Preface: with the development of urbanization, high-rise building is a feature of its prominent, and is more and more high, then followed by a question is water supply problem, whether it's residential building and office building is inseparable from the water.
So how do you maintain a constant water pressure, improve the quality of water supply is very important, also should guarantee the security and reliability of water supply.
But with the development and application of PLC
, this problem has been resolved, the following introduce everyone to PLC is how to solve.
1 a water supply way and the control system.
This design by the main water supply circuit, standby water supply circuit, a clear water reserviors and pump room.
Among them, the pump room is equipped with three pump machine, there are multiple electric gate valve or electric butterfly valve control loop of water supply and water flow.
Adopted PLC controller
control system, to prevent system against sending to frequency converter, damage the inverter, contactor KM1 and KM2, KM3 and KM4, KM5 and KM6 must be mechanical interlock, schematic diagram for the pump parts in the figure below: 2.
System control requirements
Constant water pressure requirements, must be small fluctuations, especially to ensure the good when in pump.
3 pump according to the set pressure, using the first open, first stop.
In order to prevent the pump running for a long time, need to set the running time.
To time, automatically switch to the next pump, in order to prevent the pump for a long time without rust.
To have a perfect protection and alarm function.
For there is the function of manual maintenance and emergency.
With functions of pool against time.
in the selection of PLC based on the system in improving water quality and energy saving requirements and functions, using the the letter of 200 series CPU224DPLC and converter control system.
PLC I/O allocation system takes PLC four input point and the nine dots, image below for the I/O allocation table 5.
The principle diagram of the electrical control system (
The main circuit diagram in the image below, three electric motor of M1, M2, M3, ac contactor KM1 -
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KM6 control three electric motor running, KH1, KH2, KH3 for motor M1, M2, and M3 thermal relay.
The wiring diagram of
Control circuit diagram electrical control line as shown in the figure below.
The diagram, the SA for manual/automatic switch;
KA for manual/automatic intermediate relay, playing in a '1' for manual, hit the '2' for automatic, KA and absorption at the same time.
In manual state, can through the SB1 -
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SB6 start-stop control three pump.
In the automatic state, the system according to the program in the PLC, automatic control.
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HL8 for various operation indicator light.
The intermediate relay KA I0 normally open contacts.
3, the state controlled automatic startup.
In the automatic state, the three pump under the control of PLC can orderly and switching, running smoothly.
KH1, KH2, KH3 for three pump normally closed contact of thermal relay, can be carried out on the motor over-current protection.
System programming system program includes the main program and the promoter, the main program includes involved in regulating program and motor switch;
Promoter program is actually clear 0, on the PLC electrical, VB200, VB201, first VD260 assignment is 0, as M reset relay.
in the main program, T56, T57 on the inverter frequency, lower reach filtering time relay, it is mainly used for stabilizing system.
VB200 for variable frequency pump pump, VB201 for total running pump stations, power frequency VD260 is an inverted pump storage time.
2 summarizes the design of constant pressure frequency conversion water supply equipment by PLC, inverter, sensors, low voltage electrical control cabinet and pump, etc, for the design, suitable for most of the high-rise building water supply system, some changes separately according to the scene.
This system is able to in the letter under the control of CPU224C, stable to control three pump, fully meet the control requirements needed.
The future will be more intelligent control constant pressure water supply system, this is based on PLC control, hope everybody can communicate together, let the PLC in more areas to solve the problem, bring convenience to everyone's life.
technology zone Siemens control equipment, its application in water conservancy project based on PLC, frequency converter, sensors and other equipment, real constant pressure frequency conversion water supply system based on PLC controller
and touch screen, the realization of GPRS remote control of the PLC to realize the letter product mix design of automatic classification based on the British witten human-computer interface, PLC, frequency converter corpora woodworking sealing side machine technology in pairs
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