design of automation system - universiti malaysia...

ERT 457 - Week 4 SEM 2 2016/2017 1

Firdaus Muttalib

School of Bioprocess

Engineering

07/03/2017

Design of Automation System

(ERT 457/3)

System Drives and Actuator

Part 1

Firdaus Muttalib


Engineering

7/3/2017

Course Outcome

CO2:

Ability to ANALYZE, identify, formulate and solve engineering problem of the actuator components and application of an automation system in Biosystems Engineering.

2ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017

Actuators

• Actuators are used to move or control (i.e., lifting, adjusting, tilting, pushing or pulling) a device from a source of power (i.e., manpower, hydraulic, pneumatic, electric and etc.).

• Actuators reduce the need for operator to go to every devices that need repositioning and operate the valve by hand.

3ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017

Actuators

• By using actuators, devices can be repositioned from central remote location such as a control room.

• This is important in processes where number of devices have to be repositioned accurately and quickly.

4ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017

Actuators

Previous

They only act for moving or controlling devices.

Current + Future

The actuator can be packaged together with position sensing equipment, torque sensing, motor protection, logic control, digital communication capacity and even PID control all in a compact environmentally protected enclosure as well as provide predictive maintenance data.

5ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017

Examples

• Control amount of water passing along a pipe.

• Move a load using electric motion .

• Close or open a valve.

6ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017

Basic Actuator System

7

Obtain and process input information

Data Processing and make decision

Perform actions

ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017

Actuators in Agriculture

• In a fertilizer spreader, an actuator will adjust the rate of spreading flow and the flow angle

• In seeding machines they regulate the rate and/or number of seeds required for a particular crop

• For combine harvesters, multiple devices perform a range of tasks, including accelerating the motor, stopping the motor, shifting the combine from high to low position, raising the grain cover and operating the straw spreader

8ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017

Actuators in Agriculture

• A linear motor will stop the motor, accelerate the motor, and elevate/lower the automatic stair of a grinder.

• Grass harvesters often incorporate them to turn the main tube and change its elevation or path

9ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017

Type of Actuators

Most commonly employed methods to move or control actuators are:

1. Pneumatic (Air)

2. Hydraulic (Liquids - oil)

3. Mechanical

4. Electrical

10ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017

Pneumatic Actuators

• Convert energy formed by compressed air at high pressure into either linear or rotary motion.

• Pneumatic energy is more desirable for main engine controls because it can quickly respond in starting and stopping as the power source does not need to be stored in reserve for operation.

• The operation is “smooth” if compared to hydraulic.

• Pneumatic application ?

11ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017

Hydraulic Actuators

• Pressurised liquid/oil is provided by a pump driven by an electric motor to facilitate mechanical operation.

• The mechanical output provides an output in linear, rotary or oscillatory motion.

• Liquid can not be compressed, they take longer time to gain speed and power while requiring more time to slow back down.

• It can operate at far higher pressures than a pneumatic system and, consequently, can be used to provide very large forces.

• Hydraulic application ?

12ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017

Pneumatic vs. Hydraulic

13

Pneumatic Systems Hydraulic Systems

Liquid

Air

Liquid

ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017

Mechanical Actuators

• A rotary motion is converted into linear motion to perform a movement.

• It involves gears, rails, pulley, chain and other mechanical devices.

14ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017

Electric Actuators

• Devices power by an electric motor that converts electrical energy to mechanical torque.

• The electrical energy is used to actuate equipment that requires multi-turn valves like gate or globe valves.

• It is considered as one of the cleanest and readily available form of actuator as it does not involve oil.

15ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017

A Brief System Comparison

16

Pneumatic Systems

ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017


17

Hydraulic Systems

ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017


18

Electric Systems

ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017

Examples

ERT 457 - Week 4 SEM 2 2016/2017 19

https://www.youtube.com/watch?v=8_lfxPI5ObM

Firdaus Muttalib


Engineering

7/3/2017 ERT 457 - Week 4 SEM 2 2016/2017 20

https://www.youtube.com/watch?v=fRfeN2KLhg0

Firdaus Muttalib


Engineering

7/3/2017

Exercise 1

A pneumatic cylinder is operated at a force of 10kN. Calculate the amount of air pressure needed with a piston diameter of 100 mm to move a load.

21

P = F / A= 10000 N / (×(0.05 m)2)= 10000 N / 0.007855 m2

= 12730744 N/m2 = 12.7 MPa

ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017

Exercise 2

A pneumatic system is operated at a pressure of 1000 kPa. What diameter cylinder will be required to move a load requiring a force of 12 kN.

22

A = F / P= 12000 N / 1000000 N/m2

= 0.012 m2

A = 0.012 m2 = r2

r2 = 0.012 m2 /3.142

r = 0.03819 = 0.0618 𝑚D = 2 × r = 2 × 0.0618 =0.1236 m = 123.6 mm

ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017

Summary

• Actuators are used to move or control devices from a source of power.

• Types of Actuators:

- Pneumatic Air

- Hydraulic Liquid (Oil)

- Mechanical Gear, pulley

- Electric Motor

23ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017

Pneumatic Systems

ERT 457 - Week 4 SEM 2 2016/2017 24

Firdaus Muttalib


Engineering

7/3/2017

Pneumatic Systems

25

Air

1

2

3 45

6

7

ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017

Pneumatic Systems

• The air inlet to the air compressor is filtered by a removable filter to remove dust and dirt.

• The filter should be replaced periodically to maintain its optimum functionality.

• Dirt and unwanted particle causes pressure drop and reduce the efficiency.

26ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017

Pneumatic Systems

• The filtered air passes through a silencer to reduce the noise level.

• The air compressor driven by electric motor compresses the incoming filtered air from the air inlet.

• A pressure-relief valve provides protection against the pressure in the system rising above a safe level.

27ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017

Pneumatic Systems

• The temperature of the compressed air increases, hence a cooling system is required to reduce the temperature.

• The cooled compressed air is passed through another filter and water trap to remove contamination and water from the air.

• An air receiver increases the volume of air in the system and smoothest out any short term pressure fluctuations.

28ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017

Air Compressor

Three types of air compressor

1. Reciprocating compressor

2. Rotary vane compressor

3. Screw compressor

29ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017

Reciprocating compressor

30ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017

Reciprocating Compressor

31

1. At the top dead centre, the piston begin to move downward as crank shaft rotates. Because both valves are closed, the downward moving piston reduces the pressure in the cylinder.

2. As the pressure in the cylinder falls below the pressure in the suction line, the pressure difference open the suction valve, letting low air pressure flow into the cylinder.

3. The piston continues down and pulls in more air until the cylinder is filled with low pressure air at the bottom of its stroke.

ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017


32

4. Once passed bottom dead centre, the piston begin its upward stroke and the suction valve closes.

5. As the piston moves up, it reduces the volume of the space in cylinder increasing the air pressure.

6. When the air pressure in the cylinder exceeds the pressure in the discharge line, the pressure difference pushes the discharge valve open, letting the compressed air flow out through discharge line.

ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017


Normally single acting, single stage reciprocating compressor produce air pressure up to about 12 bar.

• Single acting Air compression is affected in one ends of piston & cylinder

• Single stage Consists of one cylinders.

33ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017


How can we increase the air pressure ?

• Double acting Air compression is affected in both ends of piston & cylinder

• Double stage Consists of two cylinders. One is called low pressure cylinder and

another is calledhigh pressure cylinder.

Use multiple stages can increase the air pressure up to about 140bar.

34ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017

Rotary Vane Compressor

• One of the oldest compressor technologies.

• Has a rotor mounted eccentrically (offset) in a cylindrical chamber.

• Rotation causing the vane to be driven outwards against the walls of the cylinder chamber.

• As the rotor rotates, air is trapped in pockets formed by the vanes and the pockets become smaller and the air is compressed.

• Compressed pocket air is discharge from the discharge port.

35ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017


36

Inlet port Compressed

air

Rotor

Vane

ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017


• It can be driven by electric motor or internal combustion engines.

• Significantly quieter than reciprocating compressor.

• Mechanical efficiency of about 90%.

37ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017

Rotary Screw Compressor

38ERT 457 - Week 4 SEM 2 2016/2017

Firdaus Muttalib


Engineering

7/3/2017

Rotary Screw Compressor

• Has two intermeshing rotary screws which rotate in opposite direction.

• As the screw rotates, air is drawn into the casing through the inlet port and space between the screws.

• Then this trapped is moved along the length of a screws and compressed as the space becomes progressively smaller, emerging form the discharging port.

39ERT 457 - Week 4 SEM 2 2016/2017

design of automation system - universiti malaysia...

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