A motor protection device, a grating electrical control system and a grating cleaner

Abstract

This utility model belongs to the field of wastewater treatment technology, and relates to a motor protection device, a bar screen electrical control system, and a bar screen cleaner. The motor protection device includes a current signal acquisition module, the input of which is connected to the power supply terminal of the bar screen motor, for acquiring the three-phase current signal of the bar screen motor; a fault determination module, the input of which is connected to the current signal acquisition module, for comparing the three-phase current signal with the overcurrent threshold to determine whether the bar screen motor is overloaded; and an overload protection module, the input of which is connected to the fault determination module, and the output of which is connected to the control circuit of the bar screen motor, for outputting a passive node disconnect signal to the control circuit when the bar screen motor is overloaded, thereby cutting off the connection between the control circuit and the main circuit of the bar screen motor, thus enabling timely detection of faults in the bar screen cleaner and stopping the bar screen motor from working, reducing the equipment failure rate.

Description

Technical Field

[0001] This utility model relates to the field of wastewater treatment technology, and in particular to a motor protection device, an electrical control system for a bar screen machine, and a bar screen cleaning machine. Background Technology

[0002] The bar screen cleaner is an important component of wastewater treatment plants, primarily used to intercept and remove larger solid debris from sewage. It consists of the bar screen cleaner's electrical control system and the bar screen itself. The electrical control system includes a control circuit, a bar screen motor, and a thermal relay. The thermal relay is connected in series in the main circuit that connects the bar screen motor and the control circuit. The working principle of the bar screen cleaner is as follows: The control circuit sends a drive signal to the main circuit of the bar screen motor to control the motor to output mechanical energy. The motor shaft is connected to a reducer via a coupling. The output mechanical energy is reduced and amplified by the reducer before being transmitted to the wire rope drum. As the wire rope drum rotates, it pulls the grab bucket on the bar screen via the wire rope, causing the grab bucket to descend into the sewage along a predetermined trajectory and speed for cleaning operations. The thermal relay is used to cut off the main circuit when the bar screen motor is overloaded, stopping the motor and achieving overload protection.

[0003] In actual use, when the grab bucket on the bar screen encounters a large obstacle or gets stuck in the sewage, the movement of the grab bucket is hindered, and it cannot rise, fall, or move normally. At this time, due to the grab bucket jamming, the tension on the wire rope increases, and the bar screen motor needs to overcome greater resistance to maintain operation. Therefore, the current of the bar screen motor begins to rise. However, due to the mechanical structure and load characteristics of the bar screen, even when the grab bucket is jammed, the actual current of the bar screen motor only varies between 2.2A and 2.5A. The operating current setting value required for the thermal relay to cut off the circuit is usually about 6 times the rated current of the bar screen motor (2.1A). Therefore, when the grab bucket is jammed, the thermal relay cannot cut off the circuit in time. This causes the tension on the wire rope to exceed its limit strength under the action of the bar screen motor continuously outputting a large torque, and thus it will break in about 5 seconds.

[0004] In summary, existing bar screen cleaning machines cannot detect grab bucket jamming faults in a timely manner during use. At the same time, the thermal relay cannot cut off the main circuit of the bar screen motor when the grab bucket is jammed, which can lead to wire rope breakage, affecting the normal and stable operation of the bar screen cleaning machine and increasing the workload of daily maintenance and repair. Utility Model Content

[0005] Therefore, the technical problem to be solved by this utility model is to overcome the fact that in the use of existing bar screen cleaning machines, the grab bucket jamming fault cannot be detected in time, and the thermal relay cannot cut off the main circuit of the bar screen motor when the grab bucket is jammed, which will lead to the wire rope breaking, affect the normal and stable operation of the bar screen cleaning machine, and increase the workload of daily maintenance and repair.

[0006] To solve the above-mentioned technical problems, this utility model provides a motor protection device for a bar screen cleaning machine, comprising:

[0007] The current signal acquisition module has its input terminal connected to the power supply terminal of the bar screen motor in the electrical control system of the bar screen machine, and is used to acquire the three-phase current signal of the bar screen motor.

[0008] The fault determination module, whose input terminal is connected to the current signal acquisition module, is used to compare the three-phase current signal with the overcurrent threshold to determine whether the grid motor is overloaded.

[0009] The overload protection module has its input end connected to the fault determination module and its output end connected to the control circuit in the electrical control system of the bar screen machine. When the bar screen motor is overloaded, it outputs a passive node disconnect signal to the control circuit to cut off the connection between the control circuit and the main circuit of the bar screen motor.

[0010] Preferably, it also includes a switch signal acquisition module, which is connected to the bar screen detection sensor and is used to acquire the switch signal of the bar screen detection sensor;

[0011] The fault determination module is also used to determine whether the bar screen machine has malfunctioned based on the switch signal;

[0012] The overload protection module is also used to output a passive node disconnect signal to the control circuit when the bar screen machine fails, so as to cut off the connection between the control circuit and the main circuit of the bar screen motor.

[0013] Preferably, it also includes a zero-sequence current transformer, which is connected to the current signal acquisition module to monitor the balance of the three-phase current signal, thereby detecting the zero-sequence current in the current signal output by the grid motor;

[0014] The fault determination module is also used to determine whether the grid motor has failed based on the magnitude of the zero-sequence current;

[0015] The overload protection module is also used to output a passive node disconnect signal to the control circuit when the bar grid motor fails, so as to disconnect the connection between the control circuit and the main circuit of the bar grid motor.

[0016] Preferably, the fault determination module includes:

[0017] The analog output module is connected to the current signal acquisition module, the switch signal acquisition module and the zero-sequence current transformer, and is used to convert the three-phase current signal, the switch signal and the zero-sequence current into the first analog signal, the second analog signal and the third analog signal.

[0018] The communication interface has an input terminal connected to the analog output module and an output terminal connected to the programmable logic controller (PLC), used to output the first analog signal, the second analog signal, and the third analog signal to the PLC.

[0019] The programmable logic controller is used to determine whether the bar screen motor is overloaded based on a first analog signal, whether the bar screen motor is faulty based on a second analog signal, and whether the bar screen motor is faulty based on a third analog signal.

[0020] Preferably, it also includes an alarm module connected to the fault determination module, used to obtain the operating status of the bar screen cleaner based on the output of the fault determination module, and generate an alarm signal when the bar screen cleaner malfunctions.

[0021] Preferably, it also includes a host computer connected to the fault determination module, used to generate alarm information based on the output of the fault determination module.

[0022] Preferably, it also includes a display device connected to the host computer for displaying alarm information, thereby realizing alarm on the central control configuration screen.

[0023] Preferably, the power supply module of the motor protection device is connected to the main power supply of the bar screen cleaner through a circuit breaker. It is used to transform, rectify, filter, and stabilize the electrical signal output by the main power supply to output low-voltage DC power, thereby supplying power to the current signal acquisition module, fault judgment module, and overload protection module.

[0024] This utility model also provides an electrical control system for a bar screen machine, including:

[0025] Grille motor;

[0026] The control circuit is connected to the main circuit of the bar grid motor and is used to send drive signals to the main circuit of the bar grid motor to control the output of mechanical energy of the bar grid motor, thereby driving the bar grid machine to run.

[0027] The aforementioned motor protection device.

[0028] This utility model also provides a bar screen cleaning machine, which includes the above-mentioned bar screen machine electrical control system.

[0029] The motor protection device for a bar screen cleaning machine provided in this application uses a current signal acquisition module to collect the three-phase current signal of the bar screen motor and a fault determination module to compare the three-phase current signal with the overcurrent threshold to determine whether there is an overload risk to the bar screen motor. Since the overcurrent threshold is set based on the rated current of the bar screen motor and the actual operating current of the equipment on site, under the set overcurrent threshold, whether the increase in bar screen motor current is caused by the bar screen grab bucket jamming or other faults, as long as the current value of the bar screen motor exceeds the overcurrent threshold, the overload protection module can take protective action, that is, output a passive node disconnection signal to the control circuit in the electrical control system of the bar screen machine, thereby cutting off the connection between the control circuit and the main circuit of the bar screen motor, avoiding the wire rope breakage caused by the bar screen motor failure, ensuring the normal and stable operation of the bar screen cleaning machine, and thus reducing the daily maintenance and repair workload of the bar screen cleaning machine. The motor protection device provided in this application determines whether the bar screen motor is overloaded based on a pre-set overcurrent threshold. It can not only safely protect the equipment but also avoid the problem that in the prior art, the thermal relay can only take protective action when the current of the bar screen motor reaches 6 times the rated current, while the current of the bar screen cleaner cannot reach 6 times the rated current even under overload conditions, thus failing to effectively protect the bar screen motor. Attached Figure Description

[0030] To make the content of this utility model easier to understand, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein:

[0031] Figure 1 A schematic diagram of the motor protection device provided in this application;

[0032] Explanation of reference numerals in the accompanying drawings: 1. Motor protection device; 11. Current signal acquisition module; 12. Fault determination module; 121. Analog output module; 122. Communication interface; 123. Programmable logic device; 13. Overload protection module; 14. Switch signal acquisition module; 15. Zero-sequence current transformer; 16. Alarm module; 17. Power supply module; 2. Grille motor; 3. Control circuit. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments are not intended to limit the present invention.

[0034] Since the bar screen cleaner is an important piece of equipment for filtering and removing debris from the main influent of a sewage treatment plant, its normal and stable operation directly affects the influent flow. In the existing technology, the protection device for the bar screen cleaner uses a thermal relay. However, the thermal relay can only take protective action when the current of the bar screen motor reaches about 6 times its rated current. In actual use, even when the bar screen grab bucket jams, causing the current of the bar screen motor to rise and resulting in an overload problem, the output current of the bar screen motor cannot reach 6 times the rated current. This causes the thermal relay to fail to take protective action in time to avoid overload failure of the bar screen motor, thereby affecting the operation of the bar screen cleaner. Therefore, the purpose of this application is to detect the fault of the bar screen cleaner in time, so as to disconnect the connection of the main circuit of the bar screen motor in time when the fault occurs, thereby reducing the equipment failure rate and reducing the workload of equipment maintenance and repair.

[0035] Please see Figure 1 , Figure 1 The diagram shows the structure of the motor protection device provided in this application. In the diagram, 1 is the motor protection device, 2 is the bar screen motor in the electrical control system of the bar screen cleaning machine, and 3 is the control circuit in the electrical control system of the bar screen cleaning machine.

[0036] Specifically, the motor protection device 1 includes a current signal acquisition module 11, a fault determination module 12, and an overload protection module 13.

[0037] like Figure 1 As shown, the input terminal of the current signal acquisition module 11 is connected to the power supply terminal of the bar grid motor 2 in the electrical control system of the bar grid machine, and is used to acquire the three-phase current signal of the bar grid motor 2.

[0038] The input terminal of the fault determination module 12 is connected to the current signal acquisition module 11 and is used to compare the three-phase current signal with the overcurrent threshold to determine whether the grid motor 2 is overloaded.

[0039] Specifically, the overcurrent threshold needs to be set according to the rated current of the bar grid motor 2 and the actual operating current of the field equipment. Whether the increase in current of the bar grid motor 2 is caused by the bar grid machine's grab bucket jamming or by other faults, as long as the current signal output by the bar grid motor 2 is greater than the overcurrent threshold, it indicates that the bar grid motor 2 has been overloaded.

[0040] The input terminal of the overload protection module 13 is connected to the fault determination module 12, and the output terminal is connected to the control circuit 3 in the electrical control system of the bar screen machine. When the bar screen motor 2 is overloaded, it outputs a passive node disconnection signal to the control circuit 3 to cut off the connection between the control circuit 3 and the main circuit of the bar screen motor 2.

[0041] Specifically, such as Figure 1As shown, the output terminal of the overload protection module 13 is connected to the control circuit 3 through the contactor KM, and is also connected to KM in the main circuit of the control circuit 3 and the main circuit of the grid motor 2. The connection and disconnection of the control circuit 3 and the main circuit of the grid motor 2 can be controlled by controlling the on and off of the contactor KM.

[0042] The motor protection device provided in this application determines whether the bar screen motor is overloaded based on a pre-set overcurrent threshold. It can not only safely protect the equipment but also avoid the problem that in the prior art, the thermal relay can only take protective action when the current of the bar screen motor reaches 6 times the rated current, while the current of the bar screen cleaner cannot reach 6 times the rated current even under overload conditions, thus failing to effectively protect the bar screen motor.

[0043] Furthermore, in addition to monitoring whether the bar screen motor 2 is overloaded, the working status of the bar screen machine will also affect the operating status of the bar screen cleaner. The bar screen cleaner is often equipped with a variety of sensors for monitoring the operating status of the bar screen machine. Therefore, this application judges whether the bar screen machine has malfunctioned based on the switching signals of these bar screen machine detection sensors, so as to promptly disconnect the connection between the main circuit of the bar screen motor 2 and the control circuit 3 when a malfunction of the bar screen machine is detected.

[0044] Specifically, such as Figure 1 As shown, the motor protection device 1 also includes a switch signal acquisition module 14, which is connected to the bar screen detection sensor and is used to acquire the switch signal of the bar screen detection sensor.

[0045] Furthermore, based on the switch signal acquisition module 14, the fault determination module 12 is also used to determine whether the bar screen machine has malfunctioned based on the switch signal.

[0046] The overload protection module 13 is also used to output a passive node disconnect signal to the control circuit 3 when the bar screen machine fails, so as to cut off the connection between the control circuit 3 and the main circuit of the bar screen motor 2.

[0047] Specifically, common detection sensors for bar screen machines and their output signals include: limit sensors, which are installed at the extreme positions of the bar screen machine's mechanical movement. When the grab bucket of the bar screen machine reaches the extreme position, the sensor limit switch will be activated, and a switching signal will be output; pressure sensors, which are installed at the grab bucket resistance detection position. When the resistance on the grab bucket exceeds the set value, the internal contact will activate, and a switching signal will be output; and temperature sensors, which are installed at locations prone to heat generation, such as bearings. When the temperature at this location exceeds the threshold, the internal bimetallic strip deformation contact will activate, and a switching signal will be output. Therefore, the operating status of the bar screen machine can be determined based on the switching signals or changes in the switching signals of each sensor.

[0048] Furthermore, in some embodiments, the balance of the three-phase current signal of the bar grid motor 2 can be detected to detect whether a single-phase ground fault has occurred in the bar grid motor 2, so that when a single-phase ground fault occurs in the bar grid motor 2, the connection between the control circuit 3 and the main circuit of the bar grid motor 2 is cut off, so that the bar grid cleaner stops running.

[0049] Specifically, such as Figure 1 As shown, the motor protection device 1 also includes a zero-sequence current transformer 15, which is connected to the current signal acquisition module 11 and is used to monitor the balance of the three-phase current signal, thereby detecting the zero-sequence current in the current signal output by the grid motor 2.

[0050] Furthermore, based on the zero-sequence current transformer 15, the fault determination module 12 is also used to determine whether the grid motor 2 has failed based on the magnitude of the zero-sequence current.

[0051] The overload protection module 13 is also used to output a passive node disconnect signal to the control circuit 3 when the grid motor 2 fails, so as to cut off the connection between the control circuit 3 and the main circuit of the grid motor 2.

[0052] Specifically, the zero-sequence current transformer 15 is used to detect the vector sum of the three-phase current signals. The zero-sequence current value can be obtained by the magnitude of the vector sum. In actual use, due to factors such as load fluctuations, a small zero-sequence current is usually allowed. Therefore, by comparing the zero-sequence current value with the pre-set zero-sequence current threshold, when the zero-sequence current value is greater than the zero-sequence current threshold, it indicates that the bar grid motor 2 has an abnormality such as grounding fault or three-phase imbalance. At this time, the connection between the control circuit 3 and the main circuit of the bar grid motor 2 can be cut off to prevent the bar grid motor 2 from continuing to run and causing the bar grid cleaning machine to malfunction.

[0053] Furthermore, such as Figure 1 As shown, in some embodiments of this application, the fault determination module 12 includes an analog output module 121, a communication interface 122, and a programmable logic controller 123.

[0054] The analog output module 121 is connected to the current signal acquisition module 11, the switch signal acquisition module 14 and the zero-sequence current transformer 15, and is used to convert the three-phase current signal, the switch signal and the zero-sequence current into the first analog signal, the second analog signal and the third analog signal.

[0055] The input terminal of the communication interface 122 is connected to the analog output module 121, and the output terminal is connected to the programmable logic controller 123, which is used to output the first analog signal, the second analog signal and the third analog signal to the programmable logic controller 123.

[0056] The programmable logic controller 123 is used to determine whether the bar grid motor 2 is overloaded based on the first analog signal, whether the bar grid motor is faulty based on the second analog signal, and whether the bar grid motor 2 is faulty based on the third analog signal.

[0057] Optionally, the motor protection device 1 may further include an alarm module 16, which is connected to the fault determination module 12 and is used to obtain the operating status of the bar screen cleaner 2 based on the output of the fault determination module 12, and generate an alarm signal when the bar screen cleaner 2 malfunctions.

[0058] like Figure 1 As shown, in some embodiments of this application, the power module 17 of the motor protection device 1 is connected to the main power supply of the bar screen cleaner through a circuit breaker. It is used to transform, rectify, filter and stabilize the electrical signal output by the main power supply and then output low-voltage DC power to power the current signal acquisition module 11, the fault judgment module 12 and the overload protection module 13.

[0059] Furthermore, in some embodiments, the motor protection device 2 also includes a host computer connected to the fault determination module 12, which is used to generate alarm information based on the output of the fault determination module 12.

[0060] Furthermore, in some embodiments, the motor protection device 2 also includes a display device connected to a host computer for displaying alarm information, thereby realizing alarm on the central control configuration screen.

[0061] Based on the motor protection device provided in the above embodiments, this application also provides an electrical control system for a bar screen machine, which specifically includes a bar screen motor, a control circuit, and a motor protection device.

[0062] The control circuit is connected to the main circuit of the bar grid motor and is used to send drive signals to the main circuit of the bar grid motor to control the output of mechanical energy of the bar grid motor, thereby driving the bar grid machine to run.

[0063] This application also provides a bar screen cleaning machine, which includes the above-described bar screen electrical control system.

[0064] Through practical use verification, it was found that the bar screen cleaning machine provided in this application embodiment avoids frequent wire rope breakage. No wire rope breakage occurred during long-term operation, effectively improving the stability of equipment operation, ensuring the normal and reliable operation of the coarse bar screen water inlet system, reducing the equipment failure rate, and when the bar screen machine experiences jamming of the grab bucket mechanical transmission mechanism or exceeds the grab head tension range, the motor protection device can act in a timely and reliable manner, enabling operators to promptly notify maintenance personnel to check the equipment after discovering the central control alarm signal. Meanwhile, it also reduces damage to wire ropes, grippers, tracks, and other mechanical transmission mechanisms, comprehensively lowering the equipment failure rate, reducing manual maintenance workload, and reducing repair costs. Previously, each bar screen cleaning machine required wire rope replacement every 2-3 months, with each replacement requiring at least 3 workers and about half a day. The annual cost of replacing parts and labor for three bar screen cleaning machines was approximately 20,000 yuan. The bar screen cleaning machine provided in this application can operate stably for over a year, greatly reducing the labor and economic costs of parts replacement. Furthermore, the maintenance process of bar screen cleaning machines involves confined space operations with multiple hazards. The reduced failure rate of the bar screen cleaning machine provided in this application further reduces safety risks such as falls, mechanical injuries, and poisoning during equipment maintenance.

[0065] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the protection scope of this invention.

Claims

1. An electric motor protection device, characterized in that, For use in bar screen cleaning machines, including: The current signal acquisition module has its input terminal connected to the power supply terminal of the bar screen motor in the electrical control system of the bar screen machine, and is used to acquire the three-phase current signal of the bar screen motor. The switch signal acquisition module is connected to the bar screen detection sensor and is used to acquire the switch signals of the bar screen detection sensor. The zero-sequence current transformer, connected to the current signal acquisition module, is used to monitor the balance of the three-phase current signal, thereby detecting the zero-sequence current in the current signal output by the grid motor. The fault determination module, whose input is connected to the current signal acquisition module, is used to compare the three-phase current signal with the overcurrent threshold to determine whether the bar grid motor is overloaded; to determine whether the bar grid motor is faulty based on the switch signal; and to determine whether the bar grid motor is faulty based on the zero-sequence current magnitude. The overload protection module has its input connected to the fault determination module and its output connected to the control circuit of the bar screen motor in the electrical control system of the bar screen machine. When the bar screen motor experiences an overload, it outputs a passive node disconnect signal to the control circuit to cut off the connection between the control circuit and the main circuit of the bar screen motor; when the bar screen machine malfunctions, it outputs a passive node disconnect signal to the control circuit to cut off the connection between the control circuit and the main circuit of the bar screen motor; when the bar screen motor malfunctions, it outputs a passive node disconnect signal to the control circuit to cut off the connection between the control circuit and the main circuit of the bar screen motor.

2. The motor protection device of claim 1, wherein The fault diagnosis module includes: The analog output module is connected to the current signal acquisition module, the switch signal acquisition module and the zero-sequence current transformer, and is used to convert the three-phase current signal, the switch signal and the zero-sequence current into the first analog signal, the second analog signal and the third analog signal. The communication interface has an input terminal connected to the analog output module and an output terminal connected to the programmable logic controller (PLC), used to output the first analog signal, the second analog signal, and the third analog signal to the PLC. The programmable logic controller is used to determine whether the bar screen motor is overloaded based on a first analog signal, whether the bar screen motor is faulty based on a second analog signal, and whether the bar screen motor is faulty based on a third analog signal.

3. The motor protection apparatus of claim 2, wherein It also includes an alarm module, which is connected to the fault determination module. It is used to obtain the operating status of the bar screen cleaner based on the output of the fault determination module, and generate an alarm signal when the bar screen cleaner malfunctions.

4. The motor protection apparatus of claim 2, wherein It also includes a host computer, which is connected to the fault determination module and is used to generate alarm information based on the output of the fault determination module.

5. The motor protection apparatus of claim 4, wherein It also includes a display device, which is connected to the host computer to display alarm information, thereby realizing alarm on the central control configuration screen.

6. The motor protection apparatus of claim 1, wherein The power module of the motor protection device is connected to the main power supply of the bar screen cleaner through a circuit breaker. It is used to transform, rectify, filter and stabilize the electrical signal output by the main power supply to output low-voltage DC power, thereby powering the current signal acquisition module, fault judgment module and overload protection module.

7. A grid electromechanical control system, characterized by, include: Grille motor; The control circuit is connected to the main circuit of the bar grid motor and is used to send drive signals to the main circuit of the bar grid motor to control the output of mechanical energy of the bar grid motor, thereby driving the bar grid machine to run. The motor protection device according to any one of claims 1-6.

8. A bar screen, characterized in that The grid cleaner comprises the grid machine electrical control system according to claim 7.

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