In the power system, using a 220V DC power supply (battery) to supply power to the programmable controller can significantly reduce the interference from the AC power supply, and can also ensure the normal operation of the programmable controller when the AC power supply disappears. In the power input terminal of some programmable controllers (such as FX series programmable controllers), there is a diode rectifier bridge that directly rectifies the 220V AC power supply, and the AC voltage is rectified and sent to the switch in the programmable controller. power supply. (B&R X20BC0043-10 Bus Controller, Allen Bradley 1794-OW8 Flex Output Module, B&R X20HB2885 Ethernet Hub, Siemens 6ES7132-4BD30-0AA0 ET 200S ELECTRON MODULES)
The input voltage range of the switching power supply is very wide, and this programmable controller can also use a 220V DC power supply. When using AC power, each diode of the rectifier bridge only bears half of the load current. When using DC power, two diodes bear the full load current. Considering that the input current of the programmable controller is very small, when designing Rectifier diodes generally have a large margin, such as using a DC 220V power supply voltage, there will be no problem. After long-term industrial operation, it has been proved that the above scheme is feasible.
The power part, the control part, the programmable controller and the I/O power supply should be wired separately, and the isolation transformer should be connected with the programmable logic controller and the I/O power supply by twisted pair. The power line of the system is thick enough to reduce the line voltage drop when the large capacity asynchronous motor is started . If conditions permit, a separate power supply circuit can be used for the programmable controller to avoid the interference of the start and stop of other The power supply of the programmable controller can be taken from the lighting circuit. Relatively speaking, the interference signal on the lighting circuit is much smaller than that on the power cable.
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