Welcome to our article dedicated to exploring the fascinating world of Frequency Converter Inverters. If you're intrigued by how these innovative devices empower businesses and individuals to achieve unparalleled flexibility in their power solutions, then you are in the right place. In this piece, we delve into the essential features and capabilities of frequency converter inverters, shedding light on how they harmonize power supply with diverse energy needs. Ready to embark on a journey of energy enlightenment? Read on to uncover the limitless possibilities that frequency converter inverters can unlock for you.

The of FGI Frequency Converter Inverters

Frequency Converter Inverters, developed by FGI, are cutting-edge power solutions designed to provide flexibility and efficiency in various industrial and commercial applications. These advanced devices convert electrical power by modifying the frequency of the input voltage, allowing for seamless integration with different power sources and equipment. In this article, we will delve into the functionalities and advantages of FGI Frequency Converter Inverters, exploring how they revolutionize power management.

Enhancing Compatibility and Energy Efficiency

FGI Frequency Converter Inverters offer precise frequency conversion capabilities, enabling optimal adaptation to diverse power requirements. These inverters facilitate efficient power conversion between different grid frequencies, allowing for seamless international power compatibility. Not only do they contribute to energy savings through their improved conversion efficiency, but they also enable the use of renewable energy sources, such as solar or wind power, by matching their fluctuating output frequencies to the desired requirements.

Versatile Applications and Integration

FGI Frequency Converter Inverters are engineered to integrate seamlessly with various power systems and equipment. They find applicability in industries such as manufacturing, aerospace, mining, and transportation, where reliable power supply and flexibility are paramount. With adaptable voltage and frequency transformation capabilities, FGI Frequency Converter Inverters ensure smooth operation of machinery and equipment, safeguarding productivity while reducing downtime and maintenance costs.

Unleashing the Potential of Smart Grids and Microgrids

FGI Frequency Converter Inverters play a pivotal role in the development of smart grids and microgrids by enabling the efficient management of renewable energy sources and distributed power generation. These inverters possess advanced control features and grid synchronization capabilities, allowing for the stable and reliable integration of decentralized energy systems. Through their seamless interaction with the power grid, Frequency Converter Inverters contribute to enhanced grid stability, peak demand management, and the integration of energy storage systems.

Advanced Features and Future Prospect

FGI Frequency Converter Inverters offer a range of advanced features that enhance their flexibility and performance. These include customizable voltage and frequency settings, programmable logic controller (PLC) compatibility, and comprehensive monitoring and fault diagnosis systems. With ongoing research and development, FGI is continuously working to improve the efficiency and reliability of their frequency converter inverters, allowing businesses in different sectors to benefit from optimized power management solutions.

In conclusion, FGI Frequency Converter Inverters represent a significant advancement in power management, offering versatile and efficient solutions for industrial and commercial applications. With their compatibility with various power sources, adaptability to different grid frequencies, and contribution to the development of smart grids and microgrids, these inverters unleash the true potential of flexible power solutions. FGI aims to continue innovating in this field, ensuring that businesses around the world can achieve enhanced efficiency, reduced energy consumption, and reliable power supply through their top-of-the-line frequency converter inverters.

Conclusion

In conclusion, the advancements in frequency converter inverters have revolutionized the power solutions industry, providing flexible and efficient alternatives to traditional power sources. As a company with 15 years of experience in this field, we have witnessed firsthand the incredible transformation these inverters have brought to various sectors. By enabling the seamless conversion of power frequencies, businesses can now adapt to changing energy demands, optimize their processes, and reduce energy costs. Whether it is in manufacturing, renewable energy production, or commercial settings, frequency converter inverters offer unparalleled versatility and reliability, making them a crucial component of modern power systems. With our expertise and commitment to staying at the forefront of these technological breakthroughs, we are perfectly positioned to provide innovative solutions and help our clients harness the full potential of these flexible power solutions. As we continue to evolve in this dynamic industry, we look forward to driving further advancements and supporting businesses in their journey towards a more sustainable and energy-efficient future.

Welcome to our guide on choosing the right Variable Frequency Drive (VFD) frequency drive! In this information-packed article, we provide you with valuable tips and insights to help you navigate the world of VFD frequency drives. Whether you're a homeowner or an industrial professional, understanding how to select the perfect VFD frequency drive can greatly optimize the performance and energy efficiency of your machinery. Join us as we delve into the key considerations and expert advice, equipping you with the knowledge required to make an informed decision. Let's dive in and discover the essential factors that will empower you to enhance your systems and achieve optimal results.

Choosing the Right VFD Frequency Drive: Tips and Insights

Understanding VFD Frequency Drives and Their Importance

As industries continue to evolve and embrace modern technologies, the use of Variable Frequency Drives (VFDs) has become increasingly prevalent. VFD frequency drives are electronic devices that adjust the speed and torque of electric motors, allowing for control and optimization of various applications. However, with several options available, selecting the right VFD frequency drive for your specific needs can be challenging. In this article, we will provide you with valuable tips and insights to guide you in choosing the ideal VFD frequency drive for your machinery or equipment.

Factors to Consider when Selecting a VFD Frequency Drive

1. Power and Voltage Requirements:

One of the first steps in choosing the right VFD frequency drive is determining the power and voltage requirements of your equipment. Consider the horsepower (HP) and voltage rating of the motors you wish to control. Ensure that the VFD frequency drive you select is compatible with these specifications to avoid potential damage or inefficiency in operation.

2. Load Characteristics:

Understanding the load characteristics is crucial as it directly affects the type and size of the VFD frequency drive needed. Determine whether your application demands constant torque, variable torque, or constant horsepower. This information will help you identify the appropriate VFD model, ensuring optimal performance and energy efficiency for your specific load.

3. Integrated Safety Features:

Safety is paramount in any workplace. When choosing a VFD frequency drive, prioritize those with integrated safety features such as short-circuit protection, overvoltage protection, ground fault protection, or thermal overload protection. These features safeguard the system from faults, reduce downtime, and prevent potential hazards.

Exploring the Advantages and Limitations of VFD Frequency Drives

VFD frequency drives offer numerous advantages for various applications. Let's take a closer look at some of the benefits and limitations:

1. Energy Efficiency:

One of the most significant advantages of using VFD frequency drives is the potential for energy savings. By adjusting motor speed to match the load requirements, VFDs can reduce energy consumption by up to 50%. This energy efficiency not only helps lower operational costs but also minimizes environmental impact.

2. Enhanced Process Control:

VFD frequency drives allow for precise control of motor speed and torque, providing smoother operation and improved process control. This level of control leads to increased productivity, reduced wear and tear on machinery, and enhanced product quality.

3. Harmonic Distortion and Filtering:

A limitation of VFD frequency drives is the generation of harmonics, which can impact other equipment within the electrical system. However, VFD manufacturers often include built-in harmonic filtering mechanisms to mitigate these disturbances. When selecting a VFD frequency drive, consider the available harmonic mitigation options to ensure compatibility with your existing electrical infrastructure.

Exploring FGI VFD Frequency Drive Solutions

At FGI, we understand the importance of choosing the right VFD frequency drive to optimize your industrial processes. Our brand is committed to providing innovative and reliable solutions that cater to a wide range of applications. With our extensive experience and expertise, we offer a comprehensive line of VFD frequency drives designed to meet your specific requirements, ensuring seamless integration and optimal performance.

Consultation and Support from FGI Experts

When selecting a VFD frequency drive, it's essential to have access to expert guidance and support. At FGI, our team of knowledgeable professionals is always ready to assist you in choosing the perfect VFD frequency drive for your application. We provide consultation services, helping you identify the most suitable drive based on your specifications and offering technical support throughout the purchase and implementation process.

In conclusion, selecting the right VFD frequency drive is crucial for achieving optimal performance, energy efficiency, and process control in industrial applications. Consider factors such as power and voltage requirements, load characteristics, and integrated safety features. Take advantage of the benefits offered by VFD frequency drives while being mindful of any limitations associated with their use. Explore FGI's range of VFD frequency drive solutions and rely on our experts to guide you through the selection process.

Conclusion

In conclusion, selecting the appropriate Variable Frequency Drive (VFD) frequency drive is a crucial decision for any organization, especially in an industry where knowledge and experience are highly valued. With our impressive track record and 15 years of expertise, our company understands the significance of this task. We have witnessed firsthand the impact that a well-chosen VFD frequency drive can have on enhancing efficiency, reducing energy consumption, and extending the lifespan of equipment. Through this article, we have shared valuable tips and insights to guide individuals in making informed decisions when it comes to VFD frequency drives. We hope that by presenting important factors to consider and providing expert advice, we have empowered readers to make the right choice for their specific needs. As technology continues to evolve, we remain committed to staying at the forefront of the industry, staying updated with the latest advancements in VFD frequency drives, and offering our clients the most effective solutions. With our extensive knowledge and experience, we take pride in being a reliable partner in helping businesses maximize their operational potential and achieve their goals.

Are you curious about the different types of variable frequency drives available in the market? Look no further! In our comprehensive guide, we delve into the intriguing world of DC to AC variable frequency drives. Whether you're an industry professional or simply an inquisitive reader, this article will take you on a journey where you'll unravel the secrets, advantages, and applications of these remarkable devices. So, buckle up and get ready to explore the power of DC to AC variable frequency drives—trust us, it's an enlightening read you won't want to miss!

Understanding FGI's DC to AC Variable Frequency Drives

Advantages of FGI's Variable Frequency Drives

Applications of FGI's Variable Frequency Drives

Choosing the Right FGI Variable Frequency Drive for Your Needs

Maintaining and Troubleshooting FGI Variable Frequency Drives

FGI is a reputable brand specializing in DC to AC Variable Frequency Drives (VFDs). With an extensive range of innovative products, FGI provides solutions for various industrial applications. This comprehensive guide aims to help you understand the features and benefits of FGI's VFDs, their applications, and how to select and maintain them effectively for optimal performance.

Understanding FGI's DC to AC Variable Frequency Drives

FGI's VFDs are advanced power electronic devices designed to regulate the speed of electric motors by controlling the frequency and voltage of the input power. They convert the direct current (DC) input from the power source to alternating current (AC) output with variable frequencies and voltages. FGI's VFDs are renowned for their precision, reliability, and energy efficiency.

Advantages of FGI's Variable Frequency Drives

2.1 Energy Efficiency: FGI VFDs allow for precise motor control, resulting in significant energy savings by matching motor speed to system requirements. This feature reduces power wastage and operating costs, making FGI's VFDs an eco-friendly solution for various industries.

2.2 Enhanced Equipment Life: The soft-start and variable speed capabilities of FGI's VFDs minimize strain on motors and mechanical equipment, greatly extending their lifespan. This benefit reduces downtime and maintenance costs while increasing overall productivity.

2.3 Noise Reduction: FGI's VFDs employ advanced technology to reduce motor noise and decrease the risk of mechanical wear. Noise pollution is reduced, promoting a safer and more comfortable working environment.

Applications of FGI's Variable Frequency Drives

FGI's VFDs find extensive use in various industries, including:

3.1 HVAC Systems: FGI's VFDs control the speed of air handling units and compressors, optimizing energy consumption while maintaining precise temperature control.

3.2 Industrial Machinery: FGI's VFDs offer precise control of motor speed, making them ideal for conveyor belts, pumps, mixers, fans, and other industrial equipment.

3.3 Renewable Energy: FGI's VFDs play a crucial role in improving the efficiency of renewable energy systems such as wind turbines and solar panels. They enable safe and reliable power conversion and grid integration.

3.4 Water/Wastewater Treatment: FGI's VFDs enable accurate control of pumps and blowers, ensuring efficient water treatment processes while saving energy and reducing operational costs.

Choosing the Right FGI Variable Frequency Drive for Your Needs

Selecting the appropriate FGI VFD for your specific application is pivotal for achieving optimal performance. Consider the following factors:

4.1 Motor Specifications: Review your motor's voltage, horsepower, speed range, and load characteristics to ensure compatibility with the chosen VFD.

4.2 Application Requirements: Determine the operational demands of your equipment, such as start-up torque, speed control precision, and environmental conditions. Match these requirements with the VFD's capabilities.

4.3 Scalability and Future Needs: Assess the potential for future expansion or changes in your system, and choose a versatile VFD that can accommodate these adjustments without compromising performance.

Maintaining and Troubleshooting FGI Variable Frequency Drives

Proper maintenance and troubleshooting are crucial to ensure the longevity and efficient operation of FGI's VFDs. Regular inspections, monitoring, and servicing are essential. Consult FGI's comprehensive maintenance guidelines and troubleshoot common issues by referring to the troubleshooting manual provided with your VFD.

FGI's DC to AC Variable Frequency Drives offer precise motor control, energy efficiency, and extended equipment life, making them a reliable choice for a wide range of applications. With this comprehensive guide, you now have a better understanding of FGI's VFDs, their advantages, applications, and how to select and maintain them effectively. Embrace FGI's innovative technology to optimize your industrial processes and enhance energy efficiency.

Conclusion

In conclusion, DC to AC variable frequency drives play a pivotal role in a wide range of industries, and mastering their functionality is essential for optimizing efficiency and productivity. This comprehensive guide has provided valuable insights into the principles, applications, and benefits of these drives. As a company with 15 years of experience in the industry, we understand the importance of staying at the forefront of technological advancements. By continuously honing our expertise and embracing innovative solutions, we are committed to delivering the highest quality variable frequency drives to our clients. With an unwavering dedication to customer satisfaction, we strive to empower businesses to elevate their operations and achieve unprecedented levels of success. Through our extensive knowledge and comprehensive support, we aim to drive the future of industries towards enhanced performance and sustainability.

Welcome to our comprehensive guide on FD300 Inverter Frequency Drives, as we delve into their ultimate features and functionalities. If you are passionate about understanding the inner workings of these powerful devices and their impact on various industries, then you have come to the right place. In this article, we will explore the multitude of features that make FD300 Inverter Frequency Drives a game-changer in the field. Join us as we unravel the complexities and highlight the benefits that these drives bring to the table. Prepare to be amazed and enlightened as we take you on a journey of discovery into the world of FD300 Inverter Frequency Drives.

Understanding FD300 Inverter Frequency Drives: Features

to FGI's FD300 Inverter Frequency Drives

Exploring the Unique Features of the FD300 Inverter Frequency Drives

Benefits of Incorporating FD300 Inverter Frequency Drives in Your Operations

Installation and Maintenance Tips for Maximizing the Performance of FD300 Inverter Frequency Drives

Real-Life Applications and Success Stories of FD300 Inverter Frequency Drives

FD300 Inverter Frequency Drives are an integral part of modern industrial processes, providing precise control over motor speed and torque. In this article, we will delve into the features, benefits, installation tips, and real-life applications of FGI's FD300 Inverter Frequency Drives. These technologically advanced drives have revolutionized the way industries operate, enabling enhanced efficiency, reduced energy consumption, and improved productivity. Let's explore the world of FD300 Inverter Frequency Drives and understand how they can optimize your operations.

Exploring the Unique Features of the FD300

FGI's FD300 Inverter Frequency Drives offer a range of innovative features designed to meet the diverse requirements of industrial applications. Firstly, their advanced motor control algorithms ensure precise and smooth speed regulation, enabling seamless operation across varying loads. The built-in PID controller allows for accurate process control while maintaining stability and consistency.

One of the standout features of the FD300 Inverter Frequency Drives is their exceptional reliability and durability. With comprehensive protection mechanisms such as overvoltage, undervoltage, overcurrent, and short circuit protection, these drives can withstand harsh operating conditions, ensuring uninterrupted productivity. Moreover, the advanced thermal management system keeps the temperatures under control, extending the lifespan of both the drive and the motor.

Benefits of Incorporating FD300 Inverter Frequency Drives in Your Operations

Integrating FD300 Inverter Frequency Drives into your industrial processes can yield numerous benefits. Firstly, the precise control over motor speed allows you to optimize the energy consumption, resulting in significant cost savings. By adjusting the motor speed based on the load requirements, unnecessary energy wastage is avoided, leading to improved efficiency and reduced carbon footprint.

Furthermore, FD300 Drives offer increased flexibility and adaptability. They can be seamlessly integrated with various motor types and sizes, making them suitable for a wide range of applications. The ability to control motor speed and torque enables enhanced process control, resulting in improved productivity, reduced downtime, and higher quality output.

Installation and Maintenance Tips for Maximizing Performance

To fully harness the capabilities of FD300 Inverter Frequency Drives, proper installation and maintenance are crucial. Firstly, ensure that the drive is installed in a cool, well-ventilated location, away from excessive heat sources. Adequate clearance around the drive should be maintained to facilitate efficient air circulation and heat dissipation.

Regular inspections and maintenance checks are also essential to ensure the optimal performance of FD300 Drives. Pay attention to dust accumulation, loose connections, and any signs of wear or damage. Timely preventive maintenance can prevent costly breakdowns and prolong the lifespan of the drives. Additionally, staying up to date with firmware updates and utilizing FGI's comprehensive customer support services will further enhance the performance and reliability of the drives.

Real-Life Applications and Success Stories of FD300 Inverter Frequency Drives

FD300 Inverter Frequency Drives find applications in a wide range of industries, including manufacturing, HVAC systems, water treatment plants, and more. By incorporating FD300 drives in their operations, businesses have witnessed significant improvements in energy efficiency, reduced maintenance costs, and enhanced process control.

One success story comes from a manufacturing company that implemented FD300 Drives in their production line. By accurately controlling motor speeds, they achieved precise control over their manufacturing processes, resulting in fewer defects and improved product quality. Additionally, the energy savings from optimized motor operation led to substantial cost reductions.

In conclusion, FGI's FD300 Inverter Frequency Drives offer a wide range of features and benefits that can greatly optimize industrial operations. With their precise motor control, reliability, and cost-saving capabilities, these drives have become indispensable tools in various industries. By understanding and utilizing the features of FD300 drives, businesses can witness improved productivity, energy efficiency, and enhanced process control, ultimately leading to their overall success.

Conclusion

In conclusion, the FD300 inverter frequency drives prove to be a remarkable addition to our industry after 15 years of experience. With their impressive features and capabilities, these drives have revolutionized the way we operate, setting a new standard for efficiency and performance. From their advanced motor control algorithms to their user-friendly interface, they offer an unrivaled level of flexibility and precision. Our company has witnessed firsthand the transformative power of these drives, as they have enhanced our operations and elevated our productivity to new heights. As we move forward, we are confident that the FD300 inverter frequency drives will continue to shape the future of our industry, driving innovation and facilitating growth in a rapidly evolving landscape. With their proven track record and our extensive experience, we are excited to embrace the endless possibilities and opportunities that lie ahead.

1.Overview

At present, the world is troubled by the energy shortage, China's energy situation is particularly severe. In the face of such a reality, the country has a series of countermeasures, so it promulgated the "Energy Conservation Law", and called on the whole society to build a resource-conserving society. Energy saving transformation is one of the effective ways, there are many aspects of energy saving transformation, among them, through the high voltage and high power motor frequency conversion speed regulation to achieve energy saving, is undoubtedly the greatest potential of energy saving. With the increasing maturity of high voltage and high power frequency conversion technology, it is possible to apply this technology in high power water pump in water plant. It is under this situation that the water supply and drainage plant of Sinopec xx Co., Ltd. studies and transforms the high voltage frequency conversion technology of the water pump equipment.

2. Implementation plans

Sinopec Co., Ltd. is known as the pearl of Sinopec and is well known in Shandong province. petrochemical water supply and drainage plant for the company's water supply system, xixia water distribution station is one of the subordinate units of water supply and drainage plant, day design water supply capacity of 200000 tons, clear water pump room is equipped with five pump unit, unit power is 550KW / 6 KW, transform all constant speed before running, the water size by changing the size of the valve opening adjustment. The purpose of controlling the water pump: to keep the hydraulic pressure of the frequency converter constant; Under the maximum opening of the pump outlet, change the output frequency through the frequency converter to adjust the water supply at the speed to change the water supply; to reduce the impact of the pump start and stop on the pipe network.

After multiple investigations and the cost performance, Petrochemical water supply and Drainage Plant decided to choose the FGI FD5000 series high voltage inverter produced by FGI Science And Technology Co., Ltd., for the speed regulation transformation of the 2 # and 4 # pump units of Xixia water distribution station. After the cooperation of the technical personnel of both sides, the frequency conversion transformation plan of the pump unit was jointly formulated. The field equipment diagram is shown in Figure 1 below. The transformation scheme adopts the form of one area 2, that is, the high voltage frequency converter drags any unit of 2 # and 4 # of the water distribution station. When one of the units is faulty or repaired, the frequency converter drags the other unit for frequency conversion operation. Units 2 # and 4 # of water distribution station are of the same type, and the main parameters of motor and pump of 2 # unit are as follows:

petrochemical water supply and drainage plant decided to choose FGI FD5000 high voltage frequency converter one drag two control system to 2 #, 4 # water pump units for speed regulation transformation.

FGI FD5000 high voltage frequency converter it is a full digital AC high voltage frequency converter control device, using advanced power unit series carrier shift phase technology, sine wave PWM modulation method, full Chinese operation interface, with high reliability, superior performance, easy operation and other characteristics, the specific design requirements are as follows:

(1) The system efficiency is high. Under the rated working condition, the total efficiency is above 96%, and the partial efficiency of the frequency converter is greater than 98%.

(2) The input side is 36 pulse rectification, and the harmonic voltage and harmonic current content of the power grid caused by the frequency converter meet the technical requirements of IEEStd519-1992 and GB / T14549-93 "Harmonics of Power Quality Public Power Grid".

（3) The rated input power factor of the frequency converter is greater than 0.96, without the power factor compensation device.

(4) The inverter output harmonic content is low and can drive ordinary high voltage motor without increasing the motor temperature rise and reducing the motor capacity, the motor cable has any length limit; protect the motor insulation from the damage of dv / dt stress; the service life of the equipment is not reduced due to the harmonic torque.

(5) It has the function of unit bypass. When a unit fails, the system can automatically bypass it and continue to operate to ensure the reliability of the system.

(6) Full Chinese operation platform, 10.4-inch real color LCD display, touch screen direct operation, more suitable for the use of Chinese habits.

(7) The modular structure of the power unit is interchangeable and easy to maintain.

(8) The input voltage range is wide and can be operated continuously within 6KV (± 20%).

(9) The power unit is controlled by optical fiber communication, completely electrical isolation, and has strong anti-interference.

(10) Built-in PID regulator, which can realize closed-loop operation.

(11) Built-in PLC enables flexible control of different application sites.

3.Application advantage

The FGI FD5000 high voltage frequency converter was successfully tested and passed the acceptance of Petrochemical water supply and drainage plant. The FD5000 high voltage frequency converter ran well. From the perspective of the application effect of the frequency converter in operation, the purpose of the pump has been fully achieved, and its advantages before the transformation are reflected in:

(1) Easy to operate and easy to observe.

All the data and operation status of the inverter can be displayed on the display screen of the upper computer, such as operating frequency, input voltage, input current, output voltage, output current, open closed loop, pressure value, etc. The upper computer display screen operation is simple and clear, easy to observe.

(2) The frequency converter operates stably and has good performance.

Since the FGI FD5000 high voltage frequency converter is put into operation, the operation is stable, the speed adjustment is smooth and reliable, the voltage and current are normal, and no abnormal phenomenon occurs.

(3) Reduce the labor intensity of the personnel on duty.

Because the frequency converter has the valve linkage function, with the change of water supply, the personnel on duty through the microcomputer remote monitoring system on duty, no longer need to frequently open and stop pumps and valves, the workload is greatly reduced.

(4) Constant pressure control.

The pressure closed-loop constant pressure control is adopted. The user only needs to set the required pressure according to the actual water supply needs. The frequency converter automatically runs with constant pressure. The pressure setting is convenient, accurate and stable, to ensure the stable operation of the pipe network and improve the quality of water supply.

(5) Reduced maintenance costs.

Because the frequency converter realizes soft start to the motor, the starting current is small, there is no mechanical impact on the pump unit, reducing the flow rate is also conducive to reducing the possibility of cavitation of the centrifugal pump, correspondingly extending the service life of the pump, motor and valve, greatly reducing the maintenance workload and maintenance cost.

(6) Analysis of power-saving effect:

The transformation is the production water of petrochemical water supply and drainage plant. In the production water, the power plant is a large household, and the water supply pressure is mainly to meet the demand of the power plant. The water plant generally opens two pumps to meet the water supply requirements. When replenishing the power plant, the water supply pressure should be increased to 0.56MPa, and the first water supply is about 20-30 minutes. There is no certain rule. When the water supply is not replenished, the pressure is maintained at 0.50MPa. After frequency conversion transformation, using constant pressure water supply, from figure 6, the variable frequency pump and the power frequency pump running in parallel characteristics curve, power frequency pump running curve is shown in the figure F1, point C is the single pump working point, F2 is the same pump power frequency running characteristic curve, A is the working point, head Ha = Hf, flow Qa = 2 Qf. When the flow rate changes from Qa to Qb, the resistance curve of the pipe network becomes R2, and the above correspondence is still true. At this time, the loss of the head line is Δ H=2 * (Hb-Ha) (when adjusting the valves of two pumps) or Δ H=He-Ha (when adjusting the valves of one pump). Using a variable frequency pump and a power frequency pump parallel running water supply, F3 for frequency pump running alone characteristic curve, F3, F1 under the parallel operation of working head equal principle, flow sum, two pump running curve F4, the flow Qb = Qd + Qf head Ha = Hd = Hf, from figure 6, when the greater the flow reduction.