Control and protection device for on-off test of mine low-voltage switchgear

Abstract

The application provides a control and protection device for on-off test of a mine low-voltage switch device, which communicates with HMI, controls the action of a high-voltage side switch, a protection switch, an accompanying test switch and a test switch, realizes test timing of connection, disconnection, on-off, withstand and the like, accurately controls the consistency of energizing time through actual test current and timing backup time, realizes protection of test switch contact melting, long duration of arc and test switch disconnection failure through monitoring test current and test switch inter-electrode voltage and combining test timing, realizes state closed loop and abnormal protection through the auxiliary contact of a winding switching switch, a high-low voltage switch, an accompanying test switch and a test switch, automatically sets the high-voltage side and the low-voltage side protection through bus communication according to the voltage grade and the expected test current of the test switch, and controls synchronous recording of the data acquisition and recording equipment through bus communication.

Description

Technical Field

[0001] This invention relates to the field of control and protection technology for on / off testing of low-voltage switchgear used in mines, specifically, to a control and protection device for on / off testing of low-voltage switchgear used in mines. Background Technology

[0002] Mining low-voltage switchgear requires performance tests such as connection, disconnection, and on / off switching during type testing. During the test, depending on the specific test item, corresponding connection (c), disconnection (o), on / off switching (co), and interval (t) actions must be performed. This is generally achieved by a controller using time-series control. However, the different action times of different test specimens can lead to deviations in the actual energizing time, affecting the consistency of the test. Furthermore, simple time-series control cannot promptly detect abnormalities such as contact welding or excessively long arcing time during the test. Additionally, insufficient breaking capacity of the test specimen can cause arc short circuits, potentially leading to cascading trips (test transformers typically change the test voltage by switching the series and parallel connections of multiple secondary windings; if the protection switch is not reset in time, selective protection failure can easily occur). Summary of the Invention

[0003] To address the shortcomings of existing technologies, the purpose of this invention is to provide a control and protection device for conducting on / off tests on low-voltage switchgear used in mining.

[0004] The control and protection device for testing the on / off state of low-voltage switchgear in mining provided by the present invention includes an intelligent control protector assembly, a hollow coil current measurement unit, a Hall sensor voltage measurement unit, an operation unit, a display and setting HMI unit, and an auxiliary contact feedback unit. The intelligent control protector assembly is connected to the hollow coil current measurement unit, the Hall sensor voltage measurement unit, the operation unit, the display setting HMI unit, and the auxiliary contact feedback unit, respectively. The hollow coil current measurement unit is used to collect the test current signal and output it to the intelligent control protector assembly; The Hall sensor voltage measurement unit is used to collect the inter-electrode voltage signal of the sample and output it to the intelligent control protector assembly; The auxiliary contact feedback unit is used to connect to the auxiliary contacts of the switching switch, high and low voltage switch, test switch and sample switch, and input the status signal to the intelligent control protector component; The operation unit is used to receive external manual operation commands and transmit them to the intelligent control protector component; The display setting HMI unit is used for parameter setting and status display, and interacts with the intelligent control protector component; The intelligent control protector component controls the data acquisition and recording equipment to record waveforms synchronously via bus communication, and controls the operation of the high-voltage side switch, protection switch, test switch and test sample switch.

[0005] Preferably, the intelligent control protector assembly includes a microcontroller unit (MCU), a 6-channel analog differential front-end, a 32-channel 24V isolated DI input circuit, an 8-channel isolated relay output circuit, an Ethernet RJ45 communication interface circuit, a multi-channel isolated DC power supply, and a multi-port Ethernet switch. The 6-channel analog differential front-end is connected to the differential ADC pin of the MCU and is used to receive the differential signals output by the hollow coil current measurement unit and the Hall sensor voltage measurement unit. One end of the 32-channel 24V isolated DI input circuit is connected to external switch auxiliary contacts and operation buttons, and the other end is connected to the general-purpose input / output pin GPIO of the MCU. It is used to transmit external input signals to the MCU after passing through current-limiting resistors, TVS protection, debouncing, optocoupler isolation, pull-up buffer, and bus shaping. One end of the 8-channel isolation relay output circuit is connected to the GPIO of the MCU, and the other end is connected to an external load. It is used to activate the relay coil output contacts according to the control signal of the MCU through a current-limiting resistor, optocoupler isolation, MOSFET drive, and relay coil output contact. The Ethernet RJ45 communication interface circuit is based on the MCU's built-in gigabit media access controller MAC and is equipped with an industrial-grade physical layer transceiver chip. It supports 10 / 100 / 1000M adaptive and interconnects with the switch protector, HMI and data acquisition recorder through the multi-port Ethernet switch. The input side of the multi-channel isolated DC power supply is connected to an external power supply. Through the internal multi-channel independently isolated DC / DC conversion module, it outputs multiple sets of electrically isolated DC voltages, which are respectively supplied to the MCU, the 6-channel analog differential front end, the 32-channel 24V isolated DI input circuit, the 8-channel isolated relay output circuit, and the Ethernet RJ45 communication interface circuit.

[0006] Preferably, the hollow coil current measuring unit adopts a rigid hard epoxy ring skeleton, with the center loop wound evenly, copper foil shielding, and shielded dual-core differential BNC output; The Hall sensor voltage measurement unit has a range of 1500V / 10V, an operating voltage of ±15V, and an insulation withstand voltage of 4200V. The sampling frequency of the intelligent control protector component is 20KHz.

[0007] Preferably, the intelligent control protector assembly monitors the secondary winding switching switch of the test transformer and checks whether it is consistent with the selected voltage level; otherwise, it alarms for abnormality. The intelligent control protector component monitors the action feedback of the high and low voltage switches, the test switch, and the test sample switch, and alarms for abnormalities. The intelligent control protector assembly resets the high-voltage side protector and the low-voltage side protector via bus communication based on the test voltage and expected test current selected in the display setting HMI unit.

[0008] Preferably, the specific parameters for resetting are: When the expected test current is ≤ 2 times the rated current of the test transformer, the instantaneous tripping time on the low-voltage side is 9 times the rated current Ied on the low-voltage side, with a short delay of 1.2 × 4 × Ied and a delay of 0.3s, and a long delay of 1.1 Ied and a delay of 16s; the instantaneous tripping time on the high-voltage side is 1.3 × 7 × the rated current Ieh on the high-voltage side, with a short delay of 1.2 × 4 × Ieh and a delay of 0.2s, and a long delay of 1.05 × expected test current × Ud / Uh and a delay of 9s; where Ud is the rated voltage on the low-voltage side and Uh is the rated voltage on the high-voltage side. When the expected test current is greater than twice the rated current of the test transformer, the instantaneous tripping time on the low-voltage side is 10 times the rated current Ied on the low-voltage side, the short delay is 2.5 times the expected test current with a delay of 0.2s, and the long delay is 1.1 times the expected test current with a delay of 10s; the instantaneous tripping time on the high-voltage side is 9.5 times the rated current Ieh on the high-voltage side, the short delay is 2 times the expected test current × Ud / Uh with a delay of 0.1s, and the long delay is 1.1 times the expected test current with a delay of 5s.

[0009] Preferably, the intelligent control protector component executes the test action sequence. In the project where the test sample performs the current connection, after the test voltage is turned on by the test switch, if the 10ms average absolute value of any two of the test currents of phase A, phase B, and phase C is detected to be greater than 50A, or the 10ms average absolute value of any one of the inter-electrode voltages of phases AB, BC, and CA is detected to be less than 10V, then it is determined that the inter-electrode voltage is missing, the test disconnection is performed, and the test step sequence is terminated.

[0010] Preferably, the intelligent control protector component samples the test current in real time. When any current exceeds 50A, the actual power-on time is started. After the set power-on time is reached, the next timing action is executed. If the backup time of the timing segment has expired, the next timing action will be executed. The backup time is equal to the set power-on time plus the maximum engagement time and the asynchronous time.

[0011] Preferably, in the timing sequence after the test sample performs the disconnection, if two phase currents exceed the set expected multiple within half a cycle, the intelligent control protector component directly performs the protection switch disconnection. The protection switch disconnection prioritizes the high-voltage side protection switch, and the low-voltage side protection switch performs backup disconnection 10ms later. If the current and inter-electrode voltage coexist for a longer period than expected, a test disconnection will be performed. Each phase current corresponds to its respective inter-electrode voltage. The average absolute value of the current in 5ms is greater than 50A and the inter-electrode voltage is greater than 10V. If the inter-electrode recovery voltage of a certain phase of the test sample fails to appear within the time limit, a test disconnection will be performed.

[0012] Preferably, the expected multiple is 2.5 times the expected test current; the half cycle is 10ms; and the synchronization of the three-phase current detection is synchronously latched by the three-channel A / D hardware of the MCU.

[0013] Preferably, one time before the test switch closes, the intelligent control protector component communicates with the data logger via the Modbus TCP bus, sends the test number, test type and test count, and starts recording waveforms; one time after the test switch disconnects, it issues a stop recording waveform command. When communication fails, the intelligent control protector component will alarm, and the operator will participate in setting the protector and disabling the alarm. The auxiliary contact feedback unit is connected to one set of normally open and one set of normally closed auxiliary contacts. The diagnostic logic and control output are used for feedback, and the abnormal status is handled with priority. Specifically, if the test switch is abnormal, the accompanying test switch is disconnected first and the test is terminated, and then the test switch operation is performed. If the winding switching switch is abnormal, the high voltage switch is tripped.

[0014] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention provides a control and protection device for testing the on / off state of a mining low-voltage switchgear with real-time monitoring of test current and inter-electrode voltage of test sample, receiving feedback on the status of main circuit equipment, and having a communication bus. This device is easy to achieve precise timing control and reliable fault and abnormal protection functions. (2) This invention provides a control and protection device for testing the on / off state of low-voltage switchgear in mines. By sampling the test current and the inter-electrode voltage of the test sample in real time, it achieves precise and consistent control of the energizing time, and provides immediate protection against faults such as contact welding, excessive arcing time, and arc short circuit. It adopts bus communication, which can automatically perform protection resetting and maintain the selectivity of protection. It monitors multi-winding switching switches to effectively avoid voltage switching errors. Attached Figure Description

[0015] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the main circuit of a control and protection device for on / off testing of low-voltage switchgear in mining, as described in this invention. Figure 2 This is a circuit diagram of the control and protection device described in this invention; Reference numerals: Ut1, Ut2, Ut3: Voltage sensors for control and protection; It1, It2, It3: Current sensors for control and protection; Ur1, Ur2, Ur3, Ur4, Ur5, Ur6: Voltage sensors for waveform recording; I1, I2, I3: Current sensors for waveform recording; F: Fuse; RL: Resistor for limiting fault current; Q1: High-voltage protection switch; T: Test transformer; K: Multi-winding switching switch for the secondary side of the test transformer; Q2: Low-voltage protection switch; KM: Test-support switch; D: Electrical appliance under test (including metal mesh or casing); Z: Load circuit; N: Human-made neutral point; T: Grounding point; B: Test transformer; L1, L2, L3: High-voltage input lines for test power supply. Detailed Implementation

[0016] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0017] Example Please refer to Figure 1 and Figure 2 This invention provides a control and protection device for testing the continuity of low-voltage electrical appliances used in mines, including a hollow coil current measurement unit, a Hall sensor voltage measurement unit, an intelligent control and protection device assembly, an operation unit, a display and setting HMI unit, and an auxiliary contact feedback unit.

[0018] The intelligent control protector assembly includes a microcontroller unit (MCU), a 6-channel analog differential front end, a 32-channel 24V isolated DI input circuit, an 8-channel isolated relay output circuit, an Ethernet RJ45 communication interface circuit, a multi-channel isolated DC power supply, and a multi-port Ethernet switch, which executes test timing actions and related protections.

[0019] The high-performance MCU adopts a dual-core RISC-V architecture, features FPU and DSP hardware units, has three independent 12-bit ADCs, supports differential input and hardware triggering, and comes with dual gigabit media access controllers (MACs).

[0020] The 6-channel analog differential front end consists of: sensor differential signal input → TVS surge protection → controllable voltage divider → controllable gain → aliasing filter → voltage follower → MCU differential ADC pins, used to acquire It1, Ut1 (AD1), It2, Ut2 (AD2), It3, Ut3 (AD3).

[0021] The 32-channel 24V optocoupler isolated DI input circuit consists of: 24V input (via external contact) → current limiting resistor → TVS protection → debouncing → optocoupler isolation → pull-up buffer → bus shaping → MCU GPIO, used to connect to switch auxiliary contacts, operation buttons and other inputs.

[0022] The 8-channel isolation relay output circuit consists of: MCU GPIO output → current-limiting resistor → optocoupler isolation → MOSFET driver → relay coil, relay contacts connected to external load, controlling protection, test and sample switching actions, outputting status and alarm signals, etc.

[0023] The Ethernet RJ45 interface is based on the MCU's built-in Gigabit Media Access Controller (MAC) and is paired with an industrial-grade physical layer transceiver chip to realize an external standard RJ45 integrated transformer interface. It supports 10 / 100 / 1000M auto-sensing and can be interconnected with switch protectors, HMIs, and data acquisition recorders via a multi-port Ethernet switch for bus communication.

[0024] The input side of the multi-channel isolated DC power supply is connected to an external power supply (such as AC 220V or DC 24V). Through internal multi-channel independently isolated DC / DC (direct current to direct current) converter modules, it outputs multiple electrically isolated DC voltages (e.g., +5V, ±15V, +24V, etc.), which respectively supply the MCU digital core circuit, 6-channel analog differential front-end, 32-channel DI input circuit, 8-channel relay output drive circuit, and Ethernet communication interface circuit. Its function is to: effectively block ground loop interference and high-voltage crosstalk through electrical isolation between the output channels, improving the accuracy and stability of analog signal sampling; and simultaneously isolate the DI and DO loops from the MCU system side, protecting the controller from external high-voltage shocks and enhancing the device's anti-interference capability and operational reliability in strong electromagnetic environments.

[0025] The air-core coil current measurement unit is directly used for wide-range test current detection, while the Hall sensor voltage measurement unit is used for measuring the inter-electrode voltage of the test sample. The air-core coil uses a rigid epoxy toroidal frame with uniformly wound center loop, copper foil shielding, shielded dual-core differential BNC output, mutual inductance of 200nH, linearity of 0.1%, and insulation withstand voltage of 4200V. The Hall sensor has a range of 1500V / 10V, linearity of 0.1%, operating voltage ±15V, and insulation withstand voltage of 4200V. The sampling frequency is 20kHz. The auxiliary contact feedback unit connects to the auxiliary contacts of the winding switching switch, high / low voltage switch, test mate switch, and test sample switch for status feedback monitoring; the display and setting HMI unit is used for parameter setting and status display; and the operation unit is used for manual operation and emergency stop.

[0026] The control and protection device achieves the following: monitoring the secondary winding switching switch of the test transformer and checking whether it is consistent with the selected voltage level; otherwise, an alarm is triggered indicating an abnormality or voltage level mismatch. It also monitors the action feedback of the high and low voltage switches, the test switch, and the test object switch, and triggers an alarm if abnormality occurs. Based on the test voltage and expected test current selected in the HMI, it automatically resets the high and low voltage side protectors via bus communication. It can perform pre-test action sequence verification without load (high voltage switch not closed). During test action execution, it samples the test current and the inter-electrode voltage of the test object in real time.

[0027] In tests where the test sample performs current connection (C or CO performance), if there is a voltage gap between the electrodes after the test sample is connected to the test voltage, the contact welding protection will activate, and the test sample will disconnect. The specific criteria for a voltage gap are: after the test sample switch KM connects to the test voltage, if any two of the three-phase currents It1, It2, and It3 (10ms average absolute value) are detected as >50A (actual test currents are generally above 500A); or, if any one of the three-phase voltages Ut1, Ut2, and Ut3 (10ms average absolute value) is detected as <10V, then a voltage gap is determined, indicating welding at the test sample switch contacts, and the KM disconnection and test termination sequence will be executed. Both the operating current and operating voltage values ​​are settable to avoid interference signals; the delay time setting helps prevent erroneous operation.

[0028] After the current is applied, if the actual energizing time reaches the set value or the timing backup time has expired (the backup time takes into account the pull-in action time based on the energizing time set value), the current is interrupted, or the test interruption (C performance) or the test sample interruption (O or CO performance) is performed, so that the test energizing time achieves good consistency. Real-time sampling of the test current combined with the timing backup time is used for precise control of the consistency of the energizing time: Since the actual equipment has a certain action time, the backup time in the timing = set energizing time + maximum pull-in time and asynchronous time (actually set at 50~100ms); in terms of control, if the current in any phase is >50A, the controller starts the actual energizing time timing. When the timing reaches the set energizing duration, the next timing action is executed; if the duration of this timing segment (i.e., the backup time) has expired, the next timing action is executed, even if the actual energizing time has not reached the set value.

[0029] In the timing sequence after the test sample performs the disconnection: ① If two phase currents exceed the set expected multiple within half a cycle, the protection switch disconnection is performed directly. Specifically, the action value is 2.5 times the expected test current; half a cycle (10ms) takes into account the time difference of approximately 6.67ms between the two phase AC currents, ensuring that no two phase abnormal values ​​are missed within 10ms; the synchronization of the three-phase current detection is synchronously latched by the MCU's three-channel A / D hardware; the protection switch disconnection prioritizes the Q1 high-voltage protection switch, and the Q2 low-voltage protection switch performs backup disconnection 10ms later; the test transformer is only used for testing, and the high-voltage side current is small. ② If the current and inter-electrode voltage exist simultaneously for a longer period than expected, the protection will operate if the arcing time is too long, and the test disconnection will be performed. Specifically, each phase current corresponds to its respective inter-electrode voltage, with an average absolute value over 5ms: current > 50A, inter-electrode voltage > 10V (50A and 10V can be set according to the actual interference conditions on site); the arcing time begins when the test contact starts to break and the inter-electrode voltage begins to appear, and ends when the corresponding current disappears; the standard generally allows a maximum arcing time of 0.1S. ③ If the inter-electrode recovery voltage of a certain phase of the test object does not appear within the time limit, the contact welding protection will activate, and a test break will be performed.

[0030] Simultaneously, before the power-on sequence, a start recording command is sent to the data acquisition and recording device via bus communication; after the test disconnection sequence, a stop recording command is sent. Specifically, one sequence before the test switch closes, the control protector communicates with the data logger via the Modbus TCP bus, sending the test number, test type, and test count to start recording; one sequence after the test switch disconnects, a stop recording command is issued. The data logger records the signals acquired by voltage sensors Ur1, Ur2, Ur3, Ur4, Ur5, and Ur6, and current sensors I1, I2, and I3, for waveform data analysis and report generation.

[0031] The control and protection device is equipped with an air-core coil for direct high-current, wide-range sampling and a Hall sensor for voltage sampling. By monitoring the test current and the inter-electrode voltage of the test specimen, and in conjunction with the test sequence, it provides protection against contact welding, excessively long arcing time, and test specimen disconnection failure. Based on the test specimen voltage level and expected test current, the high-voltage and low-voltage side protections are automatically set via bus communication: high-voltage side transformer comprehensive protection (three-stage + zero-sequence + non-electrical quantity), and low-voltage side line comprehensive protection (three-stage). The specific parameters (three segments) for setting are as follows: ① When the expected test current is ≤ 2 times the rated current of the test transformer, the instantaneous trip on the low-voltage side is 9 times the rated current of the low-voltage side Ied, the short delay is 0.3s (1.2×4×Ied), and the long delay is 16s (1.1Ied); the instantaneous trip on the high-voltage side is 1.3×7× the rated current of the high-voltage side Ieh, the short delay is 0.2s (1.2×4×Ieh), and the long delay is 9s (1.05×expected test current×Ud / Uh). ② When the expected test current is greater than twice the rated current of the test transformer, the instantaneous tripping time on the low-voltage side is 10 times the rated current Ied on the low-voltage side, with a short delay of 0.2s (2.5 × expected test current) and a long delay of 10s (1.1 times the expected test current); the instantaneous tripping time on the high-voltage side is 9.5 × the rated current Ieh on the high-voltage side, with a short delay of 0.1s (2 × expected test current × Ud / Uh) and a long delay of 5s (1.1 times the expected test current). For ease of standardization, Modbus TCP is used for all communication protocols; the controller alarms in case of communication failure, and operators can manually set the protector and disable the alarm.

[0032] By connecting auxiliary contacts of the winding switching switch, high and low voltage switches, test equipment, and test sample switch, a closed-loop status protection system is achieved. One set of normally open and one set of normally closed auxiliary contacts are used. The diagnostic logic and control output are fed back, and abnormal status is handled with priority for disconnection. Specifically, if the test sample switch is abnormal, the test equipment switch is disconnected first, ending the test, and then the test sample switch is operated. If the winding switching switch is abnormal, the high voltage switch is tripped.

[0033] Two sets have already been produced and sold. The parameters of the mining low-voltage electrical continuity test bench are as follows: test voltage of 8 voltage levels including 220, 380, 660, and 1140V; maximum test current of 25KA; test items include rated and short-circuit connection, disconnection, continuity, electrical life, mechanical life, short-time withstand current, and coordination with short-circuit protection devices (SCPD), etc.

[0034] Those skilled in the art will understand that, in addition to implementing the system, apparatus, and their modules provided by this invention in purely computer-readable program code, the same program can be implemented in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system, apparatus, and their modules provided by this invention can be considered a hardware component, and the modules included therein for implementing various programs can also be considered structures within the hardware component; alternatively, modules for implementing various functions can be considered both software programs implementing the method and structures within the hardware component.

[0035] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A control and protection device for conducting on / off tests of low-voltage switchgear used in mining, characterized in that, It includes an intelligent control protector assembly, an air-core coil current measurement unit, a Hall sensor voltage measurement unit, an operation unit, a display and setting HMI unit, and an auxiliary contact feedback unit; The intelligent control protector assembly is connected to the hollow coil current measurement unit, the Hall sensor voltage measurement unit, the operation unit, the display setting HMI unit, and the auxiliary contact feedback unit, respectively. The hollow coil current measurement unit is used to collect the test current signal and output it to the intelligent control protector assembly; The Hall sensor voltage measurement unit is used to collect the inter-electrode voltage signal of the sample and output it to the intelligent control protector assembly; The auxiliary contact feedback unit is used to connect to the auxiliary contacts of the switching switch, high and low voltage switch, test switch and sample switch, and input the status signal to the intelligent control protector component; The operation unit is used to receive external manual operation commands and transmit them to the intelligent control protector component; The display setting HMI unit is used for parameter setting and status display, and interacts with the intelligent control protector component; The intelligent control protector component controls the data acquisition and recording equipment to record waveforms synchronously via bus communication, and controls the operation of the high-voltage side switch, protection switch, test switch and test sample switch.

2. The control and protection device for on / off testing of low-voltage switchgear in mines according to claim 1, characterized in that, The intelligent control protector assembly includes a microcontroller unit (MCU), a 6-channel analog differential front end, a 32-channel 24V isolated DI input circuit, an 8-channel isolated relay output circuit, an Ethernet RJ45 communication interface circuit, a multi-channel isolated DC power supply, and a multi-port Ethernet switch. The 6-channel analog differential front-end is connected to the differential ADC pin of the MCU and is used to receive the differential signals output by the hollow coil current measurement unit and the Hall sensor voltage measurement unit. One end of the 32-channel 24V isolated DI input circuit is connected to external switch auxiliary contacts and operation buttons, and the other end is connected to the general-purpose input / output pin GPIO of the MCU. It is used to transmit external input signals to the MCU after passing through current-limiting resistors, TVS protection, debouncing, optocoupler isolation, pull-up buffer, and bus shaping. One end of the 8-channel isolation relay output circuit is connected to the GPIO of the MCU, and the other end is connected to an external load. It is used to activate the relay coil output contacts according to the control signal of the MCU through a current-limiting resistor, optocoupler isolation, MOSFET drive, and relay coil output contact. The Ethernet RJ45 communication interface circuit is based on the MCU's built-in gigabit media access controller MAC and is equipped with an industrial-grade physical layer transceiver chip. It supports 10 / 100 / 1000M adaptive and interconnects with the switch protector, HMI and data acquisition recorder through the multi-port Ethernet switch. The input side of the multi-channel isolated DC power supply is connected to an external power supply. Through the internal multi-channel independently isolated DC / DC conversion module, it outputs multiple sets of electrically isolated DC voltages, which are respectively supplied to the MCU, the 6-channel analog differential front end, the 32-channel 24V isolated DI input circuit, the 8-channel isolated relay output circuit, and the Ethernet RJ45 communication interface circuit.

3. The control and protection device for on / off testing of low-voltage switchgear in mines according to claim 1, characterized in that, The hollow coil current measurement unit adopts a rigid epoxy ring skeleton, with the center loop wound evenly, copper foil shielding, and shielded dual-core differential BNC output; The Hall sensor voltage measurement unit has a range of 1500V / 10V, an operating voltage of ±15V, and an insulation withstand voltage of 4200V. The sampling frequency of the intelligent control protector component is 20KHz.

4. The control and protection device for on / off testing of low-voltage switchgear in mines according to claim 1, characterized in that, The intelligent control protector component monitors the secondary multi-winding switching switch of the test transformer and checks whether it is consistent with the selected voltage level; otherwise, it will alarm an abnormality. The intelligent control protector component monitors the action feedback of the high and low voltage switches, the test switch, and the test sample switch, and alarms for abnormalities. The intelligent control protector assembly resets the high-voltage side protector and the low-voltage side protector via bus communication based on the test voltage and expected test current selected in the display setting HMI unit.

5. The control and protection device for on / off testing of low-voltage switchgear in mines according to claim 4, characterized in that, The specific parameters for resetting are: When the expected test current is ≤ 2 times the rated current of the test transformer, the instantaneous tripping time on the low-voltage side is 9 times the rated current Ied on the low-voltage side, with a short delay of 1.2 × 4 × Ied and a delay of 0.3s, and a long delay of 1.1 Ied and a delay of 16s; the instantaneous tripping time on the high-voltage side is 1.3 × 7 × the rated current Ieh on the high-voltage side, with a short delay of 1.2 × 4 × Ieh and a delay of 0.2s, and a long delay of 1.05 × expected test current × Ud / Uh and a delay of 9s; where Ud is the rated voltage on the low-voltage side and Uh is the rated voltage on the high-voltage side. When the expected test current is greater than twice the rated current of the test transformer, the instantaneous tripping time on the low-voltage side is 10 times the rated current Ied on the low-voltage side, the short delay is 2.5 times the expected test current with a delay of 0.2s, and the long delay is 1.1 times the expected test current with a delay of 10s; the instantaneous tripping time on the high-voltage side is 9.5 times the rated current Ieh on the high-voltage side, the short delay is 2 times the expected test current × Ud / Uh with a delay of 0.1s, and the long delay is 1.1 times the expected test current with a delay of 5s.

6. The control and protection device for on / off testing of low-voltage switchgear in mines according to claim 1, characterized in that, The intelligent control protector component executes the test action sequence. In the project where the test sample performs the current connection, after the test voltage is turned on by the test switch, if the 10ms average absolute value of any two of the test currents of phase A, phase B, and phase C is greater than 50A, or the 10ms average absolute value of any one of the inter-electrode voltages of phases AB, BC, and CA is less than 10V, then it is determined that the inter-electrode voltage is missing, the test disconnection is performed, and the test sequence action is terminated.

7. The control and protection device for on / off testing of low-voltage switchgear in mines according to claim 1, characterized in that, The intelligent control protector component samples the test current in real time. When any current exceeds 50A, the actual power-on time is started. After the set power-on time is reached, the next timing action is executed. If the backup time of the timing segment has expired, the next timing action will be executed. The backup time is equal to the set power-on time plus the maximum engagement time and the asynchronous time.

8. The control and protection device for on / off testing of low-voltage switchgear in mines according to claim 1, characterized in that, In the timing sequence after the test sample performs the disconnection, if the current of two phases exceeds the set expected multiple within half a cycle, the intelligent control protector component directly performs the protection switch disconnection. The protection switch disconnection prioritizes the high-voltage side protection switch, and the low-voltage side protection switch performs backup disconnection 10ms later. If the current and inter-electrode voltage coexist for a longer period than expected, a test disconnection will be performed. Each phase current corresponds to its respective inter-electrode voltage. The average absolute value of the current in 5ms is greater than 50A and the inter-electrode voltage is greater than 10V. If the inter-electrode recovery voltage of a certain phase of the test sample fails to appear within the time limit, a test disconnection will be performed.

9. The control and protection device for on / off testing of low-voltage switchgear in mines according to claim 8, characterized in that, The expected multiple is 2.5 times the expected test current; the half cycle is 10ms; the synchronization of the three-phase current detection is synchronously latched by the three-channel A / D hardware of the MCU.

10. The control and protection device for on / off testing of low-voltage switchgear in mines according to claim 1, characterized in that, One time before the test switch closes, the intelligent control protector component communicates with the data logger via the Modbus TCP bus, sends the test number, test type and test count, and starts recording waveforms; one time after the test switch disconnects, it issues a stop recording waveform command. When communication fails, the intelligent control protector component will alarm, and the operator will participate in setting the protector and disabling the alarm. The auxiliary contact feedback unit is connected to one set of normally open and one set of normally closed auxiliary contacts. The diagnostic logic and control output are used for feedback, and the abnormal status is handled with priority. Specifically, if the test switch is abnormal, the accompanying test switch is disconnected first and the test is terminated, and then the test switch operation is performed. If the winding switching switch is abnormal, the high voltage switch is tripped.

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