An automatic heating insulation restoration device for high-voltage motor windings and its operating method

Abstract

This invention discloses an automatic heating insulation restoration device and operating method for high-voltage motor windings, belonging to the field of electrical equipment automatic control technology. The automatic heating insulation restoration device for high-voltage motor windings includes an insulation restoration system and a mounting cabinet for housing the insulation restoration system. The insulation restoration system includes: detection sensors, a human-machine interface device, a PLC logic controller, and a power supply mechanism. This invention solves the problems of existing technologies that only energize and heat the motor stator, resulting in low heating efficiency and lack of real-time monitoring and automatic power-on / off functionality for the heating circuit. This invention utilizes the motor stall effect and current heating effect, applying current to the motor stator windings to heat them, while simultaneously stalling the rotor. The stalled rotor windings generate a stall current that heats the rotor, resulting in higher heating efficiency, faster insulation restoration, and allowing the motor to be put into operation as soon as possible, reducing the impact on production.

Description

Technical Field

[0001] This invention relates to the field of automatic control technology for electrical equipment, specifically to an automatic heating insulation restoration device and operating method for high-voltage motor windings. Background Technology

[0002] High-voltage motors have higher insulation requirements than low-voltage motors. Furthermore, the assembly process for high-voltage motors is complex, requiring cumbersome on-site installation in conjunction with mechanical equipment and demanding high precision. When the insulation of a high-voltage motor deteriorates due to harsh working environments or prolonged downtime, insulation treatment is necessary. Currently, there are two main methods: one is to use drying lamps, and the other is to disassemble the motor and send it to a repair shop for drying in a large drying chamber. Both methods require significant time and labor costs, and are also wasteful in terms of energy consumption, making them uneconomical and environmentally unfriendly.

[0003] Chinese Patent No. 202222115055.X discloses a device for rapidly restoring insulation of a large electric motor, including a rectifier device comprising three sets of thyristor rectifier bridges. Each set of thyristor rectifier bridges includes a coil and four thyristors. The anode of the first thyristor is connected to the cathode of the second thyristor, the anode of the third thyristor is connected to the cathode of the fourth thyristor, the cathode of the first thyristor is connected to the cathode of the third thyristor, and the anode of the second thyristor is connected to the anode of the fourth thyristor. One end of the coil is connected to the anode of the first thyristor, and the other end is connected to the anode of the third thyristor. The anode of the second thyristor in the first set of thyristor rectifier bridges is connected to the cathode of the first thyristor in the second set of thyristor rectifier bridges, and the anode of the second thyristor in the second set of thyristor rectifier bridges is connected to the cathode of the first thyristor in the third set of thyristor rectifier bridges. This utility model adopts a technology that directly applies low voltage and high current to the stator coil, causing the stator coil to heat up directly and quickly restore the insulation resistance from the inside out.

[0004] This device only powers the motor stator to generate heat, resulting in low heating efficiency. Furthermore, it lacks the function of real-time monitoring and automatic power-on / off of the heating circuit, posing a certain risk in practical applications. Summary of the Invention

[0005] The purpose of this invention is to provide an automatic heating insulation restoration device and operating method for high-voltage motor windings. This device automatically controls the current flowing into the motor windings, utilizes the stall effect of the motor and the thermal effect of the current, sets up detection sensors to monitor various key parameters of the motor windings in real time, and automatically controls the heating circuit through a PLC logic controller. This method quickly, efficiently, environmentally friendly and safely improves the winding insulation of high-voltage motors, solving the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] An automatic heating insulation restoration device for high-voltage motor windings includes an insulation restoration system and a mounting cabinet for housing the insulation restoration system. The insulation restoration system includes: a detection sensor for real-time monitoring of various key parameters of the motor windings during heating and sending the collected monitoring signals to a PLC logic controller; a human-machine interface device for operators to set various parameters required for motor winding heating and to display real-time operating information of the detection sensor, the PLC logic controller, and the heating information of the motor windings; a PLC logic controller for performing calculations and analysis on the received monitoring signals and outputting control signals to the actuator; an actuator for controlling the opening and closing of the main circuit for heating the motor windings; and a power supply mechanism for providing power to the detection sensor, the human-machine interface device, the PLC logic controller, the actuator, and the heated motor windings.

[0008] Preferably, the detection sensor includes a current transformer, a current transmitter, a temperature sensor, and an A / D conversion module. The current transformer is used to monitor the current change in the heating circuit, the current transmitter is used to convert the measured current into a standard signal output, the temperature sensor is used to monitor the temperature of the heating motor winding, and the A / D conversion module is used to convert analog signals such as current, voltage, and temperature into digital signals that can be recognized by the PLC logic controller.

[0009] Preferably, the actuator includes an automatic air switch and an intermediate relay. The intermediate relay is used to control the opening and closing of the automatic air switch, and the automatic air switch is used to control the closing and opening of the heating main circuit. The intermediate relay is electrically connected to the PLC logic controller.

[0010] Preferably, the power supply mechanism includes a 380V three-phase AC power supply, a 380V / 220V transformer, and an AC220V / DC24V DC power supply. The 380V three-phase AC power supply is used to provide power for the heating main circuit. The 380V / 220V transformer is used to convert the voltage of the 380V three-phase AC power supply into 220V control power. The AC220V / DC24V DC power supply is used to power the current transmitter, temperature sensor, A / D conversion module, human-machine interface device, PLC logic controller, and intermediate relay.

[0011] An operation method for an automatic heating insulation restoration device for high-voltage motor windings, based on such a device, includes the following steps:

[0012] Step 1: Choose a suitable location and place the installation cabinet stably;

[0013] Step 2: Remove the motor air cooler, remove the windshields on both sides of the motor, and remove the heater covers on both sides;

[0014] Step 3: Equip two 50-square-millimeter three-core copper cables, one 2500V megohmmeter, one clamp-on ammeter, and one infrared thermometer. Before power-on, confirm that the power cable is in good condition and the terminals are tightly connected, and confirm that the insulation of the motor is not less than 0.5 MΩ;

[0015] Step 4: Set up the temperature sensor, align the temperature sensing probe with the upper part of the motor stator winding, set the operating parameters such as current and temperature on the human-machine interaction device, confirm that all parameters are set, and after checking and confirming, start the insulation recovery system through the human-machine interaction device;

[0016] Step 5: Send someone to monitor the operation of the equipment within half an hour after power-on, and confirm whether the displayed current value and temperature value are consistent with the results measured by the clamp-on ammeter and the spot thermometer;

[0017] Step 6: Check the insulation status after 4 hours of power-on, then power on for another 4 hours, and disconnect the heating circuit after the insulation is qualified.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] 1. The present invention utilizes the motor blocked-rotor effect and the current heating effect, passes current through the motor stator winding to make it heat, and blocks the rotation of the rotor. After the rotor winding is blocked, a blocked-rotor current is generated to make the rotor heat, with a higher heating efficiency, faster drying speed and insulation recovery speed, enabling the motor to be put into operation earlier to reduce the impact on production, and reducing the labor cost of motor insulation treatment work and the external repair cost of the motor.

[0020] 2. The present invention adopts the control method of PLC logic operation controller + touch screen, enabling the whole set of devices to operate automatically according to the set parameters, saving human resources and facilitating the setting and monitoring of operation parameters.

[0021] 3. The present invention sets independent automatic control logic and manual control logic in the PLC logic operation controller. When one set of control logic fails, the other set can still continue to achieve the control function, ensuring the reliability of the overall system control, and writing a protection program. When the current or temperature value exceeds the set limit, the protection program is directly triggered to operate, driving the intermediate relay to trip the automatic air switch. There is an emergency stop button on the installation cabinet, and pressing the emergency stop button in an emergency can quickly cut off the power supply to ensure safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is the automatic heating control logic diagram of the present invention;

[0023] Figure 2The motor temperature rise monitoring graph (°C / t) of this invention is shown below;

[0024] Figure 3 The diagram shows the measurement of the motor insulation resistance (MΩ / t) according to the present invention.

[0025] Figure 4 This is a diagram (A / t) showing the current measurement of the main circuit of the motor according to the present invention;

[0026] Figure 5 This is a wiring diagram of the primary equipment of the present invention;

[0027] Figure 6 This is a secondary circuit diagram of the current transformer for the stator current of the motor according to the present invention.

[0028] Figure 7 This is a wiring diagram showing the power connection of each device within the apparatus of the present invention;

[0029] Figure 8 This is a wiring diagram of the PLC logic controller of the present invention;

[0030] Figure 9 This is a schematic diagram of the electrical control principle of the automatic air switch of the present invention;

[0031] Figure 10 This is a diagram showing the contact closure of the changeover switch of the present invention;

[0032] Figure 11 This is a diagram showing all the signals received by the PLC logic controller of this invention. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] To address the problems of existing technologies that only energize and heat the motor stator, resulting in low heating efficiency and lack of real-time monitoring and automatic power-on / off functionality for the heating circuit, this embodiment provides the following technical solution:

[0035] Please see Figure 1An automatic heating insulation restoration device for high-voltage motor windings includes an insulation restoration system and a mounting cabinet for housing the insulation restoration system. The insulation restoration system includes: a detection sensor for real-time monitoring of various key parameters of the motor windings during heating and sending the collected monitoring signals to a PLC logic controller; a human-machine interface device using a touch screen mounted on the cabinet door, used by operators to set various parameters required for motor winding heating and to display real-time operating information of the detection sensor, PLC logic controller, and motor winding heating information such as the position of the automatic air switch, operating current, motor temperature, and alarm information; a PLC logic controller for processing and analyzing the received monitoring signals and outputting control signals to the actuator; an actuator for controlling the opening and closing of the main circuit for motor winding heating; and a power supply mechanism for providing power to the detection sensor, human-machine interface device, PLC logic controller, actuator, and the heated motor windings.

[0036] The PLC logic controller features both automatic and manual control logic, operating independently. Therefore, if one logic fails, the other can continue to function, ensuring overall system reliability. In addition to the overcurrent protection inherent in the automatic air switch, a protection program is written into the PLC logic controller. When the current or temperature exceeds a set limit, the protection program is triggered, outputting a 24V control signal to drive an intermediate relay to trip the automatic air switch. Furthermore, an emergency stop button is installed on the cabinet. In an emergency, regardless of whether the device is in automatic or manual control mode, pressing the emergency stop button quickly cuts off the power supply for safety.

[0037] The detection sensors include a current transformer, a current transmitter, a temperature sensor, and an A / D conversion module. The current transformer is used to monitor the current change in the heating circuit, the current transmitter is used to convert the measured current into a standard signal output, the temperature sensor is used to monitor the temperature of the heating motor windings, and the A / D conversion module is used to convert analog signals such as current, voltage, and temperature into digital signals that can be recognized by the PLC logic controller.

[0038] The actuator includes an automatic air switch and an intermediate relay. The intermediate relay is used to control the opening and closing of the automatic air switch, which is used to control the closing and opening of the heating main circuit. The intermediate relay is electrically connected to the PLC logic controller. The PLC logic controller can output a DC 24V control signal to control the intermediate relay, thereby tripping the automatic air switch.

[0039] The power supply mechanism includes a 380V three-phase AC power supply, a 380V / 220V transformer, and an AC220V / DC24V DC power supply. Considering that there are multiple components with different voltage levels in this set of devices, for the convenience of external wiring and to simplify the wiring and increase the on-site adaptability of this device, a large-capacity 380V three-phase AC power supply is directly introduced to provide the power source for the heating main circuit. The 380V / 220V transformer is used to convert the voltage of the 380V three-phase AC power supply into a 220V control power supply. The AC220V / DC24V DC power supply is used to supply power to the current transmitter, temperature sensor, A / D conversion module, human-computer interaction device, PLC logic operation controller, and intermediate relay.

[0040] An operation method of a high-voltage motor winding automatic heating insulation restoration device, which is realized based on a high-voltage motor winding automatic heating insulation restoration device, includes the following steps:

[0041] Step 1: Select a suitable location and place the installation cabinet steadily.

[0042] Step 2: Remove the motor air cooler, remove the windshields on both sides of the motor, and remove the heater covers on both sides.

[0043] Step 3: Prepare two 50-square-millimeter three-core copper cables, one 2500V megohmmeter, one clamp-on ammeter, and one infrared thermometer. Before power-on, confirm that the power cable is in good condition and the terminal connections are tight, and confirm that the motor insulation is not less than 0.5 M.

[0044] Step 4: Set up the temperature sensor, align the temperature sensing probe with the upper part of the motor stator winding, set the operating parameters such as current and temperature on the human-computer interaction device, confirm that all parameters are set, and after checking and finding no errors, start the insulation restoration system through the human-computer interaction device.

[0045] Step 5: Within half an hour after power-on, send someone to monitor the operation of the equipment, and confirm whether the displayed current value and temperature value are consistent with the results measured by the clamp-on ammeter and the spot thermometer.

[0046] Step 6: Check the insulation status after 4 hours of power-on, then power on for another 4 hours, and disconnect the heating circuit after the insulation is qualified.

[0047] Please refer to Figure 2-4 , and a further detailed description of this implementation mode is given through the description of specific examples:

[0048] For the No. 5 feed pump motor, due to the decline in the motor insulation level, the motor insulation level cannot meet the equipment operation requirements, resulting in the unstable and unreliable operation of the feed pump system. Therefore, this insulation restoration system is used to carry out the insulation restoration work, and the steps are as follows:

[0049] 1. After the feed pump is shut down, enter the maintenance site, disconnect the feed pump from the motor, and disconnect the primary incoming cable of the motor to ensure system isolation during maintenance and to ensure safety.

[0050] 2. The insulation resistance of the motor windings measured with a 2500V megohmmeter is 1.9MΩ > 0.5MΩ, which meets the safe operating conditions for the insulation restoration device.

[0051] 3. Remove the air cooler of the motor, remove the windshields on both sides of the motor, and remove the heater covers on both sides to facilitate heat dissipation during the subsequent motor insulation restoration process and remove moisture and dampness adhering to the inside of the motor.

[0052] 4. Choose a flat and suitable location to place the cabinet stably, and the placement should facilitate wiring and operation by testing personnel.

[0053] 5. Based on the stall principle and the parameters on the motor nameplate, the main circuit operating current of the device during operation is approximately 100 amps. Considering a safety margin of 1.5 times, a maintenance power supply with a rated capacity of 150A is selected on site as the power input line for the device.

[0054] 6. Based on the calculated operating current of the device, select two 50 square millimeter three-core copper power cables to tightly connect the maintenance power supply to the device and the device to the motor windings to prevent overheating and potential danger caused by loose connections.

[0055] 7. Set up the temperature sensor for collecting the temperature of the motor windings, making sure it is aligned with the upper part of the motor stator windings to accurately collect the maximum value of the motor winding temperature.

[0056] 8. Confirm that all wiring is complete, and that the connections are secure and make good contact; after confirming that all internal components are in the correct state, power on the entire device.

[0057] 9. After powering on, set the current and temperature control parameters on the touch screen. Since the No. 5 pump motor is Class B insulation and the performance reference temperature is 100℃, combined with the previously calculated working current of 100A, set the upper limit of temperature to 90℃ and the upper limit of current to 110A.

[0058] 10. After all parameters are set, check all wiring and device status again. Once everything is confirmed to be normal, press the start button on the touch screen. At this time, the intermediate relay will drive the automatic air switch to close, the heating main circuit will be connected, and the motor insulation restoration operation will begin.

[0059] 11. After the main circuit is connected, use a clamp meter and a temperature gun to verify the sampled value of the detection element. The two values ​​should be approximately equal to ensure the accuracy of the sampled value and avoid equipment failure or damage caused by measurement errors.

[0060] 12. Manually stop measuring the insulation resistance of the motor every 30 minutes, and record the temperature and current sampling values ​​to create charts to analyze the device's operating status and the motor's insulation recovery.

[0061] 13. After the motor insulation value returns to a stable state and stops rising for 1 hour, stop the device and turn off the power.

[0062] 14. Reassemble the motor after insulation restoration, restoring it to the state before the No. 5 feed pump was shut down. The motor insulation restoration work is now complete.

[0063] 15. The collected data is used to create the charts shown below.

[0064] Analysis revealed that in the initial stage, the moisture inside the insulation material was heated and formed into humid air that diffused outward, filling the motor cavity. When it adhered to the surface of the insulation material, the insulation resistance decreased. Subsequently, the moisture in the insulation material and cavity was gradually expelled, and the insulation resistance value rebounded until it stabilized, achieving the expected effect. At the same time, the current and temperature values ​​remained within a reasonable range, verifying the safety and reliability of the automatic device.

[0065] Please see Figure 5 The primary equipment wiring uses 380V AC power as the main input power.

[0066] L1, L2, L3 represent the A, B, and C phase sequence of the three alternating currents;

[0067] QL is the code for automatic air switch. It is the main automatic actuator of this device. It automatically connects and disconnects the 380V power supply to the motor by receiving the voltage signal generated by the closing of the PLC output node.

[0068] M3~ indicates a 3-phase AC motor, and UVW is the terminal code for the motor.

[0069] PE is the grounding wire for the motor casing;

[0070] TA is a small through-hole current transformer used to collect the current in the stator of the motor during device operation.

[0071] AX is the terminal number on the high-voltage side of the control transformer, and ax is the terminal number on the low-voltage side of the control transformer.

[0072] QF1 and QF2 are small air switches. QF1 is responsible for connecting and disconnecting L1. L2 is connected to the AX terminal on the high-voltage side of the control transformer. QF2 is responsible for connecting and disconnecting the AX terminal on the low-voltage side of the transformer from the control circuit.

[0073] L and N represent the phase line and neutral line codes for a single-phase 220V AC power supply.

[0074] Note: The purpose of using a control transformer here is to conveniently convert 380V AC power to 220V AC power for use in the control circuit of this device. Because some equipment has complex site conditions, it is sometimes not easy to obtain 220V AC power directly. Adding a control transformer can easily solve this problem, while also simplifying external wiring and improving efficiency.

[0075] Please see Figure 6 The secondary circuit of the current transformer for measuring the stator current of the motor: 1TA is the code of the current transformer; V411 and N411 are the codes of the secondary side terminals of the current transformer; AF is the current transmitter, and 6 and 8 are its input terminal numbers. Its function is to convert the large current collected by the current transformer into a small current signal of 4~20mA, which is supplied to the analog module of the PLC for reading.

[0076] Please see Figure 7 The power connection wiring for each device in the device: AF represents the current transmitter, and 1 and 2 are its external 220V power supply terminals.

[0077] U represents a switching power supply, which is a device that converts 220V AC power into 24V DC power. L and N are the letter symbols for the 220V input phase line and neutral line, respectively, and V+ and V- are the 24V output terminal markings of the switching power supply.

[0078] The 220V input voltage of the current transmitter AF and the switching power supply U both come from the output terminal of the control transformer of this device.

[0079] HMI stands for touchscreen; + and - indicate its power input terminals.

[0080] PLC is the abbreviation for Programmable Logic Controller, and M is its power input terminal.

[0081] BT stands for temperature sensor, and red and black are the colors of its power supply wires.

[0082] The power supplies for HMI, PLC, and BT are all drawn from the 24V output of the switching power supply U.

[0083] Please see Figure 8 Wiring between the PLC logic controller and associated devices:

[0084] S7200CPU226DC / DC / DC is a PLC model. Its function is to read input signals, perform logical operations through its internal user-defined program, and then selectively output them.

[0085] EM235 is the model number of the analog module of the PLC. Its function is to convert the 4-20MA analog current signal output by the current transmitter and temperature sensor into a digital signal recognizable by the PLC, and transmit it to the inside of the PLC for logical operation.

[0086] KA1 and KA2 are the coils of the intermediate relay. KA1 represents the closing intermediate relay coil, and KA2 represents the tripping intermediate relay coil. Their drive voltage is DC 24V, which matches the output terminal voltage of the PLC and can be directly connected in series in the output circuit of the PLC. At the same time, since the coil of the intermediate relay is an inductive load, in order to prevent the reverse overvoltage generated by the frequent on and off of the inductive load from breaking down and damaging the output terminal of the PLC, a freewheeling diode is connected in parallel to each coil in reverse to eliminate the harm of the reverse overvoltage of the coil.

[0087] DC24V indicates that this model of PLC is powered by DC 24V. V+, V-, A01, A02, B01, B02 are all terminal numbers;

[0088] KA3 is the normally open auxiliary contact of the fault auxiliary intermediate relay of the automatic air switch. Its function is that when a fault occurs inside the automatic air switch QL, the auxiliary contact QL in series with the KA3 relay coil closes, the KA3 coil is energized and attracted, and the normally open auxiliary contact of KA3 also closes. At this time, the input terminal of the PLC will receive a valid high-level signal, so as to judge that the automatic air switch QL has a fault at this time. Then, after the program operation of the PLC, the output terminal of the closing coil KA2 will be locked in the internal logic of the PLC. At this time, the automatic air switch QL cannot be closed, thus realizing the function of preventing continuous closing to cause equipment damage due to fault expansion when QL has a fault.

[0089] SV is the English abbreviation of the changeover switch, Figure 4 refers to one pair of normally open auxiliary contacts of the changeover switch. Here, it plays the role of switching the operation mode. When the handle of SV is turned to the automatic position, the normally open auxiliary contact of SV in the figure will close at this time, and the whole set of devices will enter the automatic operation state;

[0090] QL is the abbreviation of the automatic air switch. Figure 4 refers to one pair of normally open contacts and one pair of normally closed contacts of it. Their function is that when QL is in the closing state, the normally open auxiliary contact of QL closes, and the PLC can receive the closing signal of QL. On the contrary, when QL is in the tripping state, the normally closed auxiliary contact of QL closes, and the PLC can receive the tripping signal of QL. Thus, the function of the PLC to judge the current closing and tripping states of the automatic switch QL is realized;

[0091] The 4-20mA current signal reflects the real-time current in the stator coil of the motor during device operation. When this current exceeds the allowable value set in the PLC program, the PLC will issue a trip command to activate the trip relay KA2, thereby connecting the trip circuit of QL and tripping it to disconnect the main power supply from the stator coil of the motor, ensuring safety.

[0092] The 4-20mA temperature signal feedback is the real-time maximum temperature of the motor stator windings collected by an infrared temperature sensor mounted on the upper part of the motor stator windings during automatic device operation. After the PLC collects this temperature, it compares it with the temperature value set in our program. If it is lower than the limit, it issues a closing command to energize the KA1 coil, thereby connecting the closing circuit of QL.

[0093] When the temperature exceeds the limit, a trip command is issued, energizing the KA2 coil and connecting the trip circuit of QL. This enables the entire device to operate automatically.

[0094] Please see Figure 9 The electrical control principle of the automatic air switch QL is as follows:

[0095] QF2 (Miniature Air Switch); SV (Changeover Switch); SB (Emergency Stop Button); KA1 (Normal Open Auxiliary Contact of Automatic Closing Relay); KA2 (Normal Open Auxiliary Contact of Automatic Opening Relay); QL (Automatic Air Switch); A1 (Common Terminal of QL Opening / Closing Control Coil); A2 (Input Terminal of QL Closing Control Coil); A4 (Input Terminal of QL Opening Control Coil); B2, B4, 81, 82, 84 (These are QL multi-function auxiliary contacts, where 81 and 84 are a pair of normally open auxiliary contacts that only close in case of a QL fault).

[0096] When QL itself malfunctions, the coil of KA3 (fault auxiliary intermediate relay) is energized and the normally open auxiliary contact of KA3 closes.

[0097] When the miniature air switch QF2 is closed, the QL control circuit is powered on, and power is supplied to both line #1 and line #2. At this point, two control modes can be selected:

[0098] 1. Automatic Control: Turn the selector switch SV to automatic. At this time, terminals 5 and 6 of SV are connected, and line #4 is energized. Then, press the start button on the HMI (touchscreen). The PLC will enter automatic operation mode. When the temperature signal (4-20mA) collected by the PLC is lower than the minimum value set in the program, it will output a valid high level. Figure 4 When the KA1 (closing relay coil) is energized, it engages and closes. Figure 5The normally open auxiliary contact of KA1 will also close. Then A2 (the input terminal of the QL closing control coil) is energized, the QL closing circuit is fully connected, and then the QL closing coil actuates to close the QL circuit, connecting the main power supply and the motor. The motor stator winding is energized, and the heating effect of the current and the stall principle of the motor are used to directly heat the winding to improve the insulation of the motor stator winding. As heating continues, the temperature will increase. The infrared temperature sensor set on the upper part of the stator winding will collect the temperature value in real time and upload it to the PLC for logic calculation. When the collected temperature value exceeds the maximum allowable temperature set by the program (excessive temperature will cause serious damage to the stator winding of the motor), the PLC will output a valid high level. Figure 4 When the KA2 (opening relay coil) is energized, it engages. Figure 5 The normally open auxiliary contact of KA2 will also close. Then, A4 (the input terminal of the QL trip control coil) is energized, and the QL trip circuit is fully connected. The QL trip coil then actuates, tripping the QL circuit and disconnecting the main power supply from the motor. Due to the thermal effect of the de-energized motor stator coil and the stall principle, the stator coil temperature stops rising and begins to decrease over time. When the temperature drops below a minimum threshold, the PLC reconnects the QL closing circuit... This process repeats, achieving the automatic control function of this device.

[0099] 2. Manual control:

[0100] Manual closing: Turn the selector switch SV to the manual closing position. At this time, terminals 1 and 2 of SV are connected, and A2 (the input terminal of the QL closing control coil) is directly energized without PLC control. The closing circuit of QL is fully connected, and then the QL closing coil actuates to close QL, connecting the main power supply and the motor. This realizes the manual closing function of this device.

[0101] Manual tripping: Turn the selector switch SV to the manual tripping position. At this time, terminals 11 and 12 of SV are connected, and A4 (the input terminal of the QL tripping control coil) is directly energized without PLC control. The QL tripping circuit is fully connected, and then the QL tripping coil actuates to trip the QL circuit, disconnecting the main power supply and the motor. This realizes the manual tripping function of this device.

[0102] 3. Emergency stop:

[0103] For safety reasons, in addition to designing two control systems, a separate emergency stop button (SB3) is also installed. In case of an emergency, simply press the red emergency stop button (SB3) located on the control box door to directly energize A4 (the input terminal of the QL trip control coil) without PLC control. This fully connects the QL trip circuit, and then the QL trip coil actuates to trip the QL circuit, disconnecting the main power supply and the motor.

[0104] Please see Figure 10 The contact closure table for the SV (changeover switch) is LW12-46D049.4040.4, which is its model number.

[0105] When rotated to the hand-closed position, contacts 1 and 2 of SV are closed;

[0106] When rotated to the manual jump position, contacts 11 and 12 of SV are closed;

[0107] When rotated to the PLC position, contacts 5 and 6, and contacts 7 and 8 of SV are connected.

[0108] Please see Figure 11 It represents all the signals transmitted from the electrical equipment in the entire system to the PLC logic controller, all concentrated on a single diagram for easy viewing and wiring.

[0109] A01, A02, B01, B02, D01, D02, D03, D04, and D05 are terminal block numbers indicating their correspondence in different diagrams for ease of understanding and wiring.

[0110] AF 4, 5 indicates terminals 4 and 5 of the current transmitter.

[0111] BT blue and orange indicate the blue and orange insulated secondary 4-20mA output lines of the infrared temperature sensor.

[0112] SV7,8 indicates that contacts 7 and 8 of SV are turned on when the entire device is under PLC automatic control.

[0113] The normally open contact of QL in the closed position is closed when QL is in the closed state; the normally open contact of QL in the open position is closed when QL is in the open state. Their function is to provide the PLC with the closed and open position signals of QL, so that they can be conveniently and intuitively displayed on the HMI (touchscreen) for easy viewing by the operator.

[0114] KA3 is the normally open auxiliary contact of the fault auxiliary intermediate relay. When QL itself fails, it is turned on to transmit the QL fault information to the PLC, so that the PLC can make logical judgments and lock out the automatic closing function to prevent the fault from escalating.

[0115] Working principle: This device utilizes the stall principle of the motor and the thermal effect of current. Under the control of the PLC logic controller, a low-voltage current is supplied to the stator winding of the motor, and the motor rotor is stalled, causing a stall current to be generated. This converts the electrical energy in the stator and rotor into heat energy, and uses the temperature generated by the motor itself to dry the motor, thereby restoring the motor insulation to its normal state.

[0116] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0117] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. An automatic heating insulation restoration device for high-voltage motor windings, comprising an insulation restoration system and a mounting cabinet for housing the insulation restoration system, characterized in that: The insulation recovery system includes: A detection sensor, which is used to monitor various key parameters of the motor winding during heating in real time and send the collected monitoring signals to the PLC logic operation controller; A human-machine interaction device, which is used for an operator to set various parameters required for heating the motor winding and display the operation information of the detection sensor, PLC logic operation controller and the heating information of the motor winding in real time; A PLC logic operation controller, which is used to perform operations and analysis on the received monitoring signals and output control signals to the actuator; An actuator, which is used to control the opening and closing of the main circuit for heating the motor winding; A power supply mechanism, which is used to provide power for running the detection sensor, human-machine interaction device, PLC logic operation controller, actuator and heating the motor winding; The detection sensor includes a current transformer, a current transmitter, a temperature sensor and an A / D conversion module; the current transformer is used to monitor the current change in the heating circuit, the current transmitter is used to convert the measured current into a standard signal for output, the temperature sensor is used to monitor the temperature of the heating motor winding, and the A / D conversion module is used to convert the analog signals of current, voltage and temperature into digital signals recognizable by the PLC logic operation controller; The actuator includes an automatic air switch and an intermediate relay; the intermediate relay is used to control the opening and closing of the automatic air switch, and the automatic air switch is used to control the closing and opening of the main heating circuit; the intermediate relay is electrically connected to the PLC logic operation controller.

2. The automatic heating insulation restoration device for high-voltage motor windings according to claim 1, characterized in that: The power supply mechanism includes a 380V three-phase AC power supply, a 380V / 220V transformer and an AC220V / DC24V DC power supply; the 380V three-phase AC power supply is used to provide the power source for the main heating circuit, the 380V / 220V transformer is used to convert the voltage of the 380V three-phase AC power supply into a 220V control power supply, and the AC220V / DC24V DC power supply is used to supply power to the current transmitter, temperature sensor, A / D conversion module, human-machine interaction device, PLC logic operation controller and intermediate relay.

3. An operation method for an automatic heating insulation restoration device for high-voltage motor windings, implemented based on the automatic heating insulation restoration device for high-voltage motor windings as described in any one of claims 1-2, characterized in that: It includes the following steps: Step 1: Select a location and place the installation cabinet steadily; Step 2: Remove the motor air cooler, remove the windshields on both sides of the motor, and remove the heater covers on both sides; Step 3: Prepare two 50-square-millimeter three-core copper cables, one 2500V megohmmeter, one clamp-on ammeter, and one infrared thermometer. Before power-on, confirm that the power cable is in good condition and the terminal connections are tight, and confirm that the insulation of the motor is not less than 0.5M; Step 4: Set up the temperature sensor, align the temperature sensing probe with the upper part of the motor stator winding, set the current and temperature operation parameters on the human-machine interaction device, confirm that all parameters are set and checked无误, and then start the insulation recovery system through the human-machine interaction device; Step 5: Send someone to monitor the operation of the equipment within half an hour after power-on, and confirm whether the displayed current value and temperature value are consistent with the results measured by the clamp-on ammeter and the spot thermometer; Step 6: Check the insulation status 4 hours after power-on, then power on for another 4 hours, and disconnect the heating circuit after the insulation is qualified.

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