V&T VFD and VTS Frequency Inverter for Wire drawing machine

Using the ShenZhen V&T liquid cooling variable frequency drive control double-drive screw compressor, the panel data display is normal.

V&T V9-GA series crane-purposed Frequency Inverter for fixing type hoisting mechanism of Hoist Crane.

Ⅰ. Shortcomings of traditional mine shaft hoist Conventional mine shaft hoist generally uses concatenation resistance of rotor loop, which adopts the disconnection and close of the contactor to achieve step-by-step speed regulation of the motor. This method has the following obvious disadvantages: ◆ The speed regulation of concatenation resistance belongs to the pole speed regulation, the starting impact was large, and there was a speed jump in the speed switching. It was easy to drop, and the more dangerous, which seriously affects the production efficiency and the safety of people's lives and property, especially when the transporting passengers. ◆ Using concatenation resistance to regulate speed, the serious waste of energy on the resistance, the lower speed, the more serious waste. when the object was lowered, the motor was in the power generation state and It wastes energy more seriously. ◆  Rotor concatenation resistance for speed control, high failure rate, many maintenance workload. Due to the contactor for speed regulation of concatenation resistance, frequent switching during speed regulation causes the contactor damaged frequently, resulting in malfunction of speed regulation. there was a safety hazard and Increased maintenance workload. ◆  Poor stability and speed change with load. ◆ The starting torque was not enough, especially when it stops in the slope and can't be restarted. It was necessary to put the material down to a stable place and start again, which seriously affects the production efficiency. Ⅱ. V&T Inverter for mine shaft hoist Integrated control solution has obvious advantages in driving the motor: ◆ Adopt advanced DSP chip and excellent vector control to match the power required by the hoist and the output power of the inverter; ◆ The starting current was small, the starting speed was stable and no impact, which reduces the down-going phenomenon well; ◆ High reliability, the inverter has perfect protection functions, such as over-current and over-voltage overload and short circuit protection functions; ◆  Low maintenance workload. There was no need to replace the contactor frequently as in the conventional solution, which reduces maintenance costs; ◆ Wide range of speed regulation. It belongs to the step-less speed regulation, the motor control was stable during the acceleration and deceleration process, and the operation was smooth when speed was adjusted. High system reliability, and there was no heat generated by the concatenation resistance, which improves the working environment of the operator. ◆ Large energy saving space. When the mine hoist was in the elevated state, the energy saved was proportional to the speed; when in the lower state, the motor was in the power generation state. If the energy feedback unit was used, the energy saved was not only proportional to the rotational speed, but also the energy fed back. ; ◆ Moreover, It has the automatic switching function of transporting people ...

一、Introduction Escalators are generally used in supermarkets, subways, stations, etc., and their applications are quite special. Unlike the elevators, It was in a state of suspension when none. The escalator was in working state whatever someone or not, so it causes a waste of electric energy and accelerates the wear of the machine, and seriously affects the life of the escalator and lower safety. V&T Escalator Inverter adopts high-performance speed sensor-less vector control technology. According to the characteristics of the escalator, it develops the special Integrated inverter energy-saving control cabinet for the escalator, adopts advanced detection methods and control algorithm to optimize the operation and achieve huge energy savings. 二、the electrical wiring diagram and inverter wiring diagram: 三、The advantages of using V&T inverter for transformation: 1. V&T Inverter adopts high-performance vector control, which makes the start-up smooth and shock-free, greatly reduce the impact on the power grid, improves the power factor, and makes people standing more comfortable and safer; 2. V&T frequency drive was used to carry out the transformation of the escalator. Speed regulation range was wide and the power saving was quite obvious. Advanced algorithms and detection methods have been adopted to greatly improve the operation of the motor and have considerable energy saving space; 3. Adopting frequency inverter transformation can greatly reduce the wear of the machine, reduce the degree of maintenance, and extend the service life of the escalator; 4.Adopt frequency inverter transformation, the inverter starting is smooth. the starting current was small, the impact of the motor was greatly reduced, and the service life of the motor was greatly upgraded; 5, High reliability, the inverter has perfect protection functions, such as over-current, overload and over-voltage etc; 6. If the feedback unit was selected, when the escalator was in the down state, the motor was in the power generation state, and the electric power can feedback to the power grid; 7. The frequency inverter system can coexist with the original system. V&T integrated energy-saving control cabinet also has the switching function of the industrial frequency conversion, which was convenient for online switching with the original system; 8. The operation panel of the inverter has the function of parameter copying, which greatly reduces the workload of maintenance and Commissioning; 9.Compared with the saved energy and mechanical wear and maintenance costs, the equipment transformation cost can recover the investment of energy-saving transformation in a short period of time, with significant economic benefits and social benefits, greatly enhancing the brand and value of users. Shenzhen V&T Technologies Co.,Ltd. electric drive products voltage class mainly contains 200V, 400V, 690V, 1140V, and the power class varies from 0.4kW to 3000kW, which could meet var...

一、Introduction In view of the shortcomings of most of the domestic mine shaft hoist, AC winding motor rotor string resistor for speed control. It has high failure rate, large maintenance workload, poor control performance and serious power waste, the use of frequency drive speed regulation will become a trend. 二、Features of traditional mine shaft hoist Conventional mine shaft hoist generally use a series circuit of rotor loop resistors, which use the opening and closing of the contactor to achieve step-by-step speed regulation of the motor. This control method has the following obvious disadvantages: 1. The series resistance speed regulation belongs to the pole speed regulation, the starting impact was large. There was a speed jump in the speed switching, which was easy to drop, also  high danger. It seriously affects the production efficiency and the safety of people's lives and property, especially when transporting. 2, the use of string resistance speed regulation was a serious waste of electrical energy on the resistance, the lower the speed, the more wasteful; when the object was placed, the motor was in the power generation state, which was a waste of energy. 3. Due to the use of contactor with string resistance for speed regulation, the frequent switching during speed control process makes the contactor damaged frequently, resulting in failure of the speed regulation, which has potential safety hazards and increases the maintenance workload. 4. The stability was poor and the speed changes with the load. 5, the starting torque was not enough, especially It can not be restarted in the slope. Put materials to a stable place to restart, seriously affecting the production efficiency. 三、V&T Inverter for mine shaft hoist control Integration solution. It has obvious advantages in driving the motor: 1. Adopt advanced DSP chip and excellent vector control to match the power required by the hoist with the output power of the inverter; 2. the starting current was small, the starting speed was stable without impact, greatly reducing the phenomenon of drop; 3. high reliability, the inverter has perfect protection functions, such as over-current and over-voltage overload and short circuit protection functions; 4. Low maintenance workload. There was no need to replace the contactor frequently as in the conventional solution, which greatly reduces maintenance costs; 5. a wide range of speed adjustment. It belongs to stepless speed regulation. The motor control was stable during acceleration and deceleration. The operation was smooth at speed regulation, which improves the reliability of the system. At the same time, there was no heat of string resistance, which greatly improves the working environment of the operator; 6. energy saving space. When mine shaft hoist was in the elevated state, the energy saved was proportional to the speed; when in the lower state, the motor was in the power generation state. If the energy feedback unit was used, the ...

一、System solutions The system equipment was electric hoist machine, and the lifting part was used to lift the material up and down. The material was generally 6 tons. The frequency converter equipment requires for high frequency starting torque, no jitter and fast response speed, no mechanical failure during lifting process, and the speed was stable. The system of electric hoist machine was equipped with V5-H speed control special frequency drive. It adopts V/F control mode and uses terminal to control the rotation and achieve the production process of rise and fall. Multi-section digital voltage was given by multi-section frequency. Terminal wiring was shown in the figure above. Adding a braking resistor can achieve a better lifting function. During the Commissioning process, V&T special frequency drive has stable output when low speed was up at 1HZ , the torque was large and no jitter. Commissioning effect was very good. Reflecting our products can meet customer needs in low frequency output. 二、System wiring diagram 三、Commissioning comparison In the case of 1HZ, our products can upgrade and fall 6 tons of heavy objects well, and the output was stable, and the low-frequency torque was large. When some other brands use vector control low frequency, 3HZ can run. In the crane we have a very good effect in the V / F control mode. Shenzhen V&T Technologies Co.,Ltd. electric drive products voltage class mainly contains 200V, 400V, 690V, 1140V, and the power class varies from 0.4kW to 3000kW, which could meet various application demands from high, medium and low level market. So far V&T products have been exported to over 60 countries like Korea, Germany, England, Russia, UAE, Pakistan, Thailand, India, Australia, South Africa, Mexico etc.

一、The equipment Inverter model: V5-H-4T-3.7G/5.5L-H3 Motor nameplate: 380V, 2.2kW (1 unit), 4 poles, 5.0A, 1420r/min 380V, 1.5kW (2 units), 4 poles, 2.7A, 1420r/min 二、The application: For elevators and traveling machines in the galvanizing industry, 3.7kW inverter controls 3 motors (with electromagnetic brake), 2.2kW for lifting, 2 pieces 1.5kW motors for left and right walking, The contactor in the output side of the inverter , the auxiliary contact of the contactor was used for the start signal of the frequency drive. 三、Commissioning parameters (non-factory parameters): P0.06=1，P0.08=0.5，P0.09=0.5，P0.11=100，P0.13=90，P4.22=30，P4.23=65，P4.24=50,，P4.25=80，P5.00=2，P5.01=3，P5.02=09，P5.03=10，P5.04=11，P9.02=1420，P9.03=2.2，P9.04=5.2，P9.05=3.0，PA00=6，PA11=700，d000~d002=10，d003=565，d004=3.2，d005=9.5，d006=76，d007=34，d0.08=31.7，d009=219，d011=4. 四、Commissioning problems When start commissioning, each fault was EFAL short-circuit type to ground, the control board was replaced, the fault still existed and the fault of the inverter not eliminated. Each fault was EFAL short-circuit type to ground. A situation was found on the scene: there were three V&T inverters on the site, and the motor wiring of the inverter that reported the fault was the longest. Since the fault was not eliminated after replacing the inverter, it means that our construction lifting inverter has no problem. But the reasons for the scene need to be found out. Processing steps: 1. Check the fault record and find that the fault frequency d0.05 was not the given frequency during operation. It can be presumed that it was the fault reported during acceleration and deceleration, and the acceleration and deceleration time was 0.5s. The long-term acceleration and deceleration caused the motor to heat up. As a result, the insulation of the motor reduced, so the acceleration/deceleration time was increased by 1.5 s. It was observed that the fault has been reported for a long time, which proves that it was not the cause of the acceleration/deceleration time. 2. Since the inverter was replaced or the fault was reported, the problem was not in the inverter, and the carrier frequency was also changed. It was not possible to check the output line. It was found that the screw of the contactor was not tight, and there was a terminal for the motor. The screws slipped, and all the wires were tightened once. Operation did not report the fault until afternoon of the next day. It may be this reason. Of course, there may be interference factors. It was recommended that output end should be added with a magnetic ring, and the user accepts the suggestion, affirming that the quality of the inverter is good.

It is expected to open in 2020. On this subway line, there are 20 stations and 9 transfer stations. The Middle East Bridge station and Future Technology City station are the two most special points for V&T. As a result, the electric automatic control system of bridge grab crane designed by V&T and zhongchuang minghui company successfully applied to east DaQiao station and Future Science and Technology City station, and got good praise from customers. Grab crane Grab crane, is a kind of automatic fetching machinery, its grab and unloading material action is controlled by the ship unloader driver, do not need auxiliary personnel, thus avoid the heavy labor of workers, improve the efficiency of loading and unloading. Bridge grab crane for bulk and granular materials, mainly used in grasping soil and coal and other occasions. Grab crane electrical system The electric control system of the bridge grab crane, the control of the opening and closing of the grab elevator is firstly sent to the PLC by the operation console, and then the PLC comprehensively judges according to the parameters of the current, torque and speed of the two motors. The Hoist Crane Inverter gives the optimal relative running speed and torque, ensuring that there is no scene such as rolling, spreading, etc., achieving fast, accurate and efficient semi-automatic operation of the grab. When the human is mishandled, it may cause the grab to open when lifting. At this time, no human correction is required, and the low speed 1 and 2 gears are normally lifted, the grab will gradually close itself, and the normal speed can be operated at the highest speed after ten seconds, greatly reducing the operator's work intensity and the operator's operational skills and responsibilities. The heart requirements are also greatly reduced. When the grab machine is running tens of meters away from the ground, it is difficult for the operator to see the situation of the grab. If the grab machine is not intelligent, the operator's work efficiency will be very low. The V&T intelligent grab machine system perfectly solves this problem, which fully improves the operator's work efficiency. The most important thing is that the operator's technical level requirements are greatly reduced, and work can be done without experience. The speed of the grab elevator opening and closing is divided into 3 grade. The auxiliary hook, cart and trolley motor are directly controlled by the operation console, and the speed is 4 grade. The speed changes smoothly, the operation is stable, the low speed performance is stable, and the starting current is small. Even with frequent start and stop, the heat consumption of the motor is reduced, extending the life of the motor. The main speed frequency drive and the large and small frequency drive adopt the DC common bus method to reduce the number of cabinets used, thereby reducing the customer procurement cost. Each inverter communicates with the PLC through 48...

Since the establishment of the V&T Elevator Department, the elevator engineers have worked hard to develop safe, economical, energy-saving, and efficient elevator system solutions and elevator integrated drives. Some areas in China have successively used the V&T elevator system solution and equipped with corresponding elevator integrated drive products. Once V&T elevator products were used, they quickly won praise from customers in the industry;The following is the plan and process of the Chengdu Fujixin elevator system transformation project: There is a passenger elevator and a freight elevator at the Chengdu elevator site due to disrepair for a long time. In order to ensure the safety and efficiency of the passengers, they are in urgent need of upgrading. Chengdu Fujixin elevator factory asked us for help. The situation of the elevators used on site is: Monte Rally synchronous motor 27.7Kw, operating frequency 79.6Hz, motor speed 199Rmp, elevator load 1600Kg, elevator running speed 2.5m/s, and equipped with HEIDENHAIN 1387 encoder, line number 2048; The passenger elevator runs 7 floors, with 7 stops, and single door opening; The usage of the on-site freight elevator is: Xinda asynchronous motor 22Kw, operating frequency 50Hz, motor speed 970rpm, elevator load 5000Kg, elevator running speed 0.5m/s, and equipped with Tamagawa ABZ encoder, line number 1024 The freight elevator runs 2 floors, with 2 stops, and uses through doors; Both passenger elevators and freight elevators used Chongqing Gaoguan elevator system. After our company learned the details of the elevator on site, we immediately sent engineers to the site to transform and upgrade it. We adopted the more effective elevator drive controller solution and integrated drive products of V&T, and now it can operate normally if we switch to 30Kw integrated drive products. At the same time, We have completed the elevator type test and evidence collection; The following is a picture of the elevator scene:

I. Technics Introduction The spinning-frame is main spinning machine. The yield and quality of spun yarn comprehensively reflects merits and shortcomings of each working procedure in spinning process. The spinning-frame's production unit is spindle. The yield (kg) per thousand spindle hour is frequently used to measure production-level of spinning-frame. The spinning mill's production scale is represented by total spindles of spinning-frame. The spinning yarn on each spindle would be broken for all kinds of reasons. The end breakage rate is frequently represented by number of broken ends per thousand spindle hour. The end breakage rate affects labour productivity, equipment productivity, spun yarn quality and workshop dust content. The spinning-frame is a machine with the most dissipation energy in spinning. Decreasing end breakage rate and energy saving is a technical level mark of spinning-frame. The Spinning Machine Inverter is rich in application experience in spinning industry，especially in spinning-frame industry. Through multiyear  research，V&T understands each process flow and launches the dedicated inverter special for spinning-frame. Its technical features are as follows： a.Small yarn stage occupies 15% of total length，but end breakage rate is about 70%. The speed at small yarn stage can be decreased appropriately according to yarn status so as to decrease end breakage rate. b. Middle yarn stage occupies 80% of total length. The end breaking is extremely few，occupying around 10%. The motor speed can be increased appropriately at this stage so as to improve efficiency. c. Large yarn stage occupies 5% of total length. The end breaking is 20%. The motor rotation speed can be decreased appropriately at large yarn stage to decrease end breakage rate and improve the product quality. The technics curve control at multistage speeds can be performed for frequency converter according to spinning-frame features. The running schematic diagram is shown in Fig. 1. Fig. 1 Running schematic diagram of spinning-frame It can be known from Fig. 1 that low speed running of variable frequency drive is effective at initial period and frequency converter outputs low speed running command； After low speed running command is cancelled，the frequency converter runs according to a curve set by multistage speed technics. The frequency converter accelerates to multistage speed 1 for running. Along with increase of the first stage length，frequency gradually increases. After running of the first stage length is completed，frequency converter runs at multistage speed frequency 2. This process changes at uniform speed； Each section yarn length setting is increased in sequence. The parameter design can be set from full yarn length commencement，gradually decreasing each section length setting. Each section length is limited by the next section length. It satisfies the following relation：the first length < the second length < the third length…….< The 13th ...

I. Product Description V5 and V6 series inverter are high performance vector control inverter. The speed-sensorless vector control technology synchronous with currently international leading technology is adopted for product，which is not only provided with the same excellent control performance as international high-end frequency converter, but also combines application characteristics，further intensifying the product reliability and environmental adaptability. V&T inverter with large torque upon low frequency and rapid acceleration and deceleration, realizes fast response and applies to application characteristics of machine tool industry，satisfying processing technic demand of machinery device and improving processing efficiency. II. Industry lectotype and advantage Industry lectotype The advanced speed-sensorless vector control technology is adopted for V5 and V6 series frequency converter. Under open loop vector control，0.25HZ can provide 180％ startup torque and ±0.2％ speed stabilizing accuracy. Under closed loop vector control，0Hz can provide 180% startup torque and ±0.02％ speed stabilizing accuracy. It can attain quite quick response speed for spindle motor to realize its quick start and quick stop. Especially for motor running at lower frequency，its rapidity in start and stop is more evident. V5 – H series inverter with vector control 1 and vector control 2 control mode, should be selected for general machine tool to perform workpiece processing, with stable and large cutting force. The rigidity tapping and other thread processing industries require high processing velocity accuracy and large tapping force. V6–H inverter is adopted as an actuating mechanism; it can commendably satisfy demands of such industries. For high speed engraving and milling machine with running frequency exceeding 300HZ, V5–H–H3 Inverter drive for high-speed engraving and milling machine should be adopted, which support maximum output frequency up to 3200Hz. When machine performs high-speed engraving and milling or boring for PCB board，spindle speed is stable, wouldn’t be in off tracking and fall speed, which greatly improves the qualification rate of the machined products. It requires extremely large torque and no stalling when machine tool cutting workpiece at low frequency. The V6–H series inverter should be selected and encoder is needed to perform closed loop vector control mode. Under close loop vector control, the speed stabilizing precision is 10 times than the open loop vector control mode，satisfying the machine spindle processing requirement at low frequency and heavy cutting. V6–H–M0 series products realize orientation angle, 8 angles at most when select by terminal. If more than 8 angles are required, it can be realized by communication to satisfy technics demands of different machining. Under 0Hz running status, spindle accurately stays at the correct angle. The spindle keeps very large torque without changing spindle angle. V6-...

Ⅰ Application Overview in Mine Industry ◆ Industry development trend Mine resource exploitation industry has formed extensive type, high consumption, and high pollution development mode for a long time and has made resource and environment difficult to bear. Therefore it is of all-important strategy significance for mine resource exploitation enterprises to realize energy conservation and emission reduction. The hoister is a conveyor which is used most extensively in mine and is simply classified as single hook type and dual hook type. Currently most of mine hoisters universally use  serials resistance speed control , which is high in failure rate，heavy maintenance workload，poor in control performance and severe in electrical energy waste and other shortcomings. So speed regulation by inverter will become a tendency. V5-H series inverter is high performance Sensorless Control Inverter. The speed-sensorless vector control technology synchronized with currently international most leading technology is adopted for product，which is not only provided with the same excellent control performance as international high-end inverter, but also combines application features，further intensifying the product reliability, environmental adaptability and customized and industrialized design in mine resource exploitation industry. It can better satisfy demands of various driving applications. ◆ Inverter lectotype The hoister（including other hoisters）belongs to constant tension heavy load equipment, for which V5-H series AC Motor Speed Controller should be selected. With safety aspect considered，inverter power class shall be two levels greater than motor rated power.  For example，if motor is 110kW，selected inverter should be at least 160kW. In addition, it needs to add an energy braking unit or an energy feedback unit. If motor with speed encoder，V6-H series inverter can be used to perform closed loop vector control, which can further improve speed stabilizing accuracy and low frequency torque of inverter. Ⅱ advantages in mine industry Excellent control performance decreases mechanical failure rate and  improves production benefit 1. Powerful torque at low frequency eliminates hook slide phenomenon. Even if braking is performed in lifting midway，heavy load can be pulled up in midway and need not be placed onto flat ground for restart. Under open loop control, the startup torque attains 180% rated torque under 0.25Hz running, under close loop control, the startup torque attains 180% rated torque under 0Hz running. 2. The hopper derail fault rate is evidently reduced. Smooth acceleration and deceleration avoid winch derail possibility and greatly reduce abrasion of machinery and rope. Intelligent failure predication reduces maintenance workload 1. It reduces excess repair workload for contactor and speed regulation resistance of original system and greatly reduces maintenance cost. It is also provided with perfect multi-layer protection ...

Production introduction E5-P and E5-H series high performance vector control inverter is a special-purposed adjustable speed motor drive for fan and pump, combining application features in fan industry. The products is widely used for many industrial fields such as fire fighting, petrochemical, metallurgy, mine, pharmacy, paper-making, spinning, building material, transportation, etc., and civil projects, such as centralized air conditioner, etc. for the purpose of improving technique and efficiency. The good energy conservation effect can be reached for load like fan. The product can completely supersede import product, and produce significant social and economic benefits. Industrial type selection and industrial advantages 2.1 Industrial type selection Most fan loads are light-load equipment and the ratio of E5-P to motor power rating is 1:1. Other loads like Roots fan, contra-rotating fan, and induced draft fan are heavy-load equipment, and the ratio of E5-H to motor power rating is 1:1. 2.2 Industrial advantages: Optimization design for hardware and software Effectively reduce motor noise and heat dissipation, decrease workload for motor maintenance, prolong working life of motor, and reduce cost for repair; Exceptional control performance Automatic alarm for fault; double effects of motor energy conservation and stepless speed regulating; automatically adjust motor speed based on load feature; soft startup and no impulse current and mechanical vibration when startup; Wide voltage input design Wide voltage design ensure frequency converter normally works under the condition of frequent voltage fluctuation of grid, and allows AC input fluctuation scope 323V-528V; Harmonic interference proof Built-in output reactor, smoothing reactor, etc to restrain harmonic wave, and reduce the contamination to grid. Significant energy conservation Improve effective power coefficient with significant energy conservation; reduce reactive power loss of input power supply, and reduce the demand of transformer volume; Whole machine protection in all aspects Current-limiting protection to software/hardware, over-current and over-voltage protection, ground short-circuit protection, overload protection, IGBT direct-connection protection, abnormal current protection, abnormal actuation of relay protection 3. System connection diagram 4. Electricity saving rate calculation and type selection ◆ According to the fundamental law of fluid mechanics, the equipment like fan and pump are of square torque loads, which speed n, quantity of flow Q, pressure H and shaft power P have the following relations: Q∝n, H∝n2 and P∝n3; Which means that the quantity of flow is proportional to speed, pressure is proportional to square speed, and shaft power is proportional to the cubic speed. ◆ Energy calculation example 1: 1. In a steel company, there is a centrifugal pump, with rated flow of 200.16m3/h, lift of 50m, which is equipped with a motor with rated power of 45kW. According ...

I.Application overview in air compressor industry We owns abundant experience in matching and renovating air compressor. V5-H inverter has been applied in batch to domestic mainstream air compressor manufacturers. For the air compressor characteristic , Our company especially designs integrative energy-saving inverter control cabinet to ensure renovation is more convenient and fast, and composite cost is lower. ◆ Operating principle The control system takes output pressure as control object. The closed loop constant pressure control system consists of inverter, pressure sensor and motor. The pressure value can be set directly by the operating panel. The field pressure is detected by a sensor, converted to 4 ~ 20mA current signal and then feed back to inverter. The inverter performs PID calculation to adjusting its output frequency for the purpose of constant pressure control and energy-saving of air compressor. The inverter energy-saving is represented below： 1)Adjusts air flow by adjusting the motor rotation speed to ensure the motor output power is proportional to flowrate demand, so as to keep high efficiency operation of motor. It is high in power factor, small in reactive power losses and evident in energy-saving effect; 2) According to strict EMS standard design， adopt high-speed and low consuming IGBT and adopted high-efficiency vector control algorithm to ensure that inverter harmonic distortion and the motor energy loss are minimized; 3) Automatically quick dormancy ensures idle time shortens and motor completely stops to save energy to maximum extent.  The impact-less startup and low frequency large torque characteristics ensure that inverter starts and stops with load at any moment. ◆ Inverter lectotype According to load characteristic, air compressor（including other compressor）belongs to the constant torque and heavy load equipment, for which V5-H series inverter should be selected. For equipment with motor power below 75kW，the inverter power class selected should be match to motor power. For equipment with motor power above 90KW, the inverter power class should be a level larger than motor power. For Reconstruction project, V5-J integrative energy-saving control cabinet supporting conversion between power frequency and variable frequency. Not only keep the original system, but also convenient for subsequent maintenance. II.V&T frequency converter's advantages in air compressor industry High-efficiency energy-saving 1.With vector control technique， air supply of air compressor can be combined with user's air consumption amount perfectly, which completely avoids unloading power loss. 2.Under discontinuity air consumption status，peak of current and torque are avoided through inverter start，so machine can perform unlimited startup and stop, truly accomplishing infinitely variable speeds of 0 ~ 100% and farthest limiting idle work generation. 3. Without excessive 0.2Mpa pressure burden (loading and unloading pressure difference),...