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source:original    time:2016-09-14     pageviews:3153

jiangsu, a waterworks pumping a total of two pumps used to adjust the valve opening or start and stop the pump can be adjusted.
whenever the summer season, the living water to increase, often less than a water pump, two pumps too often, are often the pump pressure has reached five kilograms, while the main pipe pressure three kilograms, when the degree of opening of the shutter 60-70%. this will not only waste a lot of energy, but since the pump pressure is too high, often leading to packing leakage. increase the amount of maintenance, shortening the life of the pump, in order to solve the above problems, after many visits, decided to transform the first pump using vfd hunan branch electric co., ltd. production.
one pump head 60 meters, the nominal quantity of 2600 lb / hr, motor power 260kw, rated current 29a, rated speed 1485r / min. next to the control box is connected with the degree of vacuum forming relays, solenoid valve opening detector, the motor current display table, high-voltage switchgear and other control chain loop.
the drive is installed in accordance with the actual situation of the site, will allow high voltage inverter, closing, tripping signal into the machine next to the box, the chain added protection in high voltage cabinet, joined in the console remote control by plc unite lock, the original start and stop control process, thus ensuring the operation of the whole system unchanged.
debugging, running water for the first pump governor general acceptance of, first, the first pump inverter output is set to 50hz ,, the motor running in the frequency of state, in a single tube running condition, adjust the output flow, the following data:
frequency current flow tube pressure pump outlet valve
50,291,300 4.5 4.7 100%
50,251,150 4.2 4.9 90%
50,221,000 3.9 5.2 80%
5020850 3.5 5.5 70%
5019700 3.1 5.8 60%
5018600 2.9 6.0 50%
5017500 2.7 6.1 40%
50 16.5 400 2.5 6.2 30%
5016300 2.3 6.3 20%

looking at the results from the table, with the valve off a small flow rate is reduced, but the pump pressure increases when the flow is below 800, although traffic is reduced, but not much power consumption, resulting in a great deal of energy waste.
after 50hz constant speed test is completed, the valve will open to 100%, change the output frequency of the inverter output flow adjustment. after adjusting each holding one hour to ensure the accuracy of the data. test data are as follows:
frequency current flow tube pump valve opening pressure
50,291,300 4.9 5.2 100%
45,201,150 4.2 4.4 100%
40,151,000 3.8 4.0 100%
3511850 3.4 3.5 100%
309 700 3.1 3.2 100%
257 500 2.7 2.7 100%
205 300 2.1 2.1 100%

through the data table, indicating the speed and flow rate is declining, with the decrease of the main pipe pressure pump pressure falling, when the flow is below 700, the pump pressure and the main pipe pressure remained the same, then the motor and pump the friction loss is small, low pressure loss of the pump, shut-off valve is no loss, played a significant energy saving effect.
after comparison of fixed speed and speed data, the results are as follows:
cruise traffic speed fixed speed speed speed speed current current saving rate

conclusion described above, when the first pump motor speed control in the state, the flow rate is less than 800 saving rate of 52%, the flow rate of 300 power-saving accessible to 69%.
throughout the testing process, the power factor is always greater than 95%.
after the test is completed, the first pump will be officially put into operation, since the beginning of winter, the temperature is low, water day average flow of 1100, current 17a, frequency 43hz.
daytime peak water consumption is 1200, the night the water down to 980, only need to run the operating table between the motor speed from 45 hz to 35 hz can be speed, while the motor speed is reduced when , the noise emitted by the pump is reduced, greatly improve the production environment.
put into operation four months of examination, drive an average current of 17a, and in the same condition unused frequency average current of 24a, so the calculation:
hourly electricity savings:
24 * 6000 * 1.732-17 * 6000 * 1.732 = 72744w
daily electricity savings: 72744 * 24 = 1745856 = 1746.86kw
monthly electricity savings: 1746.856 * 31 = 54121kw
the festival runs for four months electricity consumption is: 54124 * 4 = 216486kw
section four months total electricity:
216 486 * 0.9 = 194837 = 194,800 yuan (price per kwh 0.9)
in summer, water consumption increases, generally up to about 1500 traffic, then open one pump is not enough to open two sets of pump, water pump ii 1300 flow, supplemented by the first pump 200 flow, the energy saving effect more obvious.
after the first pump frequency control, after nearly six months of operation, characteristics are summarized as follows:
1, adjust the flow greatly simplifies operation, previously required the operator to half an hour in order to complete the operation can be completed in minutes.
2, very precise flow rate adjustment, is adjusted by the governor when the console can also refer to a plurality of flow parameters, pump pressure, tube voltage and current were adjusted during the absence of up-conversion, baffle adjustment, only the reference pumping stations within a flow meter, since the flow of transient phenomena, often can not adjust danone optimum requirements.
3, start stop operation with plc control, basic and primary mode of operation is consistent, convenient for users to use.
4, with the lower speed, the pump motor noise is reduced, greatly improve the working environment.
5, at low flow rates, pump pressure decreases, water pump packing leakage phenomenon greatly reduced.
6, energy-saving effect is remarkable.
7, due to reduced pump pressure, pump cavitation and reduced bearing wear.

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