Electric leakage protection device for 110V direct current branch load

Abstract

The technical scheme of the utility model discloses a 110V DC branch load leakage protection device. According to the utility model, the direct-current shunt is adopted to directly collect the leakage current, and the positive and negative buses are adopted to respectively collect the working current, so that the inherent defect that the Hall current sensor is influenced by the temperature is avoided, and the current test precision of the Hall sensor is also prevented from being influenced by the mounting aperture and the relative position of the tested cable. According to the utility model, the value of the leakage current can be accurately tested, and then graded alarm processing is carried out.

Description

110V DC branch load leakage protection device Technical Field

[0001] This utility model relates to a device for accurate detection, graded early warning and protection of leakage current in DC loads of 110V DC power supply systems, belonging to the field of DC power distribution and protection technology of power systems. Background Technology

[0002] Currently, the 110V DC operating power supply configured for 10KV and 35KV substations on the market is a 110V 80A battery pack with nine 12V 100AH ​​blue-lined batteries. Under normal circumstances, it receives two 380V AC power inputs. The first input provides AC input power to AC / DC rectifier modules #1 and #2, and the second input provides AC input power to AC / DC rectifier modules #3 and #4. This ensures power supply to the load is guaranteed even if either AC input fails. In extreme cases, such as when both 380V power supplies fail, the backup battery pack supplies power to the load, providing at least 3 hours of power to downstream protection equipment. This ensures that the substation can promptly provide tripping power to the power protection equipment in the event of major faults such as short circuits or fires in the transformers and lines.

[0003] As shown in Figure 2, existing leakage current sensor detection devices include:

[0004] Monitor M1: Communicates with insulation monitoring module M3 via RS485 interface to monitor the operating status of the entire leakage current sensor detection device and receive and process data from insulation monitoring module M3;

[0005] DC power bus M2: Provides 80-130V operating power input to the insulation monitoring module M3, which is the power source for the device operation;

[0006] Insulation monitoring module M3: The core of the device, it receives power input from DC power bus M2, and on the one hand, it supplies power to leakage current sensor CT*32 branch M5 through ±12V output, and on the other hand, it collects leakage current data (0-5V) detected by leakage current sensor CT*32 branch M5. It can also extend communication with insulation monitoring module M4 through cascaded CAN bus, and can control alarm relay output M6. Alarm relay output M6 can output alarm signal when the insulation monitoring module M3 fails to communicate with the monitor M1.

[0007] Insulation monitoring module extension M4: Connects to insulation monitoring module M3 via cascaded CAN to extend insulation monitoring functions, such as adding monitoring nodes or monitoring range;

[0008] Leakage current sensor CT*32 branch M5: Powered by insulation monitoring module M3, it is responsible for detecting leakage current in the system and feeding back relevant data to insulation monitoring module M3. "*32" indicates that 32 branches can be connected.

[0009] Alarm relay output M6: Receives signals from insulation monitoring module M3. When the system detects abnormal conditions such as insulation faults, insulation monitoring module M3 controls alarm relay output M6 to activate the alarm function, such as triggering audible and visual alarms.

[0010] The working principle of the above-mentioned leakage current sensor detection device is as follows:

[0011] 1) Power supply

[0012] DC power bus M2 provides 80-130V operating power to insulation monitoring module M3, enabling M3 to operate normally. At the same time, insulation monitoring module M3 supplies power to leakage current sensor CT*32 branch M5 through ±12V output, ensuring its operation.

[0013] 2) Leakage current detection

[0014] The CT*32 leakage current sensor branch M5 monitors the leakage current in the system in real time (leakage current detection range 0-10 mA). When the insulation performance of the system deteriorates, leakage current will be generated. The sensor converts the detected leakage current signal into an electrical signal (0-5V) and transmits it to the insulation monitoring module M3.

[0015] 3) Data processing and judgment

[0016] After receiving leakage current data from the leakage current sensor CT*32 branch M5, the insulation monitoring module M3 analyzes and processes the data according to preset insulation standards and algorithms. It determines whether the system's insulation status is normal, for example, by comparing the detected leakage current value with a set threshold.

[0017] 4) Communication and Extension

[0018] Insulation monitoring module M3 communicates with monitor M1 via an RS485 interface, uploading processed insulation status data, leakage current data, and other information to monitor M1 for remote monitoring and management by operators. Simultaneously, insulation monitoring module M3 can communicate with insulation monitoring module extension M4 via cascaded CAN, expanding the monitoring range or adding monitoring nodes as needed.

[0019] 5) Alarm function

[0020] When the insulation monitoring module M3 detects an insulation fault in the system (such as leakage current exceeding a threshold), it reports the information to the monitor M1 via RS485, and the monitor M1 then reports the data. When the monitor M1 malfunctions, it also controls the alarm relay output M6 to activate the alarm device, such as issuing audible and visual signals, to remind staff to promptly investigate and handle the insulation fault, ensuring the safe operation of the system.

[0021] The main drawbacks of existing leakage current monitoring equipment are as follows: First, the testing accuracy of the leakage current sensor itself is affected by the external ambient temperature, the matching of the sensor aperture and cable diameter, and their relative positions, resulting in significant errors. This can lead to false alarms when the leakage current is below 10mA or no alarm when it is above 10mA. Second, when a leakage current is detected to be above the 10mA threshold, only an alarm signal is issued, without any information about the magnitude or specific value of the leakage current. This is not a problem for minor leakage currents, as maintenance personnel can dispatch staff to the site for leakage detection and repair after receiving the alarm information. However, for leakage currents greater than 30mA, only an alarm is issued, and the load cannot be tripped immediately. This may cause the fault to deteriorate rapidly, leading to a larger failure. Summary of the Invention

[0022] The purpose of this invention is to achieve accurate leakage current detection, graded alarms, and leakage protection technology by adding a leakage current detection and protection device module without changing the original 110V operating power supply.

[0023] To achieve the above objectives, the present invention discloses a 110V DC branch load leakage protection device, characterized in that it includes a contactor connected in series between the DC power output terminal of the 110V DC operating power supply and the power supply terminal of the DC load. When the contacts in the contactor are closed, the 110V DC operating power supply supplies power to the DC load; when the contacts in the contactor are open, the power supply from the 110V DC operating power supply to the DC load is cut off. A shunt 1 and a shunt 2 are connected in series between the positive terminal of the DC power output terminal of the 110V DC operating power supply and the contactor, and between the negative terminal of the DC power output terminal of the 110V DC operating power supply and the contactor, respectively. The two ends of the shunt 1 are connected to the current detection input port 1 of the control module, and the two ends of the shunt 2 are connected to the current detection input port 2 of the control module. The power supply terminal of the control module is connected to the DC power output terminal of the 110V DC operating power supply, and the control voltage output terminal of the control module is connected to the two ends of the coil inside the contactor.

[0024] Preferably, a fuse is connected in series between the power supply terminal of the control module and the DC power output terminal of the 110V DC operating power supply.

[0025] Preferably, the contactor is rated for 15A MAX.

[0026] Preferably, both the first and second shunts are rated at 15A 75mV.

[0027] Preferably, the control module is connected to an external device via an RS485 communication bus.

[0028] Preferably, the control signal output port of the control module is connected to an external alarm device.

[0029] To address the shortcomings of existing leakage current sensor detection devices as pointed out in the background art, this invention employs a DC shunt to directly acquire the leakage current (current acquisition accuracy can reach 0.1% to 0.5%), and uses positive and negative busbars to acquire the operating current separately. Those skilled in the art can calculate the difference between the two currents, avoiding the inherent temperature-dependent defects of Hall current sensors. It also avoids the influence of the Hall sensor's current testing accuracy on the mounting hole diameter and the relative position of the cable under test (Hall sensor current testing accuracy is generally 0.5% to 2%, and the accuracy is affected by Hall element temperature drift, residual magnetism, installation process, etc.). This invention can accurately measure the magnitude of the leakage current and then perform graded alarm processing.

[0030] By adding the leakage current detection and protection device provided by this utility model, it is possible to achieve

[0031] 1) Maintenance work is carried out in a targeted manner;

[0032] 2) The device provided by this utility model can be added externally without affecting the operation of the original equipment;

[0033] 3) This utility model is a beneficial supplement and improvement to the original power supply system;

[0034] 4) Regarding the magnitude of leakage current, those skilled in the art can clearly know the specific value after using the device provided by this utility model, which is of great help in fault analysis and repair. Based on fault experience and analysis of historical leakage current data, it can help to eliminate the fault more quickly.

[0035] 5) This utility model is of great help to the production and process improvement of protection equipment manufacturers, and to improve the safety and reliability of the equipment;

[0036] 6) The device provided by this utility model can improve the operation and maintenance level. It can perform AI big data analysis based on leakage current to find potential risk points, eliminate defects in a timely manner, and improve the overall safety level of the power system.

[0037] 7) This utility model has low modification costs and huge direct and potential benefits;

[0038] 8) This utility model has a simple principle, high testing accuracy, and the control threshold is adjustable online;

[0039] 9) Avoid modifying the DC power supply system. It can be used directly with 110V operating power supplies from different manufacturers, with strong compatibility.

[0040] 10) Different alarm and protection thresholds can be set for different loads, enabling refined management.

[0041] This invention improves the operational safety of the power industry, enhances the level of operation and maintenance, optimizes operation and maintenance capabilities, eliminates defects and faults without them, and has huge potential benefits. Attached Figure Description

[0042] Figure 1 is a schematic diagram of the existing leakage current sensor detection device. In the figure, 1 - leakage current sensor detection device;

[0043] Figure 2 is a circuit block diagram of an existing leakage current sensor detection device;

[0044] Figure 3 is a circuit diagram of the 110V DC branch load leakage protection device disclosed in this utility model.

[0045] Figure 4 is a schematic diagram of the application principle of the 110V DC branch load leakage protection device disclosed in this utility model, wherein 1-leakage current sensor detection device, 2-110V DC branch load leakage protection device. Detailed Implementation

[0046] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0047] As shown in Figure 3, the 110V DC branch load leakage protection device disclosed in this utility model includes contactor K1, shunt R1, shunt R2, control module, fuse FU1, and fuse FU2.

[0048] Contactor K1 is the core control element. Contactor K1's #4 and #2 contacts are connected to the positive and negative terminals of the load, respectively. Simultaneously, contactor K1's #3 contact is connected in series with shunt R1 and then to the positive input terminal of the branch interface. Contactor K1's #1 contact is connected in series with shunt R2 and then to the negative input terminal of the branch interface, thus forming the main circuit path. A 24V power supply is input to control the engagement and disengagement of contactor K1's coil K1-1, achieving on / off control of the load's power supply. In this embodiment, contactor K1 is rated for 15A MAX, capable of carrying a maximum current of 15A, ensuring the load can be properly connected to or disconnected from the power supply.

[0049] Shunt R1 and shunt R2 are both rated at 15A 75mV and are used to convert current signals into voltage signals.

[0050] Shunt R1 is connected to one branch of the main circuit, and its output terminal I1 is connected to the A+ and A- ports of the control module (model TPU201) to collect the positive circuit current data of the current branch.

[0051] Shunt R2 is connected to another branch of the main circuit, and its output terminal I2 is connected to the B+ port and B- port of the control module to collect the negative circuit current data of the current branch.

[0052] By monitoring the voltage drop of shunts R1 and R2, the control module can obtain the current information of the two branches in real time, providing a data basis for subsequent analysis (such as leakage current detection by comparing the current difference between the two branches).

[0053] The control module is model TPU201, and the specific wiring method is as follows:

[0054] Power input: The 1+ port and 2- port of the control module are connected in series with fuse FU1 and fuse FU2 respectively, and then connected to a DC110V power supply to provide energy for the operation of the module.

[0055] Signal processing: Receive the current signals from shunt R1 and shunt R2 (as mentioned above, not repeated here), analyze and process them to determine if there are any abnormalities in the circuit (such as excessive leakage current, overload, etc.).

[0056] Communication function: The RS485+ port (pin 5) and RS485- port (pin 6) of the control module are connected to an external RS485 communication bus to upload monitoring data or abnormal status to other devices (such as the monitoring backend) to realize remote monitoring and management;

[0057] Control output: The NC (normally closed) port, NO (normally open) port, and C (common terminal) port of the relay inside the control module can output control signals according to the internal logic. For example, when excessive leakage current or overload is detected, the relay inside the control module will activate and trigger the alarm device through the corresponding port output.

[0058] Fuse FU1 and fuse FU2 are connected in series in the power input path of the control module (as mentioned above, and will not be repeated here) to provide overcurrent protection. When a short circuit or overcurrent fault occurs in the power line of the control module, fuses FU1 and FU2 will quickly blow, cutting off the power supply path, preventing the fault from spreading, and protecting the control module and surrounding circuit components from damage.

[0059] Referring to Figure 4, the 110V DC branch load leakage protection device provided by this utility model controls the load switching through contactor K1, and uses shunts R1 and R2 to monitor the branch current in real time. After processing and analysis by the control module, it achieves the following functions:

[0060] 1) Monitor circuit current in real time to determine if there are any abnormalities such as leakage current or overload.

[0061] When the leakage current is less than 10mA, the load device operates normally;

[0062] When the leakage current is greater than 10mA but less than 20mA, the power supply unit will issue a leakage alarm signal, but it can maintain the load operation. The maintenance personnel can arrange on-site maintenance work according to the priority of the task.

[0063] When the leakage current exceeds 30mA and the leakage duration exceeds 10 seconds, the load must be disconnected to protect other devices from further damage and prevent the fault from escalating. Maintenance personnel must immediately go to the site for repairs.

[0064] 2) If an anomaly is detected, the control module outputs a control signal through the corresponding port (such as triggering an alarm or controlling contactor K1 to cut off the load power supply), and simultaneously uploads fault information through RS485 communication.

[0065] 3) Fuse FU1 and fuse FU2 provide overcurrent protection for the control module, ensuring the reliability and safety of system operation.

Claims

1. A 110V DC branch load leakage protection device, characterized in that, The system includes a contactor connected in series between the DC power output terminal of the 110V DC operating power supply and the power supply terminal of the DC load. When the contacts in the contactor are closed, the 110V DC operating power supply supplies power to the DC load. When the contacts in the contactor are open, the power supply from the 110V DC operating power supply to the DC load is cut off. A shunt 1 and a shunt 2 are connected in series between the positive terminal of the DC power output terminal of the 110V DC operating power supply and the contactor, and between the negative terminal of the DC power output terminal of the 110V DC operating power supply and the contactor, respectively. The two ends of the shunt 1 are connected to the current detection input port 1 of the control module, and the two ends of the shunt 2 are connected to the current detection input port 2 of the control module. The power supply terminal of the control module is connected to the DC power output terminal of the 110V DC operating power supply, and the control voltage output terminal of the control module is connected to the two ends of the coil inside the contactor.

2. The 110V DC branch load leakage protection device as described in claim 1, characterized in that, A fuse is connected in series between the power supply terminal of the control module and the DC power output terminal of the 110V DC operating power supply.

3. The 110V DC branch load leakage protection device as described in claim 1, characterized in that, The contactor is rated for 15A MAX.

4. The 110V DC branch load leakage protection device as described in claim 1, characterized in that, Both the first and second shunts are rated at 15A 75mV.

5. A 110V DC branch load leakage protection device as described in claim 1, characterized in that, The control module is connected to external devices via an RS485 communication bus.

6. A 110V DC branch load leakage protection device as described in claim 1, characterized in that, The control signal output port of the control module is connected to an external alarm device.

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