1. Use the analog output module of the PLC to control the inverterThe analog output module of the PLC outputs a 0-5V voltage signal or a 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 drives – safety precautions for the installation of drives
When the inverter is installed and wired;
Note: When more than two inverters are installed in the same cabinet, please pay attention to the installation position and spacing to ensure the heat dissipation effect.
Dangerous:
1. It should be operated by professional electrical engineering personnel, otherwise there is a risk of electric shock.
2. Please make sure before wiring...
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Various welding methods for Megmeet welding machines
1) Hand arc welding (STICK)
Shielded Arc Welding (abbreviated SMAW) in English,
The principle is: the arc occurs between the coating electrode and the base metal, and the welding method of arc thermal ablation electrode and base metal is used. The outer layer of the electrode is covered with solder, which is dissipated in case of heat.
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Megmeet welding machine - resistance welding or laser soldering who is more suitable for electronics industry applications
Today's electronics industry revolves around high-speed communication and supercomputing on the Internet, and the requirements for electronic products are getting higher and higher. A large number of micro-precision electronic products are constantly testing the response speed and level of major enterprises in the market. Electronics manufacturers perform real-time, accurate ...
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Megmeet PLC - What are the five stages of the PLC work process?
1. Common processing: reset the monitoring timer, perform hardware checks, user memory checks, etc.
2. Program execution: The CPU interprets and executes each instruction in the order of first left and then right, first up and then down, and reads out each relay according to the input image register and the component image register.
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Common faults and solutions of Megmeet inverter
1. Leakage protection switch
Phenomenon: The leakage protection switch of the equipment is activated when the inverter is powered on or running
Measures:
When the inverter drives the motor, the leakage value is larger than that of the non-inverter system, and the leakage protection value of the leakage protection switch is required to be 150mA and above, and the action delay is ...
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Megmeet inverter - maintenance precautions and items for high-voltage inverters
Precautions for maintenance of high-voltage inverters
1. Carefully monitor and record the display parameters on the man-machine interface of the inverter, and reflect the abnormality immediately
2. Carefully monitor and record the ambient temperature of the inverter room, and the ambient temperature should be between -5 °C and 40 °C. Phase-shifting transformers ...
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Megmeet inverter - common faults and treatment methods of high-voltage inverters
The high-voltage inverter has a highly intelligent computing level and a perfect fault detection circuit, and can provide accurate positioning of all faults, and make clear instructions on the main control interface. In practical application, we find that common faults can be divided into abnormal control channels, IGBT overcurrent, overvoltage...
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The principle and characteristics of Megmeet tungsten argon arc welding and resistance welding
3) Tungsten argon arc welding (TIG)
Non-melting electrode gas arc welding, TIG welding, English is Tungsten Inert Gas (abbreviated TIG), also known as Gas Tungsten Arc Welding (abbreviated GTAW)
The principle is: TIG welding is in argon and other inert gases.
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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 PLC – The importance of PLC industrial gateways
1. Realize remote control of industrial field equipment;
2. The PLC industrial gateway realizes remote upgrade of equipment firmware, downloads the program, and can flexibly access various equipment management platforms;
3. Realize remote control of industrial site touch screen and remote mapping of configuration screens;
4. PLC industry ...
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Common faults and solutions of Megmeet inverter
Fault one
Fault phenomenon: the leakage protection switch trips, the inverter is energized or the equipment leakage protection switch is operated during operation
Solution: 1. When the inverter drives the motor, the leakage value is larger than that of the non-inverter system, and the leakage protection value of the leakage protection switch is required to be more than 150mA, ...
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Maintenance inspection of Megmeet inverters
1. The Megmeet rectifier module is damaged
It is usually caused by grid voltage or internal short circuit. In the case of sweeping the internal short circuit, the rectifier bridge is replaced. When dealing with faults on site, we should focus on checking the status of the user's power grid.
Such as the power grid voltage, whether there is an electric welding machine, etc.
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Megmeet inverter - a common measure for anti-interference of high-voltage inverters
(1) The E end of the high-voltage inverter should be connected to the shell of the control cabinet and the motor, and should be connected to the ground, and the grounding resistance should be less than 100Ω, which can absorb surge interference.
(2) The input or output of the high-voltage inverter is equipped with an inductive magnetic ring filter. Flat and 3-4 turns, helps to inhibit ...
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Megmeet PLC - the basic composition of PLC
a. Power supply
The power supply of the PLC plays a very important role in the whole system. It can't work properly without a good and reliable power supply system, so PLC manufacturers also attach great importance to the design and manufacture of power supplies. General AC voltage fluctuations are +10% (+15%) ...
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Megmeet inverter - classification and introduction of high-voltage inverter
There are many types of high-voltage inverters, and their classification methods are also diverse. According to whether there is a DC part in the intermediate link, it can be divided into AC inverter and AC AC inverter; According to the nature of the DC part, it can be divided into current type and voltage type inverter; According to whether there is an intermediate low-voltage circuit, it can be divided into high...
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Megmeet welding machine - the application and precautions for the use of butt welding machine
The butt welding machine should be settled indoors, and should have a reliable grounding or zero connection, when a plurality of butt welding machines are connected to each other, the distance from each other shall not be less than 3m, and they should be connected to different corresponding power grids, and should have their own knife switches.
Before welding, the pressure of the butt welder should be checked and determined.
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Solutions to common faults of Megmeet inverter (2)
Fault three
Fault phenomenon: There is a rebound phenomenon when the rotation starts
Solution: 1. Set the start frequency P08.02 and start frequency time P08.03 appropriately (such as P08.02=P08.03=0.5)
2. Appropriately reduce the stator resistance (P03.07) and no-load current value (P03.11 ...
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Megmeet inverter - heating noise harmonic problems in inverter applications and countermeasures
First, some problems in the application of frequency converter
1.1
Harmonic problems
The devices that play a switching role in the main circuit of the inverter must generate harmonics in the process of turning on and off the circuit. The lower harmonics usually have a greater impact on the motor load, causing torque ripple; And the higher ...
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Megmeet PLC – the three basic process contents of PLC work
1. Input processing
Input processing is also called input sampling. In this phase, the through-end state of all input terminals is read sequentially, and the read information is stored in the corresponding image register in memory. Here the input image register is flushed. Then the program execution phase begins. In the execution of the procedure ...
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