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Entry type: Application example Entry ID: 23753479, Entry date: 06/04/2019
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PI Controller with LOGO! for Simple Applications - Optimum Motor Speed Control (Set 23)

  • Entry
  • Associated product(s)
A LOGO! 8 regulates the pressure of a cooling water system by means of controlling a pump. On a display all associated operating data are shown. The set value can be adjusted on the display. The water pressure and the level in the storage tank are measured with appropriate sensors.

Task
In an injection molding plant, the molded parts are cooled down to a certain final temperature by a water cooling system. Several consumers are connected for cooling down up to three parts simultaneously.
To optimize the cooling performance and to reduce failures, it is to be ensured that - independent from the number of active consumers, a constant pressure is always provided for the central feed. The adaptation of the pump flow rate, and therefore of the pressure, must be stepless.
It is to be ensured that the pump is only operated when sufficient cooling water is supplied. The current pressure (actual value) and the operating hours of the pump are to be displayed. It must be possible to edit the pressure needed by the consumers (setpoint value).
 


Fig. 01

Solution
The automation solution uses a LOGO! logic module with a connected SITRANS P pressure measuring transducer for capturing the current pressure in the cooling water cycle.
A PI controller in the LOGO! logic module adjusts the pressure by varying the motor speed depending on the pressure that is being measured. The pressure of the cooling water system is thus kept constant, independent from the number of consumers. The cooling performance is optimized and failures caused by a shortfall of pressure are prevented.

The asynchronous motor is connected to a SINAMICS V20 frequency converter, which receives the setpoint motor speed as a frequency setpoint via the analog output of the LOGO! expansion module AM2 AQ. The speed of the asynchronous motor is adjusted steplessly via the SINAMICS V20.

A SIRIUS wire electrode for level monitoring is connected to a SIRIUS monitoring relay. This is to ensure and monitor that the pump is supplied with fluid during operation. The monitoring status of the SIRIUS monitoring module is transmitted to a digital input of the LOGO! logic module.

The current pressure at the cooling water system, the setpoint pressure and the operating hours of the pump can be directly displayed on an external LOGO! TDE. The setpoint value of the cooling water system can also be edited. On an integrated display of the LOGO! logic module, the setpoint pressure, the current pressure and the speed of the pump are displayed in a bar diagram.
 


Fig. 02

Advantages
This application offers the following advantages:

  • Cost-effective set-up by using a LOGO! 8 logic module for controlling

  • Display as absolute values and in form of a bar diagram, setting operational data on the integrated display of the LOGO! 8 logic module

Benefit
This application offers the following benefit:

  • This application allows for a quick test of the hardware and software interfaces between the products described in this set.

  • Time saving in planning your configuration due to a finished project.

  • Planning safety due to a configuration successfully tested.

  • Avoiding failures with a tested code and step-by-step instruction.

Variants
Four variants are available for downloading:

  • Software package for a controlling with LOGO! 8

  • Software package for a controlling with LOGO! 8 and a simulation of the controlled system with S7-1200

  • Software package for a controlling with LOGO! 7

  • Software package for a controlling with LOGO! 7 and a simulation of the controlled system with S7-1200

Downloads

Software package for real controlling with LOGO! 8
 Flyer (156,7 KB)
  Set23_RegReal (2,0 MB)
 Registrierung notwendig Project Set 23 RegReal applying LOGO! 8 (35,9 KB)

Software package for a controlling with LOGO! 8 and a simulation of the controlled system with SIMATIC S7-1200
 Flyer (156,7 KB)
  Set23_RegSim (2,4 MB)
 Registrierung notwendig Project Set 23 RegSim applying LOGO! 8 (9,1 MB)

Software package for real controlling with LOGO! 7
 Flyer (259,3 KB)
  Set23_RegReal.pdf (2,0 MB)
 Registrierung notwendig Project Set 23 RegReal applying LOGO! 7 (36,6 KB)

Software package for a controlling with LOGO! 7 and a simulation of the controlled system with SIMATIC S7-1200
 Flyer (259,3 KB)
  Set23_RegSim (2,4 MB)
 Registrierung notwendig Project Set23 RegSim applying LOGO! 7 (6,1 MB)

Further Information
 
LOGO! Device Manual
SINAMICS V20 Inverter Operating Instructions
SINAMICS V20 Getting Started Compact Operating Instructions
STEP 7 Professional V13.0 System Manual
SIMATIC S7 S7-1200 Programmable Controller System Manual
S7-1200 Compact Switch Module CSM 1277 Operating Instructions
3UG4/3RR2 Monitoring Relays Device Manual

Last Changes

  • Flyer
  • Documentation
  • LOGO! 8
  • LOGO! TDE
  • Simulation applying STEP 7 (TIA Portal) V13
  • S7-1200 V4

 

 

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