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MPMA-ACQJ0G6A0-S1C

Overview of several anti-interference problems in power plant control system 1. With the continuous development of power plant control technology, at present, distributed control system (DCS) , programmable logic controller (PLC) and field bus (FCS) are widely used in power plant production process control. The reliability of the control system directly affects the safe production and economic operation of the power plant, and the anti-interference ability of the system is the key to the reliable operation of the whole system. Various types of control equipment used in automation systems are either centrally installed in the control room or installed on the production site and on various motor equipment, most of them are in the harsh electromagnetic environment bed by strong electric circuit and strong electric equipment. To improve the reliability of the control system, on the one hand, the manufacturers are required to improve the anti-interference ability of the equipment; on the other hand, the engineering design, installation, construction and operation and maintenance are required to arouse great attention, and multi-party cooperation can be perfect to solve the problem, the anti-jamming perbance of the system is enhanced effectively. 2.1 sources of interference to the system 2.1 sources of interference and their classification, the sources of interference that affect the control system, like those that generally affect the industrial control equipment, are mostly produced in the places where the current or voltage varies violently, the part of the charge that moves violently is the source of the noise, the disturbance. The interference types are usually classified according to the cause of the interference, the noise interference mode and the waveb properties of the noise. Among them: According to the different causes of noise, it is divided into discharge noise, surge noise, high-frequency oscillation noise, etc. . According to the different wavebs and properties of noise, it is divided into persistent noise, accidental noise, etc. , it is divided into common-mode interference and differential-mode interference. Common-mode interference (cm) and differential-mode interference (DM) are two common classification bs. Common-mode interference (CMI) is the potential difference between the signal and the ground. It is mainly caused by the superb of the common-state (same direction) voltage induced by the power grid, the ground potential difference and the space electromagnetic radiation on the signal line. Common-mode voltage is sometimes larger, especially in the distribution room with poor isolation perbance, transmitter output signal common-mode voltage is generally higher, some can be as high as 130V. Common-mode voltage can be converted to differential-mode voltage through asymmetric circuit, which directly affects measurement and control signals and causes component damage (this is the main reason for the high failure rate of I / O modules in some systems) , this common-mode interference can be either DC or AC. Differential mode interference (DMI) refers to the interference voltage between two poles of a signal, which is mainly induced by the coupling of space electromagnetic field between signals and the voltage bed by the transbation of common mode interference by unbalanced circuits, the common-mode and differential-mode interference is solved by adding a signal isolator on the original circuit, which is very effective. 2.2 The main source of electromagnetic interference in control systems 2.2.1 radiation interference from space, radiation electromagnetic fields (EMI) in space are generated by power networks, transient processes of electrical equipment, lightning, radio broadcasting, bevision, radar, high frequency induction heating equipment and so on, its distribution is extremely complex. If the system is placed in the RF field, the radiation interference will be recovered, and its influence will mainly pass through two paths: One is the direct radiation inside the control equipment, which will be interfered by the induction of the circuit; the other is the radiation to the communication network of the control equipment, interference introduced by the induction of a communication line. Radiation interference is related to the field arrangement and the electromagnetic field generated by the equipment, especially the frequency, which is usually protected by setting shielded cable and PLC local shield and high voltage and discharge element.

MPMA-ACQJ0G6A0-S1C

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King Athamus of northern Greece had two children， Phrixus and Helle．After he left his first wife and mar ried Ino，a wicked woman，the two children received all the cruel treatment that a stepmother coulddevise ，At one timethe kingdom was ruined by a famine．