5. Pressure Control Triner

7/31/2019 5. Pressure Control Triner

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PRESSURE CONTROL

TRAINER

Instruction manual

Contents

1 Description2 Specifications3 Installation requirements

4 Installation Commissioning

5 Troubleshooting6 Components used7 Packing slip

8 Warranty

9 Theory10 Software11 Experiments

12 Components manuals

Product Code314, 314A


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Pressure control trainer is designed forteaching the basic pressure control

principles. Pressure transmitter senses

the pressure inside pressure tank andtransmits the signals to interfacing

unit/control module. The output ofinterfacing unit/control module is

connected to I/P converter. A pneumaticcontrol valve adjusts compressed air

flow from the tank outlet. The processparameter (pressure) is controlled

through computer or p controller bymanipulating the control valve. These

units along with necessary piping arefitted on support housing designed for

tabletop mounting.Product No. 314 is DDC (Direct Digital

Control) model, in which PID control

action is through software by computer.Product No. 314A is SCADA (Supervisory

Control And Data Acquisition) model, inwhich PID controlling is by digital

indicating controller. The computer isconnected to controller through

communication port in supervisorymode.

SupplyPressure

SignalPressure

Air Regulator

I/P Converter

Control Valve

Set Point

PressureTransmitter

Process Tank

Vent Valve

Pressure Controller

Air Supply

TankPressure

AirSupply

N

N

Product Pressure control trainer

Product code 314 314A

Type of control DDC SCADA

Control unit Interfacing unit with

ADC/DAC conversion

Control module with digital

indicating controller

Communication RS232

Pressure Transmitter Type Two wire, Range 05 bar, Output 420 mA

I/P converter Input 4-20mA, Output 3-15 psig

Control valve Type: Pneumatic; Size: 1/4", Input: 315 psig, Air toclose, Characteristics: linear

Process tank Pressure vessel, MS

Air filter regulator Range 0-2.5 kg/cm2

Pressure gauge Range 0-2.5 kg/cm2(1No), Range 0-7 kg/cm2(2Nos)

Overall dimensions 475Wx430Dx440H mm

Optional Compressor

Specifications

Description


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Product 314

Shipping details

Gross volume 0.10m3, Gross weight 43kg, Net weight 18kgProduct 314A

Shipping detailsGross volume 0.10m3, Gross weight 43kg, Net weight 18kg

Electric supplyProvide 230 +/- 10 VAC, 50 Hz, single

phase electric supply with properearthing. (Neutral Earth voltage less

than 5 VAC) 5A, three pin socket with switch (1

No.)

15A, three pin socket with switch for

compressor (if ordered)Air supply

Clean, oil and moisture free air,pressure 6 Bar, Air consumption 7.0

m3/hrComputer

IBM compatible with standard

configurationSupport table

Size: 800Wx800Dx750H in mm.

Installation Unpack the box(es) received and ensure that all material is received as per

packing slip (provided in instruction manual). In case of short supply or breakage

contact Apex Innovations / your supplier for further action.

Place the set up on table. Connect air inlet pipe to process tank and regulator.

Pierce hole on the pressure gauges with pin or needle. Connect the cables from interfacing unit/control module to the set up. Connect the interfacing unit/control module with computer to "COM" port.Commissioning Connect electric supply to interfacing unit/control module. Ensure the regulator is full open by rotating anticlockwise. Switch on the

compressor.

Adjust the air filter regulator to set supply air pressure at 25 psig. Set the interfacing unit/digital indicating controller to manual mode by pressing

the A/M key.

Increase output of interfacing unit/digital-indicating controller from 0 to 100% insteps of 25%. Check the pressure on pressure gauge at the output of the I/P

converter is varying from 3-15 psig and ensure that control valve operates from

full open to fully close position. Switch on the computer and install the software. Execute the software and ensure correct signals are displayed on computer.NOTE: Maintain the pressure of the process tank below 6 kg/cm2.

Installation Commissioning

Installation requirements


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Note: For component specific problems refer components manual

Problems Possible causes / remedies

Control valve doesnot operate

Valve diaphragm breakage Faulty I/P converter

No output from Interfacing unitI/P converter doesnot work

Insufficient supply air pressure Faulty electrical input signal Clogged orifice

No communication

with computer Improper COM port connection Computer COM port not working

No full screen display Ensure screen display settings are at 800 x 600pixels.

On desktop right click mouse button & clickproperties option. In General option- Settings- setfont size- small fonts

Components DetailsControl unit (For 314) Make Cuadra, Model AX-401, Input 4-20mA (1No),

Output 4-20mA (1No), Communication RS232Control unit (For

314A)Make Cuadra, Model AX-403, Input 4-20mA, with

RS485 to RS232 converterPressure Transmitter Make Keller, Model 21S, Output 4-20mA(2 wire),

Supply 24VDC, Range 0-5 bar, Process conn.

1/4"BSP(male), Accuracy +/-1%Digital indicating

controller(For 314A)

Make Yokogawa, Model UT320-01 (with RS 485

communication)I/P converter Make Control air inc, Type T500-AC, Input 4-20 mADC, output 3-15 psig, end connection 1/4 NPT

Control valve Make Apex, Model MX-101, Size x1/4, BodySS316, Trim SS316, Travel 10mm, Spring range 3-15psig, Characteristics linear, Action air to close, Valve

coefficient 0.04Air filter regulator Make Airmatic, Model MB10-021-VD-PAP, Range 0-2

Kg/cm^2, Type RelievingPressure gauge Make Waaree, Code: PW2.5GNNNS9 0-2.5 1/4"B,

Dia.2.5", Gly. filled, Brass internals, S.S. casing,

Range 0-2.5 Kg/cm2, 1/4"BSP (M) back connectionPressure gauge Make Waaree, Code: PW2.5GNNNS9 0-7 1/4"B,

Dia.2.5", Gly. filled, Brass internals, S.S. casing,Range 0-7 Kg/cm2, 1/4"BSP (M) back connection

Components used

Troubleshooting


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Product No.314

BoxNo.1/1

Size W500xD450xH425 mm; Volume:0.10m3 Gross weight: 43 kgNet weight: 18 kg

1 Set up assembly(Piping set & Male stud 2nos) 1 No

2 Communication cable 1 No

3 Tool kit 1 No

4 Set of instruction manuals consisting of:Instruction manual CD (Apex)

I/P converter manual (ControlAir)

1 No

Product No.314A

Box

No.1/1

Size W500xD450xH425 mm; Volume:0.10m3 Gross weight: 43 kg

Net weight: 18 kg

1 Set up assembly(Piping set & Male stud 2nos) 1 No

2 Communication cable 1 No

3 Tool kit 1 No

4 Set of instruction manuals consisting of:Instruction manual CD (Apex)

I/P converter manual (ControlAir)Users manual UT320 (Yokogawa)

Users manual reference CD (Yokogawa)

1 No

Packing slip


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This product is warranted for a period of 12 months from the date of supply againstmanufacturing defects. You shall inform us in writing any defect in the system

noticed during the warranty period. On receipt of your written notice, Apex at its

option either repairs or replaces the product if proved to be defective as statedabove. You shall not return any part of the system to us before receiving ourconfirmation to this effect.

The foregoing warranty shall not apply to defects resulting from:

Buyer/ User shall not have subjected the system to unauthorized alterations/additions/ modifications.

Unauthorized use of external software/ interfacing.Unauthorized maintenance by third party not authorized by Apex.

Improper site utilities and/or maintenance.We do not take any responsibility for accidental injuries caused while working with

the set up.

Apex Innovations Pvt. Ltd.E9/1, MIDC, Kupwad, Sangli-416436 (Maharashtra) IndiaTelefax:0233-2644098, 2644398

Email: [email protected] Web: www.apexinnovations-ind.com

Warranty


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COMPUTER CONTROL TECHNIQUES

Direct Digital Control (DDC)The method of process control described by the term DDC (Direct Digital Control)

applies to those cases in which digital logic circuits or a computer are an integral partof the loop.

The software program defines all the control function, setpoint and deviation aboutthe nominal. Direct digital control has the capacity to control multivariable processes

with interaction between elements.

This is most economically developed process control system basically used forlaboratory scale application. In this system the process signals are transmitted to

computer through interfacing unit. Along with data acquisition the software has

capability of controlling the process.

Comparator

PID Control

Measured VariableMeasurement

Control Element Process

ControlledVariable

Load

Set Point

Computer

Supervisory Control And Data Acquisition (SCADA)In SCADA systems process signals are transmitted the local controller. The controller is in

communication with central computer. The software performs the function of data acquisition,display and analysis. The controller settings can be changed from computer. The computer has asupervisory role as controlling is done by local controller.

Comparator

PID Control

Computer

Measured Variable

Control Element Process

ControlledVariable

Load

Set Point

Digital Indicating Controller

Theory


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PROCESS CONTROLLERIn automatic controlled process the parameter to be controlled is measured and

compared with the set point by process controller. The difference between themeasured signal and the set point is error. The controller performs on-line

calculations based on error and other setting parameters and generates an output

signal. The output signal drives the final control elements like control valve or a

damper to control the process to the set point.

Error Controller OutputController

Feedback Signal

Block Digaram of Typical Controller

Process Parametert

ReferenceSignal

On/Off controllers

Time

SetValue

On-Off Controller

Dead Band

A special case of proportional control is On-Off control. If the proportional band ofthe controller is made very low (=0) the controller out put will move from one

extreme position to other for slight deviation of process value from the set point.This very sensitive action is called On-Off control because final control element is

either open (On) or close (Off) i.e. operates like a switch. These are the simplest

controllers.These controllers incorporate a dead band to keep the output from cycling rapidly

between on and off. The controller will not turn on or off until the error signal movesout of the dead band. The process variable controlled by an on/off controller always

cycles back and forth about the set point as shown in the fig. Dark line and dottedline shows process parameter and reference values respectively.

Hysteresis is a value set in the vicinity of on-off operating point. Upper hysteresis isvalue or band in which process value is allowed to operate above the set point and

lower hysteresis is value or band in which process value is allowed to operate below

the set point.

Proportional (P) controllers


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Time

Param

eterValue

Propertional Controller

Offset

In proportional controller the control algorithm generates a linear control output

proportional to deviation. In proportional action the amount of change in themeasured value (or deviation) is expressed in percent of span that is required to

cause the control output to change from 0 to 100 % is called the proportional band.The controller output is given by:

ePB

bOP +=100

Where, OP is the output, PB is proportional band in %, b is the bias value, and e is

the error signal. If there is no biasing, output OP will become zero when error iszero. Hence bias value decides the value of output when error is zero.

The proportional controllers usually show some difference between the set point andprocess variable called offset. The offset can be reduced by decreasing proportional

band or by readjusting the bias. With decrease in proportional band the processbecomes oscillatory.

There are two types of controller actions:

1) Increase-increase in which output increases as measurement increases.(error e = measurement set point)

2) Increase-decrease in which output decreases as measurement increases.

(error e = set point measurement)

Proportional- Integral (PI) controllers

Time

ParameterVale

Propertional - Integral Controller

The offset in proportional controller can be overcome by adding integral action. Thecontrol algorithm that applies changes in output as long as deviation exits, so as to

bring the deviation to zero, is called integral action. Output of proportional-Integralcontrollers is given by:

++= dteTiePBbOP1100


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Where OP is the output, b is the bias, PB is the proportional band in %, e is the error

signal, Tiis integral time; this is the time required to repeat proportional action.

Proportional-Derivative (PD) controllerThis mode of control is described by the relationship

++= dtde

TdePBbOP

100

Where OP is the output, b is the bias, PB is the proportional band in %, e is the errorsignal, Tdis derivative time.Larger the derivative time larger is the action. Smaller is the proportional band thelarger is the derivative action.

In order to achieve faster response and more stable operation in slow processesderivative action is added to apply an output component proportional to the rate of

change of input (error). Derivative action is used with P action or PI action.

ProportionalIntegralDerivative (PID) controllersPID controllers are used for controlling almost all process variables like temperature,flow, level, pressure etc. in a continuous or batch process.

The output of a PID controller is given by:

+++= dtde

TddteTi

ePB

bOP1100

Where OP is the output, b is the bias, PB is the proportional band in %, e is the errorsignal, Ti is the integral time and Tdis derivative time.Selection of proportional band, integral time and derivative time to achieve desiredprocess response to load changes is called tuning of controller.


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CONTROLLER TUNINGThe three-mode controller (PID) is the most common feedback controller used in

industrial control. The method of determination of the optimum mode gains,depending on the nature and complexity of the process is known as loop tuning.

The three parameters should be selected to meet a set of defined goals. These goals

typically require a plant response with minimum steady state error, insensitivity to

load disturbances and an acceptable transient response to set point changes anddisturbances.In practice the choice of proportional band, integral time and derivative time is a

compromise between the set point tracking and disturbances. If a mathematicalmodel of the process is known, selecting the controller parameters is relatively

simple. But in many industrial applications, a reliable mathematical model is notavailable or it is difficult to determine. So empirical rules are developed for PID

tuning which do not require mathematical model. A widely used set of rules is

proposed by Ziegler- Nichols by open loop method and close loop method in 1942.

Open loop method (Process reaction curve metood)In open loop method the process is assumed to be model of first order. The step

response i.e. process reaction curve, allows to obtain the approximate values of P, I

and D parameters. With the feedback loop open, a step response is applied tomanipulated variable and the values of P, I and D are estimated.

Time

10

10

0 20

20

30

30

40

40

ControlledVariable

L X

Y

Open loop response for input step change

(Process reaction curve)

WhereSlope R: Slope of line drawn tangent to the point of inflection.

X

Y

time

riableChangeinVaR ==

(min)

%

Dead time L: Time between the step change and the point where tangent line

crosses the initial value of the controlled variable (in min.)

P = Step change applied in %


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Using these parameters, the empirical equations are used to predict the controller

settings for a decay ratio of 1/4.

For P, PI and PID controller the parameters are calculated as follows.

Mode Proportional band(in %)

Integral time(in Min)

Derivative time(in Min)

P 100RL/P

P+I 110RL/ P L/0.3P+I+D 83RL/ P L/0.5 0.5L

Closed loop method (Ultimate gain method)This method is also called as ultimate gain method. The term ultimate was attachedto this method because its use requires the determination of the ultimate

proportional band and ultimate period. The ultimate proportional band, PBu is theminimum allowable value of proportional band (for a controller with only proportional

mode) for which the system continuously oscillates at constant amplitude. Theultimate period, Tu is the period of response with the proportional band set to its

ultimate value. To determine the ultimate proportional band and ultimate period the

proportional band of the controller (with all integral and derivative action turned off)

is gradually reduced until the process cycles continuously.

Time

Outut

Continuous Cycling

Tu

Response curve for ultimate gain and period

The process is placed in the closed loop with a proportional controller. The

Proportional band is decreased until the process goes to continuous oscillations. Thecorresponding value of proportional band is called as ultimate proportional band PBu

and the period of oscillation is called the ultimate period Tu. The PID controller

parameters are selected from the following table.

Mode Proportional Integral Derivative

P 2 PBu

P+I 2.2 PBu Tu/1.2

P+I+D 1.65 PBu 0.5 Tu Tu/8.0


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FREQUENCY RESPONSE ANALYSISLaplace transform techniques are used to express mathematical models in terms of

transfer functions in order to calculate transient response. An alternative way tointerpret the transfer function model, refereed to as the complex transfer function or

the frequency response. It shows how the output response characteristics depend

upon the frequency of the input signal. This is the origin of the term, frequency

response.

Stability analysis by using bode plotsFrequency response may be plotted in three ways:i. The rectangular plot with amplitude ratio verses frequency and phase lag verses

frequency.ii. A polar plot with magnitude and phase shown in vector form with frequency as a

parameter.

iii. A phase margin plot with magnitude shown verses a function of phase withfrequency as a parameter.

If the system is linear, the output signal for sine wave input must be a sine wavehaving the same frequency as the input.

Assume that the input to the first order system is suddenly switched from a constant

input to a sine wave input. The initial slope of the sine wave input signal may beapproximated by a ramp input or even exponential input.

If the input frequency is very low, period of the sine wave will be very long. Stated inanother way, period is very much larger than the system time constant. Under this

condition the output will have sufficient time to approach the condition, which isnearly in equilibrium with the input signal. Thus, at low frequencies both magnitude

and phase angle of the output signal will be close to magnitude and phase angle ofthe input signal. However as the frequency increases period decreases, and the

system does not have sufficient time to achieve the equilibrium status between input

and output. Under these conditions output magnitude will decrease, and outputphase angle will fall behind or lag the input phase angle. Thus it is evident that any

solution must show a decrease in ratio of output to input magnitude as frequencyincreases.

Magnitude and phase angle calculation:Let,

M Magnitude ratio

A1 Input amplitude (%)A2 Output amplitude (%)

Phase angle (degrees)x lag (seconds)

T Period (seconds)f frequency (cycles per seconds) = 1/T.

Then,M = A2/A1

= (x/T) x 360


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TimeFrequency Response

Outpu

Inpu

T

X

A2

A1

BODE diagramIn Bode diagram the magnitude ratio verses frequency is plotted on log-log co

ordinates and the phase angle verses frequency on semi-log coordinates.

Frequency

Bode Diagram

Frequency

Log Scale

0.1

0.1

-180

0.1

0.01

0.01

1

1

-90

1

10

10

0

10

PhaseA

ngleDeg

MagnitudeRatioM

Stability criteria A system is stable if the phase lag is less than 180 Deg. at the frequency for

which the gain is unity (one). A system is stable if the gain is less than one (unity) at the frequency for which

the phase lag is 180 Deg.


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Windows based control software package provided is designed to fulfill basic pressure

control study. It helps in understanding PID logic and combinations of differentcontrol actions.

Installing the software package

Switch on computer. Ensure display settings are 800x600 pixel and font size issmall fonts.

Create separate directory and copy software files & instruction manual from theCD supplied with the product.

Create a short cut on the desktop for the executable file. Click on the icon created on the desktop to execute the software.Getting startedReal time data accessFor DDC model: Select Data Access |Interface. Select Start.

For SCADA model: Select Data access| Microprocessor| COM1 or COM2 as thecase may be. Select Start.

Studying data logging from file

Select Data Access, controland then Data File. By default data file for PID controlis opened using a dialog box to select file name.

Software


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Menus

Data Access

This menu gives three options to start the experiments.

Interface/ microprocessor

Selecting this option, accesses real-time data from field using interfacing unit/control

module.Data FileThis option accesses data from stored file. Results and data of experiment conducted

are observed. A file open window lets you open the desired file. There is a predefined

file extension. While opening the file user need not know the file extensions,software lists the files related to the experiment. User can see the data, stored in

file, in the form of tables as well as graphs.Simulator

This option accesses data from PID simulation logic. The user has to enter processvalue and set point. With different values of the PID parameters, user can observe

the change in the controller output to the error produced. Changing set point

produces error to the controller.Control

This menu gives two options to select control mode.

Closed loop: This option enables, close loop control action. In this action, controllercalculates output to the process based on process parameters automatically.

Open loop: This option enables the open loop control action. Selecting this optioncontrol loop is opened i.e. output to the controller can be changed manually.

Controller does not work in open loop.

Controller


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It provides four different modes of controller for controlling the process variable.

Each controller is provided with separate controller setting facility. Select respective

controller and set the desired control parameters. Various types of controller arementioned below.

On Off: This option allows selecting on-off controller.P: This option allows selecting Proportional controller.

PD: This option allows selecting Proportional + Derivative controller.PID: This option allows selecting Proportional + Integral + Derivative controller.

Note: PI controller can be set in PID controller option by keeping the derivative time

equal to zero.Function Generator

This option is used to apply the dynamic input to the process. The dynamic

(sinusoidal) wave form is applied to the process. During the close loop operation the

function is applied to the set point, in open loop operation the function is applied to

output.

On: Enables the function generator selection. Amplitude and period is entered to the

wave.Off: Stops the function generator.

LogOn: Enables the data logging.

Off: Stops the data logging.

Print

Use Print for printing graphs and data table from Data File.Graph: To print graph click pause when you reach at the desired data plotting.

Select print then graph to get a window for printer selection. Select a printer and

click OK to print selected graph. Again clicking the run switch will start the plottingof the remaining data.

Tables: Data table for PID values is available. Select any option for printing.PID Tune contains tuning values set during experiment. Select Print then Table

with option to get a window for printer selection. Select a printer and click OK toprint selected graph.

StartClick Start to activate selected Data Access option.

Stop

Click Stop to deactivate selected Data Access option.ShutdownSelect Shutdown for closing software application.

Basic functionsON- OFF ControlOn - off control compares set point and process value and gives output an ON or OFF

signal according to the positive or negative deviation.Hysteresis: A value set in the vicinity of the on/off operating point is referred to as

the hysteresis.Upper hysteresis and lower hysteresis can be set. To set hysteresis

values Tune button is provided on the screen.PID controlPID controller compares set point and process value. It gives output by calculations

based on PID logic. To setPID values Tune button is provided. Set values for P, I,

D; Outputhigh, Output low and Action. Use Download for applying new valuesfor controller.

PProportional band value for this controller is denoted by P. Set proportional band

values.


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I

Integral time for controller denoted by I and it is applied in seconds.

DDerivative time for controller denoted by D and it is applied in seconds.

BiasBias is the value of normal output of controller at zero error. This option appears if

Proportional controller or Proportional + Derivative controller is selected..Output High

Higher bound of the controller output

Output LowLower bound of the controller output

ActionIn INC-INC mode, increase in process variable increases controller output & vise-

versa. For INC-DEC mode, increase in process variable decreases controller output& vise-versa.

Download

Use Download for applying new values for controller.PID Tune screen


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Switching between auto and manual

You can use a button, marked Auto (by default) for switching between the two

modes. Click to change the mode from Auto to Manual. Click again to change themode from Manual to Auto. In Auto mode output of process is controlled by

software and in Manual user controls mode output of process.Pause or Run trend graph in offline

In Data File, Data access mode a button marked Pause (by default) is used to stopthe trend graphs.

To run the trend graph click RUN display.

Stored data screen


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Setting parameters for digital indicating controller(For product no. 314A )[Refer instruction manual of the controller (separately provided) for controller

operation].

Operating parameter

table

Setup parameter table Input output related

LED Display Value LED Display Value LED Display Value

Press ENT for 3 sec. OP.PA (pressup/down):

STUP (press ENT)

FUnC (press up/down):I/o (press ENT)

oP.PA Pyd 0 I/O

LL (**) oFF FUnC In 41

A1 100.0 SPH (**) 100.0 RH 5.000

A2 0.0 SPL (**) 0.1 RL 1.000

A3 100.0 AL1 1 SdP 1

At oFF AL2 2 SH 100.0

SC oFF AL3 1 SL 0.0

SP.no 1 Hy1 0.5 bSL 1PId MenU or Hy2 0.5 Ot 2

FL oFF Hy3 0.5 rEt 3

bS 0.0 dY1 (**) 0.00 rtH (**) 100

UPr oFF dY2 (**) 0.00 rtL (**) 0

dnr oFF dY3 (**) 0.00 diS 1

oH 100.0 Ct 30 C.S1 oFF

oL 0.0 Po 0.0 C.S2 oFF

dr 0 C.md 0 C.S3 oFF

Hb1 oFF Zon oFF C.S4 oFF

Hb2 oFF Ar Auto LoCK oFF

HC1 0.0 tmU 1HC2 0.0 P.SL 0

orb 1.0 bPS 4

orH 100.0 PrI 0

orL 0.0 StP 1

or 0 dLn 8

1.SP 50.0 Adr 1

2.SP 0.1 rP.t 0

3.SP 0.1 test 0

4.SP 0.1

(**) Marked steps are not visible in some controller models.


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Note:The experiment nos 1 thr 6 are to get feel of the process and PID settings.

1 Study of open loop response (Manual control)

Procedure Start up the set, adjust the vent valve. Select open loop option from software. Close the control valve by increasing the controller output to 100%. Apply the step change by 10% to controller output in manual mode, wait for

process value to reach the steady state value.

Repeat the above step until the controller output reaches to minimum 0%.Observations

Tabulate the observations as follows

Controller output in % Process Value in %

100

90

80

0

From the above data, note the output required for maintaining the process atdesired set points. (for particular vent valve opening).

Set the output of the controller to the noted value and at steady state apply theload change to the process. Load change can be given by slightly varying thevent valve. Observe new steady state process value.

Experiments


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2 Study of on/off controllerProcedure

Start up the set up and select close loop option for control from software. Set the controller to On/Offmode. Press Tune & set the upper and lower hysteresis of the controller. Change the values of the set point and observe the On-Off control operation.Observations

Observe that if process value exceeds the set point, controller closes the valve and if

process value decreases below the set point control valve opens, i.e. the controlleroperates like On/Off switch.


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3 Study of proportional controllerProcedure

Start up the set up and select close loop option for control from software. Set the controller to proportional control (P) mode. Adjust the process value by switching the controller to manual mode to a

particular pressure (say 50 %) on the screen and apply output of the controlleras bias value. Change the proportional band to 100%.

Switch the controller to auto mode. Apply step change of 10% to set point. Switch the controller to manual mode. Decrease proportional band to half of the

previous value. With each decrease, obtain a new response of the step change.Ensure that the set point changes are around the same operating point (Say

50%).

Observations

Observe the effect of very low proportional band values (system works as on-offcontrol).

Observe the response of the system at load change. Load change can be given byslightly manipulating the vent valve of the tank.


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4 Study of proportional integral controllerProcedure

Start up the set up and select close loop option for control from software. Select PID controller. Set the proportional band estimated in Proportional control.

Set derivative time to 0 sec and integral time 6000 sec, which will cut off the

derivative action and widen the effect of integral action.

Set the set point to desired flow value. Allow the process to reach at steadystate. Record the steady state error.

Switch the controller to manual mode. Reduce the integral time to half of theprevious value. Switch to Auto mode and apply step change(+/- 10%) to the set

point. Note the response of the system. Repeat above step to observe the effect of changes in Integral setting.Observations

Observe the effect of reducing integral time on the response of the process.


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5 Study of proportional derivative controllerProcedure

Start up the set up and select close loop option for control. Select PD controller. Set the proportional band estimated from Proportional

control (P only) Set derivative time to 0 and integral time=6000 sec.

Set the set point to desired value. Allow the process to reach at steady state.Note the response of the system.

Switch the controller to manual mode Increase the derivative time by 1 sec.Switch to Auto mode and apply step change to the set point by 5 to 10%. Notethe response of the system.

Increase the derivative time gradually and observe the process response for stepchange.

Observations

Compare the steady state response of the PD controller with PI controllerobtained in the previous experiment.


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6 Study of proportional integral derivative controllerProcedure

Start up the set up. Select close loop option for control from software. Select PID controller. Switch the controller to manual mode. Change the proportional band to the value that estimated in proportional

controller. Set integral time and derivative time based on the responses in

previous experiments.

Adjust the set point to @ 50 %. Switch the controller to auto mode. Apply stepchange of 10%. Observe the process response.

Change the proportional band, integral time, derivative time and observe theresponse of the process for step change for each change in setting.

Observations

Compare the steady state response of the PID controller with P. PI and PD controller

obtained in the previous experiments.


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7 Tuning of controller (Open loop method)Procedure

Start up the set up and select Open loop option for control. Adjust controller output, so that the process value is maintained at 50%. Start data logging. Apply a 20 - 30 % change to controller output. (Open the control valve) Record

the step response. Wait for the steady state.

Stop data logging. Plot the step response (Process reaction curve) from stored data. Find out the

value of slope at the point of inflection and time lag.

Calculate P I D settings for different modes. Select close loop, switch auto manual key to auto mode and then select

controller to study. Set the PID values obtained from the calculations. Apply thestep change & observe the response of the system. Allow the system to reach

steady state.

Observations

(Refer theory for formulae.)

Step change to the system P = Initial output - Final output of the controller.

Plot the graph of process value Vs Time on a graph paper.From process reaction curve: Slope of the process reaction curve R = Time lag L=

Calculate P, PI, PID setting from above values.

Observe response of the system for different PID settings.


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8 Tuning of controller (Closed loop method)Procedure

Start up the set up and select close loop control. Select P controller only. Set the proportional band value to maximum (Say 200).

Set the controller to manual mode and adjust the output so that the process

value reaches to 50%.

Switch the controller to auto mode and decrease the proportional band and applythe step change to the set point and observe the process response.

Repeat the above procedure and find out correct value of proportional band forwhich the system just goes unstable i.e. continuous oscillations are observed in

the output of controller. Record the ultimate proportional band and ultimate period from the response. Calculate the PID values from the table. Select the PID controller and apply the

parameter values obtained from the above steps. Observe the response of the

process to a step change with these settings.

Observations

Record the ultimate proportional band (Pbu) and ultimate period (Tu) from aboveexperiment.

Calculate PID values by referring theory part for different control actions. Observe the process response for these settings. Compare the values obtained with open loop response method.


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9 To study stability of the system (Bode plot)Procedure

Start up the set up and select open loop option from software Start data logging. Select function generator to apply the sinusoidal input to the output of the

controller.

Enter Reference point, Amplitude and Period. Observe the sinusoidal output of the controller and sinusoidal response of the

process. Log the data for records. Change the period and repeat the observation for 3-4 different values of the

period.

Repeat above procedure for different amplitude and period values.

Observations

From the data file stored observe the output response of the process and notedown the output amplitude.

Measure output wave period and note down as T sec. Measure the phase lag x

and note down in sec.Obs.

No.

Input

amplitudeA1 %

Output

amplitudeA2 %

Output

PeriodTin sec

Lag X

In sec

Frequency

Calculations

Calculate for each observationMagnitude ratio as M = A2/A1

Phase angle = (X/T) x 360Frequency = 1/T cycles / sec.

Draw the graphs of:

Magnitude Vs frequency on log - log scalePhase angle Vs frequency on semi-log coordinates.

Study the graph for stable conditions mentioned in theory.


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Electro pneumatic transducer (I/P)The ControlAir Type 500X converts a current input signal to a linearly proportional

pneumatic output pressure.

Technical specificationsModel 500X-ACMake ControlAir

Input 4-20 mAOutput 3-15 psi

Min./Max supply pressure Min. 18 psig, Max 100 psigLinearity +/-0.75 % of span

Repeatability


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TroubleshootingProblem Check

No output or low output Zero adjustment

Supply pressure too low

Clogged orifice

Leakage ConnectionsLow or improper span Zero and span adjustments

Supply pressure too low

Output leakage

Erratic operation Electrical input signalLoose wires or connections

Liquid in air supply

Calibration1 Open protective covers to expose zero and span adjustment screws.

2 Connect the recommended air supply to the inlet of the transducer and an accuratepressure gauge at the outlet.

3 connect the electrical input and set it to 4 mA.4 Observe the output pressure. If necessary adjust zero screw until reaching

minimum output pressure setting (3 psi). Turn zero screw counter clockwise toincrease pressure, clockwise to decrease pressure. If unable to achieve output

during calibration process, turn zero adjustment screw counter clockwisefor up to 30 revolutions, until output pressure rises.

5 Increase electrical input to 20 mA


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6 Observe the output pressure. If necessary adjust the span screw until output

pressure reaching 15 psi. Turn span screw counter clockwise to increase pressure,

clockwise to decrease pressure.7 The zero span adjustments are interactive. After adjusting the span it will be

necessary to recheck the zero. Repeat steps 3-6 until both end points are at therequired values.

Manufacturers addressIf you need any additional details, spares or service support for this unit you may

directly communicate to the manufacturer / Dealer / Indian Supplier.

Control Air Inc.8 Columbia Drive, Amherst, NH 03031

USAEmail: [email protected]

Indian supplier:Control teknics

5,Aboorva Flats, old No.6, New No. 117th main road, Raja Annamalaipuram

Chennai - 600 028Email: [email protected]


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Mini combination air filter regulatorThese modular series filter regulator are high flow, low pressure, and high accuracy.

Technical specifications

Make AirmaticModel MB10-021-VD-PAP

Range 0 2 Kg/cm2Type Diaphragm, Relieving

Connection BSPBody Aluminium

Bowl PolycarbonateElement Porous material

Drain BrassSeals Buna N

Diaphragm Buna N

Spring pressure Spring steel Zn platedSpring valve Stainless steel

Spring cage and nob Acetyl resinGauge ports Two

Element rating 25 micronDrain Manual

Bowl capacity 30 ml

Max. pressure 12kg/cm2Max. temperature 500C

Overall dimensions 40diameter x 155 H mmWeight 220 gm

Manufacturers addressIf you need any additional details, spares or service support for this unit you maydirectly communicate to the manufacturer / Dealer / Indian Supplier.

Shah pneumatics

28/30, Navketan Industrial Estate,Mahakali Caves Road, Andheri (E)

Mumbai 400 093.E-mail: [email protected]

Web: www.shahpneumatics.com


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Pressure gaugeIntroduction

Pressures gauges are suitable for use with air, oil, water or compatible gases. The

phosphor bronze bourdon tube is housed within a rugged SS case. The aluminum dialand pointer are protected by an impact resistant polycarbonate window. Accuracy is

+/- 3-2-3% per ASME grade B. Brass back connection is male NPT.

Technical specificationsMake Waaree Instruments

Code PW2.5GNNNS9 0-2.5 B

Pressure gauge 2.5 diameterLiquid filled Glycerin

Internals part BrassHousing SS

Range 0 2.5 and 0 7 Kg/cm2Connection center back

Accuracy +/-3-2-3% per ASME grade B.Media Clean, no corrosive liquid

Bourdon tube Phosphor bronze

Dial/pointer Aluminum dial with black enameled pointerWetted parts Phosphor bronze bourdon tube with brass

stemTemperature range -10 to 800C

Mounting Panel mountingOverall dimensions 70diameter x 55mmL

Weight 140 gm


Waaree Instruments Ltd.10, Damji Shamji Industrial Complex,

Off Mahakali Caves Road, Andheri (E),

Mumbai 400 093.

E-mail: [email protected]: www.waaree.com


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Pressure TransmitterPressure transmitters are use for air, fluid and gas pressure in the close tank.

Technical specificationsModel 21S

Make Keller

Output 4-20mA (2wire)Supply 24 VDCPressure Range 0-5 Bar

Process connection BSP (Male)

Accuracy +/-1%

TroubleshootingProblem Check

No output at the output pin Check the wiring configuration.

Check the input + Vcc supply.

No variation in the output Check for the leakage at pressure port.

Check for the span set of indicator / controller.

Pressure not holding at constant

input pressure

Check for the leakage at pressure port.


Web: www.keller-druck.com Supplied by:

Waaree Instruments Ltd.36, Damji Shamji Industrial Complex,

Off. Mahakali Caves Road,Andheri (East), Mumbai 400 093.

Email:[email protected]:www.waaree.com

5. Pressure Control Triner

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