In the water supply system, constant pressure water supply refers to a control method that controls the outlet pressure to remain unchanged at a set value when the water pressure in the water supply network system changes by detecting the pressure of the pipe network. When the pump is generally used, the rated flow rate of the selected equipment usually exceeds the actual required flow rate, and the flow rate required during actual water use will change. For example, in the building water supply, the amount of water used during day and night changes greatly, and valves are used. The method of adjusting the flow rate is more commonly used. Although the method is simple, this method actually achieves the purpose of adjusting the resistance by artificially increasing the resistance. This kind of throttling regulation method wastes a large amount of electric energy, and at the same time, the equipment is more expensive to use and maintain. This article describes the use of SINE303 inverter built-in PID function for automatic constant pressure water supply control, to meet the energy saving requirements;
Electrical diagrams and commissioning According to the circuit shown in the figure, connect the air switch, leakage switch, and power supply. After checking the wiring is correct, close the air switch and power on the inverter. The digital display shows 0.0.
Turn off the power, after the power indicator light goes out, connect the motor, start-stop switch, remote pressure gauge, current limiting resistor, etc., and ground the inverter and the motor grounding terminal. Check it carefully.
The pressure gauge uses YTZ-150 potentiometer type remote pressure gauge and is installed on the water outlet pipe of the pump. The pressure gauge is suitable for the working environment where the general pressure gauge is applicable. It can directly observe the pressure value and output the corresponding electric signal. The output electrical signal is transmitted to the remote controller. Pressure gauges have red, yellow and blue lead-out lines.
Pressure gauge electrical technical parameters:
Resistance full scale: 400Ω (blue, red)
Zero pressure starting resistance: ≤20Ω (yellow, red)
Full-scale pressure upper limit resistance: ≤ 360Ω (yellow, red)
Terminal applied voltage: ≤6V (blue, red)
Open-loop debugging:
Check the wiring is correct, close the air switch and leakage switch, inverter power, the digital display 0.0, press the JOG key, check the pump steering, if reversed, change the motor phase sequence.
Press RUN, the operation indicator light is on (green), rotate the keyboard knob clockwise, the output frequency rises, observe the pressure indicator pressure indicator, and measure the voltage value between the inverter terminals VF and GND with the multimeter DC voltage range. The output frequency of the inverter increases, the pressure increases, the feedback voltage between VF and GND rises, and the corresponding feedback voltage value (for example, 3.1V) of the constant pressure (for example, 5 kg) to be set is recorded. Press stop key STOP, the inverter decelerates to stop.
Closed-loop constant-voltage operation:
After the start-stop switch is closed, the running indicator of the inverter is on. After the output frequency reaches 30.0Hz from 0.0Hz, it is automatically adjusted according to the water situation to ensure that the pressure at the outlet is constant at 5KG. Increase the parameter setting value of F7.04, the pressure at the outlet increases, decrease the parameter setting value of F7.04, and the pressure at the outlet decreases.