For the core electrical components of a printing machine, Ning Ken will invest a large amount at one time to avoid the trouble caused by frequent failures in the future. Of course, if you are sure about the quality and performance of other inverter brands, you can also choose, so that you can save some. After you have the inverter hardware, you must set its internal parameters. As far as speed parameters are concerned, the jog frequency can be set to 2.5 Hz, the initial printing speed is 25 Hz, and the high speed is about 60 Hz. The following uses Mitsubishi inverter A540 series 400V, 11kW products as an example to describe its specific wiring and retrofit connection with the old type printing machine. The circuit of the two is shown in the figure. The relevant precautions are as follows.
(1) The main transmission device of the original printing press is the electromagnetic speed regulating (slip) motor, low speed motor, clutch, brake and other mechanisms are not used. It is replaced by a special frequency conversion speed regulating motor produced by Shanghai Tongtai Motor Company. The machine's 11kW / 380V comes with three-phase power-off brake and cooling fan. The mounting base of the original motor can be used, and the pulley of the original motor can also be removed and installed on the new motor shaft.
(2) Because the original main motor and low-speed motor have been disassembled, the wiring of the main contacts of the contactors KM1, KM2, and KM3 in the distribution box can be removed. Use the remaining available contacts according to the new circuit as the switch contacts of the inverter control signal. Because the contacts of the original relay may be used for a long time and the contact is poor, it is best to replace it. The inverter's forward input terminal STF, reverse input terminal STR, medium speed terminal RM, low speed terminal RL, reset terminal MRS, and common terminal SD wiring need to combine related contacts in series and parallel to meet the three-stage speed regulation requirements.
(3) The original electromagnetic speed regulator ZLK-11 has also been removed. It is possible to use its installation position to make a suitable speed display box, and use a 1KΩ / ZW winding potentiometer to access the analog signal input port-10E , 2.5, use a DC voltage meter with a full range of 10V in parallel at the 2.5 end. Change the indicating unit in the dial to indicate the command speed of the inverter.
(4) Connect the normally closed contacts B and C of the inverter to the series circuit of the original control line KA1 to make it have the function of emergency stop after the operation.
(5) The contactor KMa that controls the main motor is connected to the original line KA1. If there is an alarm, it will be released, and the main motor circuit will be opened. At the same time, the KA1 normally closed contact is closed, the inverter is reset, and the output is prohibited. There are two branches connecting the cooling fan and the electromagnetic brake contactor KMb coil. One is to connect the KMa normally open contact in parallel with the KMa, and the other is to connect the normally closed contact of the crank safety switch between the power supply. Normally, the branch is disconnected. When manual rocking is required, the power supply also energizes the KMB through the safety switch, and the brake can be released when the brake is released.
(6) There are two ways to install the inverter. One is to make another control box and place it in a proper position on the lower part of Feida cardboard. The other is if the control cabinet is close to the wall or column, you can fix the control box on the wall or column. The original control cabinet is connected.
4 Conclusion
After the above steps, the author successfully transformed an old J2205 single-sheet two-color lithographic printing machine. After the transformation, the captain reported stable speed, accurate speed regulation, high efficiency and energy saving, and the maintenance staff also felt that the reliability was high and almost no extra maintenance was required. We actually measured the current consumed during the production of the printing press before and after the transformation, made a comparative calculation, and reached the conclusion that at least 30% energy saving was achieved. As shown in the attached table: 20 hours of production per day, 280 days in one year, 16800kWh of electricity can be saved in one year, and 0.7 yuan per kilowatt-hour of electricity, 11760 yuan in electricity can be saved in one year. In addition, the previous low speed The electromagnetic clutch used for clutch and brake is easily damaged due to the poor working environment. With 4 replacements per year, each of 250 yuan can save another 1,000 yuan. It costs us 7,800 yuan to buy a frequency converter, 8,000 yuan for a frequency conversion motor, plus some required wires, relays, etc., totaling about 16,000 yuan. When the input is compared with the output, the entire investment can be recovered in less than a year and a half. Of course, this does not include the indirect benefits of improved productivity and improved print quality after transformation.
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