Features, principles, and applications of frequency converters Features, principles, and applications of frequency converters

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Features, principles, and applications of frequency converters. Introduction to constant-pressure water supply frequency conversion devices: The constant-pressure water supply series of frequency converters are specialized devices designed for controlling the flow rate and pressure of fans, pumps, air compressors, and other similar equipment. This model has the basic functions of a general-purpose frequency converter. The design of the variable frequency drive takes into account energy savings and automation requirements; it features built-in functions such as automatic energy saving, PID control, a simple PLC, and RS485 communication interfaces, allowing easy communication with PLCs, computers, or buses to facilitate customer operation and monitoring. At the same time, our company has also developed a dedicated control board for constant-pressure water supply, which can be easily used in conjunction with remote pressure gauges. I. Features of variable-frequency constant-pressure water supply: This system can automatically maintain a constant pressure 24/7, and it will activate a backup pump automatically based on pressure signals. It allows for stepless adjustment of pressure, resulting in high-quality water supply. Compared to traditional water supply methods, it prevents pipe network ruptures and faucet resonance. The start-up process is smooth, which reduces the stress on motors and pumps, thereby extending their lifespan. It also eliminates the water hammer effect associated with traditional water supply systems. The variable-frequency constant-pressure water supply system comes with comprehensive protection functions and operates reliably, offering protection against low voltage, high voltage, overcurrent, and overheating. Various additional functions can be selected according to user needs, such as timed motor rotation and sleep modes.

II. Working principle: In this variable-frequency constant-pressure water supply system, the pressure is set using a potentiometer (or it can also be set via the controls on the panel). A pressure sensor is used to detect the pressure in the pipe network; the sensor sends signals in the form of 4–20mA. These signals are then fed into the PID circuit of the inverter. After processing, the PID circuit generates signals to increase or decrease the water flow rate, thereby controlling the speed of the motor. If the pressure remains insufficient or too high after a certain delay, the PLC is used to switch between fixed-frequency and variable-frequency operation, so as to bring the actual pressure in the pipeline network in line with the set pressure. Furthermore, as the water usage decreases, the frequency converter automatically reduces the output frequency, thereby achieving energy savings. III. System control diagram (taking one frequency converter controlling one motor as an example): For instance, a remote pressure gauge is used, with a range of 0–10 kg and a feedback signal of 4–20 mA. The system is required to supply water at a pressure of 5 kg, with an upper limit of 6 kg and a lower limit of 4 kg. Start/stop operations are controlled via the panel, while the potentiometer is used to set the target value. Parameters: CD032=1, CD034=1, CD035=5, CD052=32, CD150=*, CD151=*, CD152=*, CD153=50, CD154=1, CD155=60, CD156=40. Note: CD150, CD151, and CD152 should be set according to actual conditions; in the case of constant-pressure water supply systems, generally CD151=80~100, CD152=2.5~3, and CD153=0. IV. Application scope: This system utilizes variable-frequency constant-pressure water supply technology, offering advantages such as high efficiency and energy savings, stable pressure, reliable operation, simple operation, low space requirement, low noise, no pollution, low investment cost, and high returns. It is particularly suitable for: domestic water supply and hot water heating systems in hotels, office buildings, apartments, residential communities, etc.; fire protection water supply systems in high-rise buildings and large civil structures; automatic control of production lines in industrial and mining enterprises; as well as energy-saving upgrades for various mechanical devices such as injection molding machines, air compressors, constant-pressure water supply systems, central air conditioning systems, and textile printing and dyeing equipment