Application of the hottest V general frequency con

V Application of universal frequency converter drive device in mixer of chemical enterprises

frequency converter used:

midimaster vector

model MDV 750/3

input voltage 3-phase, V ± 10%

input frequency Hz

output power 11kw

output voltage V (maximum depends on input voltage)

output current 19A (23.5a under variable torque load)

frequency range Hz

overload capacity 150%, 60 seconds

ambient temperature 0 ± 40 ° C

protection grade IP21 (or IP56)

equipment configuration:

* one MDV 750/3 codeless vector control frequency converter

* one rgzzesd three-phase squirrel cage motor, 10HP, 1470rpm

* DCS distribution system and on-site monitoring instruments

user benefits:

* reliable operation, small amount of maintenance, saving maintenance costs, and increasing economic benefits of the enterprise

* as a general-purpose inverter, MDV has optimized multi-channel analog/switching i/o. Field operation circuit and DCS control system can be used conveniently and flexibly to complete production. 3. Many enterprises generally adopt ball screws? Process control, and realize the speed regulation and operation monitoring of the frequency converter

* the mixer load has viscous effect when starting. The continuous lifting function (parameter p078) and starting lifting function (parameter p079) of the frequency converter can provide 250% of the rated current of the motor during the low-frequency operation and acceleration of the mixer, increase the low-frequency torque and starting torque of the motor, and meet the requirements of mixer operation

overview:

the catalyst mixing process of a polypropylene unit in Yanhua is shown in Figure 1. The catalyst enters the mixing tank from the feed tank through the ball valve. The motor driven by the frequency converter drives the mixing fan blade for mixing, and then the mixing is uniform through the vacuum valve. The catalyst that meets the requirements is sent to the catalyst feed pump to participate in the next chemical reaction

control task:

the operator in the control room obtains the command to increase or decrease the motor speed according to the measurement signal of the on-site monitoring instrument and the actual speed signal sent by the frequency converter to the DCS system, and starts and stops mixing when necessary

System Description:

the mixer does not require high speed control accuracy, dynamic and static quality of the driving device. As long as it can operate stably and reliably according to the speed command of DCS, it can meet the requirements of production

the operation circuit is shown in Figure 2. This is an open-loop control system. The start/stop operation signal of the frequency converter comes from the field operation column or DCS system. The speed reference value of analog quantity is provided by DCS (terminal in Figure 2); At the same time, the frequency converter feeds back the actual speed value (terminal) of a motor to DCs. According to the instrument measurement signal and the actual speed value of the mixing tank, the operator sends an instruction to the frequency converter to increase or reduce the reference value of the motor speed

control features:

unlike some frequency converters, MDV must keep the output prohibited state after the frequency converter is powered on, and release the output of the frequency converter only after the "run" button on the operation panel is pressed, or a "on" signal is connected through terminal 5 or 6. Otherwise, if terminal 5 or 6 is directly connected to ± 15V voltage, the frequency converter may be damaged when the industry shuffle power is aggravated on the frequency converter. In the figure, the normally open contact (terminal) of RL2 is closed after the power on self-test is normal, and the "on" signal is connected to terminal 5, which allows the output of the frequency converter to be released, ensuring the safety of the frequency converter

operation effect:

the designer of the control circuit has designed a reasonable and correct control circuit by making full use of the hardware resources of the equipment itself through a comprehensive understanding of the functions of the frequency converter, which meets the requirements of production

mdv has the functions of continuous lifting and starting lifting. It has a viscous effect on starting. The mixer load requiring additional torque during low-frequency operation and acceleration causes uneven stress on the wedge-shaped inclined plane, which can provide a total of 250% of the motor capacity. Wuhan has overcome the world's difficult problem of nano film material testing, and the constant current makes the mixing work smoothly