm device provided by the embodiment of the present invention is provided with a temperature sensor 3, and the temperature sensor 3 is used to detect the temperature T of the surrounding environment of the sampling resistor 1. The control module 4 calculates the actual resistance R of the sampling resistor 1 according to the temperature value measured by the temperature sensor 3, and then calculates the protection current I according to the actual resistance R of the sampling resistor 1, and compares the protection current I with the critical current value I when pitting occurs on the protected cathode 92. min The size of the sampling resistor 1 is compared to control whether the alarm device 5 issues an alarm message. The marine environment protected cathode service performance monitoring and alarm device can calculate the actual resistance value of the sampling resistor 1 according to the change of the ambient temperature, so as to obtain an accurate protection current value, thereby avoiding the problem of inaccurate protection current I measured due to inaccurate resistance value of the sampling resistor 1 when the external ambient temperature changes, improving the control accuracy of the system, and being able to accurately feedback whether the protected cathode 92 is corroded.

[0066] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A marine environment protected cathode service performance monitoring and alarm device, used for detecting a protection current I generated between a sacrificial anode (91) and a protected cathode (92), wherein the sacrificial anode (91) is electrically connected to the protected cathode (92), characterized in that: The marine environment protected cathode service performance monitoring and alarm device comprises a sampling resistor (1), a voltage sampling device (2), a temperature sensor (3), a control module (4) and an alarm (5), wherein the sampling resistor (1) is used to be connected in series between the sacrificial anode (91) and the protected cathode (92), the voltage sampling device (2) is connected in parallel with both ends of the sampling resistor (1), and the voltage sampling device (2) is used to detect the voltage U at both ends of the sampling resistor (1); the temperature sensor (3) is arranged close to the sampling resistor (1), and the temperature sensor (3) is not connected to the sampling resistor (1). ), the temperature sensor (3) is used to detect the temperature T of the surrounding environment of the sampling resistor (1); the voltage sampling device (2) and the temperature sensor (3) are both connected to the control module (4) by electrical signals, and the control module (4) is connected to the alarm (5) by signal; the control module (4) is used to calculate the actual resistance R of the sampling resistor (1) according to the temperature value measured by the temperature sensor (3), and calculate the protection current I according to the actual resistance R of the sampling resistor (1), and compare the protection current I with the critical current value I when pitting occurs on the protected cathode (92) min The size of the signal is compared to control whether the alarm device (5) issues an alarm message.

2. The marine environment protected cathode service performance monitoring and alarm device according to claim 1, characterized in that: The method for calculating the actual resistance value R of the sampling resistor (1) includes: Using the temperature sensor (3) to detect the temperature T of the surrounding environment of the sampling resistor (1); When |TT R |<M, the actual resistance value of the sampling resistor (1) is R=Ra; wherein Ra is the rated resistance value of the sampling resistor (1), and T R The rated temperature corresponding to the rated resistance of the sampling resistor (1) is measured, and M is the temperature deviation; When |TT R |≥M, the actual resistance value of the sampling resistor (1) is R=Rb; wherein Rb=(a0+3.2*10 -6 )+(a1-1.6*10 -6 )*(TT R )+(a2-0.5*10 -6 )*(TT R ) 2 ; a0, a1 and a2 are temperature difference coefficients.

3. The marine environment protected cathode service performance monitoring and alarm device according to claim 2, characterized in that: The T R is 20°C and the M is 4°C.

4. The marine environment protected cathode service performance monitoring and alarm device according to claim 1, characterized in that: The method for calculating the actual resistance value R of the sampling resistor (1) includes: A data mapping table related to the actual resistance value R of the sampling resistor (1) and the ambient temperature is pre-set in the control module (4); The temperature sensor (3) is used to detect the temperature T of the surrounding environment of the sampling resistor (1), and the actual resistance value R of the corresponding sampling resistor (1) is obtained by querying the data mapping table.

5. The marine environment protected cathode service performance monitoring and alarm device according to claim 1, characterized in that: When the protection current I is less than the critical current value I when pitting occurs in the protected cathode (92) min When the protection current I is greater than or equal to the critical current value I when pitting occurs in the protected cathode (92), the alarm (5) does not issue an alarm message; when the protection current I is greater than or equal to the critical current value I when pitting occurs in the protected cathode (92) min When the alarm (5) is triggered, the alarm device (5) sends out a corresponding alarm message.

6. The marine environment protected cathode service performance monitoring and alarm device according to claim 1, characterized in that: The sampling resistor (1) is used to be arranged in seawater, the temperature sensor (3) is used to be arranged in seawater close to the sampling resistor (1), and the temperature sensor (3) is used to detect the temperature of the seawater around the sampling resistor (1).

7. The marine environment protected cathode service performance monitoring and alarm device according to claim 1, characterized in that: The marine environment protected cathode service performance monitoring and alarm device further comprises a sealed box (7), wherein the sampling resistor (1) and the temperature sensor (3) are both arranged in the box (7), and the temperature sensor (3) is used to detect the temperature inside the box (7).

8. The marine environment protected cathode service performance monitoring and alarm device according to claim 1, characterized in that: The sampling resistor (1) has a rated resistance less than or equal to 2.5*10 -6 A small resistance resistor of Ω.

9. The marine environment protected cathode service performance monitoring and alarm device according to claim 1, characterized in that: The marine environment protected cathode service performance monitoring and alarm device further comprises a communication module (6), wherein the communication module (6) is electrically connected to the control module (4), and the communication module (6) is wirelessly connected to the alarm (5).

10. The marine environment protected cathode service performance monitoring and alarm device according to claim 1, characterized in that: The number of the temperature sensor (3) is one; or the number of the temperature sensor (3) is multiple, and the multiple temperature sensors (3) are arranged at intervals around the outer periphery of the sampling resistor (1).

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