Plc Control System Of How To Solve The Interference Problem
1. Overview With the development of science and technology
, PLC Application in industrial control more and more widely. PLC control system reliability directly affects the safety of industrial enterprises and economic operation, the system of anti-interference ability is related to the reliable operation of the system key. Automated systems used in various types of PLC, some are focused installed in the control room, some are installed in production sites and Motor Devices, many of them are in strong electrical circuit and the formation of strong electrical equipment in harsh electromagnetic environment. PLC control system to improve reliability, designers only advance knowledge of all kinds of interference can effectively ensure the system reliability.
2. Electromagnetic interference and disturbance of that? PLC control system
affect general impact of interference from the interference source of industrial control equipment, as most of the current or voltage produced dramatic changes in the location, the location of these charges is the dramatic movement of noise sources, namely, the source of interference.
Disturbance is usually the cause by interference, noise interference patterns and noise properties of the different division of the waveform. Where: the noise generated by different reasons, into discharge noise, surge noise, high frequency oscillation and noise; by the noise waveform, different in nature, divided into continuous noise, occasional noise; by sound interference patterns are different, is divided into a total of mode noise and differential mode interference. Common mode and differential mode interference interference is a relatively common classification. Signal common mode interference is the potential difference on the ground, mainly by the network in series, to potential difference and the space of electromagnetic radiation in the common signal line sensor state (in the same direction) formed by voltage plus delivery. Sometimes common-mode voltage is higher, especially poor performance by isolating the electrical supply room, the transmitter output common mode voltage of generally high, some up to 130V or more. Common-mode voltage circuit can be converted by asymmetric differential mode voltage, direct impact on measurement and control signals, resulting in component damage (this is the number of system I / O module causes of the higher failure rate), this can dc common-mode interference, also for the exchange. Differential mode interference is obtained for signal interference voltage between two poles, primarily by electromagnetic field coupling between the signal sensing and conversion by the imbalance of the circuit formed by the common mode interference voltage, which directly superimposed on the signal to a direct impact on measurement and control precision.
3.PLC control system the main source of electromagnetic interference in what it?
(1) interference of radiation from space
Space electromagnetic radiation (EMI) mainly by the electric power network Electric Transient process equipment, lightning, radio, television, radar, high frequency induction heating equipment produced, often referred to as radiation interference, its distribution is extremely complex. If the PLC system placed inside the RF, interference on the recovery of the radiation, its effects mainly through two paths; First, the internal radiation directly to the PLC by the sensor circuit interference; but on the PLC Communicate Within the network of radiation sensors introduced by the communication line interference. Radiated interference and field equipment, layout and size of the electromagnetic field generated by the equipment, especially the frequency, generally shielded cable and the PLC by setting the partial shielding and High pressure Discharge protection device.
(2) lead to interference from outside the system
Mainly through Power supply And signal wires are usually referred to as conduction disturbances. This interference in China's industrial field is more serious.
(3) interference from power Practice shows that the introduction of the interference caused by power supply PLC control system failure of many, the author encountered in a project commissioning, after the replacement of a higher isolation PLC power supply problem was solved.
PLC system, the normal power supply by the power supply. As the network is extensive coverage of all space will be on a line of electromagnetic interference induced voltage and the circuit.
Plc Control System Of How To Solve The Interference Problem
By: mumu
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