Device and method for detecting liquid leakage of watertight junction box

Abstract

The invention belongs to the technical field of watertight junction box liquid leakage detection, and particularly relates to a watertight junction box liquid leakage detection device and method.The watertight junction box liquid leakage detection device comprises a watertight junction box, a wet end part and a dry end signal acquisition circuit, and the wet end part comprises a lower electrode, an upper electrode, an insulation sheet and an insulation sleeve; the dry-end signal acquisition circuit comprises a pull-up resistor R1, a current-limiting resistor R2, a photoelectric coupler U1, a pull-up resistor R3 and an MCU, the liquid leakage detection device is simple in structure, only one pair of electrodes is needed, the subsequent dry-end signal acquisition circuit is different from a 24V / open acquisition circuit of a sensor, a ground / open signal acquisition circuit is adopted, and the detection efficiency is greatly improved. Detection of liquid leakage is controlled by adjusting the positions of the upper electrode and the lower electrode, and due to the fact that the structure is simple, maintenance is easy, cost is low, service life is long, and detection accuracy is high.

Description

Technical Field

[0001] The invention belongs to the technical field of liquid leakage detection of watertight junction boxes, and in particular relates to a liquid leakage detection device and method for watertight junction boxes. Background Art

[0002] Watertight junction boxes are mostly used for underwater cable wiring. They need to face high pressure, seawater corrosion and other environments and need to have good sealing properties. Therefore, leakage detection of watertight junction boxes is very necessary.

[0003] Most of the existing leakage detection devices use capacitive sensors. The circuit of this sensor is relatively complex and needs to be calibrated before use. After a period of use, the electrical characteristics of its internal devices may change, which may cause the sensor's detection sensitivity to change, resulting in false leakage detection alarms. There is also the problem of high cost. Summary of the invention

[0004] The present invention aims to provide a device and method for detecting liquid leakage in a watertight junction box, so as to solve the deficiencies in the prior art.

[0005] The present invention provides the following technical solutions: A device for detecting leakage of a watertight junction box comprises a watertight junction box, a wet end and a dry end signal acquisition circuit, the wet end comprising a lower electrode, an upper electrode, an insulating sheet and an insulating sleeve, the insulating sleeve being arranged on the top of the watertight junction box, the bottom of the insulating sleeve being sequentially sleeved with the lower electrode, the insulating sheet and the upper electrode from bottom to top, a fixing screw being installed in the insulating sleeve, a flat washer and a spring washer being installed between the fixing screw and the top of the insulating sleeve, the fixing screw extending downward out of the insulating sleeve and penetrating into the watertight junction box, the dry end signal acquisition circuit comprising a pull-up resistor R1, a current limiting resistor R2, a photocoupler U1, a pull-up resistor R3 and an MCU, one end of the lower electrode being connected to a power supply ground, and the upper electrode being connected to the current limiting resistor R2.

[0006] Preferably, two insulating sheets are provided, which are respectively placed between the lower electrode and the upper electrode and between the lower electrode and the top of the watertight junction box.

[0007] Preferably, the power supply is a 24V isolated power supply with short-circuit protection.

[0008] A detection method using the watertight junction box leakage detection device, wherein the lower electrode is used as a power ground input terminal, and the upper electrode is used as a power ground signal output terminal. When seawater or other conductive liquid media enters the watertight junction box, the upper electrode and the lower electrode are connected, and the MCU of the dry-end signal acquisition circuit collects the isolated power ground signal to determine the water inflow status of the watertight junction box. If a leakage signal is collected, a fault alarm is issued.

[0009] Preferably, when the watertight junction box does not leak or the leakage does not reach the threshold value, the lower electrode and the upper electrode are in a disconnected state, the power supply drives the photocoupler U1 through the pull-up resistor R1 and the current limiting resistor R2, the output end of the photocoupler U1 is closed, and the MCU collects a low-level signal.

[0010] Preferably, when the watertight junction box leaks and the amount of leakage is sufficient to cause the impedance between the lower electrode and the upper electrode to become lower, the photoelectric coupler U1 cannot be driven, the output end of the photoelectric coupler U1 is disconnected, the MCU collects a high-level signal, and the MCU reports the fault.

[0011] Preferably, the leakage detection threshold value can be controlled by adjusting the thickness and quantity of the insulating sheets.

[0012] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art: The liquid leakage detection device of the present invention has a simple structure and only requires a pair of electrodes. The subsequent dry-end signal acquisition circuit is different from the 24V / open acquisition circuit of the sensor, but adopts a ground / open signal acquisition circuit. The detection of the leakage amount is controlled by adjusting the positions of the upper and lower electrodes. In addition, due to its simple structure and easy maintenance, it has a very low cost, a long service life, and a high detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the specific structure of the device for detecting leakage of a watertight junction box according to the present invention; Figure 2 It is a circuit connection diagram of the dry-end signal acquisition circuit of the present invention; Figure 3 It is a partial structural schematic diagram of the liquid leakage detection device for a watertight junction box of the present invention.

[0014] The following are marked in the figure: 1-lower electrode; 2-upper electrode; 3-insulating sheet; 4-insulating sleeve; 5-fixing screw; 6-flat washer; 7-spring washer; 8-watertight junction box. DETAILED DESCRIPTION

[0015] The specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that those skilled in the art can more clearly understand how to practice the present invention. Although the present invention is described in conjunction with its preferred specific embodiments, these embodiments are only illustrative and are not intended to limit the scope of the present invention.

[0016] A device for detecting leakage of a watertight junction box comprises a watertight junction box 8, a wet end and a dry end signal acquisition circuit, wherein the wet end comprises a lower electrode 1, an upper electrode 2, an insulating sheet 3 and an insulating sleeve 4, wherein the insulating sleeve 4 is arranged at the top of the watertight junction box 8, and the bottom of the insulating sleeve 4 is sequentially sleeved with the lower electrode 1, the insulating sheet 3 and the upper electrode 2 from bottom to top, wherein a fixing screw 5 is installed in the insulating sleeve 4, and a flat washer 6 and a spring washer 7 are installed between the fixing screw 5 and the top of the insulating sleeve 4, and the fixing screw 5 extends downwardly out of the insulating sleeve 4 and penetrates into the watertight junction box 8, wherein the dry end signal acquisition circuit comprises a pull-up resistor R1, a current limiting resistor R2, an optocoupler U1, a pull-up resistor R3 and an MCU, wherein one end of the lower electrode 1 is connected to a power supply ground, and the upper electrode 2 is connected to the current limiting resistor R2.

[0017] Specifically, two insulating sheets 3 are provided, which are respectively placed between the lower electrode 1 and the upper electrode 2 and between the lower electrode 1 and the top of the watertight junction box 8 .

[0018] Specifically, the power supply is a 24V isolated power supply with short-circuit protection.

[0019] A detection method using the watertight junction box leakage detection device, wherein the lower electrode 1 is used as a power ground input terminal, and the upper electrode 2 is used as a power ground signal output terminal. When seawater or other conductive liquid media enters the watertight junction box 8, the upper electrode 2 and the lower electrode 1 are connected, and the MCU of the dry-end signal acquisition circuit collects the isolated power ground signal to determine the water inflow status of the watertight junction box 8. If a leakage signal is collected, a fault alarm is issued.

[0020] Specifically, when the watertight junction box 8 does not leak or the leakage amount does not reach the threshold value, the lower electrode 1 and the upper electrode 2 are in a disconnected state, the power supply drives the photocoupler U1 through the pull-up resistor R1 and the current limiting resistor R2, the output end of the photocoupler U1 is closed, and the MCU collects a low-level signal.

[0021] Specifically, when the watertight junction box 8 leaks, and the amount of leakage is sufficient to cause the impedance between the lower electrode 1 and the upper electrode 2 to become lower, the photoelectric coupler U1 cannot be driven, the output end of the photoelectric coupler U1 is disconnected, the MCU collects a high-level signal, and the MCU reports the fault.

[0022] Specifically, the leakage detection threshold value can be controlled by adjusting the thickness and number of the insulating sheets 3 , that is, the leakage detection threshold value can be controlled by adjusting the distance between the lower electrode 1 and the upper electrode 2 .

[0023] In addition, when the watertight junction box 8 leaks, the water ingress status of the watertight junction box 8 is determined by collecting the signal of the isolated power ground. Therefore, even if the water ingress causes the isolated power ground to contact the watertight junction box 8 casing or other power sources, it will not cause a short circuit or other faults, and the MCU can still prepare to collect the leakage signal.

[0024] In the present invention, after seawater or other conductive liquid media enters the watertight junction box 8, the upper electrode 2 and the lower electrode 1 are connected, and the MCU of the dry-end signal acquisition circuit collects the ground signal of the isolated power supply to judge the water inflow state of the watertight junction box 8, and a fault alarm is issued if a leakage signal is collected. The leakage detection threshold can be controlled by adjusting the position of the lower electrode 1 and the upper electrode 2. The wet end has a simple structure, convenient maintenance, high reliability, a leakage detection rate of 100%, and extremely low cost. At the same time, the dry-end signal acquisition circuit collects the ground signal instead of the 24V signal, which can avoid other faults such as short circuit caused by the connection of 24V and the casing after leakage.

[0025] The above description is only a preferred implementation manner of the present invention, but the protection scope of the present invention is not limited thereto, and any modification and replacement based on the technical solution and inventive concept provided by the present invention should be included in the protection scope of the present invention.

Claims

1. A watertight junction box leakage detection device, characterized in that: The invention comprises a watertight junction box (8), a wet end and a dry end signal acquisition circuit, wherein the wet end comprises a lower electrode (1), an upper electrode (2), an insulating sheet (3) and an insulating sleeve (4), wherein the insulating sleeve (4) is arranged on the top of the watertight junction box (8), and the bottom of the insulating sleeve (4) is sequentially sleeved with the lower electrode (1), the insulating sheet (3) and the upper electrode (2) from bottom to top, wherein a fixing screw (5) is installed in the insulating sleeve (4), and a flat washer (6) and a spring washer (7) are installed between the fixing screw (5) and the top of the insulating sleeve (4), wherein the fixing screw (5) extends downward out of the insulating sleeve (4) and penetrates into the watertight junction box (8), wherein the dry end signal acquisition circuit comprises a pull-up resistor R1, a current limiting resistor R2, a photoelectric coupler U1, a pull-up resistor R3 and an MCU, wherein one end of the lower electrode (1) is connected to a power supply ground, and the upper electrode (2) is connected to the current limiting resistor R2.

2. A watertight junction box leakage detection device according to claim 1, characterized in that: The insulating sheets (3) are provided in two pieces, and are respectively placed between the lower electrode (1) and the upper electrode (2) and between the lower electrode (1) and the top of the watertight junction box (8).

3. A watertight junction box leakage detection device according to claim 1, characterized in that: The power supply is a 24V isolated power supply with short-circuit protection.

4. A detection method using the watertight junction box leakage detection device according to any one of claims 1 to 3, characterized in that: The lower electrode (1) serves as a power ground input terminal, and the upper electrode (2) serves as a power ground signal output terminal. When seawater or other conductive liquid media enters the watertight junction box (8), the upper electrode (2) and the lower electrode (1) are connected, and the MCU of the dry-end signal acquisition circuit acquires the isolated power ground signal to determine the water inflow state of the watertight junction box (8). If a leakage signal is acquired, a fault alarm is issued.

5. A detection method using a watertight junction box leakage detection device according to claim 4, characterized in that: When the watertight junction box (8) does not leak or the amount of leakage does not reach the threshold value, the lower electrode (1) and the upper electrode (2) are in a disconnected state, the power supply drives the photoelectric coupler U1 through the pull-up resistor R1 and the current-limiting resistor R2, the output end of the photoelectric coupler U1 is closed, and the MCU collects a low-level signal.

6. A detection method using a watertight junction box leakage detection device according to claim 4, characterized in that: When a liquid leakage fault occurs in the watertight junction box (8), and the amount of liquid leakage is sufficient to cause the impedance between the lower electrode (1) and the upper electrode (2) to become lower, the photoelectric coupler U1 cannot be driven, the output end of the photoelectric coupler U1 is disconnected, the MCU collects a high-level signal, and the MCU reports the fault.

7. A detection method using a watertight junction box leakage detection device according to claim 4, characterized in that: The leakage detection threshold value can be controlled by adjusting the thickness and quantity of the insulating sheets (3).

Images