AC contactor monitoring control circuit

Abstract

The utility model belongs to the technical field of electrical control, and particularly discloses a monitoring control circuit of an alternating current contactor. The circuit comprises a power supply, a single-chip microcomputer, a state monitoring module, an inter-phase voltage and inter-contact terminal voltage isolation monitoring module, a three-phase input voltage isolation monitoring module, a power-off contact, an alarm contact and a master control circuit contact. The state monitoring module is connected with two coil terminals of the contactor; three monitoring points of the three-phase input voltage isolation monitoring module are connected with three input power supply contacts of the contactor; six monitoring points of the inter-phase voltage and inter-contact terminal voltage isolation monitoring module are connected with three power input contacts and three output contacts of the contactor; the output end of the single-chip microcomputer is respectively connected with the input ends of the power-off contact, the alarm contact and the master control circuit contact. According to the utility model, the parameters of the AC contactor in the start-stop state can be monitored, faults can be found in time, and the operation safety of the motor is protected. The AC contactor monitoring device is suitable for monitoring the AC contactor.

Description

Technical Field

[0001] The utility model belongs to the technical field of electrical control and relates to an AC contactor monitoring control circuit. Background Art

[0002] AC contactors play a crucial role in the motor control circuits of large-scale equipment. However, during routine operation, AC contactors are prone to two common faults: 1. Contact erosion, poor contact, or loss of power, which can lead to unbalanced three-phase load currents; 2. Contacts sintering, preventing proper disconnection, or even preventing normal disconnection. This poses the risk of the motor self-starting upon power-up. Consequently, due to a lack of monitoring of AC contactors, any problems with the contactors can result in equipment failure, at best, or even motor damage due to phase loss, overcurrent, or even spontaneous combustion, leading to safety incidents and significant losses. This hazard is particularly severe when the equipment is unattended. Summary of the Invention

[0003] The purpose of this utility model is to provide an AC contactor monitoring control circuit, which can monitor various parameters of the AC contactor in the stopped state and the working state throughout the whole process, timely discover sudden faults of the AC contactor, and protect the safe operation of the motor.

[0004] In order to achieve the above-mentioned purpose, the technical solutions adopted by the present invention are as follows:

[0005] An AC contactor monitoring and control circuit includes a power supply and a single-chip microcomputer, as well as a status monitoring module, a phase-to-phase voltage and contact terminal voltage isolation monitoring module, a three-phase input voltage isolation monitoring module, a power-off contact for powering off the AC contactor, an alarm contact, and a main control circuit contact for controlling the start and stop of the AC contactor;

[0006] The two monitoring points of the state monitoring module are respectively connected to the two coil terminals of the AC contactor, and the signal output end of the state monitoring module is connected to the signal input end of the single chip microcomputer;

[0007] The three monitoring points of the three-phase input voltage isolation monitoring module are respectively connected to the three input power contacts of the AC contactor, and the signal between the three-phase input voltage isolation monitoring module and the single-chip microcomputer is interconnected at both ends;

[0008] The six monitoring points of the phase-to-phase voltage and contact terminal voltage isolation monitoring module are respectively connected to the three power input contacts and three output contacts of the AC contactor, and the phase-to-phase voltage and contact terminal voltage isolation monitoring module and the single-chip microcomputer have two-terminal signal communication;

[0009] The power supply is connected to the power supply port of the single chip microcomputer, and the signal output end of the single chip microcomputer is respectively connected to the signal input ends of the power-off contact, the alarm contact and the main control circuit contact.

[0010] As a limitation, the monitoring circuit also includes three contact temperature measuring resistors and a temperature monitoring module;

[0011] The three contact temperature measuring resistors are located on the three-phase static contacts of the AC contactor. The three monitoring points of the temperature monitoring module are respectively connected to the three contact temperature measuring resistors. The temperature monitoring module and the single chip microcomputer have dual-end signal communication.

[0012] As a further limitation, the contact temperature measuring resistor is a ceramic package resistor.

[0013] As a further limitation, the contact temperature measuring resistor is connected to the three-phase static contact through a thermally conductive adhesive.

[0014] As a limitation on the connection method, the status monitoring module, phase-to-phase voltage and contact terminal voltage isolation monitoring module, three-phase input voltage isolation monitoring module, temperature monitoring module, power-off contact, alarm contact and main control circuit contact are connected to the microcontroller through the RS485 bus.

[0015] As a second limitation, the monitoring and control circuit further includes a host computer and a communication circuit;

[0016] The single chip microcomputer is connected to the host computer via a communication circuit.

[0017] As the present invention adopts the above technical solution, compared with the prior art, the technical progress achieved is:

[0018] (1) The utility model adds a monitoring circuit with independent power supply to the AC contactor, which can monitor the voltage of the AC contactor in the stopped state and the voltage and temperature in the working state throughout the whole process, timely detect the contact failure of the AC contactor, and protect the safe operation of the motor and equipment;

[0019] (2) The utility model uses a ceramic package resistor when measuring the temperature of the three-phase static contact of the AC contactor, which can continuously and stably measure the temperature with high precision, thereby improving the reliability of temperature measurement;

[0020] (3) The utility model uses thermal conductive glue to connect the contact temperature measuring resistor and the three-phase static contact, thereby strengthening the temperature transfer between the contact temperature measuring resistor and the three-phase static contact and improving the measurement accuracy of the contact temperature measuring resistor;

[0021] (4) The utility model uses the RS485 bus to communicate between the contacts of each module and the single-chip microcomputer, which can ensure the transmission rate and stability of communication between multiple modules;

[0022] (5) The present invention adds a communication circuit and a host computer. The single chip microcomputer can upload the monitored information to the host computer through the communication circuit for display and storage, which is conducive to the subsequent analysis of the AC contactor monitoring data.

[0023] The utility model belongs to the field of electrical control technology, can monitor various parameters of an AC contactor in the start and stop states throughout the entire process, timely discover sudden failures of the AC contactor, and protect the safe operation of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation to the present invention.

[0025] In the attached figure:

[0026] Figure 1 This is a schematic diagram of the overall connection relationship of the AC contactor monitoring control circuit in Example 1 of the present utility model.

[0027] In the figure: 1. AC contactor, 2. Input U-phase power contact, 3. Input V-phase power contact, 4. Input W-phase power contact, 5. Coil A1 terminal, 6. Coil A2 terminal, 7. U-phase contact temperature measuring resistor, 8. V-phase contact temperature measuring resistor, 9. W-phase contact temperature measuring resistor, 10. Output R-phase contact, 11. Output S-phase contact, 12. Output T-phase contact, 13. Main control circuit contact, 14. Alarm contact, 15. Power-off contact. DETAILED DESCRIPTION

[0028] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0029] Example 1 An AC contactor monitoring control circuit

[0030] like Figure 1 As shown, this embodiment includes a power supply, a single-chip microcomputer, a host computer, a communication circuit, a status monitoring module, a phase-to-phase voltage and contact terminal voltage isolation monitoring module, a three-phase input voltage isolation monitoring module, a temperature monitoring module, three contact temperature measuring resistors, a power-off contact 15 for powering off the AC contactor 1, an alarm contact 14, and a main control circuit contact 13 for controlling the start and stop of the AC contactor 1.

[0031] The two monitoring points of the status monitoring module are respectively connected to the two coil terminals, coil A1 terminal 5 and coil A2 terminal 6, of the AC contactor 1; the three monitoring points of the three-phase input voltage isolation monitoring module are respectively connected to the input U-phase power contact 2, input V-phase power contact 3 and input W-phase power contact 4 of the AC contactor 1; the six monitoring points of the phase-to-phase voltage and contact terminal voltage isolation monitoring module are respectively connected to the input U-phase power contact 2, input V-phase power contact 3, input W-phase power contact 4, output R-phase contact 10, output S-phase contact 11 and output T-phase contact 12 of the AC contactor 1.

[0032] The three contact temperature measuring resistors are ceramic packaged resistors and are attached to the three-phase static contacts of AC contactor 1 using thermally conductive adhesive. Based on their positions, they are divided into U-phase contact temperature measuring resistor 7, V-phase contact temperature measuring resistor 8, and W-phase contact temperature measuring resistor 9. The three monitoring points of the temperature monitoring module are connected to the three contact temperature measuring resistors respectively.

[0033] The power supply is connected to the microcontroller's power supply port. The microcontroller's signal output is connected to the power-off contact 15, alarm contact 14, and the signal input of the main control circuit contact 13, respectively. The microcontroller and the host computer are connected via a communication circuit. The signal output of the status monitoring module is connected to the signal input of the microcontroller. The three-phase input voltage isolation monitoring module, the phase-to-phase voltage and contact terminal voltage isolation monitoring module, and the temperature monitoring module are interconnected with the microcontroller.

[0034] In this embodiment, the communication between the components is connected using the RS485 bus, which can ensure the transmission rate and stability of communication between multiple modules.

[0035] When this embodiment is in use, after the three-phase power supply is sent to the input U-phase power supply contact 2, the input V-phase power supply contact 3 and the input W-phase power supply contact 4 of the AC contactor 1, the status monitoring module detects that there is no voltage between the coil A1 terminal 5 and the coil A2 terminal 6 of the AC contactor 1, and transmits the information to the single-chip microcomputer. The single-chip microcomputer simultaneously sends a voltage monitoring instruction to the three-phase input voltage isolation monitoring module and the phase voltage and contact terminal voltage isolation monitoring module.

[0036] The three-phase input voltage isolation monitoring module monitors the voltages of the three points of the input U-phase power contact 2, the input V-phase power contact 3 and the input W-phase power contact 4 of the AC contactor 1. If the voltages of the three points are found to be abnormal, the three-phase input voltage isolation monitoring module transmits the information to the single-chip microcomputer, and the single-chip microcomputer sends a closing instruction to the alarm contact 14. The alarm contact 14 closes and the external alarm sounds. The single-chip microcomputer uploads the relevant information to the host computer through the communication circuit for display and storage. The phase-to-phase voltage and contact terminal voltage isolation monitoring module monitors the voltage between the input U-phase power contact 2 and the output R-phase contact 10, between the input V-phase power contact 3 and the output S-phase contact 11, and between the input W-phase power contact 4 and the output T-phase contact 12. If abnormal voltage is detected, this situation is generally caused by contact adhesion. The phase-to-phase voltage and contact terminal voltage isolation monitoring module will transmit the information to the microcontroller, and the microcontroller will send a closing instruction to the alarm contact 14, the alarm contact 14 will close, and the external alarm will sound; the microcontroller will upload the relevant information to the host computer through the communication circuit for display and storage; at the same time, the microcontroller will send a power-off signal to the power-off contact 15, and the power-off contact 15 will close, causing the circuit breaker or the upper-level contactor to trip.

[0037] If neither the three-phase input voltage isolation monitoring module nor the phase-to-phase voltage and contact terminal voltage isolation monitoring module detects an abnormality, the microcontroller sends a close command to main control circuit contact 13, causing it to close and AC contactor 1 to begin normal operation. At this point, the status detection module detects that the voltage between coil A1 terminal 5 and coil A2 terminal 6 of AC contactor 1 is normal and transmits this information to the microcontroller. The microcontroller then continues to send monitoring commands to the three-phase input voltage isolation monitoring module, the phase-to-phase voltage and contact terminal voltage isolation monitoring module, and the temperature monitoring module.

[0038] The three-phase input voltage isolation monitoring module monitors the voltages at three points in real time: AC contactor 1's input U-phase power contact 2, input V-phase power contact 3, and input W-phase power contact 4. If a voltage anomaly is detected, the module transmits this information to the microcontroller. The microcontroller issues a disconnect command to main control circuit contact 13, causing the main control circuit contact 13 to open, de-energizing the coil of AC contactor 1 and placing it in a stopped state. The microcontroller also issues a close command to alarm contact 14, causing it to close and trigger an external alarm. The microcontroller then uploads this information to the host computer via a communication circuit for display and storage.

[0039] The phase-to-phase voltage and contact terminal voltage isolation monitoring module monitors the voltage between input U-phase power contact 2 and output R-phase contact 10, between input V-phase power contact 3 and output S-phase contact 11, and between input W-phase power contact 4 and output T-phase contact 12 in real time. If the voltage exceeds the set value, the phase-to-phase voltage and contact terminal voltage isolation monitoring module transmits the information to the microcontroller. The microcontroller issues a disconnect command to main control circuit contact 13, causing it to open, de-energizing the coil of AC contactor 1 and placing it in a stopped state. The microcontroller also issues a close command to alarm contact 14, causing it to close and triggering an external alarm. The microcontroller also uploads the relevant information to the host computer via the communication circuit for display and storage.

[0040] The temperature monitoring module monitors the temperature of the U-phase contact temperature measuring resistor 7, the V-phase contact temperature measuring resistor 8 and the W-phase contact temperature measuring resistor 9 in real time. Once the contact temperature exceeds the set value, the temperature monitoring module transmits the information to the single-chip microcomputer, and the single-chip microcomputer sends a closing instruction to the alarm contact 14, the alarm contact 14 closes, and the external alarm sounds; at the same time, the single-chip microcomputer uploads the relevant information to the host computer through the communication circuit for display and storage; if the contact temperature continues to rise and reaches the set power-off temperature, the single-chip microcomputer sends a disconnection instruction to the main control circuit contact 13, the main control circuit contact 13 is disconnected, the AC contactor 1 coil loses power and is in a stopped state.

[0041] In summary, this embodiment can monitor various parameters of the AC contactor 1 in the start and stop states throughout the entire process, detect faults of the AC contactor 1 in a timely manner, and protect the safe operation of the motor.

Claims

1. An AC contactor monitoring control circuit, comprising a power supply and a single chip microcomputer, characterized in that: It also includes a status monitoring module, a phase-to-phase voltage and contact terminal voltage isolation monitoring module, a three-phase input voltage isolation monitoring module, a power-off contact for powering off the AC contactor, an alarm contact, and a main control circuit contact for controlling the start and shut down of the AC contactor; The two monitoring points of the state monitoring module are respectively connected to the two coil terminals of the AC contactor, and the signal output end of the state monitoring module is connected to the signal input end of the single chip microcomputer; The three monitoring points of the three-phase input voltage isolation monitoring module are respectively connected to the three input power contacts of the AC contactor, and the signal between the three-phase input voltage isolation monitoring module and the single-chip microcomputer is interconnected at both ends; The six monitoring points of the phase-to-phase voltage and contact terminal voltage isolation monitoring module are respectively connected to the three power input contacts and three output contacts of the AC contactor, and the phase-to-phase voltage and contact terminal voltage isolation monitoring module and the single-chip microcomputer have two-terminal signal communication; The power supply is connected to the power supply port of the single chip microcomputer, and the signal output end of the single chip microcomputer is respectively connected to the signal input ends of the power-off contact, the alarm contact and the main control circuit contact.

2. An AC contactor monitoring control circuit according to claim 1, characterized in that: The monitoring circuit also includes three contact temperature measuring resistors and a temperature monitoring module; The three contact temperature measuring resistors are located on the three-phase static contacts of the AC contactor. The three monitoring points of the temperature monitoring module are respectively connected to the three contact temperature measuring resistors. The temperature monitoring module and the single chip microcomputer have dual-end signal communication.

3. The AC contactor monitoring control circuit according to claim 2, characterized in that: The contact temperature measuring resistor uses a ceramic package resistor.

4. The AC contactor monitoring control circuit according to claim 3, characterized in that: The contact temperature measuring resistor is connected to the three-phase static contact through heat-conducting glue.

5. An AC contactor monitoring control circuit according to any one of claims 2 to 4, characterized in that: The state monitoring module, phase-to-phase voltage and contact terminal voltage isolation monitoring module, three-phase input voltage isolation monitoring module, temperature monitoring module, power-off contact, alarm contact and main control circuit contact are connected to the single-chip microcomputer via an RS485 bus.

6. An AC contactor monitoring control circuit according to any one of claims 1 to 4, characterized in that: The monitoring and control circuit also includes a host computer and a communication circuit; The single chip microcomputer is connected to the host computer via a communication circuit.

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