Cascade

Hi

I want to run 4 water pump for pressure control between low level (example:4 bar) and high level (example:6bar).

if pressure is low than 4 bar then run a pump. if a pump can not provide 6 bar then run another pump. This process will continue up to fourth.

Most often only one pump is turned on. To divide the depreciation, i want run these pump by periodic.

this process done by LOGO? or do I have to work with other models?

Hello Masoodes,

Please, take a look in the draft attached.

Something else is necessary for your requirements. 

Dinos

Dinos

Hello Masoodes,

Please, take a look in the draft attached.

Something else is necessary for your requirements. 

Dinos

 Thank you for attention

But your program only simply part of my problem. My main problem is running the pumps periodically.

I'm re-define the problem:

I have 4 pumps and a pressure sensor.  If line pressure is less than 4 bar then run a pump. If after 10 seconds the pressure is still less than high level (6 bar) run second pump. This process continues until the fourth pump.

Any time the pressure was more than 6 bar turn off last pump. After 10 seconds if pressure was more than 6 bar turn off 3rd pump. This process continues until turned off all pumps.

you program done this stages somewhat. The problem is that I want to start the next time the operation of the second pump.

Like this picture (but it is for boiler)

Hello Masoodes,

The first draft I sent you, I had consider using a analog sensor....

I think you are using a pressotate with a diferential pressure control. Good: it's cheaper than analog pressure control. And you don't need nothing more.

See attached draft version1.

It use a shift register. When the pressure goes down under 6 bar the first pump runs. If the pressure remains below 6 bars a second pump runs too after a defined time. And that happens until the fourth pump. When the pressure reachs 6 bars the pumps stops in the same way: Pump 1,2,3 and 4. (it´s better then 4,3,2 and 1).

That´s a little thing to arrange: for example, if pump 1 and 2 are running and the pressure reaches 6 bar, the run sequence continues. But the stop sequence take effect normally.

I hope it helps you

Thank you for very useful answer

What is SET or RESET shift register bit? example RST S1.1

Masoodes

Thank you for very useful answer

What is SET or RESET shift register bit? example RST S1.1

 Hello,

Go to online help and then to Shift Register how it work:

LOGO!Soft Comfort Online Help - Siemens Industry Online Support

Ste39

 

Masoodes

Thank you for very useful answer

What is SET or RESET shift register bit? example RST S1.1

 Hello,

Go to online help and then to Shift Register how it work:

LOGO!Soft Comfort Online Help - Siemens Industry Online Support

there are not anythings In the soff comfort help about SET or RESET, only wrote "Shift register bit" and "Shift register" instructions

Hello Masoodes,

A Shift register has eight bits.  You can use up to 8 bits. The bits work like flags. The bits (S1.1, S1.2...., S1.8) are subordinated to shift register S1.The bits state ("0" or "1" ) depends on the state of entries "In", "Trigger" and "Dir".

Operating example

With "In" enabled and "Dir" disabled, for each pulse in Trigger, the bits change from "0" to "1"  in the sequence: S1.1, S1.2....

Thats I did in the draft program I sent you: when the pressure goes down below 6 bar, the entry "In" is enabled. A timer sends pulses to the Trigger. For each pulse one bit is activate (and the bit, like a flag, activies a contactor coil). When the pressure goes  to 6 bar the entry "In" is desactiveted and so, for each pulse in the Trigger the bits will change to state "0". It was added thermal contacts to protect the motors and Stop button for maintenance  or if you want simply to stop any pump.

Attached a simple draft. You can "play", switching "In", "Trgger" and "Dir" seeing what happens of the bits state. There is a variety of possibilities. Understanding this, you will be able to program your pumps exactly to your necessity.