Summary of frequency conversion transformation of

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Summary of frequency conversion transformation of paper mill (III)

4, several schemes in trial operation RB ⑵

in the continuous steaming test machine, the frequency converter was not used, but it was found that the flow of the four-stage motor was too large, which was far beyond the range of water level control. If the six-stage motor was used, the lift was not enough, and the reed pieces could not be pumped up, so the four-stage motor was used. Once I wanted to reduce the flow head by changing the impeller size of the motor pump, but after the impeller is reduced, the flow cannot be changed. After using the frequency converter, change the flow through speed regulation to make the system operate normally

the table below is for comparison (pump: 37KW, motor: 37KW, speed: 480r/min, △ connection method, rated current 70A)

it can be seen from the above table that when the frequency converter is not used, the motor and pump are overloaded. In the test, it is found that the pump bearing and motor are hot after less than half an hour of operation. In order to ensure the safety of the equipment, it has to stop the machine, and the liquid level of the washer cannot be stabilized, and the liquid level has been falling

5, the measured data of process parameters after using the frequency converter

in actual production, the concentration of the scrubber of 3% is not easy to control. The measured data twice are as follows (3% is the design index)

6. The flatness of the screw is mostly within 0.01mm. The installation of the frequency converter

the side of the scrubber is extremely wet, so the frequency converter is installed in the MCC cabinet (motor centralized control cabinet) room, about 15m away from the reed pump. It is connected by cable electrical appliances. The installation is strictly in accordance with the instructions, and the grounding is properly handled, It is found from the installation and test run that grounding is very important. When the motor ground wire is not connected, due to the rich harmonic of the frequency converter, a voltage of 4V to the ground is induced on the motor ground wire, and the three-phase wire of the motor also has induced current, resulting in the error of the metering instrument and three-phase imbalance (when only pumping water, the measured three-phase power current is 36a, 50a, 50A when it is not grounded, and the three-phase current is 41a, 40a, 41a after grounding to ensure safety)

7, operation condition

during operation, strictly implement the quality assurance procedure of Jinan gold testing machine in accordance with the operating regulations, and do not operate against rules From the use of the frequency converter, in addition to its excellent speed regulation performance, the damage to the impeller during startup is very small. The frequency converter has a soft start function, and the starting current is small, which effectively protects the motor Using frequency converter can not only save energy, but also meet the requirements of production process, improve product quality and output If the operating frequency is below 40Hz, the energy saving can reach more than 30%

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