Hey every one,

Constant pressure water supply for a tall building, using a pressure sensor detecting the pressure in pipes, reduce the pump speed when the pressure reach to the upper limitation; And increase pump speed when pressure fall down to minimum limitation, therefore, to achieve constant pressure in the pipes.

What I want to know is the constant pressure water supply plc and inverter wiring diagram? As well as the operation parameters setting, control procedures?

The constant pressure control system you talked about is not complicated;
Adopt PLC programming to achieve PID control, the pipeline pressure sensor feedback analog current signal to PLC through inner PID control, to control the variable frequency drive output frequency analog signal in real-time or use digital communication interface connection to transfer data directly to achieve control purpose.

You also can use the variable frequency drive internal PID controller to control it directly, The pressure sensor feedback pressure signal to the VFD PID control module, then through the ac drive's own program or adjust some control parameters to achieve the automatic adjustment function.

Specific programming and wiring, it depends on the brands and models of PLC and VFD drives to analyze specific issues, I do not know what products you installed, so it's impossible to make a specific answer. However, I recommend to find a professional company to do it, this type of technology is very mature and simple, not a big cost, the key value is the contractor will do maintenance and fault handling in future operation.

A simple word, the pressure sensor is treated as a feedback signal in the whole system, conventional application will adopt plc analog module, this pressure value and the pressure you hope to keep will be calculated through PID and then control the variable frequency drive output frequency. Wiring and parameter setting is simple actually, read the instruction carefully you will know.

The above situation is PLC PID operation, in fact, the water supply VFD drive has it's own pid pressure function, means the signal also can be fed to the drives input terminal directly, so that the VFD itself can regulate the pressure already. In this case, the plc role is to control the ac drive start/stop, and the main circuit contactor open/close etc!

The shaft is 120m deep, but the pump is at 110m to prevent it from clingogg up. And also, the drillers found the last source of water at 90m but tried their luck till 120.The pump controller can be configured for a set pressure and will control the pump speed up to that pressure. This also effectively acts as the on/off switch for the pump, i.e. instead of turning the pump off, we simply close the tap and the pressure will reach it's cut off point and the pump will turn off. When we open the tap again, the pressure drops and the pump turns on again.The water will go to a dam which we've yet to construct, so if the system fails, the dam will overflow. But of course the whole system will be electronically monitored (can't wait for that phase of the project ) so we'll know if the pump is on when it shouldn't be.