【正文】 the pressure of the pipe network in real time through the pressure sensor , and change into the electric signal and offer the frequency converter to to make operation, through the controlling monly of frequency converter , programmable controller PLC and relay array, adjust the system of supplying water rapidly after forming perfect fullautomatic frequency conversion.Frequency converter is various in kind, for instance the types , such as Mitsubishi , , three and ABB ,etc.. Generally often select the pumps , specialpurpose series of air blower for use. Whether take Mitsubishi FRA140E as an example, it except general function had of brand , there are the following characteristics : The inside adopts the intellectual power module of IPM, it is lowest to make the noise of the electrical machinery to reduce 。 Frequency converter, and workfrequency power can is it switch over to go on frequently, user is it is it start , stop through PLC and switch over the order automatically to input to need only, can conveniently through to lock movement switch over different water pump each other contactor, and does not need to design the tedious control procedure by oneself like the thing that in the past , this is one of this peculiar functions of frequency converter。 Builtin instantaneous power cut starts and retries and starts the function , in a situation that nobody guarded, even if can be started by oneself after the frequency converter shuts down, totally realize with the operation of the automatic way. PID regulator available frequency converter of system this builtin value very heavy, this will store deviation in regulate. During the process of dispelling the deviation to regulate , must lead to the fact the system and present greater ultra mediation longtime vibration , can produce the serious integration saturation phenomenon also at the same time , thus influence the normal running of the equipment. Is it drop the influence to most low to want , should adopt PID control method that integration separate among controlling algorithm, in order to reach the anticipated result. After dealing with like this , can shorten the system and reach steady transition course time greatly System allocate two 11kW water pump support 600 over resident water. Two pump offer large peak flow most when working at the same time, single platform meet the small flow and supply water at night. In addition all water pump can run by way of frequency conversion , can circulate way soft to start, in this way , can reduce the impact to the electric wire netting and pipe network . What merits attention is two pump when frequency conversion and worker are switched over frequently , have procedure it locks to be enough each other only, outputting must adopt machinery to interlock the contactor , can avoid the situation that two contactors close at the same time in the twinkling of an eye in this way, so as not to short out in twinkling of an eye causing power .pressure sensor P monitors the size of the water pressure signal in real time, the signal is dealt with by PID, input it to the frequency converter. At the small flow, water pump electrical machinery turn round (whether 1 is it shut to suck), and through feedback password change his rotational speed constantly, it is invariable in order to keep the pressure。 In case of large flow , pare frequency conversion by pressure circuit send out through PLC constant/changed switch over frequently operate and interlock the order, machinery interlocks the contactor (1 +2 ), contactor have the electricity. At this moment, electrical machinery is started by way of frequency conversion, is switched over and run at full speed frequently to run . In this way, this system can maintain water consumption on a invariable pressure all the time . Built up in the aforesaid district initial stage , supply water and adopt the way frequently of workers, because of energy consumption being heavy dependability is bad, the household reflects strongly. Use instead after frequency conversion supply water, installation total capacity reduce 25% than original equipment , economize on electricity the index is close 30% synthetically actually, the result is remarkable.The environment for use of the scene is paratively abominable . Though frequency converter has very strong protection functions itself, such as owe keep , excessive pressure , is it flow to pass, electric current amplitude limiting is it make exactly to choose, overload, overheated lacking looking , shorting out and disconnected ink protect the function But must prevent trouble before it happens . Through using finding , two kinds of brands of Mitsubishi , , because has fully considered various kinds of abominable running environment in design and manufacture. The dependability and service life under the same condition are higher than some brands. One small city of mountain area of west place in Hubei in Hubei, average above sea level, the humidity on the high side of longterm most of the time (about 80%), the sulfur dioxide is seriously polluted, a set of frequency conversion that one factory produces supplies water of the equipment, because has not considered abovementioned factors , less than one year, the relevant parts of the equipment are corroded seriously. And the like product which we designed , installed in the same area, because has fully considered the situations of different difference, on the selecting types of the equipment and ponent , have adopted the ship standard. Through the use of more than two years , ran well , stood the tests of different sternness. Find in using actually , the frequency converter itself is that a strong interference takes place in the source , will often influence the normal running of the equipment. Especially when the low rotational speed of the water pump operates, the frequency shown on the frequency converter does not correspond to actual operation frequency. Generally there are