Introduces the frequency changer union small PLC technology in the water supply system, not only change tradition with valve control water volume how many, moreover in aspects and so on energy conservation, constant pressure control had the extremely good effect, this article introduced the frequency changer--PLC regulation technology in water pump control application.

The control system may bring three water pumps with a frequency changer, each water pump already may work in the conventional power frequency pump pattern, also may work in the frequency conversion pump pattern. Each pump only can be in the frequency conversion or the power frequency one kind of working pattern, guarantees its safety and the unreliability mutually through two relay locks. System structure as shown in Figure one, the use places in the domestic water pressure transmitting instrument the water pressure signaling regulator, and reports to the police the bound according to and the regulator setting value to compare, delivers a letter the number for PLC and the frequency changer, the system stops the pump separately decided by the regulator low pressure limit signal and the frequency changer lower frequency limit signal, if the pressure is low, the regulator for a PLC low pressure limit signal, the PLC start frequency changer, and causes the first pump to be at the frequency conversion active status, the output frequency increases gradually, passes through a period of time adjustment, if the pressure is also low, by now, PLC let the first pump be at the power frequency conditionThe work, causes the second pump to be at the frequency conversion active status pump, if the pressure is also low, then lets the second pump be at the power frequency condition work, causes the third pump to be at the frequency conversion active status, so analogizes. When the pressure achieved when the regulator upper limit reported to the police the value, the regulator outputs reduces, the frequency changer frequency reduces, lowers to the lower frequency limit setting value, by now the frequency changer gave a lower frequency limit signal the principle which opened first for the PLC, PLC basis stops first to control the pump the movement order, when for example, PLC received the lower frequency limit signal, in the system the pump condition was a power frequency, two power frequencies, three frequency conversion, the first pump first started by now, therefore stopped first, like the pressure also was then high then stopped the second pump. The system used all has each time carried on the low speed to start, the high speed movement enhanced the operating efficiency.

Uses the frequency changer - PLC constant pressure water supply installment to have following several merits:

A:The electricity saving benefit is high. The traditional water pump electrical machinery uses the large capacity electrical machinery, is constant with the valve control water volume, creates the electrical energy waste.

Frequency conversion system, regardless of the operational parameter how, the electrical machinery efficiency can't reduce, the electrical machinery power factor can obtain the enhancement.

B:Moves is reliable, is stable. In the system core part - frequency conversion velometer itself reliability is very high, in the ordinary circumstances may the long-term usage 100,000/Above h. The system also selects the soft start method, does not have the electrical impact, does not pollute the electrical network, moreover frequency changer bringing owes presses, the pressure, the overflow, the overload, superheat as well as loses speed and so on each kind of protection function. The system adopts damping filter processing to the pipe network fluctuation of pressure, the water supply constant pressure precision is high, usually can control in the 0.002Mpa scope.

C:The structure is simple, the operation is simple. The installment control system uses the integration rate to be high, necessary plan nimble perse, obtains water pump movement each kind of combination by the programmable controller. The velocity modulation scope is broad, to water volume change adaptiveness.