| Constant pressure water supply technology with frequency converter as the core has been widely used in the water supply industry because of its advantages of safe use, energy conservation and environmental protection, and high water supply quality. Frequency converter is widely used in constant pressure water supply system. The frequency converter can carry out stepless speed regulation for the water pump motor, with small starting current and small impact on the power grid. The internal PID of the frequency converter can automatically adjust the operation frequency of the frequency converter according to the change of water consumption pressure, so as to keep the water pressure constant to meet the water consumption requirements. ² Main composition: the water supply part of the water supply system is mainly composed of water pumps, motors, pipelines and valves, remote pressure gauges, etc. Usually, the asynchronous motor drives the water pump to rotate to supply water, and the motor and the water pump are made into one. The speed of the asynchronous motor is adjusted by the frequency converter, so as to change the water flow of the water pump and realize constant pressure water supply. ² During the operation of the system, if the actual water supply pressure is lower than the set pressure, the control system will get a positive pressure difference. After calculation and conversion (PID calculation), the increased value of the output frequency of the frequency converter will be calculated. Add this increment to the current operating frequency value of the frequency converter, and the resulting value is the current frequency that the frequency converter should output. This frequency increases the speed of the water pump unit, thereby increasing the actual water supply pressure. On the contrary, the operation frequency of the frequency converter decreases. This process will be repeated during operation until the actual water supply pressure is equal to the set pressure. ² System advantages: 1. The frequency converter can adjust speed steplessly, and can accurately adjust the frequency of the water pump motor, so as to accurately adjust the outlet pressure of the water pump and greatly reduce the efficiency lost due to pressure fluctuations; 2. It has automatic sleep function, with adjustable sleep time and obvious energy-saving effect; 3. Because the customer's demand flow is less than the rated flow most of the time, the water pump works below the power frequency, and the speed of the water pump decreases, which reduces the wear and heating of the bearing and extends the mechanical service life of the pump and motor; The motor does not need to operate at power frequency, which can save 25% - 60% of electric energy. The system can recover the investment quickly and benefit for a long time, and its social benefits are also very huge; 4. Due to the realization of constant pressure automatic control, there is no need for operators to operate frequently, which reduces the labor intensity of personnel and saves manpower; 5. The water pump motor adopts the soft start mode and accelerates according to the set acceleration time, so as to avoid the current impact when the motor is started and the impact on the grid voltage fluctuation, and also avoid the surge of the pump system caused by the sudden acceleration of the motor. ² Wiring diagram of water supply system (one for one) ² matters needing attention: 1. For the selection of remote pressure gauge, it is best to choose the actual pressure that is about 2/3 of the whole range, so that the pressure error is small, the water pressure fluctuation is small, and the accuracy is high; 2. When connecting the slip resistance remote pressure gauge externally, first confirm whether the short press piece J4 of the down converter control board is short circuited at the V end, that is, short circuited to the lower 2 and 3 pins; The wiring method assumes that the wire number is ① ② ③ respectively. If the resistance value between ① and ② is 400 Ω, the resistance value between ① and ③ is 15 Ω, and the resistance value between ② and ③ is 385 Ω (at this time, the water pressure of the pressure gauge is very low), then there is R ① ③ + R ② ③ = R ① ②. It can be determined as ③ intermediate tap, which is connected to Ai1 terminal of frequency converter, ① GND terminal, ② 10V terminal; 3. When connecting an external current type pressure sensor, first confirm whether the short press piece J4 of the down converter control board is short circuited at the I end, that is, short circuited to the upper 1 and 2 pins; Wiring mode com and GND need to be short circuited. Usually, the red one is the power line, connected to 24V terminal, and the blue one is the current output terminal, connected to Ai1. ² Parameter adjustment Parameter setting Specific instructions (set according to actual needs) T500 series T510 series F0.02＝1 F0.01＝1 Start and stop of external terminal F0.03＝8 F0.02＝8 PID closed loop is effective (constant pressure water supply) F0.14＝25Hz F0.17＝1 Lower limit frequency (can be set according to actual demand) F0.17＝XX F0.21＝XX Acceleration time (set according to actual demand) F0.18＝XX F0.22＝XX Deceleration time (set according to actual demand) F4.00＝1 F4.01＝1 X1 is defined as closed forward running （F4.13＝2） （F5.01＝2） When Ai1 signal is 4 ~ 20mA, it corresponds to 4mA value. If it is 0 ~ 10V, this parameter does not need to be set F A.00＝0 F9.00＝0 PID given source setting F A.01＝20 F9.01＝20 Set the required pressure, which can also be modified by pressing the up and down keys on the keyboard F A.02＝0 F9.02＝0 PID feedback channel is Ai1 F A.04＝1.0 F9.04＝1.0 Range of remote pressure gauge, unit: MPa; 1MPa = 10ba (kg) The following parameters need to be set during sleep function A9.07＝75 F9.36＝75 Awakening coefficient; Is the percentage of set pressure, which can be modified according to needs A9.08 = 1 second F9.37＝1 Awakening delay time; Wait for the awakening time after reaching the awakening conditions A9.09＝XX F9.38＝XX Sleep frequency; When there is no water for the customer, the frequency required by the frequency converter to maintain the pipeline pressure is increased by 2 ~ 3Hz. For example, when there is no one to maintain the pipeline pressure, the frequency is 32 Hz, t500 can be set as a9.09 = 35, and the principle of T310 is the same as above A9.10 = 60 seconds F9.39 = 60 seconds Sleep delay time; After reaching the sleep condition, the frequency converter continues to operate for this set time and then sleeps, in order to prevent the frequency converter from starting and stopping frequently. | |||||||
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