Analysis and of anti-interference measures for the

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Analysis and Research on anti-interference measures of l-120-mod20 actuator


in order to improve the scientific and technological level and automatic input rate, increase the stability of equipment, combine the actual production and development, deeply grasp the scientific and technological progress, and carry out technical innovation and transformation on the system equipment and the factors affecting the safe operation of the unit. Now the anti-interference measures of l-120-mod20 actuator are discussed as follows

1 project overview

l-120 humidity experimental box has high temperature control accuracy - the analysis and research project of anti-interference measures for mod20 actuator belongs to technical innovation to solve the problem of actuator interference. Aiming at the anti-interference ability of interference source, interference path and actuator, research countermeasures, formulate and implement measures in combination with system wiring. It is characterized by imported equipment, complex circuit structure, advanced technology, reaching the domestic advanced level. It is widely promoted in the anti-interference of control equipment, and has high application value

2 problem raising and cause analysis

#1 and #2 units are designed with 8 sets of boiler steam temperature automatic regulation system. Since Heze Power Plant was put into operation, it cannot be put into automatic operation. Due to the poor characteristics of the valve, it was replaced with imported regulating valve, and the structure and configuration of the regulation system were also improved; After the test, it is found that there are many problems, including problems in all links of the system, as well as the influence between systems, which is mainly reflected in the mutual interference between actuators, resulting in the damage of servo discharge and high failure rate, which seriously affects the automatic input of the system. The automatic input rate is an important part of the assessment of the plant Department and an important condition for creating a first-class power plant. In the development plan of scientific and technological progress, it is required to reach more than 95%. Therefore, The problem of actuator interference must be solved first to improve the integrity rate of servo and release

actuator interference reason:

1) there is no isolation device at the input end

2) shield cable wiring is incorrect

3) improper grounding point

4) high damage rate of relay failure

5) feedback current sloshing

according to the experience of maintenance and placement, the reasons for the high damage rate are as follows:

1) the circuit design is unreasonable

2) improper selection of component parameters

3) when the relay acts, the arc is large, and the contact is poor and burnt black

4) the actuator cover is not fastened, and the actuator is splashed with rain or flushing water

5) the installation quality of the servo board is poor, the insulating paper pad is forgotten, and the screws are not fully fixed

further analyze the causes of feedback current shaking as follows:

1) potentiometer is easy to wear

2) free stroke of gear transmission

3) the potentiometer shaft is not fixed tightly

3 technical scheme and implementation effect

general idea: according to the problems found in the process of system operation, overhaul and maintenance, carefully analyze various factors causing interference from the aspects of equipment installation, circuit design, component parameter selection, etc., and take targeted measures to eliminate interference and improve the integrity rate of actuator

technical scheme:

cooperation prospect between Shanghai chlor alkali and Bayer materials technology

1) install isolation module at signal input end

2) the shielded cable is twisted and then connected to eliminate the transverse interference through the input cable

3) change the grounding point to eliminate the longitudinal interference through the grounding wire

4) circuit improvement and selection of components with appropriate parameters are shown in Figure 1 below:

refer to the above figure, and the specific improvement measures are as follows:

1) the input end of u4a operational amplifier is grounded through capacitor C3 instead of resistance capacitor RC3, that is, from C filter to RC filter. The improved circuit can eliminate both AC and DC components generated by interference, so as to improve the anti-interference ability of the actuator. As shown in the figure below:

2) U2 voltage stabilizing block: 78m20 has low power and is easy to burn out. It is changed from 0.5A and 20V to 1.0A and 20V. Even if the error increases, the power is changed from 10W to 20W

3) the capacitance values of C9 and C10 are too small and easy to breakdown; After the breakdown, when Q1 and Q2 are on and off, the high voltage formed by the coils of relays CR1 and CR2 breaks through triodes Q1 and Q2, and then burns out operational amplifiers U3a and U3B. Capacitance value from 47 μ Change f to 100 μ f。

in addition, the phenomenon of feedback current sloshing is comprehensively analyzed and effective measures are taken

it can be seen from the above figure that the signal board, the servo board, the power supply grounding for operation and the servo terminal 2 are all grounded through the actuator shell, while the actuator 6. Effective stretching space stroke: About 800mm actuator is connected to a common grounding point close through the desuperheating water pipe, forming common mode interference; It can be eliminated by connecting the cable to the centralized control room for grounding

implementation effect: according to the measures implemented in the technical scheme, good results have been achieved after the implementation of the measures. It can be seen from the following table:

1) the anti-interference ability of the actuator has been significantly improved, and the interference phenomenon has been basically eliminated

2) the intact rate of the equipment is improved, and the damage of the servo board is completely eliminated

4 innovation points

l-120-mod20 actuator is a foreign product with complex structure and advanced technology. The regulating valve has equal percentage characteristics, which is most suitable for the regulating system; However, at the production site, due to the operating equipment and environmental factors, it is easy to produce interference. The operator operates one regulator and the rest move, indicating that the anti-interference ability of the product is poor; The interference factor is not considered in the selection of component parameters. When there is a strong alternating magnetic field and the interference AC and DC is large, the components will be broken down and burned; The project can combine the system, analyze the circuit, find out the causes and take measures to eliminate interference and improve the equipment integrity rate, which shows that the project has high technical level, appropriate measures and strong pertinence

1) an isolation module is installed before the regulating signal is connected to the servo amplifier

2) horizontal interference and longitudinal interference are eliminated, and the C filter is changed to RC filter to filter out the AC and DC components generated by interference

5 promotion and benefit analysis

by using the analogy method, this achievement has been popularized and applied to the anti-interference measures of 2 unit electric regulation, and great achievements have been made

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