The hottest saipu frequency converter is produced

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Sepp inverter in Shanxi Changning group zhangzehu steelmaking plant production line energy-saving transformation

I. application background

variable frequency speed regulation technology is a new technology developed in recent years, which has incomparable advantages over traditional speed regulation methods. With the continuous development of automatic control technology and high-power semiconductor devices, its technical level is also constantly improving and maturing, It is more and more widely used in metallurgical enterprises

at present, there are still a large number of traditional speed regulation systems in zhangzehu steelmaking plant, such as the rotor series resistance speed regulation of crane, the use of wound asynchronous motor, and the step-by-step removal of resistance through AC contactor to realize motor speed regulation; In addition, there is a DC speed regulating device, which has complex system composition and high failure rate. Although the star delta starting mode is adopted in the water pump control system of the steel plant, there is still a secondary impulse at the time of starting, and the electric impulse is still severe, and the failure rate is high, which is not conducive to the normal production of the equipment. These problems can be well solved by using variable frequency speed regulation technology

II. Advantages of frequency converter

Sepp sap500g general purpose frequency converter adopts magnetic flux (current) vector control technology, and the low-speed torque output can reach 200% of the rated torque, with 0-40% starting torque compensation, which is suitable for the reliable starting of any load. Emc-frl protection design, with less harmonic components, greatly reduces the interference caused by high-order harmonics. The speed regulation range is wide, and the frequency range is 0-400hz, which can exceed the rated speed of the motor for constant power speed regulation. With overvoltage, overcurrent and other protection functions and self-regulation functions, it has high reliability, and can automatically diagnose the actual fault type. The structure of the matching motor is simple, which greatly reduces the maintenance work of the system. There are various selection functions, and t--f characteristics and acceleration and deceleration time can be selected according to various mechanical torque characteristics, which can realize soft start and reduce starting current. The multi-purpose external interface terminal can realize the process parameter closed-loop control system composed of external control and monitoring instruments, and can also form the production process program control system with PLC. The frequency converter has both switching input/output and analog input/output terminals, which can be used very conveniently. For example, the continuous casting water treatment system in the steel plant uses the pressure signal (4-20mA analog signal) detected by the external pressure sensor to send it to the analog input port of the frequency converter, which is adjusted by the PID regulator to realize the functions of constant pressure water supply

III. frequency conversion transformation of frequency converter in the steel pusher

the main task of the steel pusher in the steel plant is to push the finished steel transported through the raceway to the designated position. After the quantity meets the requirements, it is lifted by the crane. In the whole working process of the current steel pusher, the AC contactor is used to control the forward and reverse rotation of the motor, and the electromagnetic holding brake is used to realize rapid shutdown. At present, the power of the running motor is 25kW, the rated current is 50a, the starting mode is direct starting, the starting current is 5-8 times the rated current, and the starting current can reach 400A. The impact on equipment and electricity is very large, and the failure rate is high. The transformation of pusher with frequency converter can effectively solve these problems. Using the frequency converter, the steel pusher can start and stop smoothly, and the starting current will not exceed the rated current, which will effectively avoid the impact on the motor and electricity, and improve the power factor of electricity. The frequency converter can effectively monitor all kinds of conditions in the operation of the steel pusher, so as to effectively protect the normal operation of the motor. The figure below shows the frequency conversion transformation of the steel pusher:

the front and rear rows of the steel pusher shown in the figure above can be directly controlled by the run and f/r of the frequency converter, which can be realized without the conversion of the AC contactor, thus greatly reducing the maintenance rate of the equipment. After the transformation by the inverter Shanghai Jung Exhibition Co., Ltd., it can operate below 50Hz, which greatly reduces the operating current and achieves the effect of power saving. The transformation cost is 21056.00 yuan, and the cost can be recovered in about 12 months

IV. frequency conversion transformation of blast furnace charging car hoist

the traditional speed regulation method of blast furnace charging car hoist is to use a wound rotor asynchronous motor, by connecting the frequency sensitive rheostat FR in series in the rotor winding,

due to the equivalent resistance of the frequency sensitive rheostat, the fine wire of the fixed weight must be tightened, and the resistance will decrease with the reduction of the rotor current frequency, so as to achieve the purpose of automatic resistance change. The disadvantages of this speed regulation are: it can be because he wants to bend the prosthetic limb, but the travel line designed by the prosthetic limb is straight forward, the consumption is high, the low-speed mechanical characteristics are soft, and the electric voltage has a great impact on the speed; Because the reduction of rotating speed is achieved by the energy consumption of the frequency sensitive rheostat external to the rotor, and the lower the rotating speed, the softer the mechanical characteristics, and the greater the proportion of energy consumed in the resistance, which is extremely uneconomical. The above problems can be solved by using frequency converter control

the small and medium-sized blast furnaces in China basically use the skip hoist as the standard feeding equipment, which is characterized by heavy load, high position control accuracy, and high requirements for reliability and safety performance. The safe operation of the windlass of the blast furnace charging car should meet the following conditions: 1. The angle signal is also input into the plotter through the rotation sensor:

1. It has sufficient lifting and carrying capacity, and the feeding speed should meet the blast furnace production

2. The operation is reliable, stable and durable, ensuring the continuity of blast furnace production

3. It can realize automatic feeding, improve production efficiency and reduce labor intensity

4. Simple structure and convenient maintenance

working condition requirements: slow starting speed, large torque, smooth acceleration, smooth operation and accurate parking

winch frequency conversion transformation schematic diagram:

transformation steps:

1. Remove the original speed control circuit

2. Remove the connection between the wound rotor and the external frequency sensitive rheostat, and short circuit the wiring terminal. Directly short circuit the three outgoing lines of the rotor winding to avoid future faults

3. Separate the holding brake line of the skip from the motor, and control it with a single contactor. The power supply is from the input end of the frequency converter. It is required that the holding brake and the motor are powered at the same time

4. In order to ensure absolute reliability, keep the positive and negative rotation control contactor of the raw material truck, and use the auxiliary normally open point of the contactor as the positive and negative rotation control of the external terminal of the frequency converter

5. A fault reset button is installed on the operation console, and a buzzer is used as the fault alarm indication of the frequency converter

6. The lk4 master controller calls out a high-speed point, and a test switch is installed on the operation console. When it is disconnected, the charging car has been running at low speed. Set 10Hz at low speed and 50Hz at high speed

operation after transformation:

the transformed skip hoist has stable startup, large torque, smooth acceleration and deceleration, accurate parking position, and basically the same parking positions of loaded and empty cars. So far, there has been no dropping accident of the skip, and the wear of the wire rope of the skip winch has been significantly reduced. And it can start normally when the electric voltage is low, and the operation is stable. This material

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