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With the development of science and technology, Mitsubishi PLC in industrial control applications more and more widely, Mitsubishi reliability of PLC control system directly affects the production safety and economic operation of industrial enterprises. Mitsubishi PLC in practical applications there are many kinds of electromagnetic interference, the main source of Mitsubishi converter agent empty simple introduction Mitsubishi electromagnetic interference in PLC control system:
1, from space radiation interference
Space radiation electromagnetic field (EMI) is generated by electrical equipment of power network, the transient process, lightning, radio, TV, radar, high frequency induction heating equipment, usually called the radiation interference, its distribution is very complex. If Mitsubishi PLC system on the RF field, you'll be radiated interference, and its effects are mainly through two paths; one is the direct radiation on Mitsubishi inside PLC, interference by circuit induction; two is the radiation on the Mitsubishi Mitsubishi PLC communication network, introducing the interference by the communication line induction. Electromagnetic field radiated interference and field equipment layout and equipment produced, especially related to the frequency, usually by setting the shield cable and Mitsubishi PLC local shielding and high voltage discharge element protection
2, from the system outer lead interference
Mainly through power and signal line is introduced, usually called the conducted interference. This interference is serious in our country industrial field.
3, from the source of interference
The practice proved that, due to interference power caused by Mitsubishi PLC control system fault situation many, I encountered in some engineering commissioning, after the replacement Mitsubishi PLC power supply isolation performance is higher, the problem was solved.
The normal power supply Mitsubishi Mitsubishi PLC system by power supply. As the grid covering a wide range, will have all the space electromagnetic interference in line induction voltage and circuit. Especially the changes in the internal network, switching surges, large-scale power equipment start and stop, AC and DC rotating device caused by harmonics, grid short-circuit transient impact, through the transmission line to the supply side. Mitsubishi Mitsubishi PLC power usually adopts isolation power, but its mechanism and manufacturing process factors make the isolation is not ideal. In fact, the distribution parameters especially the distributed capacitance exist, absolute isolation is not possible.
4, from a signal line interference
All kinds of signal transmission line connected to the system control and Mitsubishi PLC, except for the transmission of various signal effectively, there are always external interference signal intrusion. This interference has mainly two ways: one is through the power interference in power supply transducer or shared signal meter in series, which are often ignored; two is the signal line interference from electromagnetic radiation induction of space, namely, external inductive interference signal line, this is a very serious. I/O signal interference can cause abnormal and the measurement accuracy is greatly reduced by signal is introduced, serious will cause the components damage. For the system isolation performance is poor, will also cause the signal mutual interference caused by system bus, total reflux, cause logical data change, malfunction and crash. PLC control system is introduced Mitsubishi because the signal interference caused by I/O module number quite serious damage, caused by system failure situation also many.
5, from direct interference to the system chaos
The ground is to improve the electromagnetic compatibility of electronic equipment (EMC) is one of the effective means of. Proper grounding, can inhibit the effect of electromagnetic interference, but also inhibit equipment outward emitted interference; and a false ground, but will introduce serious interference signals, the Mitsubishi PLC system will not work properly. Ground Mitsubishi PLC control system including system, shield, communication and protection etc.. Interference grounding system confusion on the Mitsubishi PLC system is the main place of potential uneven distribution of access, different ground potential difference exists between locations, causing ground loop currents, affecting the normal work of the system. For example, cable shielding layer must be a little ground, if the cable shielding layer ends A, B are grounded, have potential difference, current flows through the shielding layer, when abnormal states with lightning, line current will be greater. In addition, a shielding layer, a grounding wire and the earth may constitute a closed loop, changes in the magnetic field, the shielding layer may appear to have induced currents, the coupling between the shielding layer and a core wire, the interference signal circuit. If the system with other ground handling chaos, the resulting circulation may have unequal potential distribution on the ground line, affecting the normal work Mitsubishi PLC logic circuit and analog circuit. The logic voltage disturbance Mitsubishi PLC work of a lower tolerance, distributed interference logic ground potential tends to affect Mitsubishi PLC logic and data storage, data confusion, caused by the program running fly or crash. Distribution of potential analog measurement accuracy will lead to decline, caused serious distortion of the signal and control and false action.
6, from the internal Mitsubishi interference in PLC system
Mainly by the internal components in the system and circuit of the interaction of electromagnetic radiation is produced, such as mutual radiation logic circuit and its effect on analog circuits, analog and logic of mutual influence and mutual use does not match the components etc.. It belongs to the Mitsubishi PLC factory inside the system EMC design content, more complex, as the application department is unable to change, but don't have too much to consider, but to choose has more application performance or after the system test.

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