恒压供水外文翻译.doc

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1、外文文献原稿和译文原 稿The water supply system is the national production and life indispensable important one annulus. The traditional method of water supply area, water pollution, infrastructure investment, but the main drawback is that water can not be kept constant, causing part of the equipment can not wo

2、rk normally. Variable frequency speed control technology is a new mature AC motor stepless speed regulating technology, its unique excellent control performance is widely applied to the speed control field, especially in water supply industry. Due to the safety in production and the water quality of

3、 special needs, for constant pressure water supply with the stringent requirements, so the frequency control technology has been more in-depth application. Constant pressure water supply ways to advanced technology, constant pressure, convenient operation, reliable operation, energy saving, high deg

4、ree of automation, in pump station water supply can perform the following functions:( 1) to maintain constant pressure;( 2) the control system can be manual or automatic operation;( 3) a plurality of pump automatic switch operation;( 4) system of sleep and wake, when people stop when water, the syst

5、em is in a sleep state, until the water demand automatically wake;( 5) adjusts the PID parameters on line;( 6) pump unit and circuit protection detection alarm, signal display.The actual pressure of the pipe network feedback and a given pressure were compared, when the pressure of a pipe network is

6、low, increase the output of frequency converter, pump speed faster, water supply quantity increases, forcing the pipe network pressure rise. Vice pump speed slow down, reduce the water supply pipe network pressure drop, to keep the constant pressure water supply.System hardware structureSystem uses

7、a pressure sensor, PLC and inverter as a central control device, to achieve a desired function. Source: network transmission and distribution equipment installation in pipe line pressure sensor, for detecting the water pressure of the pipe network, converting pressure is 4 20 mA current or voltage s

8、ignal is 0 10V, supplied to the inverter.Converter pump motor control device, in accordance with the constant water pressure needs to be 0 50 Hz frequency signal supply pump motor, adjust its speed SAJ converter is powerful, i.e. pre-programmed set parameter set, will use the required in the process

9、 of setting the number of parameters is reduced to a minimum, default value according to the application parameter of the macro choice and different. The system adopts the PID control application macro, closed loop control. Inverter based on a constant pressure corresponding to the voltage setting v

10、alue and from the pressure sensor to obtain the feedback current signal, the use of PID control macro automatically adjust, change the frequency output value to adjust the control the speed of the pump motor, to ensure that the pipe network pressure constant requirements.The application of inverter

11、in the constant pressure water supply一The characteristic and analysis of variable frequency speed regulationThe water users in general is dynamic, so the water supply is insufficient or excess water supply situation has occurred. The water supply and the imbalance between the concentrated reflection

12、 in water supply pressure, namely water and water supply is less, the low pressure; less water consumption and water supply, the pressure. Keep the water pressure constant, can make the water supply and water balance between water supply and water for a long time, that is, less water when the water

13、is less, so as to improve the quality of water supply.Constant pressure water supply system for the user is very important. In production and living water, if water supply due to insufficient pressure or short of water, may affect the quality of life, serious when can influence the survival safety,

14、such as when a fire occurs, if the water pressure is insufficient or water supply, can quickly fire, may cause significant economic losses and casualties. Therefore, water area by means of Arts is the constant pressure water supply system, can produce great economic benefit and social benefit.With t

15、he development of electric power technology, frequency conversion technology perfected, with variable frequency speed control as the core of the intelligent water control system replaced the previous high level water tank and a pressure tank and water supply equipment, stable starting, the starting

16、current can be limited within specified current, thereby avoiding the starting time of the impact of power grid; because the average rotational speed of pump is reduced, which can extend the pumps and valves and other things of life; to eliminate the start and stop of the water hammer effect. The st

17、able and safe performance, simple and convenient operation, and complete and thoughtful function, will make the water supply and water conservation, energy saving, labor saving, ultimately achieve efficient operation.二 The application of variable frequency control constant pressure water supply mode

18、Usually in the same way in the water supply system, setting multiple common pump, water supply when the quantity of multi pump full open, water supply on one or two hours. In the variable frequency speed control for constant pressure water supply, in two ways, one is all pumps with a frequency conve

19、rter; and each water pump with a frequency converter. After a method based on pressure feedback signal, operated by PID automatically adjusts the output frequency of the inverter, change the speed of the motor, eventually reaching the purpose of network voltage, a closed loop, is relatively simple,

20、but the cost is high. The previous method of low cost, less than kind of poor performance, but the control program is complex, is the future direction of development, such as the Shanghai arts and science and technology of constant pressure water supply control system can realize a inverter control

21、any number of motor function. The principle mentioned below are multiple motor inverter drive system.三The PID control principleAccording to the feedback principle: to maintain a physical quantity unchanged or essentially unchanged, it should bring the physical quantity and the constant comparison, t

22、o form a closed loop system. We want to keep the pressure constant, so we must introduce the hydraulic feedback value with a given value, thereby forming a closed loop system. But the control system is characterized by nonlinear, inertial system, now the control method combined with PID in the large

23、 pressure fluctuation, using fuzzy control, in order to accelerate the response speed in the pressure range; using PID to maintain static accuracy. This through the PLC and intelligent instrument can show the algorithm, while the PLC programming to show when the pump frequency and inverter switching

24、 between. Practice has proved that, using this method is feasible, and the cost is not high.To maintain the constant pressure water supply network, according to the feedback theorem in network management system installed on the pressure transmitter as a feedback element, because of long, large diame

25、ter pipe system of water supply, pipeline pressure charging are slower, so the system is a big time lag system, is not easy to directly with PID regulator for control, and adopts PLC is involved in the control of the way to achieve the control system regulates the effect.四Frequency controlUsing freq

26、uency control to realize constant pressure water supply, with adjustable valve to realize constant pressure water supply, energy-saving effect is very significant ( according to the specific circumstances calculated ). The utility model has the advantages of:1, starting balance, the starting current

27、 can be limited within specified current, thereby avoiding the starting time of the impact of power grid;2, because the average rotational speed of pump is reduced, thereby prolonging the service life of pump and valve etc.;3, can eliminate the start and stop of the water hammer effect;Generally spe

28、aking, when performed by a frequency converter to control a motor, just make the inverter motor capacity and the actual capacity of the motor can be. When one inverter control two motors, principle of inverter motor capacity should be equal to the capacity of the two motors. But if the peak load of

29、water more than two pumps at full supply a lot of difference, Shanghai arts and science and technology engineers suggested, may be considered appropriate to reduce the capacity of the frequency converter, but attention should be paid to leave enough capacity.Although the pump at low speed, small wor

30、king current of the motor. However, when the user with the water volume changes frequently, the motor will be in frequent ascending, descending and ascending, descending speed state, the current speed slightly over the motor rated current, cause the motor overheat. Therefore, the motor thermal prote

31、ction is required. For this due to frequent ascending, descending speed and accumulated temperature rise, frequency converter in electronic thermal protection function is difficult to play a protective role, so should be used in thermal relay for motor thermal protection.The main function of preset,

32、 the highest frequency should be rated motor frequency converter the highest working frequency. Ascending, descending speed time in using PID regulator case, ascending, descending velocity time should be set to be short, so as not to affect the PID adjuster determines the dynamic response process. S

33、uch as the frequency converter with PID regulation function, as long as the preset set PID function effectively, the setting of the acceleration and deceleration time will automatically lapse.五Constant pressure water supply system1, power: the optimal energy-saving control software, so the pump to a

34、chieve maximum energy efficiency;2. according to the actual water use, water saving setting pressure of the pipe network, the automatic control pump out the water, reducing the water running, leakage phenomenon;3, reliable operation: by the frequency converter to realize the soft starting of pump, t

35、he pump is realized by frequency to the frequency of the bumpless transfer, prevent network impact, to avoid the pipe network pressure gauge, pipe rupture.4, network function : the whole Chinese industrial control configuration software, real-time monitoring of each site, such as the motor voltage,

36、current, frequency, pipe network pressure and flow. And the ability to accumulate each site electricity use, cumulative per pump out the water, at the same time to provide various forms of print statements, in order to analyze the statistical.5, flexible control: section water supply, water supply,

37、manually select working mode.6, self protection functions: such as a pump failure, take the initiative to the PC alarm information, at the same time start standby pump, in order to maintain water balance. If the control system failure, the user can directly operate manual system, in order to protect

38、 the water supply.六The system application1, water plant, pressure pump2, the residents living area, hotels and other buildings3, enterprise production water4, boiler circulating water system 5, the farmland irrigation systemCompared with other water supply, frequency constant pressure water supply s

39、ystem, in addition to having significant energy-saving effect obviously, has the following advantages: 1, constant pressure water supply technology by using the frequency converter to change the motor power supply frequency, and to adjust the pump speed to change the pump outlet pressure, than by re

40、gulating valve control pump outlet pressure, has a reduced resistance greatly reduced the effectiveness of the interception loss.2, because of the variable pump work in the frequency condition, at its outlet flow rate is less than the rated flow rate, pump speed is reduced, reducing the abrasion of

41、the bearing and fever, to extend the pump and motor of the service life of the machine.3, pump adopts soft starting mode, by setting the accelerated acceleration time, avoid the motor starting current impact, on the grid voltage fluctuations caused by the impact, but also to avoid the sudden acceler

42、ation caused by motor pump systems surge. The complete elimination of water hammer.4, to realize automatic control, operating personnel do not need frequent operation, reduces labor intensity of workers, saves the manpower.Constant pressure water supply equipment1, frequency conversion control cabin

43、et structure and principleVariable frequency pump control system through the pipeline pressure, the inverter system with built-in PID regulator operation, regulate the output frequency, and then to achieve a constant pressure water supply pipe network. The frequency of the transducer overrun signal

44、( generally used as pipeline pressure limit signal ) can be timely informed the PLC variable frequency pump switch. In order to prevent the occurrence of water hammer, pump switch is linked to the outlet valve.Variable frequency water pump control cabinet works as follows:Various types of directly f

45、rom the municipal pipe network water tank ( box ). Such as: the construction of various types of ground water reservoir water, ground boiler cold water supplying, ground air conditioning system cooling water circulating pool water, ground water circulating pool water, fire and spray for ground water

46、 reservoir inlet. The intelligent variable frequency constant pressure water supply energy-saving control cabinet, frequency conversion water supply energy-saving control cabinet assumes the entire system is composed of four pumps, a converter, a PLC and a PID and a pressure transmitter and a plural

47、ity of auxiliary components. The function of each part are as follows : installed in the water supply pipe network pressure pressure transmitter will be converted into 1-5 volt electrical signal; frequency conversion speed regulator used for adjusting the pump speed to regulate the flow; PLC for log

48、ic switching. In addition, the system is also equipped with an auxiliary circuit, in order to ensure automatic control system failure can be regulated through the artificial way to maintain the system operation, to ensure continuous production.2, frequency conversion control cabinet features:Accordi

49、ng to tank ( box ) the height of the water level in the automatic control electromagnetic valve ( or electric valve ) opening and closing, in order to control the water tank ( pool ) of the water inlet and the tank ( box ) to automatically maintain a certain amount of water for use by the user.3, frequency conversion control cabinet selection instructions of variable frequency water pump control cabinet is mainly composed of variable frequency control box, a pre