Automation Module Engineering Foundation Course 2011

Automation Module

Engineering Foundation Course 2011

Contributors to the CourseSteven Laycock: Technology Leader for Process Control and Automation in Unilever Europe since 2003 and the Global Engineering Excellence Team. Joined Unilever (Leeds) in 1996, after working for an independent systems integrator.

Stuart Dow: Systems Development Manager with Haden Freeman Ltd. (engineering design and consultancy company). 13 years as engineer & manager working on projects in a variety of industry sectors.

Karam Rehani: Head of Instrumentation & Controls in Unilever India & AAMET since 1994. Joined Unilever (HLL) in 1981 & has worked at various locations manufacturing soaps, detergents, personal products & chemicals. Before joining Unilever, worked for 9 Yrs with Leading fertiliser co’s in India.

Endress + Hauser : Live Product Demo

Rockwell Automation : Live Product Demo

Siemens : Totally Integrated Automation Concept (Presentation Content)

Adhi Winata K : Instrumentation, Control, Automation & Electrical Manager in Unilever Indonesia. Joined Unilever in 2006. Before joining Unilever, worked with telecommunication company.

Objective

What are we going to cover today

3 key areas

- Understanding of the use of control systems

- Key knowledge necessary to manage an automation project

- Reasons to choose from the control options available

Agenda

Section 1:Introduction to ControlBuilding blocks – Measurement & Action

Example Equipment (Endress & Hauser)

Section 2: Building Blocks – Evaluation & Logic

Pack Line Case Study : OMAC (Rockwell)

Section 3:Automation Projects & Industry Standards

Process Plant Case Study : Implementation of ISA S88 & ISA S95 (Rockwell)

Section 4: Multiple Choice Questionnaire

Agenda



Section 2: Building Blocks – Evaluation & Logic





Reasons for Automation

Marketing: A marketing push may require increased production, re-branding,

re-packaging or new formulations for example, or a requirement to search for new growth or markets

Commercial: Higher output, lower utility costs, better yield, less labour

Quality : Better quality, fewer

rejects

It is to realize highest productivity enhancements by intelligently connecting quality, speed, and cost and finding the optimal balance

between all three

Challenge for Automation

Automation CharacteristicsSoftware for Controller and HMI programming :• STEP 7 (Siemens)• RSLogix 5000 (Allen-Bradley)

IT Security in the network :• Restricted Access• Firewall• Encoding• VPN Network

Safety for humans & machines :• Safety Interlock• Alarm Management• Safety Integrated Solutions (SIS)

Standard data transparency across all automation levels :• Communication Protocol• Logger / Historian• Report

Diagnostic functionalities that enable fast detection and correction of errors :• Maintenance Station• Engineering Station

Industrial capability equipment with highest robustness :• Industrial Type Hardware

The Automation Pyramid

Automation System Components

ERP Enterprise Resource Planning SystemBasic functions of the business. Production Planning, Material Management

MES Manufacturing Execution SystemMeasure and control critical production activities. Equipment tracking, product genealogy, scheduling, KPI monitoring

SCADA “Supervisory Control & Data Acquisition” SystemInterface to monitor & control the manufacturing plantHMI, Data Logger / Historian, Batch Management

Control LevelMonitor & control the manufacturing plantPLC - “Programmable Logic Controller”, PC Based Controller, Single / Multiple Loop PID (Proportional, Integral, Derivative) Controller

Field Level Final executor of the manufacturing plant Sensors, Actuators, I/O Module, Hardware

Response time and hierarchical level

PlanningLevel

ExecutionLevel

ControlLevel

SupervisoryLevel

ms seconds hours days weeks month years

ERP(Enterprise Resource

Planning)

DCS

MES(Manufacturing

Execution System)

PLC(Programmable Logic Controller)

(Distributed Control System)

(Supervisory Control and Data Acquisition)

SCADA

Automation System Components

Automation System ComponentsLayer Function Application Example Product Example

ERPCovers all basic functions of the business

• Production Planning SAP

• Orders Oracle

• Finance

• Material Management

MES

Measure and control critical production activities

• Equipment tracking SIMATIC IT

• Product genealogy FactoryTalk Integrator

• Scheduling InSQL

• KPI monitoring

• Workflow

SCADA

Interface to monitor & control the manufacturing plant

• Operator Station WinCC, FT View, InTouch

• Engineering Station

• Batch Control SIMATIC Batch, FTBatch, InBatch

• Logger

ControlMonitor & control the manufacturing plant

• PLC SIMATIC S7-400, ControlLogix

• PID Controller SIPART, Eurotherm T640

• PC Based Controller ACCOSS (Invensys Integrator)

• Motion Controller, CNC SIMOTION, SINUMERIK

FieldFinal executor of the manufacturing plant

• I/O Module SIMATIC ET200 M, Flex I/O

• Field Instruments E+H, Emerson, SITRANS

• Actuator Motor, Valve

Production Order Management

Detailed Production Scheduling

Product Specification Management

Production Operations Recording

Material Management

Production Planning

HMI ServerBatch Server

Data Logger Server

HMI ClientBatch Client

Event Logger

Automation System ComponentsApplication Example : Siemens Totally Integrated Automation

Automation System ComponentsReal Plant Example : Skin Care Processing Plant Cikarang

Basics

Monitor Evaluate Action

How Do We Control?

Information

Basics

We monitor the temperature.

Is it too cold or too hot?

If so we adjust the tap to correct.

Wait for a bit (system dynamics)

If temperature OK then have shower

Else if temperature not OK adjust again(but with benefit of knowing impact of last adjustment)

Go to ‘Wait for a bit’ and repeat.

An Everyday Example

BasicsControl Loop

Instrumentation

Engineering Foundation Course 2011

Agenda



Section 2: Building Blocks – Evaluation & Logic (Process & Packing Line)





Building Blocks:Measurement & Action

I. Monitoring & measurement1. Process Instrumentation

• Flow Measurement• Level Measurement• Temperature Measurement• Pressure Measurement• Analytical Measurement

2. Packing Line Sensors

II. Action1. Process Instrumentation2. Packing Line Actuators

III. Hardware Selection : Which to Pick







Measure the velocity flowrateExample :

Magnetic Turbine Ultrasonics

Flow Measurement1. Velocity

2. Inferential

3. Mass

Determine flow by measuring some other physical property such as differential pressure, area meter, impact force, etc and then correlate it to flowExample :

Differential Pressure (DP) : Orifice, Pitot Tube, Venturi Area Meter : Rotameter Impact Force : Target

Measure the mass flowrateExample :

Coriolis Mass Flowmeter Thermal Mass

Flow Measurement

1. Velocity Flow : Magnetic Flowmeter

• A magnetic field at right angles to the flow stream is generated• Two opposing electrodes measure the voltage produced by the fluid moving

Flow Measurement1. Velocity Flow : Magnetic Flowmeter

Video Time !!!

Flow Measurement

1. Capable of handling extremely low flow2. Having very low pressure drop (no obstruction), minimize pumping cost3. Suitable for most acids, bases, waters, and aquaeous solutions, because

the lining materials are corrosion resistant4. Widely used for slurry services5. Can be used as bidirectional meters

Limitations :

1. Work only with conductive fluids (can not measure pure substances, hydrocarbons, and gases)

2. Electrical installation care is essential (Proper Grounding)3. Flow measurement inaccuracy due to fluids with magnetic properties

(Liquid Sodium and its solutions)

Advantages :

1. Velocity Flow : Magnetic Flowmeter

Flow Measurement

1. Velocity Flow : Turbine/Paddlewheel

A rotor (like a propeller) is supported by bearings to allow free rotation in the fluid flow.

As the blades spin in the moving flow a pickup device counts the passing rotor blades and generates a frequency.

As this frequency is proportional to the rate of flow and we know how much quantity each pulse represents we can calculate the volumetric flow.

Flow Measurement

1. One of the most accurate flow meter (use for trading)2. Having a fast response3. Not sensitive to changes in fluid density (though at very low specific

gravities, rangeability may be affected)

Limitations

1. Not recommended for measuring steam2. Sensitive to dirt3. Can not be used for highly viscous fluids or for fluids with varying

viscosity4. Potential for being damaged by over-speeding (esp. during

commissioning or start up)

Advantages

1. Velocity Flow : Turbine/Paddlewheel

Flow Measurement

2. Inferential Flow : dP Orifice Plate

Orifice plate : a flat piece of metal with a hole bored in it.

A dP (differential pressure) is created across the plate.

D d

p+p-

)(2

1

2

pp

A

A

ACQ

pipe

orifice

orificed

Flow Measurement

2. Inferential Flow : dP Orifice Plate

An instrument that can measure dP is connected by pipework (called impulse lines) to a tapping point on either side of the plate.

The square root of the dP measured is proportional to the flow. (Normally accounted for in the electronics of the measuring instrument)

Flow Measurement2. Inferential Flow : dP Orifice Plate

Video Time !!!

Flow Measurement

Elbow Taps

2. Inferential Flow : dP VariousPitot Tube Venturi Tube

Flow Nozzle

Flow Measurement

2. Inferential Flow – dP VariousType Advantages Limitation

Orifice

Wide range of applications Low accuracy

Simplest & cheapest among dp types (except big size) High irrecoverable pressure loss

Sturdy

Pitot Tube

Applicable for measurement of large flows Low accuracy

Can be used to obtain the velocity profiles Depend much on velocity profiles in one point

Very Low pressure loss

Venturi Tube

Low Pressure Loss More expensive than orifice

Resistant to abrasion Installation is more difficult

Can be used to measure dirty fluids & slurry

Elbow TapsLow cost solution for large pipe Inaccurate measurement

Very Low Pressure Loss Requiring high flow velocities & short radius elbow

Venturi NozzleLess expensive than venturi tube Higher Pressure Loss than venturi tube

Resistant to abrasion Installation is more difficult

Flow Measurement3. Mass Flow : Coriolis Effect

Tube(s) are forced to oscillate at their natural frequencies perpendicular to the flow direction.

The resulting Coriolis forces induce a twist movement in the tubes which is measured and is related to the mass flow.


Video Time !!!


Two most common types are the

1. Used mainly for multiphase fluids and for fluids that can coat or clog since the straight type can be easily cleaned

2. Having a low pressure loss3. Reduces the probability of air

and gas entrapment4. Must be perfectly aligned with

the pipe

1. Having a wider operating range, measures low flow more accurately

2. Available in larger sizes3. Tends to be lower in cost4. Having a higher operating

temperature range 5. More sensitive to plant

vibrations

Straight Tube Curved Tube

Flow Measurement

Advantages :

• Directly measures mass flow with high accuracy

• High rangeability

• Directly measure density

• Highly independent of the flow profile and fluid properties (specific gravity and viscosity)

• Can be used for many different applications, including corrosive fluids

Limitations :

• High Price

• Can not be used for liquids with any significant gas content

• Not available for large pipelines

• Not suitable for low pressure gases

3. Mass Flow : Coriolis Effect

Flow MeasurementOther Methods

Thermal Mass Flowmeter

Vortex Shedding

Ultrasonic

Target

Weir & Flume

Variable Area / Rotameter

Flow MeasurementFlowmeter Comparison Table

Flow MeasurementFlowmeter Comparison Table (cont’d)







Level Measurement

Wave : Radar, ultrasonic, Guided Radar (TDR) Nuclear radiation Electrical Properties : Capacitance, Conductance Mechanical Contact : Floats, Tuning fork, Paddle wheel

2. Position (height) of the surface

3. Weight

Load Cells

1. Pressure / Force

Pressure : Differential pressure, Diaphragm, Air bubblers Buoyancy Force : Displacer

Level MeasurementPulse 6 GHz

RadarPressure Guided Wave

Radar TDRFMCWPulse

24 GHz RadarCapacitance Ultrasonic

Level Measurement

1. Pressure Static Head

Pressure/Static Head: (also known as hydrostatic)- Based on the height of the liquid head & the density of the liquid - Accurate level calculation requires known & constant density

Advantages :1. Have a wide range of measurement2. Straightforward calibration

Limitations :1. Affected by changes in liquid density (only

for liquids with fixed SG)2. Susceptible to dirt or scale entering the

tubing

Pressurized Vessel

Atmospheric Vessel

Level Measurement

Wave is transmitted to target, reflected, and total transit time is determined

2. Position of Surface : Wave

Type Wave Source Carrier Medium Wave Speed

RadarElectromagnetic Wave (4-30 GHz)

Not needed (able to propagate in empty / vacuum space)

Speed of Light (300,000 km/s)

UltrasonicMechanical Wave (> 20 kHz)

Needed (air, liquid, solid)Speed of sound (344 m/s)

Free Wave

Radar

Ultrasonic Guided Radar

Free Wave Guided Wave

Level Measurement

Type Advantages Limitation

Ultrasonic

1. Able to measure the level without making physical contact with process material

1. May not be used if vapour space of the material is dusty, or it contains foam, water vapour, or mists

2. Unaffected by changes in the composition, density, moisture content, electrical conductivity, and dielectric constant of the process fluid

2. Not applicable should the material has sound-absorbing surface (fluffy solids)

3. Reliable performance for difficult slurry or sludge-type services

3. Require a consistent temperature, since it is affected the speed of sound

Radar

1. Able to measure the level without making physical contact with process material

1. Not applicable for low-dielectric material that absorb the microwave

2. Unaffected by changes in the composition, density, moisture content of the process fluid

3. Changing vapour and foam has less effect than on ultrasonic type

4. Reliable performance for applications of medium difficulty, such as fuming acids, asphalt, LNG, tars, and other heavy hydrocarbons

Guided Radar

1. Able to measure liquid interface level (with some conditions related with dielectric constant of the material & no emulsion layer)

1. Not applicable for low-dielectric material that absorb the microwave

2. Position of Surface : Wave

Level Measurement

• Measures the changing electrical capacitance• Applicable for both conductive and nonconductive fluids• Provide both continuous and point measurement• The dielectric constant of the fluid must remain constant• Can not measure liquid interface

• Electric current flows through the fluid, container wall and the probe which actuates a relay

• Applicable for conductive fluids only• Provide only point measurement• Can provide differential level control (three-probe-

type)

2. Position of Surface : Electrical PropertiesCapacitive

Conductive

Level Measurement

• A radioactive source radiates through the vessel. The gamma quantum is seen by the radiation detector (such as a Geiger counter) and is transformed into a signal

• Unaffected by temperature, pressure, and corrosion

• Applied where other types of measurement cannot be used

2. Position of Surface : Nuclear Radiation

Level Measurement

• Keeping the probe vibrate in its natural frequency• Relay triggered when process material in the tank reaches

the vibrating elements and damps out the vibration• Applicable for both liquid and solid material

• Small synchronized motor keeps the paddle in motion at very low speed

• When level raised to the paddle, it is stopped

• Applicable for solid material

• Applicable for liquid material

• Applicable for both point and continuous measurement

2. Position of Surface : Mechanical ContactTuning Fork (Vibration)

Rotating Paddle Switch Float

Level Measurement

3. Load Cells

The strain gauge (either foil or semiconductor) measures the stress which is introduced into a metal element, both compression & tension

A bending beam type designuses strain gauges to monitor the stress in the sensing elementwhen subjected to a bending force.

Level Measurement

3. Load Cells TypeType Explanation Picture

Compression (Canister)

Designed to operate in compression only

Load can be applied at one end only, for some types it can be compressed by force at both ends

Shear BeamFixed rigidly at one end with the force being applied to the other end

Bending Beam

It consists of a straight beam attached to a base at one end and loaded at the other. Its shape can be that of a cantilever beam, a binocular design, an S-shaped or a ring design .

Ring TorsionRound and flat bending beam sensors consisting of bonded foil strain gages encapsulated in a housing

HelicalThe operation of a helical load cell is based on that of a spring. A spring balances a load force by its own torsion moment

http://www.sartorius-mechatronics.com/uploads/tx_sartoriushires/wi0784d1-WH.jpg

Level Measurement

3. Load Cells Comparison Table

Level Measurement

Level Sensor Comparison Table

Level Measurement

Level Sensor Comparison Table (cont’d)







Temperature Measurement

Thermocouples

1. Voltage

2. Resistance

3. Radiation Pyrometer (Infra Red)

4. Material Expansion

RTD Thermistor

Optical Ratio / Two-Color Broadband (Total) Radiation

Liquid-in-glass Bimetallic Filled system


1. Thermocouples

A thermocouple consists of two dissimilar metals, joined together at one end. When the junction of the two metals is heated or cooled a voltage is produced that can be correlated back to the temperature.

Temperature MeasurementThermocouples Type

Type

Wire Material Range (in °C)

Scale LinearityAtmosphere Environment

RecommendedFavorable Points Less Favorable Points

Positive Negative Min Max

BPt 70% - Rh 30%

Pt 94% - Rh 6%

0 1860Good at high temps. Poor below 535 °C

Inert or Slow Oxidizing

E Chromel Constantan -184 982 Good Oxidizing Highest mV/°CLarger drift than other base metal couples

J Iron Constantan 0 816Good; nearly linear from 150°C to 425°C

Reducing Most economicalBecomes brittle below 0°C

K Chromel Alumel -184 1260Good; most linear of all TCs

Oxidizing Most LinearMore expensive than T or J

RPt 87% - Rh 13%

Platinum 0 1649Good at high temps. Poor below 535 °C

OxidizingSmall size, fast response

More expensive than K

SPt 90% - Rh 10%

Platinum 0 1760Good at high temps. Poor below 535 °C

OxidizingSmall size, fast response

More expensive than K

T Copper Constantan -184 399Good but crowded at low end

Oxidizing or reducing

Good reststance to corrosion from moisture

Limited temperature

Y Iron Constantan -129 982Good; nearly linear from 150°C to 425°C

Reducing Not Industrial Standard


2. RTD (Resistance Temperature Detector)Measure temperature by correlating the resistance of the RTD element with temperature.

The RTD element is made from a pure material whose resistance at various temperatures has been documented. It has a predictable change in resistance as the temperature changes

• Winding the wire on a glass or ceramic bobbin and sealing with molten glass

• Limited by strain induced at higher temperature

• Threading a wire helix through a ceramic cylinder• Allows the wire coil to expand more freely over temperature • Not suited for extreme vibration

• Depositing a thin film on a ceramic substrate• Small, fast, inexpensive, less stable

Wire-Wound

Coil Elements

Thin Film

RTD element construction type


Metal

Range (in °C) Ice Point

ResistanceCharacteristic

Min Max

Platinum -200 850

Thin Film Type : 100, 1000 Ω

Most Linear

Wire-wound Type : 100, 200, 500 Ω

Widely used

Nickel -196 316

120, 500, 1000 Ω Not linear

Strain-sensitive

Highest Temperature coefficient

Copper -196 120 10, 100 ΩUsed in electrical machinery due to very low reactanceRTD Wiring configuration

RTD Detector Type

• Poor Accuracy• No compensation for resistance of

the connecting wires • Transmitter must be placed very

near with the sensor

• Best accuracy• Another pair of wires to form an

additional loop that cancels out the lead resistance

• Better accuracy than 2-wire• Two leads to the sensor are

on adjoining arms, therefore the lead resistance is cancelled out

2-wire 3-wire 4-wire


Characteristic Thermocouple RTD

Measurement Range Wide Narrow

Response Time Fast Slow

Linearity Less Linear More Linear

Price Cheap Expensive

Accuracy Less Accurate More Accurate

Sensitivity Less sensitive More Sensitive

Repeatability Fair Excellence

Long-Term Stability Fair Good

Self Heating Effect Medium N/A

Point (end) sensitive Fair Excellent

Lead Effect Medium High

Thermocouples Vs RTD


3. Optical

The most basic design consists of a lens to focus the infrared (IR) energy on to a detector, which converts the energy to an electrical signal that can be displayed in units of temperature after being compensated for ambient temperature variation.

Infrared pyrometers allow users to measure temperature in applications where conventional sensors cannot be employed. Specifically, in cases dealing with moving objects ( i.e., rollers, moving machinery, or a conveyor belt),


Temperature Sensor Comparison Table







Pressure Measurement

Bourdon Tubes Diaphragm Bellows

1. Elastic Pressure Chamber (Mechanical)

3. Liquid Level Column

Manometer

Capacitive Strain Gauge (Piezoresistive) Piezoelectric Inductive

2. Electronics

Pressure Measurement1. Mechanical

Bourdon

A bent oval tube.One end of the tube is linked tothe process pressure, and the other end is sealed and linked to the mechanism operating the PointerShapes : C, Spiral, Helical

Converts the increasing process pressure on one side of the disk into a mechanical movement by monitoring the bulging of the disk

One-piece axially expandable and collapsible element.Consists of many folds

Diaphragm

Bellows

Pressure Measurement2. ElectronicsA typical electronics pressure transmitter consists of two parts:

1. Primary elementConverts the pressure into an displacement / torque / mechanical value to be read by the secondary value. It may be diaphragm, bellows, etc

2. Secondary elementThe electronics that output from the primary element to a readable signal. It may be strain gauges, capacitive, piezoelectric, etc

Primary Element

Secondary Element

Pressure Mechanical Electric

- Displacement- Torque

- Resistance- Capacitance- Voltage- Current

Pressure Measurement2. Electronics

The inlet pressure activates a diaphragm that ismounted between two fixed plates. This causes a capacitance change

Piezoresistive materialchanges its resistance when strain is applied

Strain Gauges / Piezoresistive

Capacitive

additional temperature sensor for permanent self monitoring

dPceramic cell

fill fluid

ceramic membrane

capacitor plates C1

C2

process pressure

ceramic body

additional temperature sensor for permanent self monitoring

dPceramic cell

fill fluid

ceramic membrane

capacitor plates C1

C2

process pressure

ceramic body

Pressure Measurement2. Electronics

The inlet pressure activates a diaphragm / bellows that applies strain on a crystal (e.g., quartz). The strained quartz produces an electrical charge that is measured by the electronics

The inlet pressure activates a diaphragm / bellows moves a magnetic core inside the transformer. It creates an imbalance that is measured in the electronics

Inductive

Piezoelectric

Pressure MeasurementPressure Measurement Reference1. Gage pressure

Reference : Atmospheric pressure

2. Absolute pressure Reference : Complete vacuum

3. Differential pressureDifference between two pressure levels

Absolute

DP

Level

Gauge

Absolute Zero Pressure

Atmospheric Pressure

Absolute Pressure(psia, bara)

Vacuum Pressure(-psig, -bar)

Gauge Pressure(psig, bar)

Pressure MeasurementPressure Sensor Comparison Table







Analytical Measurement

pH Conductivity Gas Detector

MC Meter Chlorine Meter Turbidity







MeasurementPosition

Position and distance sensors detect the presence or not of items on the move. This can be used to identify when an item arrives, count how many items have passed or when an item has left.

Position technologies include photoelectric, laser, mechanical switches, proximity switches and pressure sensors.

MeasurementColour

Colour sensors can detect the presence or not of a successful operation. Has the label been printed, has the bottle got the right fluid in it, did the shrink wrap go on successfully

MeasurementMachine Vision

Machine vision is successfully applied to many industrial inspection problems, leading to faster and more accurate quality control. Machine Vision allows the

manufacturing industry toDetect Defects

Calibrate and control the manufacturing processOptimise the use of resources







ActionValves

Switching a pneumatic air supply to a valve or piston cylinder

• Achieving precise control of a process fluid• Usually connected to I/P transducer that convert electrical signal into pressure signal

• Switching feeds on and off or, when used in conjunction with other valves, to select routes through pipework systems• It is usually connected to solenoid valve that switch on/off the air supply

Solenoid Valves

Modulating / Control Valves

Discrete Valves

Action

Motors

Motors allow us to move things around whether it’s a pump moving liquids or a conveyor line moving boxes.

Motor operation (start/stop) is usually controlled in the MCC (Motor Control Center). The control circuit in MCC usually consists of contactors & relays.

Variable Speed Drives (VSD / Inverter) connected to the motor allows the motor speed to be controlled.







Action

Motors

Servo drive motors allow added control functionality (ramp up, ramp down, torque) and faster positioning.

Stepper motors give precise control of movement.

Switching a pneumatic air supply to a valve or piston cylinder

Solenoid Valves

Action

Equipment

Remote device interfaces allow us to control and “talk” with an enormous range of equipment and devices. This can take the form of a simple on/off control or a complex data/control interface.

ActionMechatronics







Which to Pick

Environment & System

What are the the parameters the device will be exposed to and expected to perform in during both routine and exceptional circumstances?

What are the performance criteria: speed, size, pass/fail criteria for the line?

With which chemicals and under what conditions will the device be expected to operate?

What hazards will be present and does this impact on the choice of device?

What’s the commercial impact? Cost v benefit.

Which to PickANSI/ISA 60529

Degrees of ProtectionProvided By Enclosures

IP XX

Protection against solid objects

Protection against water

ATEX DIRECTIVES

Minimise, or completely eliminate, the risk of ignition in explosive areas and to limit the harmful effects in case of an explosion.

Which to Pick

ATEX DIRECTIVES

Which to Pick

Documents

Automation Module Engineering Foundation Course 2011