MPS-PA Solutions 709743 En

709743 EN

MPS•

PA

Solutions

2 © Festo Didactic GmbH & Co. KG • MPS®

PA

The Festo Didactic Learning System has been developed and produced solely for

vocational and further training purposes in the field of process automation. The

company undertaking the training and / or the instructors is / are to ensure that

trainees observe the safety precautions specified in this workbook.

Festo Didactic herewith excludes any liability for damage or injury caused to

trainees, the training company and / or any third party, which may occur if the

system is in use for purposes other than purely for training; unless the said damage

/ injury has been caused by Festo Didactic deliberately or through gross negligence.

Order No.: Status: Authors: Editorial team: Graphics:

709743 12/2006 J. Helmich, ADIRO H. Kaufmann M. Linn V. Xhemajli, C. Green, T. Schwab, ADIRO

© Festo Didactic GmbH & Co. KG, 73770 Denkendorf, Germany, 2007 Internet: www.festo-didactic.com e-mail: [email protected]

The copying, distribution and utilisation of this document as well as the communication of its contents to others without express authorisation is prohibited. Offenders will be held liable for the payment of damages. All rights reserved, in particular the right to carry out patent, utility model or ornamental design registration.

Parts of this documentation may be copied solely for training purposes by the authorised user.

Intended use

© Festo Didactic GmbH & Co. KG • MPS®

PA 3

Solutions – Filtration station

Solution 1.1: Analysis and appraisal of the system

Solution 1.1.1: Designation of the process components ______________________ 5

Solution 1.1.2: Completing the P&I diagram ________________________________ 7

Solution 1.1.3: Completing the pneumatic circuit diagram ____________________ 9

Solution 1.1.4: Determining the technical data of a system___________________ 11

Solution 1.1.5: Drawing up the allocation list ______________________________ 13

Solution 1.2: Measurement and control

Solution 1.2.1: Characteristics of the proportional pressure regulator/filter system16

Solution 1.2.2: Logic operation _________________________________________ 19

Solution 1.2.3: Operating range and operating point of a controlled system _____ 26

Solution 1.2.4: Identifying a controlled system_____________________________ 28

Solution 1.2.5: Ramped pressure stages__________________________________ 30

Solution 1.3: Closed-loop control

Solution 1.3.1: Two-position controller __________________________________ 32

Solution 1.3.2: Closed-loop control using continuous-action controllers (P, I, PI) _ 34

Solution 1.3.3: Controller setting according to Ziegler-Nichols ________________ 39

Solutions – Mixing station


Solution 2.1.1: Designation of process components ________________________ 43

Solution 2.1.2: Completing the P&I diagram ______________________________ 45

Solution 2.1.3: Completing the pneumatic circuit diagram ___________________ 47

Solution 2.1.4: Determining the technical data of a system___________________ 49



Solution 2.2.1: Characteristics of the piping/pump system ___________________ 54

Solution 2.2.2: Logic operation _________________________________________ 61

Solution 2.2.3: Operating range and operating point of a controlled system_____ 69

Solution 2.2.4: Identifying a controlled system_____________________________ 71

Solution 2.2.5: Mixing according to quantity_______________________________ 73


Solution 2.3.1: Two-position controller ___________________________________ 76

Solution 2.3.2: Closed-loop control using continuous-action controllers (P, I, PI) _ 78

Solution 2.3.3: Manual setting of control parameters _______________________ 83

Contents


PA

Solutions – Reactor station


Solution 3.1.1: Designation of process components ________________________ 85

Solution 3.1.2: Completing the P&I diagram _______________________________ 87

Solution 3.1.4: Determining the technical data of the system _________________ 89



Solution 3.2.1: Characteristics of the heating system medium ________________ 94

Solution 3.2.2: Logic operation ________________________________________ 100

Solution 3.2.3: Operating range and operating point of a controlled system ____ 106

Solution 3.2.4: Identifying a controlled system____________________________ 108


Solution 3.3.1: Two-position controller __________________________________ 110

Solution 3.3.2: Closed-loop control using continuous-action controllers (P, I, PI) 112

Solution 3.3.3: Tuning method according to the rate of rise _________________ 117

Solutions – Filling station


Solution 4.1.1: Designation of process components _______________________ 121

Solution 4.1.2: Completing the P&I diagram ______________________________ 123

Solution 4.1.3: Completing the pneumatic circuit diagram __________________ 125

Solution 4.1.4: Determining the technical data of the system ________________ 127

Solution 4.1.5: Drawing up the allocation list _____________________________ 129


Solution 4.2.1: Characteristics of the metering tank-pump system ____________ 132

Solution 4.2.2: Logic operation ________________________________________ 136

Solution 4.2.3: Operating range and operating point of a controlled system ____ 142

Solution 4.2.4: Identifying a controlled system____________________________ 143

Solution 4.2.5: Inlet and outlet behaviour of the metering tank ______________ 145


Solution 4.3.1: Two-position controller _________________________________ 151

Solution 4.3.2: Closed-loop control using continuous-action controllers (P, I, PI) 153

Solution 4.3.3: Optimisation method according to Chien-Hrones-Reswick (CHR)_ 158

Solutions MPS®

PA Filtration station


PA 5

Solution 1.1: Filtration station – system analysis and appraisal

Name: Date:

1.1.1 Designation of process components Sheet 1 of 2

3

1

2

4

Designation of process components

Solutions MPS®



PA

Solution1.1: Filtration station – system analysis and appraisal

Name: Date:


No. Designation Meaning or function

1 1B1

Pressure sensor

2 F101

Filter

3 V102

Gate valve

4 V103

Butterfly valve

5 V106

3-way ball valve

In the electrical circuit diagram and P&I diagram of the filtration station you will find

two different designations for the gate valve.

– Explain the difference.

Comprehension questions

The designation V102 from the P&I diagram is a process designation. The process related functions in

an EMCS plan (Electronic Measuring Control System) are known as EMCS points. The measured

variable or another input variable, its processing, direction of action and positional data should be

based on this designation.

An EMCS point consists of a circle and is designated with a code letter ((A – Z) and a code number. The

code letters are entered in the upper section of the EMCS circle and the number in the lower section.

The sequence of code letters can be established from the table "EMSR code letters to DIN 19227".

The designation 1M4 from the electrical circuit diagram describes the electrical function.

All electrical equipment of an MPS®

PA station is labelled with equipment designations according to

the electrical circuit diagram. The designation of equipment in the electrical circuit diagrams is

effected according to the standard DIN/EN61346-2.

Designation

of process components

Solutions MPS®



PA 7


Name: Date:

1.1.2 Completing the P&I diagram Sheet 1 of 2

P&I diagram

Solutions MPS®



PA


Name: Date:


Designation Meaning or function

F Filter

LS- Proximity sensor

LA+ Status, limit value alarm

P101 Digital pump

V Valve

– State the difference between the measuring point designations

LA+ and LS+.


The designations LA+ and LS+ differ with regard to the function within the station. Whereas both

sensors indicate the water level in the tank, LA+ signals an error message. (often in the form of

Emergency-Stop).

Functional description of

components

Solutions MPS®



PA 9


Name: Date:

1.1.3 Completing the pneumatic circuit diagram Sheet 1 of 2

Pneumatic circuit diagram

Solutions MPS®



PA


Name: Date:

1.1.3 Pneumatischen Schaltplan vervollständigen Sheet 2 of 2

Symbol Meaning or function

Flow control valve

5/2-way valve

Butterfly valve with pneumatic swivel actuator

– What is the meaning of the 5/2-way valve designation?

– What is the function of a flow control valve on a pneumatic cylinder?

Comprehension question

The 5/2-way valve has 5 ports and 2 switching positions. One port is intended for the supply of

compressed air. The remaining 4 ports are for the connection of the working and exhaust lines.

Depending on the design, the valve can be actuated either by means of applied pressure via pilot air

or electronically.

Exhaust air flow control valves are screwed into the exhaust ports 3 and 5 of control valves and enable

the regulation of cylinder piston speed by means of exhaust air restriction. The flow control screw

facilitates an adjustable restriction of exhaust air. The exhaust air is discharged via the integrated

silencer to reduce noise levels.

Functional description

of pneumatic components

Solutions MPS®



PA 11


Name: Date:

1.1.4 Determining the technical data of a system Sheet 1 of 2

Component Designation

in flow

diagram

Function Characteristics

Pump P201

Delivers a liquid

from a tank via the

piping system

Voltage [V] 24 V

Electrical power [W] 26 W

Max. throughput [l/min] 9

l/min

Proportional

pressure

regulator

Prop_V

Regulates pressure

proportional to a

preset setpoint

value.

Setpoint voltage [V] 0 - 10 V

Druckbereich [bar] 0.15 - 6 bar

3-way ball

valve V106

Changes the

direction of flow

within the station

Min. pneum. pressure [bar] 1 bar

Power consumption [W] 5.65 W

Pressure

sensor

1B1

Measures pressure

Pressure range [bar] 0 - 10 bar

Sensor signal [V] 0 - 10 V

Limit switch

top ( B101)

LS + 101

Status, upper limit

value

Filling amount up to contact [l] 6 l

Type (normally open/

normally closed) Norm. open

Limit switch

bottom

(B101)

LS- 102

Status, lower limit

value

Filling amount up to contact [l] 0 l



Implementation

Technical data

Solutions MPS®



PA

Solution 1.1: Filtration station – System analysis and appraisal

Name: Date:


– Describe the design and function of a proportional pressure regulator?


The proportional pressure regulator is used to control pressure proportional to a preset setpoint

value. Its main function is to be able to replace previously manually adjustable pressure regulators

with electrical, remotely adjustable regulators, for example in order for different machine parameters

to be automatically and instantly available. An integrated pressure sensor determines the pressure at

the working port and compares this value with the setpoint value. In the case of setpoint/actual

deviations, the regulating valve remains actuated until the output pressure has reached the setpoint

value.

Solutions MPS®



PA 13


Name: Date:

1.1.5 Drawing up the allocation list Sheet 1 of 3

Symbol EasyPort /

Simbox

address

PLC address Description Check

1B1 DI 0 I 0.0 Air jet pressure

1B2 DI 1 I 0.1 Tank B101 top

1B3 DI 2 I 0.2 Tank B101 bottom

1B4 DI 3 I 0.3 Tank B102 top

1B5 DI 4 I 0.4 Tank B102 unten

1B6/1B7 DI 5 I 0.5 Butterfly valve open and gate valve

down

1B8/1B9 DI 6 I 0.6 Butterfly valve open and gate valve

up

1PA_FREE DI 7 I 0.7 Receiver downstream station free

Symbol EasyPort /

Simubox

address


1PV1 AI0 EW256 Actual value X (pressure)

Allocation list of

digital inputs

Allocation list of

analogue inputs

Solutions MPS®



PA


Name: Date:


Symbol EasyPort /

Simubox

address


1M1 DO 0 O 0.0 Air jet pressure

1M2 DO 1 O 0.1 Pump P101, waste water

1M3 DO 2 O 0.2 Pumpe P102, downstream station

1M4 DO 3 O 0.3 Gate valve

1M5 DO 4 O 0.4 Butterfly valve

1M6 DO 5 O 0.5 3-way ball valve

1M7 DO 6 O 0.6 Stirrer

1PA_BUSY DO 7 O 0.7 PA station busy

Symbol EasyPort /

Simubox

address


1CO1 AO 0 AW256 Manipulated variable Y,

Proportional pressure regulator

Allocation list of

digital outputs

Allocation list of

analogue outputs

Solutions MPS®



PA 15


Name: Date:


– Describe the behaviour of the analogue final control element (proportional

pressure regulator) if actuated via an analogue signal.


The bridge in the connection board must be converted to „analogue“ to enable analogue control of an

analogue final control element.

The analogue final control element responds as a function of the voltage applied. The valve is closed

in the unactuated state, i.e. if 0V voltage is applied. If an analogue signal is applied, the valve

response is proportional to the signal level. Pressure is thus infinitely adjustable as required.

Solutions MPS®



PA

Solution 1.2: Filtration station – measurement and control

Name: Date:

1.2.1 Characteristics of the proportional pressure regulator/filter system Sheet 1 of 3

The solution has been realised using digital/analogue EasyPort and FluidLab®

-PA.

Voltage at

prop_V in V 0,00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00

Signal

pressure

sensor in V

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.00 3.00 3.00 3.00

Pressure

in bar. 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.00 3.00 3.00

3.00

Voltage at

prop_V in V 5.50 6.00 6.50 7.00 7.50 8.00 8.50 9.00 9.50 10.00

Signal

pressure

sensor in V

3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00

Pressure

in bar. 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00 3.00

3.00

Control of proportional pressure regulator.

Note

Value table

Solutions MPS®



PA 17


Name: Date:



-PA.

Note

Characteristics of prop_V-

Filter system

Solutions MPS®



PA


Name: Date:



-PA.

No. Question Answer Comment

1 Form of characteristic curve Linear

A small hysteresis

exists. Operating

range only up to

3 bar.

2 Hysteresis is dependent on: The speed of the setpoint change Greater hysteresis

with higher speeds

Slow setpoint change

H = 0.1 3 Determine hysteresis:

Fast setpoint value change

H = 0.3

4

What setpoint value (V)

must be set if the filter is to

be flushed using the

pressure given opposite?

p = 0.5 bar = 0.5 Volt

p = 1.0 bar = 1.0.Volt

p = 1.5 bar = 1.5.Volt

– Explain the characteristic curve!

– State the reasons for the system response at low voltages!


At low voltages, the proportional pressure regulator is not within the preset operating range. The

linear range of the proportional pressure regulator begins as from 0.15 volts.

Note

Solutions MPS®



PA 19


Name: Date:

1.2.2 Logic operation Sheet 1 of 7

– Pushbutton S1, start of „stirring“ subprocess

– Pushbutton S2, start of „filtration“ subprocess

– Pushbutton S3, start of „flushing“ subprocess

The solution has been realised using digital/analogue EasyPort and FluidSIM®

Setting condition for stirrer R104

P&I

diagram

symbol

Electr.

circuit

diagram

symbol

Address Logic

operation

Comment

- S1 - & Pushbutton

LS- 102 1B3 DI 2 & Sensor

(lower filling level at Tank B101)

- 1B9 DI 6 & Sensor

(gate valve up)

Resetting condition for stirrer R104

P&I

diagram

symbol

Electr.

circuit

diagram

symbol

Address Logic

operation

Comment

- S2 - ≥1 Pushbutton


LS- 102 1B3 DI 2 ≥1 Not sensor

(lower filling level at tank B101)

- 1B9 DI 6 ≥1 Not sensor

(gate valve up)

Solution

Note

Solutions MPS®



PA


Name: Date:


Setting condition for gate valve V102

P&I

diagram

symbol

Electr.

circuit

diagram

symbol

Address Logic

operation

Comment

- S2 - & Pushbutton



- 1B7 DI 5 & Not sensor

(butterfly valve open)

Resetting condition for gate valve V102

P&I

diagram

symbol

Electr.

circuit

diagram

symbol

Address Logic

operation

Comment

- S1 - ≥1 Pusbutton

- S3 - ≥1 Pusbutton

LS+ 101 1B2 DI 1 ≥1 Sensor

(upper filling level at tank B101)





Solutions MPS®



PA 21


Name: Date:


Setting condition for pump P102 - downstream station

P&I

diagram

symbol

Electr.

circuit

diagram

symbol

Address Logic

operation

Comment

- S3 - & Pushbutton



- 1B9 DI 6 & Sensor

(gate valve up)

Resetting condition for pump P102 – downstream station

P&I

diagram

symbol

Electr.

circuit

diagram

symbol

Address Logic

operation

Comment




(upper filling level at B101)



Solutions MPS®



PA


Name: Date:


Setting condition for pump P101 – waste water pump

P&I

diagram

symbol

Electr.

circuit

diagram

symbol

Address Logic

operation

Comment





Resetting condition for pump 101 – waste water pump

P&I

diagram

symbol

Electr.

circuit

diagram

symbol

Address Logic

operation

Comment




LS+ 103 1B4 DI 3 & Sensor


- 1B9 DI 6 & Not sensor

(gate valve up)

Solutions MPS®



PA 23


Name: Date:


– Stirrer R104 on

– Gate valve V102 up

Logic diagram

Network 1

Network 2

Solutions MPS®



PA


Name: Date:


– Pump P102 – downstream station on

– Pump P101 – waste water pump on

Network 3

Network 4

Solutions MPS®



PA 25


Name: Date:


– Why is air in the piping system to be avoided?


Air in the piping system prevents the correct operation of the system.

The pump must be prevented from running dry as this will cause damage to the pump.

Solutions MPS®



PA


Name: Date:

1.2.3 Determining the operating range and operating point of a controlled system Sheet 1 of 2


-PA.

Determining the operating point of the controlled system

Pressure sensor Manipulated variable

prop_V [V] Pressure [bar] Output signal [V]

Minimum measured

value O.2 0.1 0.1

Operating point 3 1.25 1.25

Maximum measured

value 6.2 2.6 2.6

Note

Solutions MPS®



PA 27


Name: Date:


– Name the system conditions which could influence the operating range of the

proportional pressure regulator and effective range of the sensor.


A least 1 bar operating pressure must be available for the optimal operation of the proportional

pressure regulator.

The operating pressure has been reduced to 0 – 2.6 bar using a pressure limiter.

The sensor assembly position, as well as loss of air pressure, influence the measurement result of the

sensor.

Solutions MPS®



PA


Name: Date:

1.2.4 Identifying a controlled system Sheet 1 of 2

Example for the calculation of the time constant Ts

Solutions MPS®



PA 29


Name: Date:


– What is the value determined for the system gain Ks?

– What type of system, i.e. order of system are we dealing with?

– What is/are the time constant/s Ts obtained?

– Explain the system behaviour.


System gain Ks = 1

PT1, 1st order system

Ts = 32 ms

Self-regulating systems (PT1- controlled systems) are systems whose characteristic it is to „run on“.

The energy supplied then becomes = dissipated energy. The following applies in the case of a

pressure control system: The greater the applied pressure, the greater is the pressure level in the

filter. Consequently, the volumetric discharge from the filter increases with rising pressure. If the

output pressure is equal to the supply pressure, a final value (pressure compensation) exists,

whereby the pressure within the filter no longer changes.

Solutions MPS®



PA


Name: Date:

1.2.5 Pressure stages with ramp Sheet 1 of 2


-PA.

Note

Solutions MPS®



PA 31


Name: Date:

1.2.5 Ramped pressure stages Sheet 2 of 2

– What is the difference between a proportional valve and a proportional pressure

regulator?


The proportional pressure regulator is used to control a pressure proportional to a preset setpoint

value. Its main function is to be able to replace previously manually adjustable pressure regulators

with electrical, remotely adjustable regulators, for example in order for different machine parameters

to be automatically and instantly available. An integrated pressure sensor determines the pressure at

the working port and compares this value with the setpoint value. In the case of setpoint/actual

deviations, the regulating valve remains actuated until the output pressure has reached the setpoint

value.

A proportional valve enables the flow control of neutral gases and liquids. It can be used as a remotely

adjustable final control element or in control loops. The proportional valve is a directly actuated

2/2-way valve. The valve piston is raised off its seat as a function of the solenoid coil current and

releases flow from port 1 to port 2. Without current, the valve is closed. The valve is spring returned.

An external standard signal is converted into a PWM signal whereby the valve opening is infinitely

adjustable. The frequency of the PWM signal can be adjusted to the valve used.

Evaluation

Solutions MPS®



PA

Solution 1.3: Filtration station – closed-loop control

Name: Date:

1.3.1 Two-position controller Sheet 1 of 2


-PA.

Parameter Standardised

value

Physical value

Setpoint value (w) at

operating point

0.21 1.26

Upper switching limit - 0.5

Lower switching limit - 0.5

Note

Solutions MPS®



PA 33


Name: Date:


– How does the system respond?

– Describe the control behaviour.

– Name typical areas of application for two-position controllers.


The manipulated variable with this controller type can only assume two defined states. The controller

output in this case switches to and fro between these two states, depending on whether the upper or

lower threshold value has been exceeded. In our example, the manipulated variable jumps to its

maximum value at the moment of switch-on until the controlled variable reaches the upper threshold

value. The controller responds by decreasing the manipulated variable. The controlled variable

decreases until the lower setpoint value is reached and the reverse procedure begins.

Depending on requirement, the hysteresis can be increased or reduced, i.e. the switching interval is

reduced or prolonged.

The two-position controller is particularly suitable for the control of systems with large time constants;

in our example the control of pressure. Other areas of application are for example the control of a

compressor, the control of room temperature or humidity.

Evaluation

Solutions MPS®



PA


Name: Date:

1.3.2 Closed-loop control using continuous-action controllers (P, I, PI) Sheet 1 of 5


value

Physical

value [bar]

Setpoint value (w) at operating

point

0.21 1.3

Solutions MPS®



PA 35


Name: Date:


P controller

Example for Kp = 5

Implementation

Solutions MPS®



PA


Name: Date:


I controller

Example for Tn = 5

Implementation

Solutions MPS®



PA 37


Name: Date:


PI controller

Example for Kp = 2, Tn = 5

Implementation

Solutions MPS®



PA


Name: Date:


– How does the system respond with closed-loop control using a P controller?

– How does the system respond with closed-loop control using an I controller?

– How does the system respond with closed-loop control using a PI controller?

– Which PI parameter pair results in the smallest overshoot and/or smallest

adjustment time?

– Which controller is suitable for this controlled system if the system deviation is to

be corrected to zero?


P controller: The system responds relatively rapidly to the input step. The disadvantage is the

remaining system deviation. If the Kp selected is too large, the system starts to oscillate.

I controller: The system responds very slowly to a setpoint value change. The advantage is that the

system deviation is corrected to zero.

PI controller: The system responds relatively quickly to a setpoint value change. The system deviation

is completely is completely corrected. The PI controller combines the positive properties of a P and I

controller. The P component ensures a quick step response and the I controller ensures that system

deviations are corrected to the setpoint value.

Since the pressure control system is a P-controlled system, the I controller is ideally suited for closed-

loop control.

Solutions MPS®



PA 39


Name: Date:

1.3.3 Optimisation method to Ziegler-Nichols Sheet 1 of 4


-PA.

Note

Solutions MPS®



PA


Name: Date:


– Which value have you selected and why?

– What is the value determined for Kp, Tn, Tv?

– What criteria are you using to evaluate your result?


Kp: P controller: 2.2

PI controller: 1.98

PID controller: 2.64

Tn: PI controller: 0.298

PID controller: 0.175

Tv: PID controller: 0.042

On the basis of the preset parameters, different response patterns can be read at the step response.

In the case of closed-loop control using a P controller, the output signal is relatively quick in the

steady state, although the system deviation cannot be corrected. If the experiment is conducted using

a PI controller, a slight overshoot of the output variable can be observed. The setpoint value is

reached quickly without remaining system deviation. The PID controller effects the fastest correction

of the system deviation. The steady state is reached after a few overshoots.

Evaluation

Solutions MPS®



PA 41


Name: Date:


Example for Kpr = 2.2.

Example for Kpr = 1.98, Tn = 0.298.

Solutions MPS®



PA


Name: Date:


Example for Kpr = 2.64, Tn = 0.175, Tv = 0.042.

Solutions MPS®

PA Mixing station


PA 43

Solution 2.1: Mixing station – system analysis and appraisal

Name: Date:


3

4

2

1

5


1 V201

2/2-way ball valve

2 B201

Holding tank

3 2B2

Proximity sensor „tank B201 top“

4 2B1

Flow sensor

5 P201

Mixing pump

Designation of

process components

Solutions MPS®

PA Mixing station


PA


Name: Date:


You will find two different designations for the proximity sensor „tank B201 top“ in

the electrical circuit diagram and P&I diagram for the mixing station.



The designation from the P&I diagram is a process designation. The process related functions in an

EMCS plan (EMCS = Electronic Measuring Control System) are known as EMCS points. The measured

variables or other input variables, their processing, direction of action and positional data should

follow from this designation.

An EMCS point consists of an EMCS circle and is designated with a code letter (A-Z) and a code

number. The code letters are entered in the upper section of the EMCS circle and the numbering in the

lower section. The sequence of code letters can be established on the basis of the table "EMSR code

letters to DIN 19227".

The designation from the electrical circuit diagram describes an electrical function.


PA station is identified by means of equipment designations

according to the electrical circuit diagram. The designation of equipment in the electrical circuit

diagrams is effected according to the standard DIN/EN61346-2.

Solutions MPS®

PA Mixing station


PA 45


Name: Date:



FI Flow sensor

FIC Flow sensor



P201 Analogue pump

V Valve

Solutions

P&I diagram


components

Solutions MPS®

PA Mixing station


PA


Name: Date:


– What is the difference between the designations of the measuring points FI and

FIC?

– What is the difference between the designations of the measuring points LA+ and

LS+?


The designations FI and FIC are process designations. An EMCS point consists of an EMCS circle and is

designated by a code letter (A-Z) and a code number. The code letters are entered in the upper section

of the EMCS circle and the numbering in the lower section. The sequence of the code letters is

established on the basis of the table "EMSR code letters to DIN 19227".

Example: F stands for flow; I stands for display (indicator); C corresponds to closed-loop control, i.e.

the sensor supplies an analogue signal in the form of an actual value of the control loop.

The designations LA+ and LS+ differ with regard to their function within the station. Whilst both

sensors indicate the water level within the tank, LA+ signals an error (alarm) message (often used as

Emergency-Stop.

Evaluation

Solutions MPS®

PA Mixing station


PA 47

Solution2.1: Mixing station – system analysis and appraisal

Name: Date:



Solutions MPS®

PA Mixing station


PA

Solution2.1: Mixing station – system analysis and appraisal

Name: Date:



Flow control valve

5/2-way valve

Butterfly valve with pneumatic swivel actuator

– What is the meaning of the 5/2-way valve designation?

– What is the function of an exhaust air flow control?



compressed air. The remaining 4 ports are for the connection of the working and exhaust lines.

Depending on the design, the valve can be actuated either by means of applied pressure via pilot air

or electronically.

Exhaust air flow control valves are screwed into the exhaust ports 3 and 5 of control valves and enable

the regulation of cylinder speed by means of exhaust air restriction. The flow control screw facilitates

an adjustable restriction of exhaust air. The exhaust air is discharged via an integrated silencer to

reduce noise levels.


pneumatic components

Solutions MPS®

PA Mixing station


PA 49


Name: Date:

2.1.4 Determining the technical data of the system Sheet 1 of 2


in flow

diagram


Pump P201 Pumps water into

the mixing tank

Voltage [V] 24 V

Electrical power [W] 26 W

Max. throughput [l/min] 9 l/min

Flow sensor 2B1

Measures

throughput of

liquid

Measuring principle:

The rotor generates pulses which are

converted into a voltage signal t

Measuring range [l/min] 0.3-9 l/min

Sensor signal [Hz] 40-1200 Hz

Measuring

transducer

F/U

2A1 Adapts the sensor

signal

Input:

Square-wave frequency generator 0-1 kHz

Limit switch

top

2B6

Status, upper limit

value

in tank B204

Filling quantity up to contact [l] 6 l



Limit switch

bottom

2B7

Status, lower limit

value

in tank B204

Filling quantity up to contact [l] o.5 l



Technical data

Solutions MPS®

PA Mixing station


PA


Name: Date:


– What is the frequency delivered by the flow sensor for a flow rate of 2l/min?

Solution by calculation is required!


s

pulseIm67,266

s60

pulseIm80002

s

dm

pulseIm8000

min

l2

f

s

pulseIm40

s60

pulseIm80003.0

s

dm

pulseIm8000

min

l3.0

f

s

1f

dm

Impulse8000FactorK

3

min/l2

3

min

3

=

⋅

=

⋅

=

=

⋅

=

⋅

=

=

=−

Solutions MPS®

PA Mixing station


PA 51


Name: Date:


Symbol EasyPort /

Simbox

address


2B1 DI 0 I 0.0 Flow sensor

2B2 DI 1 I 0.1 Holding tank B201 top

2B3 DI 2 I 0.2 Holding tank B201 bottom



2B6 DI 5 I 0.5 Mixing tank B204 top

2B7 DI 6 I 0.6 Mixing tank B204 bottom

2PA_Free DI 7 I 0.7 Receiver PA downstream station

free

Symbol EasyPort /

Simubox

address


2PV1 AI0 IW256 Actual value X (flow) √

Allocaion list of

digital inputs

Allocation list of

analogue inputs

Solutions MPS®

PA Mixing station


PA


Name: Date:

2.1.5 Erstellen der Zuordnungsliste Sheet 2 of 3

Symbol EasyPort /

Simubox

address


2M1 DO 0 O 0.0 Mixing pump P201 on √

2M2 DO 1 O 0.1 Pump P202, downstream station, on √

2M3 DO 2 O 0.2 Mixing valve V201 on √



Not busy DO 5 Not busy Not busy √

Not busy DO 6 Not busy Not busy √

2PA_Busy DO 7 O 0.7 Sender PA station busy √

Symbol EasyPort /

Simubox

address


2CO1 AO 0 AW256 Manipulated variable Y, (pump

P201) √

Allocation list of

digital outputs

Allocation list of

analogue outputs

Solutions MPS®

PA Mixing station


PA 53


Name: Date:


– What particular situation should be considered if the analogue final control

element (pump) is to be digitally controlled?


The bridge in the connection board must be converted to „digital“ to enable digital control of the

analogue final control element.

Solutions MPS®

PA Mixing station


PA

Solution 2.2: Mixing station – measurement and control

Name: Date:

2.2.1 Characteristics of the piping/pump system Sheet 1 of 7

The solution has been realised using digital/analogue EasyPort, and FluidLab®

-PA.

Voltage at

pump

control in V

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00

Flow sensor

signal in V 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.2 0.7

Flow rate

in l/min. 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.12 0.44

Voltage at

pump

control in V

5.50 6.00 6.50 7.00 7.50 8.00 8.50 9.00 9.50 10.00

Flow sensor

signal in V 1.5 1.7 1.9 2.6 3.0 3.5 3.8 4.1 4.4 4.8

Flow rate

in l/min. 1.1 1.25 1.45 1.9 2.4 2.6 2.9 3.05 3.3 3.6

Water is pumped only from holding tank 1.

Note

Value table

holding tank 1

Solutions MPS®

PA Mixing station


PA 55


Name: Date:


Voltage at

pump

control in V

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5,00

Flow sensor

signal in V 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.2 0.3 0.8 1,7

Flow rate

in l/min. 0.0 0.0 0.0 0.0 0.0 0.0 0.06 0.18 0.27 0.6 1,2

Voltage at

pump

control in V

5.50 6.00 6.50 7.00 7.50 8.00 8.50 9.00 9.50 10.00

Flow sensor

signal in V 1.9 2.2 2.5 2.8 3.0 3.2 3.6 3.9 4.4 4.8

Flow rate

in l/min. 1.4 1.6 1.8 2.1 2.3 2.4 2.7 2.95 3.3 3.6


Value table

Holding tank 2

Solutions MPS®

PA Mixing station


PA


Name: Date:


Voltage at

pump

control in V

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00

Flow sensor

signal in V 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.2 0.5 1.1 1.5

Flow rate in

l/min. 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.13 0.4 0.8 1.1

Voltage at

pump

control in V

5.50 6.00 6.50 7.00 7.50 8.00 8.50 9.00 9.50 10.00

Flow sensor

signal in V 1.8 2.2 2.7 2.9 3.1 3.5 3.8 4.2 4.4 4.7

Flow rate in

l/min. 1.3 1.65 2.0 2.2 2.4 2.6 2.8 3.1 3 3.5


Value table

holding tank 3

Solutions MPS®

PA Mixing station


PA 57


Name: Date:


Voltage at

pump

control in V

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.0

Flow sensor

signal in V 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.2 0.8 1. 1.

Flow rate

in l/min. 0.0 0.0 0.0 0.0 0.0 0.0 0.04 1.18 0.6 1.0 1.3

Voltage at

pump

control in V

5.50 6.00 6.50 7.00 7.50 8.0 8.50 9.00 9.50 10.00

Flow sensor

signal in V 2.1 2.4 2.7 3.0 3.6 3.9 4.1 4.3 4.7 4.9

Flow rate in

l/min. 1.55 1.8 2.0 2.3 2.7 2.9 3.1 3.3 3.5 3.7

Water is pumped simultaneously from all holding tanks.

All holding tanks are filled identically prior to starting.

Value table

holding tank 1 – 3

Solutions MPS®

PA Mixing station


PA


Name: Date:


Holding tank 1

Holding tank 2

Solutions MPS®

PA Mixing station


PA 59

Solution 2.2: Mixing station – measuring and control

Name: Date:


Holding tank 3

Holding tank 1 – 3

Solutions MPS®

PA Mixing station


PA


Name: Date:


– Compare the characteristic curves and discuss the possible causes which result

in their differences.

– State the reasons for the system response with a decreasing quantity of water in

the holding tank.

– State the reasons for the system behaviour at low voltages.

– What would be the effect on the characteristic curves of different quantities of

water in the holding tank?


The cause of the different characteristic curves is the different piping systems on the one part and the

different quantities of water in the holding tank on the other. Depending on the length of the

controlled system, the work to be carried out increases in order to pump the liquid into the mixing

tank. With a decreasing fill level in the holding tanks, the pressure of the water gauge drops to the

tank floor whereby the pressure in the piping system also decreases. This means that the decrease in

flow velocity is proportional to the reducing tank level.

At low voltages the pump does not operate within its operating range. The pump delivers its full

capacity only after a certain voltage is reached.

Different quantities of water result in different characteristic curves. The maximum flow rate of liquid

drops with a decrease in the level of water in the holding tanks. The characteristic curve exhibits a

flatter rise.

Solutions MPS®

PA Mixing station


PA 61


Name: Date:


– Pushbutton S1, to pump water from tank B201 into tank B204

– Pushbutton S2, to pump water from tank B202 into tank B204

– Pushbutton S3, to pump from tank B203 into tank B204

– Pushbutton S4, to pump water from tank B204 back into tank B201 or B202 or

B203.

The solution has been realised using digital/analogue EasyPort, and FluidSIM®

.

Setting condition for valve V201

P&I

diagram

symbol

Electr.

circuit

diagram

symbol

Address Logic

operation

Comment

- S1 - & Pushbutton

LS202 2B3 DI 2 & Sensor

(lower fill level at tank B201)

Resetting condition for valve V201

P&I

diagram

symbol

Electr.

circuit

diagram

symbol

Address Logic

operation

Comment

- S1 - ≥1 Not pushbutton

LS202 2B3 DI 2 ≥1 Not sensor


Note

Solutions MPS®

PA Mixing station


PA


Name: Date:



P&I

diagram

symbol

Electr.

circuit

diagram

symbol

Address Logic

operation

Comment

- S2 - & Pushbutton




P&I

diagram

symbol

Electr.

circuit

diagram

symbol

Address Logic

operation

Comment




Solutions MPS®

PA Mixing station


PA 63


Name: Date:



P&I diagram

symbol

Electr. circuit

diagram symbol

Address Logic

operation

Comment

- S3 - & Pushbutton


(lower fill level at B203)


P&I diagram

symbol

Electr. circuit

diagram symbol

Address Logic

operation

Comment




Setting condition for pump P201

P&I diagram

symbol

Electr. circuit

diagram

Address Logic

operation

Comment




Resetting condition for pump P201

P&I diagram

symbol

Electr. circuit

diagram symbol

Address Logic

operation

Comment

- S1 - & Not pushbutton



Solutions MPS®

PA Mixing station


PA


Name: Date:



P&I

diagram

symbol

Electr.

circuit

diagram

symbol

Address Logic

operation

Comment

- S4 - & Pushbutton

LS 206 2B7 DI 6 & Sensor


Resetting condition for pump P202

P&I

diagram

symbol

Electr.

circuit

diagram

symbol

Address Logic

operation

Comment


LS 206 2B7 DI 6 ≥1 Not sensor


Solutions MPS®

PA Mixing station


PA 65


Name: Date:


– Mixing valve V201 on

– Mixing valve V202 on

Logic diagram

Network 1

Network 2

Solutions MPS®

PA Mixing station


PA


Name: Date:


Mixing valve V203 on

– Pump P201 – mixing pump on

Network 3

Network 4

Solutions MPS®

PA Mixing station


PA 67


Name: Date:


– Pump P202 – mixing pump on

Network 5

Solutions MPS®

PA Mixing station


PA


Name: Date:


– Why should air in the piping system be avoided?


Air in the piping system prevents the correct operation of a system.

Pumps must be prevented from running dry as this will cause damage to the pump.

Solutions MPS®

PA Mixing station


PA 69


Name: Date:

2.2.3 Determining the operating range and operating points of a controlled system Sheet 1 of 2


-PA.

Determining the operating point of the flow rate control system

Flow sensor

operating range of pump Float flow meter

Manipulated

variable

pump P201

[V]

Flow rate

[l/min.]

Output signal

measuring

transducer [V]

Display value

[l/h]

Minimum measured

value 3.3 0.1 0.1 --

Operating point 6.6 2.6 2.6 125-

Maximum measured

value 10 4.9 4.9 240

Note

Solutions MPS®

PA Mixing station


PA


Name: Date:


– State the system conditions which could influence the operating range of the

pump and the measuring range of the sensor.


Air in the piping system can influence the operating range of the pump. In addition the system is

dependent on the fill level of the holding tank. With a high fill level a high flow rate is reached, which

decreases with a drop in fill level. With a time variant measurement, the maximum flow rate therefore

decreases proportional to the current fill level.

If the pump is not operated within its operating range, e.g. if the selected pump voltage is too low, this

results in inaccurate measurement results. The operating range of the pump depends on the particular

piping system.

Evaluation

Solutions MPS®

PA Mixing station


PA 71


Name: Date:



-PA.

T

Note

Solutions MPS®

PA Mixing station


PA


Name: Date:



– What type of system, i.e. order of system, are we dealing with?

– What is/are the time constant(s) obtained?

– Explain the system behaviour?


Ks = 1

PT1, 1st order system.

Ts = 1.0s.

Self-regulating systems (PT1-controlled systems) are systems whose characteristics it is to „run on“ to

a final steady-state value after a certain time. The energy supplied then becomes dissipated energy.

The following applies in the case of a flow rate control system: Once the pump is switched on, the

pump blades within the pump start to draw in the liquid from the piping system and pump it to the

other side into the mixing tank. During this, the flow velocity increases rapidly. If the flow energy is

equal to the driving force of the pump blades, a steady state (equilibrium) exists whereby the flow

velocity no longer changes.

Solutions MPS®

PA Mixing station


PA 73


Name: Date:

2.2.5 Mixing according to quantity Sheet 1 of 3


-PA.

Note

Solutions MPS®

PA Mixing station


PA


Name: Date:


Determining the operating point of the flow rate control system

Holding tank Mixing tank

No.

Desired

quantity

[ml]

Voltage at

pump [Volt] From tank No.

Water level

before Water level after Before After

1 1 2650 2470 1000 1200

2 2 2600 2410 1200 1400

3

500 4

3 2750 2650 1400 1490

4 1 2700 2500 1000 1250

5 2 2600 2400 1250 1450

6

500 6

3 2650 2550 1450 1550

7 1 2800 2600 1000 1250

8 2 2640 2420 1250 1400

9

500 7

3 2580 2460 1400 1500

10 1 2740 2520 1000 1250

11 2 2610 2400 1250 1450

12

500 9

3 2610 2500 1450 2600

Solutions MPS®

PA Mixing station


PA 75


Name: Date:


– Why can’t the transfer of a specific quantity be time-controlled?

– Why is the method of „mixing according to quantity“ better?

– Why is the quantity of water still not exact using this method?

– At what pump voltage do you get minimal measurement inaccuracies?


The flow rate during pumping is not constant which is why time-controlled measurement leads to

inaccurate results.

When „mixing according to quantity“ the actual flow rate is acquired and accumulated continuously

until the desired quantity of water is obtained. This method allows more accurate measurement..

Even so, the results do not meet expectation 100%. The reason lies within the system itself. The pump

and moving liquid are relatively inert. At the time it is switched off, the blades still continue to rotate

by a few rotations and so continues to transport a small quantity of liquid. Consequently, flow does

not stop immediately the pump is switched off but just a few split seconds later. The higher the flow

velocity, the more inaccurate is the measurement result. The same is the case with very low flow

velocities.

Minimal measurement inaccuracies are obtained using an applied pump voltage of 7 volts. The exact

quantity specified is pumped from the holding tanks into the mixing tank.

Solutions MPS®

PA Mixing station


PA

Solution 2.3: Mixing station – closed-loop control

Name: Date:

2.3.1 Two-position controller Sheet 1 of2


-PA.


value

Physical

Value


operating point

O.35 2.63

Upper switching limit - 0.4

Lower switching limit - 0.4

Note

Solutions MPS®

PA Mixing station


PA 77


Name: Date:

2.3.1 Two-position controller Sheet 2 of2



– State some typical areas of application for two-position controllers.


The manipulated variable with this type of controller can only assume two defined states - in our

example 0 and Vmax, whereby the controller output switches to and fro between these two states,

depending on whether the upper or lower threshold value is exceeded. In our example, the

manipulated variable jumps to its maximum value the moment it is activated until the controlled

variable reaches the upper threshold value. The pump is switched off. The controlled variable now

decreases until the lower threshold value is reached and the reverse procedure begins.

The hysteresis can be increased or reduced according to requirement, i.e. the switching interval

reduced or extended.

The two-position controller is particularly suitable for the control of systems with large time constants;

in our example the regulation of a flow rate control system. Other areas of application are for example

the control of an air reservoir (compressor), the control of room temperature or humidity.

Solutions MPS®

PA Mixing station


PA


Name: Date:



-PA.

Parameter Stadardised

value

Physical

value l/min


point

0.3 2.6

Note

Solutions MPS®

PA Mixing station


PA 79


Name: Date:


P controller

Example for Kpr = 50

Solutions MPS®

PA Mixing station


PA


Name: Date:


I controller

Example for Tn = 2

Solutions MPS®

PA Mixing station


PA 81


Name: Date:


PI controller

Example for Kpr = 2, Tn = 2

Solutions MPS®

PA Mixing station


PA


Name: Date:




– How does the system respond with closed-loop control using a PI controller?

– Which PI parameter pair results in the smallest overshoot and/or shortest

settling time?

– Which controller is suitable for this controlled system, if the system deviation is

to be corrected to zero?


P controller: The system responds relatively rapidly to the input step. The disadvantage is the

remaining system deviation. If the Kp selected is too large, the system starts to oscillate.

I controller: The system reacts very slowly to a setpoint value change. The advantage is that the

system deviation is corrected to zero.

PI controller: The system reacts relatively fast to a setpoint value change. The system deviation is

completely corrected. The PI controller combines the positive characteristics of a P and I controller.

The P component ensures a fast step response, the I controller ensures that system deviations are

corrected to the setpoint value.

The smallest overshoot is obtained for Kpr=2 and Tn =2.

Since the flow rate control system is a P controlled system, the I controller is optimally suitable for

closed-loop control.

Solutions MPS®

PA Mixing station


PA 83


Name: Date:

2.3.3 Manual tuning of controller parameters without knowledge of the system behaviour Sheet 1 of 2


-PA.

Note

Solutions MPS®

PA Mixing station


PA


Name: Date:


– What is the value determined for Kp?



The following values result for Kp and Tp for the setpoint value in the operating point:

Kp=2;

Tn=2;

Accuracy: The system deviation is completely corrected and maximum accuracy is therefore achieved.

This is due to the I component of the controller. Its function is to reach the exact setpoint value and

thus correct the system deviation between the input and output signal. The P component ensures a

fast system response.

Speed: A change in the parameters Kp and Tn influences the speed of the system. The greater the

reset time Tn, the greater is the rise time, whereby too small a selected Tn can result in overshoot. The

following applies for the proportional coefficient Kp: The larger the Kp, the smaller is the rise time. If

the Kp selected is too large, this results in overshoot of the characteristic curve and, in a worst case

scenario, in an oscillating system.

Solutions MPS®

PA Reactor station


PA 85

Solution 3.1: Reactor station – system analysis and appraisal

Name: Date:



Solutions MPS®

PA Reactor station


PA


Name: Date:



1 TIC301

Temperature sensor

2 B301

Reactor tank

3 R304

Stirrer

4 W303

Heater

5 P301

Cooling pump

You will find two different designations for the heater in the electrical circuit diagram

and P&I diagram of the reactor station.





variables or other input variables, their processing, direction of action and positional data should


An EMCS point consists of a circle and is designated with a code letter (A-Z) and a code number. The

code letters are entered in the upper section of the EMCS circle and the numbering in the lower

section. The sequence of code letters can be established on the basis of the table "EMCS code letters

to DIN 19227".

The designation in an electrical circuit diagram describes an electrical function.

All electrical equipment of an MPS® PA station is identified by means of equipment designations


diagrams is effected according to the standard DIN/EN°61°346-2.

Designation of

process components

Solutions MPS®

PA Reactor station


PA 87


Name: Date:


P&I diagram

Solutions MPS®

PA Reactor station


PA


Name: Date:



W303 Heater

TIC Temperature sensor

LS+ Proximity sensor


TA+ Temperature sensor, alarm

V Valve

– What is the difference between the measuring point designations TIC and TA+?

– What is the difference between the measuring point designations LA+ and LS+?


The designations TA+ and TIC are process designations. An EMCS point consists of an EMCS circle and

is designated with a code letter (A-Z) and a code number. The code letters are entered in the upper

section of the EMCS circle and the numbering in the lower section. The sequence of code letters is

established on the basis of the table "EMCS code letters to DIN 19227".

Example: T stands for temperature; I stands for display; C corresponds to automatic control, i.e. the

sensor supplies an analogue signal in the form of an actual value of the control loop.

TA corresponds to a sensor with alarm

The designations LA+ and LS+ differ with regard to their function within the station. Whilst both

sensors indicate the level of water within the tank, LA+ signals an error message (often used as

Emergency-Stop.


of components

Solutions MPS®

PA Reactor station


PA 89


Name: Date:



in flow

diagram


Heater W303

Heats water in the

reactor tank

Heating capacity [W] 1000 W

Control voltage [V DC] 24 V

Temperature

sensor

TIC301

Measures water

temperature


The change in the electrical resistance of the

platinum wire is measured and converted

into a voltage

Measuring range [°C] -50 - 150°C

Sensor resistor PT100

Pump P301 Transfers water via

pump

Voltage [V] 24 V

Electric power [W] 26 W


Limit switch

top

LS+ 302

Status, upper limit

value


Type (n. open/n.closed n.open

contact

Limit switch

bottom

LS- 303

Status, lower limit

value


Type (n. open/n.closed) n.open

contact

Solutions MPS®

PA Reactor station


PA


Name: Date:


– What is the resistance supplied by the temperature sensor for a temperature of

20 °C?

– What is the meaning of the term Pt100?


The sensor supplies a resistance of approx. 107.8 ohm for a temperature of 20°C.

The temperature sensor contains a platinum resistance thermometer with a positive temperature

coefficient. The sensor has a basic resistance value of 100 ohm at 0°C. (PT=Platinum).

Solutions MPS®

PA Reactor station


PA 91


Name: Date:


For Simatic S7-300 CPU

Symbol EasyPort /

Simubox

address


3B1 DI 0 I 0.0 Temperature sensor



Not busy DI 3 I 0.3 Not busy





free

Symbol EasyPort /

Simubox

address

PLC address Designation Check

3PV1 AI0 EW 256 Actual value X (temperature)

Note

Allocation list of

digital inputs

Allocation list of

analogue inputs

Solutions MPS®

PA Reactor station


PA


Name: Date:


Symbol EasyPort /

Simubox

address


3M1 DO 0 O 0.0 Heater W303 on

3M2 DO 1 O 0.1 Pump P301

3M3 DO 2 O 0.2 Pump P302

3M4 DO 3 O 0.3 Stirrer R304

Not busy DO 4 O 0.4 Not busy



2PA_Busy DO 7 O 0.7 Sender PA Station busy

Symbol EasyPort /

Simubox

address


3CO1 AO 0 AW 256 Manipulated variable Y, (heater

W303)

Allocation list of

digital outputs

Allocation list of

analogue outputs

Solutions MPS®

PA Reactor station


PA 93


Name: Date:


– What particular situation in the reactor station should be considered if the

analogue final control element (heater) is to be digitally controlled?


To enable digital control of the analogue final control element, the bridge in the connection board

must be converted to „digital“.

Solutions MPS®

PA Reactor station


PA

Solution 3.2: Reactor station – measurement and control

Name: Date:

3.2.1 Characteristics of the heating system medium Sheet 1 of 6

Symbol Designation Parameter Value

3M1 Heater Power P 522 W

3M1 Heater Voltage V 5.2 V DC

3M1 Heater Eficiency factor η 0.8 ( 80%)

H2O Water Specific heat capacity c 4182 J/(kg*K)

H2O Water Minimum temperature (room temperature)

Tmin 21.°C

H2O Water Desired temperature Tmax 36.°C

H2O Water Temperature difference ΔT 15 K

H2O Water Measurement 1 mass m 4 l

- Heating time Time t 600 s

η

Δ

⋅

⋅⋅

=

t

TcmP

Measurement 1

Solutions MPS®

PA Reactor station


PA 95


Name: Date:


Symbol Designation Parameter Wert


3M1 Heater Voltage U 8 VDC

3M1 Heater Efficiency factor η 0,8 ( 80%)



Tmin 21 °C

H2O Water Desired temperature Tmax 44 °C



- Heating

time- Time t 600 s

TminTΔTmax

cm

ηtPTΔ

+=

⋅

⋅⋅=

Measurement 2

Solutions MPS®

PA Reactor station


PA


Name: Date:


Symbol Designation Parameter Value


3M1 Heater Voltage V 8 VDC

3M1 Heater Efficiency factor η 0.8 ( 80%)



Tmin 19,5 °C

H2O Water Desired temperature Tmax 33 °C



- Heating time Time t 600 s

cm

ηtPTΔ

⋅

⋅⋅

=

Measurement 3

Solutions MPS®

PA Reactor station


PA 97


Name: Date:


Time in s 10 20 30 40 50 100 200 300 400 500 600

Temperature

sensor signal

in V

2.1 2.1 2.1 2.1 2.1 2.2 2.4 2.7 3.0 3.3 3.6

Temperature

in °C. 21 21 21 21 21 22 24 27 30 33

36

4 l of water are heated.

Time in s 10 20 30 40 50 100 200 300 400 500 600

Temperature

sensor signal

in V

2.1 2.1 2.1 2.1 2.2 2.3 2.65 3.15 3.6 4.05 4.5

Temperature

in °C. 21 21 21 21.5 22 23 26.5 31.5 36 40.5

45


Time in s 10 20 30 40 50 100 200 300 400 500 600

Temperature

sensor signal

in V

1.9 1.9 1.95 2.0 2.0 2.1 2.3 2.55 2.75 3.0 3.25

Temperature

in °C. 19 19 19,5 20 20 21 23 25.5 27.5 30

32.5


Value table

measurement 1

Value table

measurement 2

Value table

measurement 3

Solutions MPS®

PA Reactor station


PA


Name: Date:


Characteristic curve of

The controlled systems

Solutions MPS®

PA Reactor station


PA 99


Name: Date:


– How does the heating time change?

– Compare the characteristic curves and discuss the possible causes which result

in the different characteristic curves.

– How does the curve behaviour with double the quantity?

– How does the curve behave if the heating capacity is increased?

– How does the stirring influence the curve?


The speed of heating depends on the quantity of water and heating capacity.

The different values of the test parameters are the causes of the different characteristic curves. The fill

level quantity and the level of heating capacity considerably influence the test result. Thus, if the

heating capacity is doubled during the same test time, this results in temperature change almost

doubling, whereby if the quantity of water is doubled during the same test time and at the same

heating capacity the temperature change is virtually halved.

The stirring process ensures the water content is evenly heated during the test and also ensures a

virtually linear temperature curve.

Solutions MPS®

PA Reactor station


PA


Name: Date:


– Pushbutton S1, to heat water

– Pushbutton S2, to stirr water

– Pushbutton S3, to recirculate water

Solution has been realised using digital/analogue EasyPort and FluidSIM®

Setting condition for heater W301

P&I

diagram

symbol

Electr.

circuit

diagram

symbol

Address Logic

operation

Comment

- S1 - & Pushbutton



Resetting condition for heater W301

P&I

diagram

symbol

Electr.

circuit

diagram

symbol

Address Logic

operation

Comment


.



Note

Solutions MPS®

PA Reactor station


PA 101


Name: Date:


Setting condition for stirrer R304

P&I

diagram

symbol

Electr.

circuit

diagram

symbol

Address Logic

operation

Comment

S2 & Pushbutton



Resetting condition for stirrer R304

P&I

diagram

symbol

Electr.

circuit

diagram

symbol

Address Logic

operation

Comment

S2 ≥1 Not pushbutton



Solutions MPS®

PA Reactor station


PA


Name: Date:


Setting condition for pump 301

P&I

diagram

symbol

Electr.

circuit

diagram

symbol

Address Logic

operation

Comment

S2 & Pushbutton



LS- 302 3B2 DI1 & Not sensor

(upper fill level at tank B301)

Resetting condition for pump 301

P&I

diagram

symbol

Electr.

circuit

diagram

symbol

Address Logic

operation

Comment

S2 ≥1 Not pushbutton

LS- 302 3B2 DI 1 ≥1 Sensor

(upper fill level at tank B301)



Solutions MPS®

PA Reactor station


PA 103


Name: Date:


– Heater W301 on

– Stirrer R304 on

Logic diagram

Network 1

Network 2

Solutions MPS®

PA Reactor station


PA


Name: Date:


Pump P301

Network 3

Solutions MPS®

PA Reactor station


PA 105


Name: Date:


– Why must air in the piping system be avoided?


Air in the piping system prevents efficient operation of the system.

The pumps must be prevented from running dry as this will damage the pump.

Solutions MPS®

PA Reactor station


PA


Name: Date:



-PA.

Determining the operating point of the temperature control system

Temperature sensor

Operating range of heater

Temperature

[˚C]

Output signal

measuring transducer [V]

Minimum measured

value Room temperature 2.0

Operating point 40 °C 4.0

Maximum measured

value 60 °C 6.0

Note

Solutions MPS®

PA Reactor station


PA 107


Name: Date:



heater and the measuring range of the sensor.


Different system conditions can influence the operating range of the heating element and temperature

sensor. One aspect is the medium itself and the quantity to be heated. This aspect is to be considered

if other liquids apart from water are to be heated. In this case the different temperature coefficients

need to be taken into consideration. Furthermore, the fill level should not fall below the lower fill level

sensor. This may damage the heating element and water tank.

A further influencing factor is the tank in which the medium is heated. Here temperature maintenance,

i.e. the heat dissipated to the environment, plays a role, whereby the efficiency factor of the heating

process depends on the insulation of the water tank.

To enable you to work more easily with the characteristic curve plotted, it is important that the liquid

is evenly heated. Therefore the stirrer should be in continuous operation throughout the

measurement test. In the case of stagnant media, heat is not evenly distributed but only around the

heating element and temperature may vary considerably in the various areas of the water tank.

Solutions MPS®

PA Reactor station


PA


Name: Date:


Tt Tu

Tu

Solutions MPS®

PA Reactor station


PA 109


Name: Date:


– What is the value of the are time constants Tt and Tu obtained?

– Explain the system response?


Tt=7s

Tu=663s

The dead time in the example can be attributed to the fact that heating capacity is not fully available

at the heating element the moment it is switched on. It takes a while until the heating element outputs

the specified heating power to its environment. The medium between the heating element and

temperature sensor needs to be heated first and then the temperature sensor by the medium itself.

The first signal at the output is measured when the heated liquid reaches the sensor.

The slow system reaction results in a correspondingly high delay time. This depends on the quantity

and type of medium to be heated.

Evaluation

Solutions MPS®

PA Reactor station


PA

Solution 3.3: Reactor station – closed-loop control

Name: Date:



-PA.

Parameter Value


operating point

0.4

Upper switching limit 2

Lower switching limit 2

Example for digital increase in heating using a two-position controller

Note

Solutions MPS®

PA Reactor station


PA 111


Name: Date:



– Is a two-position controller suitable for this control task?

– Describe the control response.


The system responds with an increase in the water temperature. If the preset threshold values are

exceeded or fallen short of, the heating is switched on or off. Depending on the quantity of the liquid,

such switching intervals can involve long time spans.

Two-position controllers are used most frequently for temperature control. Unlike in the case of other

control examples, such as speed control, the actual value does not need to be continuously

monitored, since it is not crucial to set the temperature value exactly at the setpoint value. However, a

two-position controller can be used nevertheless for precision control by adjusting the hysteresis

appropriately. The switching frequency can thus be influenced according to threshold values

specified.

Solutions MPS®

PA Reactor station


PA


Name: Date:



-PA.

Parameter Dimensionless

value

Value

˚C


point

0.3 30

Note

Solutions MPS®

PA Reactor station


PA 113


Name: Date:


P controller

Example for Kp = 10

Implementation

Solutions MPS®

PA Reactor station


PA


Name: Date:


I controller

Example for Tn = 50

Implementation

Solutions MPS®

PA Reactor station


PA 115


Name: Date:


PI controller

Example for Kp = 5, Tn = 50

Implementation

Solutions MPS®

PA Reactor station


PA


Name: Date:




– How does the system respond with closed-loop control using PI controller?


settling time?


P controller: The system responds relatively fast. The disadvantage is the remaining system deviation

at the output. A P controller cannot be operated without a system deviation, i.e. the manipulated

variable would also be zero.

I controller: The system responds very slowly to a setpoint change. The advantage is that the system

deviation is corrected to zero.

PI controller: The system responds relatively fast to a setpoint change. The system deviation is

completely corrected. The PI controller combines the positive properties of P and I controllers. The

P component ensure a fast step response; the I controller ensures that the system deviation is


Kp=5 and Tn=50 result in the smallest overshoot and shortest settling time.

Solutions MPS®

PA Reactor station


PA 117


Name: Date:

3.3.3 Tuning method according to the rate of rise Sheet 1 of 4

Tt Tu

XΔ

tΔ

t

XV m a x

Δ

Δ=

Controller Kp Tn Tv Description

P HUMAX

PyTV

y%100K

⋅⋅

Δ⋅=

PI

HUMAX

P

yTV

yK

⋅⋅⋅

Δ⋅=

2.1

%100 UNTT ⋅= 3.3

PID

HUMAX

P

yTV

yK

⋅⋅⋅

Δ⋅=

83.0

%100 UNT2T ⋅=

UVTT ⋅= 5.0

ΔY= Maximum correcting range (100%)

YH= Specified step height

Solutions MPS®

PA Reactor station


PA


Name: Date:


– What are the values determined for Kp, Tn, Tv?




4.0*)11*017.0(

1=

PI controller: 78.1

4,0*)11*017.0(

83.0=

PID controller: 57,2

4.0*)11*017.0(

2,1=

Tn: PI controller: 3.3611*3.3 =

PID controller: 2211*0.2 =

Tv: PID controller: 5.511*5.0 =

On the basis of the preset parameters, different modes of behaviour can be established by the step response. With closed-loop control using a P controller, the manipulated variable is set to a predefined value. The manipulated variable decreases towards zero with decreasing system deviation. The system deviation is not fully corrected. In the case of a PI controller, the value of the manipulated variable increases to a certain point and then slowly decreases as in the case of a P controller. The maximum value of the output variable is above the setpoint value. A steady state can be assumed in this case since the cooling of the liquid is associated with long periods. The best result so far can be obtained with a PID controller, whereby the steady state is above the setpoint value as in the case of a PI controller, although the setpoint value is reached more quickly in the case of a PID controller.

Solutions MPS®

PA Reactor station


PA 119


Name: Date:


Example of P controller

Example of PI controller

Solutions MPS®

PA Reactor station


PA


Name: Date:


Example of PID controller

Solutions MPS®

PA Bottling station

© Festo Didactic GmbH & Co. KG • MPS® PA 121

Solution 4.1: Bottling station – system analysis and appraisal

Name: Date:


3

1

2

4


Solutions MPS®

PA Bottling station

122 © Festo Didactic GmbH & Co. KG •MPS®

PA


Name: Date:



1 4M3

Conveyor motor

2 B401

Holding tank

3 B402

Metering tank

4 V403

Metering valve

5 4M4

Feed separator

You will find two different designations for the metering valve in the electrical circuit

diagram and flow diagram for the bottling station.





variable or other input variables, their processing, direction of action and positional data should


An EMCS point consists of an EMCS circle and is designated with a code letter (A-Z) and a code

number. The code letters are entered in the upper section of the EMCS circle and the numbering in the

lower section. The sequence of code letters is established on the basis of the table "EMCS code letters

to DIN 19227".

The designation in an electrical circuit diagram describes an electrical function.


PA station is identified by means of equipment designations


diagrams is effected according to the standard DIN/EN61346-2.

Designation of

process components

Solutions MPS®

PA Bottling station

© Festo Didactic GmbH & Co. KG •MPS®

PA 123


Name: Date:


P&I diagram

Solutions MPS®

PA Bottling station


PA


Name: Date:



LIC 403 Acoustic sensor



P 401 Analogue pump

V Valve

– What is the difference between V401 and V402?

– What is the difference between the measuring point designations LA+ and LS+?


The valve V402 is a hand valve. V401 is a non-return valve. It allows a medium to flow in one direction

and inhibits it in the other direction.

The designations LA+ and LS+ differ with regard to their function within the station. Whereas both

sensors indicate the level of water in the tank, LA+ signals an error message. (often used as

Emergency-Stop.


of components

Solutions MPS®

PA Bottling station


PA 125

Solution4.1: Bottling station – system analysis and appraisal

Name: Date:



Solutions MPS®

PA Bottling station


PA

Solution4.1: Bottling station – system analysis and appraisal

Name: Date:



Silencer

5/2-way valve

Double-acting cylinder

– What does the designation 5/2-way valve mean?

– What is the function of a silencer?



compressed air. The remaining 4 ports are for the connection of working and exhaust lines. Depending

on design, the valve can be either pneumatically actuated via pilot air or electronically actuated.

The silencer reduces the noise levels of escaping air.


pneumatic components

Solutions MPS®

PA Bottling station


PA 127


Name: Date:


Component Designation Function Characteristics

Pump P401 Pumps water into

mixing tank

Voltage [V] 24 V

Electric power [W] 26 W


Acoustic

sensor

4B1

Measures the level

of water.


An acoustic signal is generated and the

reflection time is measured. This signal is

converted into a voltage signal

Measuring range [mm] 300-50 mm

Sensor signal [V] 0-10 V

Geared

motor -

Transports bottles

to the filling

position

Voltage [V] 24 V

Nominal current[A] 1.5 A

Speed of

drive shaft [r.p.m.] 65 r.p.m.

Limit switch

top

4B2

Status, upper limit

value

in Tank B401


Type (n. open/n. closed contact)

n. open contact

Limit switch

bottom

4B3

Status, lower limit

value

in tank B401


Type (n. open/n. Closed contact)

n. open contact

Technical data

Solutions MPS®

PA Bottling station


PA


Name: Date:


– What is the voltage supplied by the acoustic sensor for a filling quantity of 2l?


2.5l � 10V

0l � 0V

2l � 8V

Solutions MPS®

PA Bottling station


PA 129


Name: Date:


Symbol EasyPort /

Simubox

address


4B1 DI 0 I 0.0 Acoustic sensor B402



4B4 DI 3 I 0.3 Bottle at start of conveyor

4B5 DI 4 I 0.4 Bottle being filled

4B6 DI 5 I 0.5 Bottle at end of conveyor



free

Symbol EasyPort /

Simubox

address


4PV1 AI0 EW256 Actual value X (fill level)

Allocation list of

digital inputs

Allocation list of

analogue inputs

Solutions MPS®

PA Bottling station


PA


Name: Date:


Symbol EasyPort /

Simubox

address


4M1 DO 0 O 0.0 Pump P401 on

4M2 DO 1 O 0.1 Filling valve On

4M3 DO 2 O 0.2 Conveyor motor on

4M4 DO 3 O 0.3 Feed separator active




4PA_Busy DO 7 O 0.7 Sender PA station busy

Symbol EasyPort /

Simubox

address


4CO1 AO 0 AW256 Manipulated variable Y, (pump

P401)

Allocation list of

digital outputs

Allocation list of

analogue outputs

Solutions MPS®

PA Bottling station


PA 131


Name: Date:


– What particular situation should be considered in the bottling station if the

analogue final control element (pump) is to be digitally controlled?


To enable digital control of the analogue final control element (pump), the bridge in the connection

board must be converted to „digital“.

Solutions MPS®

PA Bottling station


PA

Solution 4.2: Bottling station – measurement and control

Name: Date:

4.2.1 Characteristics of the metering tank/pump system Sheet 1 of 4


-PA.

Voltage at

pump

control in V

0.00 0.50 1.00 1.50 2.00 2.0 3.00 3.50 4.00 4.50 5.00

Acoustic

sensor

signal in V

0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.2 3.3

Fill level

in l. 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.18 0.5

Voltage at

pump

control in V

5.50 6.00 6.50 7.00 7.50 8.00 8.50 9.00 9.50 10.00

Acoustic

sensor in V 6.7 max max max max max max max max max

Fill level

in l. 1.5 Max max max max max max max max max

Closed drain valve.

Note

Value table

closed drain valve

Solutions MPS®

PA Bottling station


PA 133


Name: Date:


Voltage at

pump

control in V

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00

Acoustic

sensor

signal in V

0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Fill level in l. 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

0.0

Voltage at

pump

control in V

5.50 6.00 6.50 7.0 7.50 8.00 8.50 9.00 9.50 10.00

Acoustic

sensor

signal in V

0.0 0.0 0.0 2.2 4.6 6.9 9.4 max max max

Fill level

in l. 0.0 0.0 0.0 0.33 0.87 1.56 2.33 max max

max.

Drain valve fully open.

Value table

open drain valve

Solutions MPS®

PA Bottling station


PA


Name: Date:



-PA.

Example for closed drain valve

Red characteristic curve: 5.0 V

Blue characteristic curve: 5.5 V

Green characteristic curve: 6.0 V

Note

Solutions MPS®

PA Bottling station


PA 135


Name: Date:


– Compare the characteristic curves and discuss the possible causes leading to

their differences.

– Explain the reasons for the system behaviour at low voltages.


The back pressure in the metering tank is constantly increasing, the higher water level rises and

the pump has to counteract this. Depending on the rate of delivery of the pump a steady state

occurs where the fill level remains virtually constant.

The pump only pumps water into the metering tank as of approx. 4.5V if the drain valve is closed,

and as of 7V if the drain valve is fully open.

Note: The bend in the characteristic curve at 0.5 l can be attributed to the shape of the metering

tank. In the lower section, the volume is not linear in relation to the delivery height.

Solutions MPS®

PA Bottling station


PA


Name: Date:


– Pushbutton S1, pumps water

– Pushbutton S2, fills bottles

– Pushbutton S3, transports bottles

The solution has been realised using digital/analogue EasyPort and FluidSIM®

.


P&I

diagram

symbol

Electr.

circuit

diagram

symbol

Address Logic

operation

Comment

- S1 - & Pushbutton



Resetting condition for pump V401

P&I

diagram

symbol

Electr.

circuit

diagram

symbol

Address Logic

operation

Comment





Note

Solutions MPS®

PA Bottling station


PA 137


Name: Date:



P&I

diagram

symbol

Electr.

circuit

diagram

symbol

Address Logic

operation

Comment

- S2 - & Pushbutton

- 4B5 DI4 & Diffuse sensor

(bottle at filling position)


P&I

diagram

symbol

Electr.

circuit

diagram

symbol

Address Logic

operation

Comment




- 4B5 DI4 ≥1 Not diffuse sensor


Solutions MPS®

PA Bottling station


PA


Name: Date:


Setting condition for conveyor motor 4M3

P&I

diagram

symbol

Electr.

circuit

diagram

symbol

Address Logic

operation

Comment

- S3 - & Pushbutton

- 4B4 DI3 & Diffuse sensor

(bottle at start of conveyor)

Resetting condition for conveyor motor 4M3

P&I

diagram

symbol

Electr.

circuit

diagram

symbol

Address Logic

operation

Comment

- 4B5 DI4 -

Diffuse sensor


Solutions MPS®

PA Bottling station


PA 139


Name: Date:


– Pump P401 on

– Metering valve V403 on

Logic diagram

Network 1

Network 2

Solutions MPS®

PA Bottling station


PA


Name: Date:


Conveyor motor 4M3 on

Network 3

Solutions MPS®

PA Bottling station


PA 141


Name: Date:


– Why should air in the piping system be avoided?


Air in the piping system prevents correct operation of the system.

Pumps must be prevented from running dry as this will cause damage.

Solutions MPS®

PA Bottling station


PA


Name: Date:


Determining the operating point of the fill level control system

Acoustic sensor

operating range of pump

Manipulated

variable of pump

P201 [V]

Fill level

[l] Output signal [V]

Minimum measured

value 5 0.5 3.3

Operating point 5.5 1.5 6.6

Maximum measured

value 6 2.5 9.9


pump and measuring range of the sensor.

– Where does the linear range of the controlled system begin?


The position of the drain valve, piping system, mounting position of the sensor level, whether filling is

from the bottom or the top

The linear range of the controlled system begins at 0.5 l.

Solutions MPS®

PA Bottling station


PA 143


Name: Date:


63%

Ts

Example of the calculation of the time constant Ts

Solutions MPS®

PA Bottling station


PA


Name: Date:



– What type of system is it, i.e. of what order?

– What is/are the time constant(s) obtained?

– Explain the reasons for the system behaviour?


System gain Ks= 0.867

PT1, 1st order system.

Ts= 59.5s

A characteristic of PT1 controlled systems is to „run on“ to a final steady-state value when the energy

supplied = dissipated energy; in this case, the pump capacity against the pressure of the metering

tank.

Solutions MPS®

PA Bottling station


PA 145


Name: Date:

4.2.5 Inflow and outflow behaviour of the metering tank Sheet 1 of 6

Pump voltage in V

Fill level [l] Time [s] Fill level [l] Time [s]

0.5 4.0 1.8 15.25

0.6 5.2 1.9 16.0

0.7 6.2 2.0 17.0

0.8 6.7 2.1 17.75

0.9 8.0 2.2 18.5

1.0 8.5 2.3 19.5

1.1 9.0 2.4 20.25

1.2 10.25 2.5 21.00

1.3 11.25 2.6 -

1.4 12.0 2.7 -

1.5 13.0 2.8 -

1.6 13.75 2.9 -

1.7 14.5 3.0 -

Measurement 1

drain valve closed,

pump on

Solutions MPS®

PA Bottling station


PA


Name: Date:


Pump voltage in V 0 V


3.0 - 1.7 9.6

2.9 - 1.6 10.8

2.8 - 1.5 12.0

2.7 - 1.4 13.2

2.6 - 1.3 14.4

2.5 0 1.2 15.6

2.4 1,5 1.1 17.0

2.3 2,6 1.0 18.2

2.2 3,8 0.9 19.4

2.1 5,0 0.8 20.6

2.0 6,2 0.7 21.8

1.9 7,4 0.6 23.2

1.8 8,6 0.5 24.6

Measurement 2

drain valve open,

pump off

Solutions MPS®

PA Bottling station


PA 147

Solution 4.2: Bottling station – Messen und Steuern

Name: Date:


Pump voltage in V


0.5 10 1.8 37.5

0.6 11 1.9 41

0.7 13 2.0 44

0.8 15 2.1 47

0.9 17 2.2 50

1.0 19 2.3 54

1.1 21 2.4 57.5

1.2 23 2.5 61.5

1.3 25 2.6 -

1.4 27 2.7 -

1.5 29.5 2.8 -

1.6 32.5 2.9 -

1.7 35 3.0 -

Measurement 3

drain valve open,

pump on

Solutions MPS®

PA Bottling station


PA


Name: Date:


Example of inflow behaviour – filling from the bottom with drain valve closed

Example for outfow behaviour

Solutions MPS®

PA Bottling station


PA 149


Name: Date:


Example for inflow behaviour – filling from the bottom with drain valve open

Special solution:

Example for inflow behaviour – filling from the top with drain valve closed

Solutions MPS®

PA Bottling station


PA


Name: Date:


– How does the curve progress in measurement 1?

– What is the difference between the curve progressions of measurements 1

and 3?

– Why does the curve progression of measurement 2 exhibit a decaying behaviour?


A linear behaviour is evident in measurement 1, provided that the pump capacity is sufficiently high.

In the case of measurement 3, the filling process takes longer until the metering tank is full and a

decaying behaviour is also apparent. This can be attributed to the fact that the pump not only has to

counteract the water pressure in the metering tank, but in addition also has to cope with the drain

quantity rate.

Measurement 2 exhibits linear as opposed to decaying behaviour. The cause of this is that the level in

the metering tank is not sufficient to illustrate this. The slightly different progression from 0.5 l can be

attributed to the shape of the metering tank.

In the case of measurement 3, the open drain valve prevents a rapid rise of liquid in the metering tank

since part of the liquid delivered flows back into the holding tank via the open valve. However, since

the outflow via the valve is less than the inflow via the pump, part of the liquid reaches the metering

tank and the fill level gradually increases. If the system moves into its steady state (fill level does not

rise further), the liquid is pumped back virtually directly into the holding tank via the drain valve, since

the set pump performance is no longer sufficient to overcome the water pressure in the metering tank.

The water pressure practically „seals“ the metering tank.

Solutions MPS®

PA Bottling station


PA 151

Solution 4.3: Bottling station – closed-loop control

Name: Date:



-PA.

Parameter Value


operating point

0.67

Upper switching value 0.1

Lower switching value 0.1

Example of two-position controller

Note

Solutions MPS®

PA Bottling station


PA


Name: Date:



– State some typical areas of application of a two-position controller.



With this controller type, the manipulated variable can only assume two defines states, in our example

0V and 10V(Vmax). The output of the controller switches to and fro between these two states

depending on whether the upper or lower threshold value is exceeded. In our example the

manipulated variable increases to its maximum value at the moment of switch-on until the controlled

variable reaches the upper threshold value. The pump is switched off and the controlled variable now

decreases until the lower threshold value is reached when the reverse process takes over.

The two-position controller is particularly suitable for the control of systems with large time constants.

Other areas of application are for example the control of a reservoir (compressor), the control of room

temperature or humidity.

Solutions MPS®

PA Bottling station


PA 153


Name: Date:



-PA.

Parameter Dimensionless

value

Value

l


point

0.67 1.51

Note

Solutions MPS®

PA Bottling station


PA


Name: Date:


P controller

Example for Kpr = 10

Solutions MPS®

PA Bottling station


PA 155


Name: Date:


I controller

Example for Tn = 10

Solutions MPS®

PA Bottling station


PA


Name: Date:


PI controller

Example for Kpr = 2, Tn = 5

Solutions MPS®

PA Bottling station


PA 157


Name: Date:



– How does the system react with closed-loop control using an I controller?

– How does the system react with closed-loop control using a PI controller?


settling time?

– Which controller is suitable for this controlled system if the system deviation is to

be corrected to 0?


P controller: The system responds relatively fast to the input step. The disadvantage is the remaining

system deviation. If the Kp selected is too large, the system starts to oscillate.

I controller: The system responds very slowly to a setpoint change. The advantage is that the system

deviation is corrected to zero after a certain period. If the Tn is too small, the system becomes limit

stable? or instable.

PI controller: The system responds relatively fast to a setpoint change. The system deviation is

completely corrected. The PI controller combines the positive characteristics of a P and I controller.

The P component ensures a fast step response, the I controller ensures that the system deviations are


Kpr=2 and Tn =5 result in the smallest overshoot.

Both a PI controller and an I controller would be suitable. The PI controller reaches the settling time

fastest.

Solutions MPS®

PA Bottling station


PA


Name: Date:

4.3.3 Controller tuning according to Chien-Hrones-Reswick Sheet 1 of 2


–PA.

Tu

Tg

Note

Solutions MPS®

PA Bottling station


PA 159


Name: Date:

4.3.3 Controller tuning according to Chien-Hrones-Reswick Sheet 2 of 2

– Which controller have you selected and why?

– What are the values determined for Kp, Tn, Tv?

– What criteria do you use to evaluate your result?



1

7*

1

3.0*

3.0==

Ts

Tg

Ks

PI controller: 45.2

1

7*

1

35.0*

35.0==

Ts

Tg

Ks

PID controller: 2.4

1

7*

1

6.0*

6.0==

Tu

Tg

Ks

Tn: PI controller: 2.11*2.1*2.1 ==Tu

PID controller: Tg= 7

Tv: PID controller: 5.01*5.0*5.0 ==Tu

With the preset parameters, various behaviours can be observed from the step response. In the case

of closed-loop control using a P controller, the output signal is relatively quick in the steady state,

although the system deviation cannot be corrected. If the test is carried out using a PI controller, a

slight overshoot can be observed. The setpoint value is reached quickly without remaining system

deviation. The PID controller corrects the system deviations the fastest. A steady state is obtained

after a few small overshoots.

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MPS-PA Solutions 709743 En