(1) Use the analog output module of PLC to control the analog output module of the inverter The analog output module of the PLC outputs 0-5V voltage signal or 4-20mA current signal, which is used as the analog input signal of the inverter to control the output frequency of the inverter. This control mode wiring is simple, but the PLC output module that needs to be matched with the input impedance of the inverter needs to be selected, and the analog output module of the PLC is more expensive, in addition, the voltage divider measures are also needed to make the inverter adapt to the voltage signal range of the PLC, and the wiring is separated when connecting, so as to ensure that the noise on one side of the main circuit is not transmitted to the control circuit.
(2) Use the switching output of PLC to control the inverter. Generally, the switching output of the PLC can be directly connected to the switching input of the inverter. The wiring of this control method is simple and the anti-interference ability is strong. The switching output of PLC can control the start/stop, forward/reverse, jogging, speed and addition and subtraction time of the inverter, etc., which can realize more complex control requirements, but can only have step-by-step speed regulation.
When connecting with relay contacts, there may be misoperation due to poor contact. When using transistors for connection, it is necessary to consider factors such as the voltage and current capacity of the transistors themselves to ensure the reliability of the system. In addition, when designing the input signal circuit of the inverter, it should also be noted that the input signal circuit is not properly connected, which sometimes causes the malfunction of the inverter. For example, when the input signal circuit uses an inductive load such as a relay, and the relay is opened and closed, the noise caused by the inrush current generated may cause malfunction of the inverter, so it should be avoided as much as possible.
(3) The connection between PLC and RS-485 communication interface. All standard Siemens drives have an RS-485 serial interface (some also offer RS-232 interfaces) with a two-wire connection, and are designed as standard for applications in industrial environments. Up to 30 drives can be connected to a single RS-485 link, and the converters that need to communicate can be found depending on the address of each inverter or the broadcast information used. There needs to be a master controller (master) in the link, and each inverter is a subordinate control object (slave).
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Megmeet inverters – what are the development directions of inverter-related technologies?
1. Intelligent network
The intelligent inverter does not need to set a lot of parameters when it is used, and it has the function of fault self-diagnosis, which has high stability, high reliability and practicability. The Internet can be used to realize the linkage of multiple inverters, and even the inverter complex in the factory.
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Megmeet Inverter - Precautions for the Use of Inverter (1-10)
1. The inverter must be selected correctly.
2. Read the product manual carefully, and wiring, installation and use in accordance with the requirements of the manual.
3. The inverter device should be reliably grounded, and the radio frequency interference should be suppressed to prevent the inverter from causing electric shock due to leakage.
4、 ...
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Megmeet PLC - What is the difference between PLC and MCU?
1. PLC is a relatively mature control system composed of single-chip microcomputer, which is the product of a mature and stable single-chip microcomputer application system that has been debugged. It is highly versatile.
2. The single-chip microcomputer can form a variety of application systems, and the application range is wider. In the case of a single "microcontroller", it ...
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Megmeet inverter – the basic principle and application of high-voltage inverter
The basic principle of a high-voltage inverter
There are two categories of frequency conversion process of frequency converter: AC-AC form and AC-DC-AC form. Now it is mostly in the form of AC-DC-AC, and the following is a brief introduction to the working principle of this form.
Three-phase high-voltage electricity enters the high...
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Megmeet welding machine - failure and maintenance method of DC welding machine
1. Fault phenomenon: light voltage abnormal indicator
Cause: Due to the slow start-up action, the switch contact is not synchronized.
Solution: You can turn the device off and on again.
2. Fault phenomenon: the fan does not rotate, and the abnormal voltage indicator light is lit together
Causes ...
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Megmeet PLC – the maintenance steps of the PLC control cabinet
1. Data backup
When carrying out maintenance, we must cut off the power, data backup between power outages is an important link, for the data that needs to be archived for a long time, you can back up the historical trend data to the mobile hard disk, and then turn off the Windows-based operating system (Note...
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Megmeet inverter - heat dissipation design considerations for high-power high-voltage inverters
(1) Select components and materials with good heat resistance and thermal stability to increase their allowable working temperature;
(2) Reduce the heat generated inside the equipment (device). To this end, micropower devices, such as low-loss IGBTs, should be used more often, and the number of heat-generating components should be minimized in the circuit design.
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The application of Megmitte industrial control products in high-speed precision CNC machine tools
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Megmeet PLC - the difference between PLC and frequency converter
1. The role is different
A PLC (Programmable Logic Controller) is an electronic system designed for digital operations in an industrial environment.
The inverter is the application of frequency conversion technology and microelectronics technology to control the AC motor by changing the frequency of the motor working power supply.
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Megmeet drive common fault repair methods
When the oscilloscope looks at the current monitoring output of the driver, it is all noisy and cannot be read
Cause: The current monitoring output is not blocked from the AC power supply (transformer).
Solution: You can use a DC voltmeter to detect and investigate.
Servo motor high-speed rotation ...
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Megmeet PLC – Analysis of common failures of PLC
1. The CPU is abnormal
When the CPU is abnormally alarmed, check all the devices connected to the internal bus of the CPU unit. The specific method is to replace the potentially problematic units sequentially, find out the problematic units, and deal with them accordingly.
Second, the memory is abnormal
Memory anomaly alarm ...
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Analysis of the fault code of Megmeet welder
1. E1: indicates sensor failure. In this case, it is necessary to check whether the sensors of Megmeet are damaged or whether the wiring is loose.
2. E2: Indicates overweight load. At this point, it is necessary to check whether the load of Megmeet exceeds the set maximum load.
3. E3: Indicates battery ...
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Megmeet inverter – the difference between voltage type inverter and current type inverter
1. The load of the buffer inverter without functional quantity is an asynchronous motor, which is an inductive load, and in addition to transmitting active power between the intermediate DC link and the motor, there is also the exchange of reactive power. Since the power electronic switching devices cannot be stored for energy, the non-functional energy can only rely on the energy storage elements (filters).
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Megmeet PLC - the hardware composition of PLC control
1. Power components
The power supply assembly is used to provide the power required for the operation of the PLC, and the external power supply can be converted into a power supply for the PLC internal and applicable to the case.
2. Microprocessor CPU and memory components
Microprocessor CPU is the core device of PLC, and CPU is different from each manufacturer.
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Megmeet Electric participated in the 2021 CHINAPLAS World Rubber and Plastics Exhibition
From April 13 to 16, 2021, CHINAPLAS 2021 was grandly held at the Shenzhen World Convention and Exhibition Center (Bao'an New Hall) with the theme of "New Era· New Power, · Sustainable Innovation".
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Megmeet drives – what are the components of a drive?
The inverter is composed of a main circuit, a rectifier, a flat wave circuit, and an inverter.
1) Main circuit:
The main circuit is the power conversion part that provides voltage regulation and frequency regulation power supply for the asynchronous motor, and the main circuit of the inverter can be roughly divided into two categories: the voltage type is the DC ...
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Megmeet inverter - the role and application of the inverter control cabinet introduction
Inverter control cabinet (inverter electrical control cabinet / electric control cabinet / electric control box) is an electrical control cabinet developed by using inverters from Siemens, ABB, Schneider, Fujifilm, Mitsubishi, Panasonic, Delta, Shilin, Inovance and other manufacturers.
According to the needs of working conditions, AC transmission can be installed in the frequency conversion cabinet.
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Megmeet drives – a common fault in low-voltage drives
External electromagnetic interference can easily cause malfunctions
If there are interference sources around the inverter, they will invade the inside of the inverter through radiation or power lines, causing the control loop to malfunction, causing abnormal operation or shutdown, and even damage to the inverter in severe cases. Noise suppression on the outside ...
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Megmeet welding machine - an introduction to the advantages and disadvantages of resistance welding
Advantages of resistance welding:
1。 When a nugget is formed, it is always surrounded by a ring of plastic, the molten metal is isolated from the air, and the metallurgical process is simple
2。 The heating time is short, the heat is concentrated, the heat affected zone is small, and the deformation and stress are small. In general, there is no need to arrange calibration and heat after welding.
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Megmeet PLC - the core components of PLC introduction
(1) Central Processing Unit (CPU)
The central processing unit (CPU) is the control center of the PLC. It accepts and stores user programs and data typed from the programmer, checks the status of the power supply, memory, I/O and alert timer in accordance with the functions assigned by the PLC system program, ...
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