PLC programming example: Heat exchange station automatic monitoring system PLC controls the frequency converter to adjust the circulation pump and water replenishing pump to control the pressure and f

PLC programming example: Heat exchange station automatic monitoring system PLC controls the frequency converter to adjust the circulation pump and water replenishing pump to control the pressure and flow of the pipe network

PLC controls the frequency converter to regulate the circulation pump and water replenishing pump.

First determine the control method.

For example, the circulation pump is controlled by the pressure difference between the supply and return water, and the replenishing pump is controlled by constant pressure.

Circulation pump control: Read the outlet and return water pressure values ??of the secondary network to the PLC through the analog module and then perform a difference calculation to set a range.

The upper limit corresponds to 50HZ and the lower limit corresponds to your lowest frequency.

Water replenishment pump control: After collecting the return water pressure on the secondary side through the analog module, the constant pressure you set is used as a fixed value. If the pressure is high, reduce the frequency and stop when it reaches the lowest frequency.

When the pressure is as low as the negative value of your constant pressure, start the frequency converter; when the pressure is low, just keep running at power frequency.

I know the principle, as long as the processing of some data is disgusting.

You'd better find an example to see. The conversion multiple of each PLC is different.