Device and method for testing short-circuit time of mining lighting signal comprehensive protection device

Abstract

The invention relates to the technical field of mining equipment, in particular to a mining lighting signal comprehensive protection short-circuit time testing device and method. The mining lighting signal comprehensive protection short-circuit time testing device comprises a control cabinet, an impedance cabinet and a three-phase electric voltage regulator group, a PLC in the control cabinet controls the on-off combination of a plurality of alternating current contactors according to an operation instruction, and a head-end or tail-end interphase short-circuit fault loop is automatically constructed at the output end of the tested lighting signal comprehensive protection device; a plurality of groups of switchable non-inductive resistors and air core inductance networks are arranged in the impedance cabinet and are used for accurately simulating impedance characteristics of different cables; the method comprises the following steps: calibrating the no-load action time of a contactor, deducting the no-load action time from an on-load test result, acquiring a starting signal of a short-circuit contactor contact or a programmable logic controller and an opening control signal of a tested device by a high-precision timing instrument to accurately measure the millisecond time from fault application to protection action, and finally measuring the protection time of the device. And safe, automatic and accurate comprehensive performance testing is realized.

Description

Technical Field

[0001] This invention relates to the field of mining equipment technology, and in particular to a short-circuit time testing device and method for integrated protection of mining lighting signals. Background Technology

[0002] The explosion-proof integrated protection device for lighting and signaling in mines (hereinafter referred to as the lighting protection device) is a key piece of equipment for ensuring the safe and reliable operation of underground lighting and signaling systems in coal mines. The reliability of its short-circuit protection and leakage protection functions directly affects the safety of underground power supply and the safety of personnel and property. Therefore, the national industry standard MT / T 1123-2011 has made clear and strict provisions for its performance testing, especially the key protection characteristics such as the short-circuit trip time at the beginning and end of lighting and signaling lines and the 1kΩ leakage trip time. However, with the development of underground power supply systems in coal mines, the rated capacity of the lighting protection device has increased from the 2.5kVA / 4kVA specified in the standard to the current 20kVA. This increase in capacity directly leads to a sharp increase in short-circuit current, posing a serious challenge to the test methods and existing test equipment designed according to the original standard. Currently, when testing the lighting protection device with a maximum capacity of 20kVA according to the standard requirements, the following technical difficulties and safety hazards mainly exist: (1) Existing testing methods are mostly temporary setups or simple devices based on small capacity designs, which cannot safely and reliably simulate the high current conditions generated when a 20kVA lighting protection cable is short-circuited at the end of a cable of different lengths such as 400m, 600m, 1400m, and 1500m.

[0003] (2) Existing methods fail to fully consider the resistance and inductive reactance characteristics of actual cables when simulating line impedance. Especially under high current, the eddy current effect of the test line itself will seriously affect the waveform and amplitude of the short-circuit current, resulting in distortion of the fault signal injected into the device under test. At the same time, the traditional timing method introduces mechanical action delay, which cannot accurately capture the actual action time of the electronic protection circuit, resulting in large errors in the test results and making it impossible to make an accurate judgment on the product performance.

[0004] (3) When testing different cable specifications and different short circuit types, it is necessary to frequently change the wiring and simulate the impedance manually. The operation is complicated and inefficient, and it is difficult to ensure the consistency of the circuit connection for each test, which further introduces human error and operational risks. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a short-circuit time testing device for integrated protection of mine lighting signals in order to solve the problems of high testing risk, poor accuracy and low efficiency in the existing technology mentioned above.

[0006] The technical solution adopted by this invention to solve its technical problem is: a short-circuit time testing device for integrated protection of mine lighting signals, comprising: The control cabinet contains a programmable logic controller, a high-precision timer, an operation selection switch, and multiple three-phase or single-phase AC contactors for connecting or disconnecting test circuits. Impedance cabinet, which has multiple sets of switchable resistor and inductor networks inside, is used to simulate the impedance characteristics of mining cables with different cross-sectional areas and lengths. A three-phase electric voltage regulator is used to provide adjustable input power to the tested explosion-proof lighting signal integrated protection device for mines. The programmable logic controller controls the on / off combinations of multiple AC contactors according to the instructions of the operation selection switch, so as to automatically construct different types of short-circuit fault circuits at the output end of the integrated protection device for the lighting signal under test; the high-precision timer is electrically connected to the auxiliary contacts of the AC contactors and the protection output contacts of the integrated protection device for the lighting signal under test, and is used to accurately measure the time between the application of the short-circuit fault and the occurrence of the protection action.

[0007] This invention provides a device that allows hazardous short-circuit tests to be conducted within a controlled system, enhancing testing safety and avoiding risks of personal injury and equipment damage. Furthermore, the automatic control via a programmable logic controller and precise measurement via a timing device lay the foundation for all subsequent accurate testing functions.

[0008] Furthermore, the multiple sets of resistors and inductors in the impedance cabinet simulate at least three different impedance groups with different cable cross-sectional areas: Group I corresponds to 4mm² cables and includes four resistance values: 0.137Ω, 0.274Ω, 0.548Ω, and 1.096Ω. Group II corresponds to 6mm² cables and includes four resistance values: 0.216Ω, 0.432Ω, 0.864Ω, and 1.728Ω. Group III corresponds to 10mm² cables and includes four resistance values: 0.369Ω, 0.738Ω, 1.476Ω, and 2.952Ω. Furthermore, the inductance values ​​for each group range from 0.09Ω to 0.101Ω, in order to collectively simulate the resistance and inductive reactance of the cable.

[0009] By providing multiple sets of resistor and inductor networks based on different cross-sectional areas and lengths, the testing device can realistically reproduce the line conditions for various underground power supply distances ranging from 400m to 1500m.

[0010] Furthermore, multiple AC contactors, including K1, K2, K3, K4, K5, K6, K7, K8, K9, and K10, are controlled by a programmable logic controller through their on / off combinations. Normal operating circuit: Controls K1, K3, K5, K2, K4, and K6 to engage, ensuring the normal connection of the output terminal of the device under test; Short circuit between phases at the beginning: including short circuit at the beginning of phases AB, short circuit at the beginning of phases BC, and short circuit at the beginning of phases AC; Terminal phase-to-phase short circuit loop: By inserting the impedance of the impedance cabinet into the loop, including terminal short circuit of phases AB, phases BC, and phases AC.

[0011] By controlling this group of contactors with a programmable logic controller, the switching between normal operation and various start-end short-circuit and end-end short-circuit modes can be completed, improving testing efficiency and eliminating the risk of misoperation that may be caused by manual wiring.

[0012] Furthermore, the timing start / stop control method of the high-precision timer is as follows: For the initial short-circuit time test, the start signal of the timer is provided by the closing of the auxiliary normally open contact of the contactor that performs the short-circuit operation; For the end-short-circuit time test, the start signal of the timer is issued by the programmable logic controller after confirming that the end-short-circuit loop has been constructed; The stop signal of the high-precision timer is provided by the trip control signal output by the integrated protection device for the measured lighting signal when the protection is activated.

[0013] For a short circuit at the beginning, it uses the auxiliary contact of the short-circuit contactor itself as the timing start point, capturing the instant the fault is applied; for a short circuit at the end, the programmable logic controller issues the command after confirming that the impedance has been connected and the circuit has been constructed, with the starting point also being precise. The stop signal is taken from the tripping control signal, which is the action signal of the non-mechanical contactor, so there is no mechanical delay.

[0014] Furthermore, the contactor used in the initial short-circuit test has contact materials and switching capacity that meet the instantaneous high current surge conditions when no simulated impedance is connected in series.

[0015] When the first end is short-circuited, since no analog impedance is connected in series, the short-circuit current reaches its maximum value, which has a huge impact on the material and switching capacity of the contactor contacts. The contactor used is limited to withstand multiple large current impacts without contact welding or damage, ensuring the safe and stable operation of the device itself.

[0016] Furthermore, the programmable logic controller is also connected to a display unit for real-time display of the current test type, contactor status, and action time value measured by a high-precision timer.

[0017] Through the display unit, operators can monitor the current test type, the on / off status of each contactor, and the final precise action time in real time.

[0018] Furthermore, the resistive elements in the impedance cabinet are formed by winding a resistance alloy strip onto a ceramic insulating frame, and the inductor elements adopt a hollow spiral tube structure.

[0019] The resistive element adopts a structure in which resistance alloy strip is wound on an insulating frame, and the inductor adopts a hollow spiral tube structure, which is a non-inductive resistor and a linear inductor. It can effectively suppress the eddy current effect mentioned in the background technology, ensure that the impedance value remains stable under high current, and will not generate additional losses and changes in inductive reactance due to eddy current, thereby ensuring the accuracy of the simulated impedance and the authenticity of the test current waveform.

[0020] A test method for the short-circuit time test device for integrated protection of mine lighting signals described in the above scheme is also provided, comprising the following steps: S1. Provide the rated voltage to the integrated protection device for the lighting signal under test through a three-phase electric voltage regulator; Without any load or analog impedance connected to the output of the integrated protection device for the lighting signal under test, the programmable logic controller controls all contactor combinations required in subsequent tests to perform a no-load switching operation; a high-precision timer records the time required from the issuance of the switching command to the confirmation of complete closure of all auxiliary contacts of the contactors, which is taken as the no-load operation time T_no-load and stored. S2. Select the short circuit type to be tested by operating the selection switch; S3. The programmable logic controller receives instructions and automatically controls the corresponding AC contactor combination to engage, constructing a short-circuit fault circuit of the selected type. S4. The high-precision timer automatically detects the completion of the loop construction and the occurrence of a fault, and starts timing. S5. When the protection function of the tested lighting signal integrated protection device is activated and the circuit breaker is tripped, the high-precision timer receives the tripping signal, stops timing, and records and saves the total action time of this test. From the total motion time Subtract no-load action time The calibrated protection action time is obtained. ; S6. The programmable logic controller resets all contactors, ending the test.

[0021] By performing a no-load switching operation without any load or impedance, the mechanical delay time from the PLC issuing the command to the complete closure of all relevant contactors was accurately measured. This time includes the total delay caused by a series of asynchronous mechanical actions such as contactor electromagnetic coil excitation, core movement, and contact closure. In subsequent real short-circuit tests, the total operating time was measured. Essentially, it is the superposition of the actual action time of the protection device and the inherent mechanical delay of the system, achieved through execution. The calculation fundamentally eliminates the millisecond-level errors introduced by the testing system itself.

[0022] Furthermore, in S3, when performing an end-short circuit test, the programmable logic controller automatically connects the impedance group in the impedance cabinet corresponding to the selected cable specification and length to the test circuit while controlling the contactor to engage.

[0023] During end-short circuit testing, the programmable logic controller synchronously controls the connection to the impedance group that corresponds exactly to the selected cable specifications and length, ensuring that each end-short circuit test can realistically simulate the line voltage drop and short-circuit current at a specific distance, making the test results highly representative of real-world downhole conditions.

[0024] The beneficial effects of this invention are: The device of this invention consists of a control cabinet, an impedance cabinet, and a voltage regulator, etc. It transforms the high-risk short circuit and leakage current testing from dangerous and non-standard manual operation to a process automatically executed by PLC in a closed cabinet. By automatically switching the contactor through program control to simulate the fault, the operator does not need to directly contact the high-voltage live circuit, completely eliminating the risk of electric arc burns and equipment explosion, and meeting the safety requirements for testing large-capacity integrated protection devices. The impedance cabinet of this invention, through multiple sets of switchable resistor and inductor networks, can accurately simulate the impedance characteristics of various cable cross-sections such as 4mm², 6mm², and 10mm² at different lengths such as 400m, 600m, 1400m, and 1500m. Combined with the flexible control of multiple contactors by PLC, it can automatically complete all phase-to-phase short circuit tests of AB, BC, and AC phases at the beginning and end of lighting and signal lines, as well as the 1kΩ leakage current action time test, realizing a comprehensive and effective test of the performance of the mine lighting protection device. This invention achieves fully automatic control of the testing process through PLC programming. Users only need to set the test items by selecting the switch, and the device can automatically complete the circuit construction, fault application, accurate time measurement and data recording and display, and finally automatically reset, reducing the time of a single test, reducing the technical dependence on the operator, and ensuring the consistency of test conditions. To address the massive instantaneous current surge caused by a short circuit at the first end, this invention selects a contactor with contact material and switching capacity that meet the requirements of high current surge conditions, ensuring the durability of the core actuator of the device. At the same time, a display unit is provided to display the test status, contactor operation, and precise operating time in real time, facilitating data recording and analysis. Using the trip control signal as the timing stop signal, instead of the auxiliary contacts of the mechanical contactor, effectively eliminates the mechanical action delay and directly captures the true response time of the electronic protection circuit, solving the problem of overestimation in traditional methods. The impedance cabinet uses non-inductive resistive elements and hollow spiral tube inductors to accurately simulate the impedance of downhole cables and eliminates the interference of eddy current effects on the test waveform and amplitude, providing the tested device with a true and accurate fault signal. This ensures that the test results can accurately reflect the product performance at the millisecond level, fully meeting the requirements of standards such as MT / T 1123-2011. Attached Figure Description

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0026] Figure 1 This is a schematic diagram of the connection structure of the testing device of the present invention.

[0027] Figure 2 This is a schematic diagram of the control panel layout in the testing device of the present invention.

[0028] Figure 3 This is a wiring diagram of the no-load time test in the test method of this invention.

[0029] Figure 4 This is a wiring diagram of the specific test method of the present invention. Detailed Implementation

[0030] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0031] Example 1 like Figure 1 and Figure 2 As shown, a short-circuit time testing device for integrated protection of mine lighting signals includes a control cabinet, an impedance cabinet, and a three-phase electric voltage regulator. The control cabinet is the core control unit, which houses a Siemens S7-200 series programmable logic controller (PLC), a high-precision timer with an accuracy of 0.1ms, and ten three-phase or single-phase AC contactors, labeled K1 to K10. Their main contacts are used to construct and switch the main test circuit. An operation selection switch integrated on the cabinet panel has multiple positions, including "Normal Power Supply Test," "AB Phase First End Test," "BC Phase First End Test," "AC Phase First End Test," "AB Phase End Test," "BC Phase End Test," "AC Phase End Test," and "Action Time Test." Preferably, an LCD touch screen can also be provided as a display unit, connected to the PLC via an RS485 communication interface.

[0032] The impedance cabinet is an independent unit containing multiple sets of high-power non-inductive resistors and hollow inductors. The resistors are constructed from nickel-chromium resistance alloy strips wound around a ceramic insulating frame. The inductors utilize a multi-tap hollow spiral tube structure, allowing adjustment of the inductance by changing the taps. All impedance elements are led out through high-capacity terminals and connected to corresponding terminals within the control cabinet via shielded cables. Three impedance values ​​are preset. Group I corresponds to 4mm² cable and includes four resistors: 0.137Ω, 0.274Ω, 0.548Ω, and 1.096Ω, with a matching inductor of approximately 0.09 to 0.101Ω.

[0033] Group II corresponds to 6mm² cables and includes four resistors: 0.216Ω, 0.432Ω, 0.864Ω, and 1.728Ω, with matching inductors of approximately 0.09 to 0.101Ω.

[0034] Group III corresponds to 10mm² cables and includes four resistor levels: 0.369Ω, 0.738Ω, 1.476Ω, and 2.952Ω, with matching inductors ranging from approximately 0.09 to 0.101Ω.

[0035] The input terminal of a three-phase electric voltage regulator with a capacity ≥35kVA is connected to a three-phase 380V mains power supply, and the output terminal is connected via a cable to the power input terminal of the explosion-proof lighting signal integrated protection device under test. The U, V, and W phases of the output terminal of the explosion-proof lighting signal integrated protection device under test are respectively connected to the test input terminal of the test device in this embodiment. Furthermore, the stop signal input terminal of the high-precision timer is connected via a wire to the normally open output contact of the internal protection relay of the explosion-proof lighting signal integrated protection device under test, or to the normally open contact of the intermediate relay driving the tripping, to obtain a precise electronic tripping command signal.

[0036] Traditional testing methods cannot quantitatively simulate the impedance of long-distance cables underground, leading to distortion of short-circuit current. This embodiment uses a non-inductive resistor and hollow inductor network in a resistor-capacitor series model in an impedance cabinet to realize the impedance characteristics of a real cable at power frequency. By switching different combinations of resistance and inductance, the amplitude and phase of short-circuit current at the ends of cables with different cross-sections and lengths can be accurately simulated, providing the device under test with fault signals that conform to its real working scenario.

[0037] Traditional methods measure the total time from the occurrence of a short circuit to the mechanical disconnection of the main contactor, which includes the processing time of the protection circuit and the mechanical action time of the contactor. This results in an inflated value and does not accurately reflect the performance of the protection chip. This embodiment defines the timing stop signal as a tripping control signal directly driven by the internal protection circuit of the device under test. This signal is issued immediately after the protection logic decision is completed, much earlier than the mechanical action of the main contactor. Therefore, the test time in this embodiment has no mechanical delay, thus achieving millisecond-level precise capture of the inherent operating time of the electronic protection circuit.

[0038] Example 2 A test method for a mine lighting signal integrated protection short-circuit time test device using Embodiment 1 includes the following steps: Step 1: Provide the rated voltage to the integrated lighting signal protection device under test using a three-phase electric voltage regulator; With no load or analog impedance connected to the output of the tested lighting signal integrated protection device, the programmable logic controller (PLC) controls all contactor combinations required for subsequent tests to perform a no-load switching operation. A high-precision timer records the time required from the issuance of the switching command to the confirmation of complete closure of all contactor auxiliary contacts as the no-load operating time. and store; Step 2: Select the short circuit type to be tested by operating the selector switch; Step 3: The programmable logic controller receives instructions and automatically controls the corresponding AC contactor combination to engage, constructing a short-circuit fault circuit of the selected type. Step 4: The high-precision timer automatically detects the completion of the loop construction and the occurrence of a fault, and starts timing; Step 5: When the protection function of the integrated protection device for the lighting signal under test activates and trips, the high-precision timer receives the trip signal, stops timing, and records and saves the total action time of this test. From the total motion time Subtract no-load action time The calibrated protection action time is obtained. ; Step 6: The programmable logic controller (PLC) resets all contactors, ending the test.

[0039] Because multiple contactors (K1 to K10) in the control circuit experience an inherent, asynchronous mechanical delay between the energization of their electromagnetic coils and the physical closure of their main contacts after receiving a PLC command, this delay will be mixed into the final measured total action time, especially when testing millisecond-level fast protection, introducing a non-negligible error. To solve this problem, this embodiment performs a no-load calibration test before performing any on-load short-circuit or leakage current tests.

[0040] The specific implementation steps are as follows: like Figure 3 As shown, before the formal test, the system prompts or automatically enters the no-load calibration mode; the PLC controls the contactors required for subsequent tests to engage in the correct sequence; the start signal for the high-precision timer is provided by the PLC issuing the engagement command at the moment of activation; the stop signal for the high-precision timer is provided by the closing of the auxiliary normally open contact of the last contactor in that group of contactors, thus obtaining the measured time. This refers to the inherent mechanical delay of the test system under this configuration; the system saves this. The value, measured by a high-precision timer, during subsequent load tests, is the time from fault application to protection activation. It actually includes the actual operating time of the protective device. and inherent system latency ,Right now = + Therefore, the calibrated, actual protection action time is: .

[0041] Specifically, according to Article 5.9.1 of MT / T 1123-2011 "Integrated Protection Device for Explosion-proof Lighting and Signaling in Mines", the short-circuit action time of the lighting circuit at the beginning and end should be less than 0.1s; Article 5.9.2 requires that the short-circuit action time of the signal circuit at the beginning and end should be less than 0.4s; and Article 5.8 requires that the 1kΩ leakage current action time should be less than 0.25s. like Figure 4 As shown, during normal operation: contactors K1, K3, K5, K2, K4, and K6 at the output end of the test object are engaged, while K7, K8, K9, and K10 are disengaged; When the first end is short-circuited: test the short circuits of phases AB, BC, and AC respectively. When phase AB is short-circuited, K3, K5, and K8 will be engaged; when phase BC is short-circuited, K3, K1, and K7 will be engaged; when phase AC is short-circuited, K5, K1, and K8 will be engaged. Short-circuit time test at the first end: After the contactor control process at the first end is completed, the closed contact of the contactor of the explosion-proof lighting signal integrated protection device under test needs to be connected to the auxiliary normally open contact of K8, the auxiliary normally open contact of K7, and the contactor contacts of K7 and K8, and the input signal circuit of the timer for closing timing and opening stopping should be connected; when the main circuit contactor is closed, the timer starts timing, and the timer ends timing after the explosion-proof lighting signal integrated protection device detects the short-circuit current; When the end is short-circuited: connect the impedance resistor R1 of phase A of the impedance cabinet to the output terminal of contactor K5, and connect the L1 impedance output to the input terminal of contactor K6; connect the impedance resistor R2 of phase B of the impedance cabinet to the output terminal of contactor K3, and connect the L2 impedance output to the input terminal of contactor K4; connect the impedance resistor R3 of phase C of the impedance cabinet to the output terminal of contactor K1, and connect the L3 impedance output to the input terminal of contactor K2. During the AB phase short circuit test: K3, K5, K4, K6 and the series line impedances R1, R2, L1, L2 are engaged; during the BC phase short circuit test: K1, K3, K4, K2 and the series line impedances R2, R3, L2, L3 are engaged; during the AC phase short circuit test: K5, K6, K1, K2 and the series line impedances R1, R3, L1, L3 are engaged. Short-circuit time test: After the contactor control process at the end is completed, the normally open contact of the contactor of the explosion-proof lighting signal integrated protection device under test needs to be connected to the programmable logic controller (PLC). Then, the short-circuit test is performed as required, and the short-circuit test time can be displayed.

[0042] Taking the test of the short-circuit time at the end of phases AB as an example, the test process of this embodiment is explained in detail: (1) The operator closes the main power supply, starts the three-phase electric voltage regulator, and adjusts its output voltage to the rated voltage of the tested explosion-proof lighting signal integrated protection device of the mine, 127V, so as to provide normal power supply to the tested explosion-proof lighting signal integrated protection device of the mine.

[0043] (2) The operator turns the operation selection switch to the "AB phase end test" position and selects the cable specification to be simulated in this test through the touch screen. The cable is 6mm², 600m, and the corresponding impedance value is 0.432Ω resistor and corresponding inductor in group II.

[0044] (3) After receiving the instruction, the programmable logic controller (PLC) automatically performs the following operations: a. Engage contactors K1, K3, K5, K2, K4, and K6 to establish a normal operating circuit. At this time, the output terminal of the integrated protection device under test is normally loaded. b. The programmable logic controller (PLC) controls the switching mechanism in the impedance cabinet to connect the corresponding resistor and inductor to the B-phase and A-phase circuits according to the selected impedance value; c. The programmable logic controller (PLC) controls contactors K3, K5, K4, and K6 to remain engaged, while simultaneously disengaging K1 and K2 and engaging the contactor responsible for short-circuiting, thereby creating an A / B phase short circuit at the ends of the A and B phase lines with the analog impedance introduced in series. At this point, the short-circuit fault circuit is completed.

[0045] (4) At the moment when the programmable logic controller (PLC) confirms that all designated contactors have operated correctly and the short-circuit circuit has been established, the programmable logic controller (PLC) sends a pulse signal to the high-precision timer to start timing, and the timer immediately starts timing.

[0046] (5) The explosion-proof lighting signal integrated protection device for mine under test monitors the output current in real time. When a huge short-circuit current of phase AB is detected, its internal protection circuit drives its trip protection relay to operate after a very short processing time. The normally open contact of the relay closes, and this closing signal is immediately transmitted to the stop terminal of the high-precision timer. After the timer captures the signal, it immediately stops timing and displays the recorded time on the touch screen.

[0047] (6) Regardless of whether the test is successful or not, the programmable logic controller (PLC) will automatically disconnect all contactors after a preset short delay, so that the device can return to the initial safe state and prepare for the next test.

[0048] For the initial short-circuit test, the process is similar, but in step three, the impedance of the impedance cabinet is not connected. Instead, a specific contactor is directly short-circuited on the output terminal block of the explosion-proof lighting signal integrated protection device for mine under test. The start signal of the timer is provided by the auxiliary normally open contact of the short-circuit contactor.

[0049] For the leakage current action time test, the operator selects the "Action Time Test" setting. The programmable logic controller (PLC) will control a dedicated contactor to connect a 1kΩ standard test resistor between the main circuit and ground. The timer starts timing from the moment the resistor is connected until the leakage current protection of the integrated protection under test trips, and its trip signal stops the timing, thus measuring the leakage current action time.

[0050] To illustrate the testing accuracy and effectiveness of this embodiment, the following is a set of actual test examples: Test object: A mine explosion-proof integrated protection device for lighting and signals with a rated capacity of 10kVA; Test item: Line AB phase end test, action time <100ms; Simulation conditions: Using 6mm² cable, 600m in length, corresponding impedance: R=0.432Ω, L=0.092Ω.

[0051] Test process and results: Using the auxiliary contact of the main contactor to stop the timing, the test was repeated 3 times, and the measured action times were 112ms, 108ms and 115ms respectively. The results fluctuated and were close to or exceeded the standard limit, making it impossible to accurately determine whether the product was qualified or not.

[0052] Using the test apparatus of Example 1, the relay contacts were stopped from timing. The test was repeated three times on the same device under test, and the measured action times were 28.5ms, 28.1ms and 28.7ms, respectively.

[0053] Therefore, it can be concluded that the results measured in Example 1 are stable and far below the standard limit, indicating that the device has excellent protection performance. Furthermore, the difference between the two methods is approximately 80ms, which is precisely the mechanical action delay time of the main contactor.

[0054] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A short-circuit time testing device for integrated protection of mine lighting signals, characterized in that, include: The control cabinet contains a programmable logic controller, a high-precision timer, an operation selection switch, and multiple three-phase or single-phase AC contactors for connecting or disconnecting test circuits. Impedance cabinet, which has multiple sets of switchable resistor and inductor networks inside, is used to simulate the impedance characteristics of mining cables with different cross-sectional areas and lengths. A three-phase electric voltage regulator is used to provide adjustable input power to the tested explosion-proof lighting signal integrated protection device for mines. The programmable logic controller controls the on / off combinations of multiple AC contactors according to the instructions of the operation selection switch, so as to automatically construct different types of short-circuit fault circuits at the output end of the integrated protection device for the lighting signal under test; the high-precision timer is electrically connected to the auxiliary contacts of the AC contactors and the protection output contacts of the integrated protection device for the lighting signal under test, and is used to accurately measure the time between the application of the short-circuit fault and the occurrence of the protection action.

2. The short-circuit time testing device for integrated protection of mine lighting signals according to claim 1, characterized in that, The impedance cabinet contains multiple sets of resistors and inductors that simulate at least three different cable cross-sectional areas: Group I corresponds to 4mm² cables and includes four resistance values: 0.137Ω, 0.274Ω, 0.548Ω, and 1.096Ω. Group II corresponds to 6mm² cables and includes four resistance values: 0.216Ω, 0.432Ω, 0.864Ω, and 1.728Ω. Group III corresponds to 10mm² cables and includes four resistance values: 0.369Ω, 0.738Ω, 1.476Ω, and 2.952Ω. Furthermore, the inductance values ​​for each group range from 0.09Ω to 0.101Ω, in order to collectively simulate the resistance and inductive reactance of the cable.

3. The short-circuit time testing device for integrated protection of mine lighting signals according to claim 1, characterized in that, Multiple AC contactors, including K1, K2, K3, K4, K5, K6, K7, K8, K9, and K10, are controlled by a programmable logic controller (PLC) through their on / off combinations. Normal operating circuit: Controls K1, K3, K5, K2, K4, and K6 to engage, ensuring the normal connection of the output terminal of the device under test; Short circuit between phases at the beginning: including short circuit at the beginning of phases AB, short circuit at the beginning of phases BC, and short circuit at the beginning of phases AC; Terminal phase-to-phase short circuit loop: By inserting the impedance of the impedance cabinet into the loop, including terminal short circuit of phases AB, phase BC, and phase AC.

4. The short-circuit time testing device for integrated protection of mine lighting signals according to claim 3, characterized in that, The timing start / stop control method of the high-precision timer is as follows: For the initial short-circuit time test, the start signal of the timer is provided by the closing of the auxiliary normally open contact of the contactor that performs the short-circuit operation; For the end-short-circuit time test, the start signal of the timer is issued by the programmable logic controller after confirming that the end-short-circuit loop has been constructed; The stop signal of the high-precision timer is provided by the trip control signal output by the integrated protection device for the measured lighting signal when the protection is activated.

5. The short-circuit time testing device for integrated protection of mine lighting signals according to claim 3, characterized in that, The contactor used in the initial short-circuit test has contact materials and switching capacity that meet the instantaneous high current surge conditions when no simulated impedance is inserted.

6. The short-circuit time testing device for integrated protection of mine lighting signals according to claim 1, characterized in that, The programmable logic controller is also connected to a display unit, which is used to display in real time the current test type, contactor status, and action time value measured by a high-precision timer.

7. The short-circuit time testing device for integrated protection of mine lighting signals according to claim 1, characterized in that, The resistive elements in the impedance cabinet are made of resistive alloy strips wound on a ceramic insulating frame, and the inductor elements adopt a hollow spiral tube structure.

8. A test method for the short-circuit time test device for integrated protection of mine lighting signals as described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Provide the rated voltage to the integrated protection device for the lighting signal under test through a three-phase electric voltage regulator; Without any load or analog impedance connected to the output of the integrated protection device for the lighting signal under test, the programmable logic controller controls all contactor combinations required in subsequent tests to perform a no-load switching operation; a high-precision timer records the time required from the issuance of the switching command to the confirmation of complete closure of all auxiliary contacts of the contactors, which is taken as the no-load operation time T_no-load and stored. S2. Select the short circuit type to be tested by operating the selection switch; S3. The programmable logic controller receives instructions and automatically controls the corresponding AC contactor combination to engage, constructing a short-circuit fault circuit of the selected type. S4. The high-precision timer automatically detects the completion of the loop construction and the occurrence of a fault, and starts timing. S5. When the protection function of the tested lighting signal integrated protection device is activated and the circuit breaker is tripped, the high-precision timer receives the tripping signal, stops timing, and records and saves the total action time of this test. ; From the total action time Subtract no-load action time The calibrated protection action time is obtained. ; S6. The programmable logic controller resets all contactors, ending the test.

9. The test method for the short-circuit time test device for integrated protection of mine lighting signals according to claim 8, characterized in that, In S3, when performing an end-short circuit test, the programmable logic controller automatically connects the impedance group corresponding to the selected cable specification and length in the impedance cabinet to the test circuit while controlling the contactor to engage.

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