“AUTOMATIC SOLAR TRACKING SYSTEM USING PLC &

V/F DRIVE”

Project report submitted in partial fulfillment of the requirements for the award of the degree

BACHELOR OF TECHNOLOGY

IN

ELECTRICAL AND ELECTRONICS ENGINEERING

By

P.ANIL KUMAR (09241A0258)

B.MUKTESHWAR (09241A0281)

D.SHIVA KRISHNA (09241A0299)

J.SHIVA SAGAR (09241A02A0)

Under the guidance of

Mrs.V.V.S.Madhuri

(Assistant Professor)

Department of Electrical and Electronics Engineering

GOKARAJU RANGARAJU INSTITUTE OF ENGINEERING

AND TECHNOLOGY BACHUPALLY, HYDERABAD-500090

2013

Gokaraju Rangaraju Institute of Engineering and Technology

Bachupally, Hyderabad-500090

Department of Electrical and Electronics Engineering

CERTIFICATE

This is to certify that the major project entitled “AUTOMATIC SOLAR TRACKING

SYSTEM USING PLC & V/F DRIVE” done by

P.ANIL KUMAR (09241A0258)

B.MUKTESHWAR (09241A0281)

D.SHIVA KRISHNA (09241A0299)

J.SHIVA SAGAR (09241A02A0)

Of Department of Electrical and Electronics Engineering, is a record of bonafide

work carried out by them. This major project is done as a partial fulfillment of obtaining

Bachelor of Technology Degree to be awarded by Jawaharlal Nehru Technological University

Hyderabad.

The matter embodied in this project report has not been submitted to any other

university for the award of any other degree.

Prof. P. M. Sarma Mrs.V.V.S.Madhuri Signature of the Examiner

(HOD, EEE) (Assistant Professor) GRIET, Hyderabad. (PROJECT GUIDE)

ACKNOWLEDGEMENT

This is to place on record our appreciation and deep gratitude to the persons without

whose support this project would never seen the light of day.

We wish to express my propound sense of gratitude to Mr. P. S. Raju, Director, G.R.I.E.T

for his guidance, encouragement, and for all facilities to complete this project.

We also express my sincere thanks to Mr. P. M. Sarma, Head of the Department, Department of Electrical Engineering,G.R.I.E.T for extending his help.

We have immense pleasure in expressing my thanks and deep sense of gratitude to my

guide Mrs.V.V.S.Madhuri Assistant Professor, Department of Electrical Engineering, G.R.I.E.T for her guidance throughout this project.

We express my gratitude to Mr. E. Venkateshwarlu, Associate Professor, Department of

Electrical and Electronics Engineering, Coordinator, G.R.I.E.T for his valuable recommendations and for accepting this project report.

We are also thankful to Mr. M. Chakravarthi, Associate Professor, Department of

Electrical Engineering, G.R.I.E.T who helped us a large with his excellent guidance.

Finally we express my sincere gratitude to all the members of faculty and my friends who contributed their valuable advice and helped to complete the project successfully.

P.ANIL KUMAR (09241A0258)

B.MUKTESHWAR (09241A0281)

D.SHIVA KRISHNA (09241A0299)

J.SHIVA SAGAR (09241A02A0)

ABSTRACT

The solar tracker is used to orient various payloads toward the sun in order to trap the

energy to the maximum extent. Payloads can be photovoltaic cells, reflectors, lenses or other

optical devices. This tracker circuit finds the sun at dawn, follows the sun during the day, and

resets for the next day. Here the payload is a Solar Photo Voltaic Panel.

Sunlight has two components, the "direct beam" that carries about 90% of the solar energy, and

the "diffuse sunlight" that carries the remainder .The diffuse portion is the blue sky on a clear

day. As the majority of the energy is in the direct beam, maximizing collection requires the

sunlight to fall straight onto the panels as long as possible. This is where the tracker comes.

The tracker is basically a mechanical device consisting of an induction motor and moves

according to the command from the controller in response to the sun’s direction. The controller

used is Programmable Logic Controller (PLC).

Speed and direction of the motor is controlled by the V/f Drive. The tacking is done by

programmed Time-Delayed movement of the panel throughout the day. The delay is set in the

PLC and the step-by-step movement is achieved by proximity sensor which senses the teeth of a

Cog wheel there by providing the feedback to the PLC.

The output of the panel which is DC Voltage is measured with multi meter.

CONTENTS

Chapter

number Chapter

Page

number 1

2

3

4

5

Introduction

Description 2.1 Hardware setup 2.2 Procedure

2.3 Delay calculation 2.4 PLC logic program

Solar Photo Voltaic Panel 3.1 Information

3.2. Theory and Construction 3.2.1. Overview

3.2.2 structure of solar cell 3.3 Efficiency 3.4. Working

3.4.1. Converting Photons to Electrons

Three-Phase Induction Motor 4.1. Star connection 4.2. Delta Connection

4.3. Reversing a Three-Phase Induction Motor 4.4. Methods of Starting Three-phase Induction Motors

4.4.1. Direct-On-Line Starting (D.O.L.) 4.5. Speed Control Methods 4.5.1. Changing Applied Voltage

4.5.2. Changing applied frequency 4.5.3. Changing the number of stator poles

4.5.4. Changing the rotor resistance Programmable Logic Controller

5.1 Introduction 5.2 Types of PLC 5.2.1 XD 26 PLC

5.2.2 CD 12 PLC 5.2.3 CB 12 PLC

5.2.4 CD 20 PLC 5.2.5 CB 20 PLC 5.3 Thrifty series AC to DC converter

5.4 Advantages of PLC

1

2 2 3

4 5

6 6

7 7

9 10 11

12

13 13 14

16 17

17 18 18

19 20

21

23

23 24 24

25 26

26 27 28

28

6

7

8

9

10

Software Development 6.1 Information 6.2 Ladder Language

6.3 Function Block Diagram Language (FBD) 6.4 Operating Modes

6.5 FBD Program in Edit Window 6.5.1 a) Edit Window in Program View 6.5.1 b) Edit Window in Settings View

6.5.2 Supervision Window 6.6 Discrete-Type Inputs

6.7 Discrete-Type Outputs Variable-Frequency Drive

7.1. Introduction 7.2. System Description and Operation

7.2.1. Operator interface 7.2.2. Drive operation 7.3. Emerson Commander SK AC Drive

Miscellaneous components

8.1 Proximity Sensor 8.2Relay Module

Result

Conclusion & Future Scope References

Appendices DATA SHEET OF XD 26 PLC

29 29 29

30 30

31 31 33

33 34

35

36

36 36

37 37 39

42

42 43

44

45

46

47

List of Figures: Fig: 2.1. Power and Logic Circuit------------------------------------------------------------- 3

Fig: 2.2. Flow Chart --------------------------------------------------------------------------- 4

Fig: 2.3. PLC Logic --------------------------------------------------------------------------- 5

Fig: 3.1. Solar Panel --------------------------------------------------------------------------- 6

Fig: 3.2. Inner view of solar pane ------------------------------------------------------------- l8

Fig: 3.3. Structure of Solar panel-------------------------------------------------------------- 10

Fig: 4.1. Terminal block arrangement for a motor connected in star ------------------------- 13

Fig: 4.2. The schematic diagram and the star graphical symbol ------------------------------ 14

Fig: 4.3. The terminal block arrangement for a motor connected in delta -------------------- 14

Fig: 4.4. The schematic diagram and the delta graphical symbol----------------------------- 15

Fig: 4.5. Cut-away View of a Three-Phase Induction Motor --------------------------------- 15

Fig: 4.6. Connections for Clockwise Rotation ------------------------------------------------ 16

Fig: 4.7. Connections for Anti Clockwise Rotation------------------------------------------- 16

Fig: 4.8. Starting Torque vs Speed characteristics -------------------------------------------- 20

Fig: 4.9. The torque speed characteristics for different rotor resistances -------------------- 22

Fig: 5.1 PLC ----------------------------------------------------------------------------------- 23

Fig: 5.2.1 XD 26 PLC ------------------------------------------------------------------------- 24

Fig: 5.2.2 CD 12 PLC ------------------------------------------------------------------------- 25

Fig: 5.2.3 CB 12 PLC ------------------------------------------------------------------------- 26

Fig: 5.2.4 CD 20 PLC ------------------------------------------------------------------------- 26

Fig: 5.2.5 CB 20 PLC ------------------------------------------------------------------------- 27

Fig: 5.3.Thrifty series converter--------------------------------------------------------------- 28

Fig: 6.1 Ladder Network ---------------------------------------------------------------------- 29

Fig: 6.2 Function Block Diagram ------------------------------------------------------------- 30

Fig: 6.5.1 Edit Window in FBD Language---------------------------------------------------- 32

Fig: 6.6 Discrete-Type Inputs ----------------------------------------------------------------- 34

Fig: 6.7 Discrete-Type Outputs --------------------------------------------------------------- 35

Fig: 7.1. Power Conversion ------------------------------------------------------------------- 36

Fig: 7.2. Quadrant Operation ------------------------------------------------------------------ 37

Fig: 7.3. Emerson Commander SK AC Drive ------------------------------------------------ 40

Fig: 7.4. Voltage Preset Mode ---------------------------------------------------------------- 41

Fig: 8.1. Proximity sensor --------------------------------------------------------------------- 43

Fig: 8.2. Relay module ----------------------------------------------------------------------- 44

Fig: 9.1. Automatic Solar Tracking System -------------------------------------------------- 45

1

CHAPTER-1

INTRODUCTION

The Automatic Solar Tracking system is used to track the Sun automatically with the

incorporation of the PLC and VFD. The tracker works on the principle of the movement of the Sun

along the horizon from east to west which takes twelve hours. The panel is made to track the sun by

programming of PLC. The VFD controls the motor‟s direction of rotation as well as the speed. The

panel is made to rotate in steps with the help of Proximity Sensor-Cog Wheel setup. The VFD itself is

controlled by PLC but the motor control is achieved by preset values set in it.

The cog wheel teeth are detected by the proximity sensor which sends the signal to the

PLC. In the PLC, it is programmed to stop the motor for every teeth undetected. The detection of

tooth starts the motor with a preset delay of 32 minutes. The delay is incorporated to track the sun as

it moves along the horizon.

An 8-channel Relay is used to automate the switches of the VFD which control the

direction of the motor. The input of the relay is given from the PLC and the output is connected to the

VFD by overriding its switches.

The panel rotates in steps till evening 6 PM and then it starts rotating forward without

stopping till it reaches its original position. Or it can also be made to rotate reverse till it reaches

original position. Either of the two movements can be achieved.

The output of the Solar Panel is measured in multi meter or a bulb can be made to glow to

check the output

2

CHAPTER-2

DESCRIPTION

The Automatic Solar Tracking is done by using PLC. Power supply to the PLC and the

Proximity sensors is given by the AC-DC Convertor whose input voltage is 230V AC and the output

is 24V DC. The PLC is programmed in Computer. Output of the PLC is given to 8-Channel Relay

Module.

The Speed and Direction Control of the motor is done by the VFD. The Drive is connected to

the motor input. The speed of the motor is preset and the direction is controlled by the input switches

provided to the drive. The drive is controlled by the PLC by overriding the switches through the Relay

Module.

The input of the PLC is the proximity sensor which provides feedback to the PLC. The sensor

is made to sense the teeth of the Cog Wheel. The power supply for the sensor as well is provided by

the converter.

The output of the panel is checked with the help of a multi meter.

2.1. Hardware Setup

The Hardware setup of the tracker consists of:

Solar Photo Voltaic Panel

3 Phase 0.5 HP Induction Motor

Crouzet Millenium 3XD26 Programmable Logic Controller

Thrifty Series AC-DC Converter

Emerson Control Commander SK VFD

8-Channel Relay Module

Proximity Sensor

Cog Wheel

Computer

3

The entire setup is placed on a pair of railings on which the motor base made of wood is placed as

well as two stands on whom the shaft is placed with the help of bearings. The solar panel is attached to

the shaft rod by means of clamps. A cog wheel is framed as well. The proximity sensor is affixed right

below the cog wheel teeth with the help of an L-shaped clamp which is fixed to one of the stands. The

balancing of the panel is done with the help of a wooden solid cuboid affixed to the rod with two tall

bolt-nut arrangements which is perpendicular to the panel.

Fig: 2.1. Power and logic circuit

2.2. Procedure

1. The input power supply to the motor is given by the VFD which applies the required

voltage and frequency so as to rotate the motor at a preset speed.

2. The preset speed is set by applying the “AV.Pr” mode in the V/f Drive.

3. The speed is preset at 5 rpm.

4. The direction of the motor can be changed by the command from the PLC to the V/f

drive.

5. The logic is written in the millennium software for the PLC.

4

6. The PLC output is given to an 8-Channel Relay module which is in turn connected to the

V/f Drive.

7. A proximity sensor is placed beneath the teeth of the Cog Wheel which is placed on the

same shaft. It provides feedback to the PLC.

2.3. Delay Calculation

1 Day = 24 Hours =1440 minutes

Cog Wheel = 44 teeth

Delay =32.72 minutes

Total Revolution of Cog Wheel =15* 32.72 = 1440 minutes

Frequency = 5 Hz

8. The motor starts with a delay of 32 minutes at 5.40 am in the morning

9. As soon as the next tooth is detected by the sensor, the motor is programmed to stop and

delay is incorporated.

10. The procedure is continued till 6 pm in the evening and then it is programmed to rotate

continuously forward without stopping in steps till it reaches the original position.

11. The reading of the power output of the panel is recorded using a multi meter.

Fig: 2.2. Flow chart

5

2.4. PLC Logic Program

Fig: 2.3. PLC Logic

The Logic for the entire tracking is done in the PLC software Millenium 3. The Logic consists of

following steps :

1. Starting of the motor

2. Presetting Delay of 32 minutes

3. Detection of Depression of the Cog wheel by proximity sensor

4. Automatic Stopping of the motor on the detection of depression

5. Automatic restarting of the motor after 32 min delay

6. Counting of the no. of teeth i.e. 44 teeth

7. After attaining the above step, either reverse motion of the motor or continuous

forward motion till original position is attained, is to be started

8. The whole process is to be restated the next day early morning

6

CHAPTER-3

SOLAR PHOTO VOLTAIC PANEL

3.1. Information

A solar cell (also called a photovoltaic cell) is an electrical device that converts

the energy of light directly into electricity by the photovoltaic effect. It is a form of photoelectric cell

which, when exposed to light, can generate and support an electric current without being attached to

any external voltage source. A solar panel (also solar module, photovoltaic module or photovoltaic

panel) is a packaged, connected assembly of photovoltaic cells. The solar panel can be used as a

component of a larger photovoltaic system to generate and supply electricity in commercial and

residential applications. Each panel is rated by its DC output power under standard test conditions,

and typically ranges from 100 to 320 watts. The efficiency of a panel determines the area of a panel

given the same rated output - an 8% efficient 230 watt panel will have twice the area of a 16% efficient

230 watt panel. Because a single solar panel can produce only a limited amount of power, most

installations contain multiple panels. A photovoltaic system typically includes an array of solar panels,

an inverter, and sometimes a battery and or solar tracker and interconnection wiring.

Fig: 3.1. Solar Panel

7

3.2. Theory and Construction

Solar panels use light energy (photons) from the sun to generate electricity through

the photovoltaic effect. The majority of modules use wafer-based crystalline silicon cells or thin-film

cells based on cadmium telluride or silicon. The structural (load carrying) member of a module can

either be the top layer or the back layer. Cells must also be protected from mechanical damage and

moisture. Most solar panels are rigid, but semi-flexible ones are available, based on thin-film cells.

These early solar panels were first used in space in 1958.

Electrical connections are made in series to achieve a desired output voltage and/or in

parallel to provide a desired current capability. The conducting wires that take the current off the

panels may contain silver, copper or other non-magnetic conductive transition metals. The cells must

be connected electrically to one another and to the rest of the system. Externally, popular terrestrial

usage photovoltaic panels use MC3 (older) or MC4 connectors to facilitate easy weatherproof

connections to the rest of the system.

Bypass diodes may be incorporated or used externally, in case of partial panel shading, to

maximize the output of panel sections still illuminated. The p-n junctions of mono-crystalline silicon cells

may have adequate reverse voltage characteristics to prevent damaging panel section reverse current.

Reverse currents could lead to overheating of shaded cells. Solar cells become less efficient at higher

temperatures and installers try to provide good ventilation behind solar panels.

Some recent solar panel designs include concentrators in which light is focused by lenses or

mirrors onto an array of smaller cells. This enables the use of cells with a high cost per unit area (such

as gallium arsenide) in a cost-effective way.

3.2.1. Overview

We decided that for our car we would build panels of solar cells to make them easier to

construct and more interchangeable. We did not want to use off the shelf panels because they used

lower grade solar cells and were too heavy (consisting of large amounts of glass).

Because our car will be 1.8m wide, and we had a >3m area clear of most obstructions at the

back, and the cells are 100*100mm, we decided to initially target the rear area of 17*30 cells. Since 5

and 6 divide 30, and since 6 + 5 + 6 is 17, we decided to make 5*6 cell panels, and tile them across

8

this area (3 panels across the car and five or six panels along the area). Using a 2mm gap between

cells and at the edges of the panel, this gives a panel size of 512*614mm. These panels will also be

used alongside the drivers‟ cockpit (two on each side) for a total of 20 panels (600 cells). Additional

cells will be mounted on the car as space permits.

Each cell has four contact wires (tabs) coming off it, two positive ones on the bottom (about

8.5mm in from the edge) and two negative ones immediately on the edge. These are joined together

via fine wires on the cell. Consecutive cells need to be joined positive to negative all the way along the

panel. For each cell on the panel, five holes are drilled, one for each contact, plus one "air" hole under

the centre of the cell which helps to avoid cracking by preventing pressure from building up. The 3mm

holes for the positive tabs are drilled 7mm from the edge of the cell; the holes for the negative tabs are

drilled 1mm outside the cell edge.

No attempt at "air cooling" was made, although some people recommend cutting a large hole out

underneath the center of the cell for this purpose - this was considered too fragile for our needs. Since

we did not want any drilled holes directly on the edge of the panel, we arranged them as shown which

allowed most of the cells to be easily connected together to the next cell in the circuit, but kept the

negative contact points on the edge of the cell away from the edge of the panel.

Fig: 3.2. Inner view of solar panel

The basic idea is to tab the cells, and place the double sided tape on the back of the cells.

Then drill small holes in the fibreglass panels, and place the cells onto the panels carefully passing the

solar cell tabs through the holes in the fibreglass panel.

9

3.2.2. Structure of a Solar Cell

A typical solar cell is a multi-layered unit consisting of a: Cover - a clear glass or plastic layer

that provides outer protection from the elements. Transparent Adhesive - holds the glass to the rest of

the solar cell. Anti-reflective Coating - this substance is designed to prevent the light that strikes the cell

from bouncing off so that the maximum energy is absorbed into the cell. Front Contact - transmits the

electric current. N-Type Semiconductor Layer - This is a thin layer of silicon which has been mixed

(process if called doping) with phosphorous to make it a better conductor. P-Type Semiconductor

Layer - This is a thin layer of silicon which has been mixed or doped with boron to make it a better

conductor. Back Contact - transmits the electric current.

N-Layer- is often formed from silicon and a small amount of Phosphorus. Phosphorus gives

the layer an excess of electrons and therefore has a negative character. The n-layer is not a charged

layer- it has an equal number of protons and electrons-but some of the electrons are not held tightly to

the atoms and are free to move.

P-Layer- is formed from silicon and Boron and gives the layer a positive character because it

has a tendency to attract electrons. The p-layer is not a charged layer and it has an equal number of

protons and electrons. P-N Junction - when the two layers are placed together, the free electrons from

the n-layer are attracted to the p-layer. At the moment of contact between the two wafers, free

electrons from the n-layer flow into the p-layer for a split second then form a barrier to prevent more

electrons from moving from one layer to the other. This contact point and barrier is called the p-n

junction.

10

Fig: 3.3. Structure of Solar panel

Once the layers have been joined, there is a negative charge in the p-layer and a positive

charge in the n-layer section of the junction. This imbalance in the charge of the two layers at the p-n

junction produces an electric field between the p-layer and the n-layer.

If the PV cell is placed in the sun, radiant energy strikes the electrons in the p-n junction

and energizes them, knocking them free of their atoms. These electrons are attracted to the positive

charge in the n-layer and are repelled by the negative charge in the p-layer. A wire can be attached

from the p-layer to the n-layer to form a circuit. As the free electrons are pushed into the n-layer by

the radiant energy, they repel each other. The wire provides a path for the electrons to flow away from

each other. This flow of electrons is an electric current that we can observe.

The electron flow provides the current, and the cell‟s electric field causes a voltage.

With both current and voltage, we have power, which is the product of the two.

3.3 Efficiency

Depending on construction, photovoltaic panels can produce electricity from a range

of frequencies of light, but usually cannot cover the entire solar range

(specifically, ultraviolet, infrared and low or diffused light). Hence much of the incident sunlight energy

is wasted by solar panels, and they can give far higher efficiencies if illuminated

11

with monochromatic light. Therefore, another design concept is to split the light into different

wavelength ranges and direct the beams onto different cells tuned to those ranges. This has been

projected to be capable of raising efficiency by 50%. Currently the best achieved sunlight conversion

rate (solar panel efficiency) is around 17.4% in new commercial products typically lower than the

efficiencies of their cells in isolation. The most efficient mass-produced solar panels have energy

density values of up to 16.22 W/ft2 (175 W/m2).

3.4. Working

Converting sunlight to electricity Know that solar energy is the radiation from the sun that

reaches the Earth‟s surface Explain how solar cells are used to generate electricity Understand that

solar energy doesn‟t release carbon dioxide therefore helping to reduce green house gas emissions Use

a voltmeter to measure energy produced by a solar panel

In Advance Solar or photovoltaic (PV) cells are made up of materials that turn sunlight into

electricity. Photovoltaic (PV) technologies including solar thermal hot water are renewable energy

technologies and are clean energy alternatives compared to non renewable energy technologies that

burn fossil fuels. PV cells are composed of layers of semiconductors such as silicon. Energy is created

when photons of light from the sun strike a solar cell and are absorbed within the semiconductor

material. This excites the semiconductor‟s electrons, causing the electrons to flow, and creating a

usable electric current. The current flows in one direction and thus the electricity generated is termed

direct current (DC). One PV cell produces only one or two watts which isn‟t much power for most

uses. In order to increase power, photovoltaic or solar cells are bundled together into what is termed a

module and packaged into a frame which is more commonly known as a solar panel. Solar panels can

then be grouped into larger solar arrays.

12

3.4.1. Converting Photons to Electrons

The following two demonstrations will introduce students to a number of concepts key to

Understanding how solar cells work. Set the stage by using a prop to introduce the PV cell and

component parts to the students. Display three calculators (or other common object that the students

can relate to) at the front of the room: one that plugs into an outlet, one that runs on batteries, and one

that is solar powered.

During the demonstrations highlight the following: Light energy (photons) strikes the PV cell. The

silicon cells absorb some of the light energy. The absorbed energy knocks some of silicon‟s electrons

loose. Electrons flow creating an electrical current. Current flows through metal contacts on the top

and bottom of the PV cell. The metal contacts or leads can direct the current through wires that are

attached to a battery or motor.

13

CHAPTER-4

THREE-PHASE INDUCTION MOTOR

This motor is very robust and, because of its simplicity and trouble free features, it is the type

of motor most commonly employed for industrial use. There are only three essential parts, namely the

stator frame, the stator windings and the squirrel cage rotor. The stator frame may be constructed from

cast iron, aluminium or, rolled steel. Its purpose is to provide mechanical protection and support for

the stator laminated metal core, windings and arrangements for ventilation.

4.1. Star connection

To make a star connection, the three finish ends are connected together. This connection point

is referred to as the star point. The three-phase supply is connected to the three start ends.

Motor Terminal Block

W2 U2 V2

V1 W1

L 2

PE

Two Links

L 1 L 3 PE

U1

Fig: 4.1. Terminal block arrangement for a motor connected in star.

14

230V 230V

230V

W1

U1

U2

STAR Point

V1

L1

L2

L3

ELECTRICAL

SUPPLY 400V 3 Phase

Motor Windings connected in Star

ROTOR

STAR Symbol

W2

V2

Fig: 4.2. The schematic diagram and the star graphical symbol

When connected to a 400 Volt three-phase supply, a star connected motor will have 230

Volts across each winding. Some three-phase motor windings are only suitable for 230 Volts. If

connected in delta in this situation, they will quickly burn-out. (Check motor nameplate ).

Warning: Under no circumstances should the three-phase supply be connected to the star point of the

motor i.e. onto W2-U2-V2 as this will cause a short circuit across the supply.

4.2. Delta Connection

To make a delta connection, the finish end of one winding is connected to the start end of the next

winding and so on.

U2 V2

V1 W1

L 2

PE

3 Links

L 1 L 3 PE

W2

U1

Fig: 4.3. The terminal block arrangement for a motor connected in delta

15

400V

400V

400V

W1

U1 W2

V1

L1

L2

L3

ELECTRICAL SUPPLY

400V 3 Phase

Motor Windings connected in Delta

ROTOR

DELTA Symbol

U2 V2

Fig: 4.4. The schematic diagram and the delta graphical symbol

l

A three-phase motor having windings rated for 400 Volts should be connected in delta to a 400 Volt

three-phase supply. If connected in star in this situation it will only develop one third of its output

power, and will stall under load. (Check motor name plate).

A three-phase motor having windings rated for 230 V may be connected in delta to a 230 Volt three-

phase supply OR in star to a 400 Volt three-phase supply. This type of motor is referred to as a Dual

Voltage Motor. (The windings are rated for the lower of the two voltages).

Fig: 4.5. Cut-away View of a Three-Phase Induction Motor

Rotor

Stator

Frame

Drive-shaft

Stator

Winding

Cooling

Fan

Terminal

Block

Fan

Cover

Bearing

16

4.3. Reversing a Three-Phase Induction Motor

The phase sequence L1 (Brown), L2 (Black), L3 (Grey), applied to the stator windings, which

causes the magnetic field to rotate in a clockwise direction. If the field rotates in a clockwise direction

the rotor also rotates in a clockwise direction.

Connections for Clockwise Rotation

Fig: 4.6. Connections for Clockwise Rotation

Changing any two of the phase connections to the stator windings, reverses the rotating magnetic field

and this in turn, reverses the direction of rotation of the rotor.

Connections for Anti-Clockwise Rotation

Fig: 4.7. Connections for Anti Clockwise Rotation

To reverse any three-phase induction motor, reverse any two line connections. For example, reverse

either L1 and L3, or L1 and L2, or L2 and L3.

PE

L1

L2

L3

Motor Starter

M

3

L1

L2

L3

PE

L1

L3

L2

Motor Starter

M

3

L1

L2

L3

17

4.4. Methods of Starting Three-phase Induction Motors

Motor requires an efficient method of starting and stopping, which takes into account the starting

current of the motor. There are several methods employed for starting three-phase induction motors.

Direct-On-Line Starting

Resistance Starting

Reactance Starting

Auto-transformer Starting

Star-Delta Starting

Part-Winding Starting

Solid State Starting

During this course we will only consider the Direct-On-Line (D.O.L) method of starting. This is the

simplest and most commonly used method.

4.4.1. Direct-On-Line Starting (D.O.L.)

Unlike the other starting methods listed above, the D.O.L. starter does nothing to limit the

starting current of the motor. This starting current may be as high as six to seven times the Full Load

Current (FLC). This can cause supply difficulties such as dimming and flickering of lights and

disturbances to other apparatus due to voltage drop. The limit to the size of motor, which may be

started by this method, is almost entirely dependant upon the conditions of the supply.

18

4.5. Speed Control Methods:

Unlike D.C. Motors, A.C. Induction Motors are not suitable for variable speeds. Their speed

control and regulation is comparatively difficult when compared with D.C. Motors. These are some of

the methods which are commonly used for the speed control of squirrel cage induction motors:

Changing Applied Voltage

Changing Applied Frequency

Changing Number Of Stator Poles

Changing the rotor circuit resistance

Of the above four methods first three can be used for both squirrel cage and slip ring induction motors,

where as forth method is only applicable for slip ring induction motor.

4.5.1. Changing Applied Voltage:

As we know the Electromagnetic torque developed by the motor is given by the equation is

Where

S = Slip of the motor,

E2= Rotor induced EMF at standstill condition,

R2= Rotor resistance,

X2= Rotor winding reactance at standstill condition

At normal working conditions the Slip of the induction motor is very low and for constant torque load,

Therefore equation can be written as

19

Therefore, sE22 = constant

Since the Rotor induced EMF is directly proportional to the applied voltage to the Stator,

Since the synchronous speed (Ns) is constant, by changing the applied voltage „V‟, it is possible to

vary the Rotor running speed (Nr).

Though it is the easiest method, it is rarely used due to following reasons:

For small change in speed, there must be a large variation in voltage.

This large change in voltage, it results in large change in flux density there by disturbing the

magnetic distribution of the motor.

This method also requires large power electronic circuit.

As the slip is inversely proportional to the square of the voltage, to increase the speed above the

synchronous speed, voltage has to be increased more than the rated; therefore v/f ratio greatly

increases. Thereby the flux density increases and causes some abnormal condition.

4.5.2. Changing applied frequency:

We all know that the synchronous speed of the induction motor is given by

Ns = 120f / P

So from this relation, it is evident that the synchronous speed and thus the speed of the induction motor

can by varied by the supply frequency.

Limitations of these methods are:

The motor speed can be reduced by reducing the frequency, if the induction motor happens to

be the only load on the generators.

20

If supply is taken from the GRID, It requires a cyclo-converter circuit at the stator side which

is very complex.

Even then the range over which the speed can be varied is very less. This method is famous in

some electrically driven ships although not common in shore.

V/f control:

For the speeds below rated speed for large variation of voltage, small change in speed occurs.

Therefore normally „v/f‟ control is used. In this method, voltage and frequency are varied with respect

to each other, so that the ratio is maintained constant. Therefore the flux density will be maintained

constant. This method combines the advantages of both above two methods. But this method requires

A Converter- Inverter circuit at the stator side.

Fig: 4.8. Starting Torque vs Speed characteristics

4.5.3. Changing the number of stator poles:

As we know the relation between the synchronous speed and the number of poles,

Ns = 120f/P

So the number of poles is inversely proportional to the speed of the motor. This change of number of

poles can be achieved by having two or more entirely independent stator windings in the same slots.

Each winding gives a different number of poles and hence different synchronous speed.

21

Since the Induction motors are normally designed for a Specific number of poles, by changing the

number of poles it works with less efficiency. And by using this method only two sets of speeds can be

achieved.

4.5.4. Changing the rotor resistance:

As we discussed in the voltage control,

For a constant torque and constant applied voltage, the slip to rotor resistance ratio is constant.

Therefore

S = kR2

By increasing the rotor resistance, it is possible to increase the slip; thereby we can control the speed

of the induction motor.

This method of speed control of is also useful for starting of the induction motor.

Since rotor is short circuited, at the time of starting motor will draw large currents into the rotor. So to

reduce the starting current this method is used. This method not only reduces the starting current but

also increases the starting current.

As we know the torque equation of induction motor is

22

And the starting torque is

And the slip corresponding to maximum/Breakdown torque is

S = R2 / X2

By considering all the above points Torque-slip or Torque speed characteristics are given as below.

R2> R1> R0

Fig: 4.9. The torque speed characteristics for different rotor resistances

23

CHAPTER-5

PROGRAMMABLE LOGIC CONTROLLER

5.1 Introduction

A Programmable Logic Controller (PLC) is a digital operating electronic apparatus which uses

a programmable memory for internal storage of instruction for implementing specific

function such as logic, sequencing, timing, counting and arithmetic to control through analog or

digital input/output modules various types of machines or process.

Control engineering has evolved over time. In the past humans was the main method for

controlling a system. More recently electricity has been used for control and early electrical control

was based on relays. These relays allow power to be switched on and off without a mechanical switch.

It is common to use relays to make simple logical control decisions. The development of low cost

computer has brought the most recent revolution, the Programmable Logic Controller (PLC). The

advent of the PLC began in the 1970s, and has become the most common choice for manufacturing

controls.

Fig: 5.1 PLC

24

The above Fig: 5.1.Shows the XD 26 PLC. This is the heart of the project. I t works on the software

of MILLENIUM 3 Programming Language

5.2 Types of PLC

There are different types of PLC‟S used for various methods of projects. The following types

of PLC‟S are given below.

5.2.1 XD 26 PLC

Fig: 5.2.1 XD 26 PLC

Description of XD 26 PLC

Part Number Power Supply Inputs Output

88970162 24 V DC 16 digital (of which

6 are analogue)

10 Discrete Static

Relay Outputs

The numbering for the XD 26 PLC is given in such a way that as it is containing 16

Digital (of which 6 are analog) inputs and 10 discrete static relay outputs. And the sum of these inputs

and outputs gives us 26. Similarly for the other PLC‟S it is done in the same manner.

25

5.2.2 CD 12 PLC

Power supply

Inputs Outputs

Fig: 5.2.2 CD 12 PLC

Description of CD 12 PLC

Part Number Power Supply Inputs Outputs

88970045 12V DC 8 digital (including

4 analogue)

4 relays 8 A

The numbering for the CD 12 PLC is given in such a way that as it is containing 8

26

Digital (of which 4 are analog) inputs and 4 relay outputs. And the sum of these inputs and outputs

gives us 12. Similarly for the other PLC‟S it is done in the same manner.

5.2.3 CB 12 PLC

Fig: 5.2.3 CB 12 PLC

Description of CB 12 PLC

Part Number Power Supply Inputs Outputs

88970840 12 V DC 8 digital (including

4 analogue

4 solid state 0.5 A

(including 1

PWM)

5.2.4 CD 20 PLC

Fig: 5.2.4 CD 20 PLC

27

Part Number Power Supply Inputs Outputs

88970051 24 V DC 12 digital (including

6 analogue)

8 relays 8 A

5.2.5 CB 20 PLC

Fig: 5.2.5 CB 20 PLC

Description of CB 20 PLC

Part Number Power Supply Inputs Outputs

88970033 100 240 V AC 12 digital 8 relays 8 A

28

5.3. Thrifty series AC-DC converter

The power supply for the PLC is 24 V DC which is given by the AC_DC converter which converts

the 240V AC supply to 24 v dc supply by means of a step down transformer and a converter. The

converter used is “PHEONIX Contacts Thrifty series” converter. The power supply for the proximity

sensor as well is taken from the same

Fig: 5.3.Thrifty series converter

5.4. Advantages of PLC

Shorter project implementation time.

Easier modification.

Project cost can be accurately calculated.

Shorter training time required.

Design easily changed using software (changes and addition to specifications can be

processed by software).

A wide range of control application.

Easy maintenance.

High Reliability.

29

CHAPTER-6

SOFTWARE DEVELOPMENT

6.1 Information

The Software used for this project is MILLENIUM 3 Programming Language. The controller

offers two programming languages:

LD Language:- LADDER Language

FBD Language: Function Block Diagram Language

These Languages use:

Predefined Function blocks such as Timers and Counters

Specific Functions such as Time Management, Character String, Communication, etc.

6.2 Ladder Language

Ladder Language (LD) is a graphic Language. It can be used to transcribe relay diagrams,

and is suited to combinational processing. It provides basic graphic symbols: contacts, coils, blocks.

Specific calculations can be executed within the operation blocks.

Example of a program in Ladder Language:

Fig: 6.1 Ladder Network

30

6.3 Function Block Diagram Language (FBD)

FBD mode allows graphic programming based on the use of predefined function blocks. It

offers a large range of basic functions: timer, counter, logic, etc.

Example of a program in FBD Language:

Fig: 6.2 Function Block Diagram

6.4 Operating Modes

There are several operating modes for the programming workshop:

Edit Mode: Edit mode is used to construct programs in FBD mode, which corresponds to the

development of the application.

Simulation Mode: In simulation mode the program is executed offline directly in the

programming workshop .In this mode, each action on the chart (changing the state of an

input, output forcing) updates the simulation windows.

Monitoring mode: In Monitoring mode, the program is executed on the controller; the

programming workshop is connected to the controller (PC « controller connection).

In this project we have done the software program or developed the program in the Function Block

Diagram Mode. Since it has the components or the blocks which is pictorially understood and easy for

31

verification. Now let us go in detail or let us study in deep about the Function Block Diagram

Language.

6.5 FBD Program in Edit Window

FBD mode allows graphic programming based on the use of predefined function blocks and pre-

defined or archived Macros.

In FBD programming, there are two types of window and two displays:

The Edit Window: It consists of Program View and Settings View.

The Supervision Window

6.5.1 a) Edit Window in Program View

The edit window is made up of three zones:

The wiring sheet, where the functions and Macros that make up the program are inserted.

The Inputs zone on the left of the wiring sheet where the inputs are positioned

The Outputs zone on the right of the wiring sheet where the outputs are positioned

The I/O is specific to the type of controller and extension chosen by the user.

The program in the edit window corresponds to the program that is:

Compiled.

Transferred to the Controller.

Compared to the contents of the controller

Used in simulation mode

Used in supervision mode

32

The figure below shows an example of an edit window in FBD language:

Fig: 6.5.1 Edit Window in FBD Language

The table below lists the different elements in the edit window which is shown in the figure: 6.5.1.

Number

Description

1 Function block input zone.

2 Connection between two function blocks

3 Function bar

4 Function block.

5 Wiring sheet.

6 Functions block number.

7 Output function block zone.

33

6.5.1 b) Edit Window in Settings View

The Settings view can be accessed in Edit mode using the button. It is used to list all

automation functions with parameters used in the application.

The general interface allows the user to view all the information:

Block: function block diagram

Function: Timer, Counter, etc.

Block num: function block ID

Parameters: the target value for a counter, etc.

Modification authorized: indicates whether or not parameter modification is possible from the

controller front panel

Comment: comments associated with the function.

To adjust the various parameters, double-click on the desired line.

6.5.2 Supervision Window

The Supervision window can also be accessed from the following modes:

Simulation : the Mode/Simulation menu or using the simulation button on the controller

bar.

Monitoring: the Mode/Monitoring menu or using the monitoring button on the controller

bar .

Now let us discuss the various function blocks that are used in this project. The blocks that

are used in the Timer Program and even for the LDR circuit are discussed in this Chapter.

The blocks used in these programs are Discrete Input Block, Discrete Output Block,

TIMER PROG Block, Summer/Winter Block, Timer A-C Block, AND GATE, NOT GATE,

OR GATE, Analog Input Block, Comparison Value Zone Block, Set-Reset Block, NUM

Block.

34

All these blocks are explained thoroughly in this chapter. And these blocks are implemented

with the program in the later Chapters.

6.6 Discrete-Type Inputs

The Discrete-type input is available for all controller types. Discrete inputs can be arranged

over all the controller inputs. The inputs blocks are used to switch on the experiment and for closed

loop operation (with Proximity Sensor) respectively. The type of Discrete input can be selected from

the Parameters window. This is then displayed in the edit and supervision windows.

Fig: 6.6 Discrete-Type Inputs

35

6.7 Discrete-Type Outputs

The controllers feature two types of discrete outputs:

a. Solid state outputs for certain controllers supplied with a DC voltage,

b. Relay outputs for controllers supplied with an AC or DC voltage

Fig: 6.7 Discrete-Type Outputs

36

CHAPTER-7

VARIABLE-FREQUENCY DRIVE

7.1. Introduction

A variable-frequency drive (VFD) (also termed adjustable-frequency drive, variable-speed

drive, AC drive, micro drive or inverter drive) is a type of adjustable-speed drive used in electro-

mechanical drive systems to control AC motor speed and torque by varying motor input

frequency and voltage.

VFDs are used in applications ranging from small appliances to the largest of mine mill drives

and compressors. However, about a third of the world's electrical energy is consumed by electric

motors in fixed-speed centrifugal pump, fan and compressor applications and VFDs' global market

penetration for all applications is still relatively small. This highlights especially significant energy

efficiency improvement opportunities for retrofitted and new VFD installations.

Over the last four decades, power electronics technology has reduced VFD cost and size and

improved performance through advances in semiconductor switching devices, drive topologies,

simulation and control techniques, and control hardware and software.

VFDs are available in a number of different low and medium voltage AC-AC and DC-AC

7.2. System Description and Operation

Fig: 7.1. Power Conversion

37

7.2.1. Operator interface

The operator interface provides a means for an operator to start and stop the motor and adjust

the operating speed. Additional operator control functions might include reversing, and switching

between manual speed adjustment and automatic control from an external process control signal. The

operator interface often includes an alphanumeric display and/or indication lights and meters to provide

information about the operation of the drive. An operator interface keypad and display unit is often

provided on the front of the VFD controller as shown in the photograph above. The keypad display

can often be cable-connected and mounted a short distance from the VFD controller. Most are also

provided with input and output (I/O) terminals for connecting pushbuttons, switches and other

operator interface devices or control signals. A serial communications port is also often available to

allow the VFD to be configured, adjusted, monitored and controlled using a computer.

7.2.2. Drive operation

Fig: 7.2. Quadrant Operation

Electric motor speed-torque chart

Referring to the accompanying chart, drive applications can be categorized as single-quadrant, two-

quadrant or four-quadrant; the chart's four quadrants are defined as follows:

Quadrant I - Driving or motoring, forward accelerating quadrant with positive speed and

torque

Quadrant II - Generating or braking, forward braking-decelerating quadrant with positive

speed and negative torque

38

Quadrant III - Driving or motoring, reverse accelerating quadrant with negative speed and

torque

Quadrant IV - Generating or braking, reverse braking-decelerating quadrant with negative

speed and positive torque.

Most applications involve single-quadrant loads operating in quadrant I, such as in variable-torque

(e.g. centrifugal pumps or fans) and certain constant-torque (e.g. extruders) loads.

Certain applications involve two-quadrant loads operating in quadrant I and II where the speed is

positive but the torque changes polarity as in case of a fan decelerating faster than natural mechanical

losses. Some sources define two-quadrant drives as loads operating in quadrants I and III where the

speed and torque is same (positive or negative) polarity in both directions.

Certain high-performance applications involve four-quadrant loads (Quadrants I to IV) where the

speed and torque can be in any direction such as in hoists, elevators and hilly conveyors. Regeneration

can only occur in the drive's DC link bus when inverter voltage is smaller in magnitude than the motor

back-EMF and inverter voltage and back-EMF are the same polarity.

In starting a motor, a VFD initially applies a low frequency and voltage, thus avoiding high inrush

current associated with direct on line starting. After the start of the VFD, the applied frequency and

voltage are increased at a controlled rate or ramped up to accelerate the load. This starting method

typically allows a motor to develop 150% of its rated torque while the VFD is drawing less than 50%

of its rated current from the mains in the low speed range. A VFD can be adjusted to produce a

steady 150% starting torque from standstill right up to full speed. However, motor cooling deteriorates

and can result in overheating as speed decreases such that prolonged low speed motor operation with

significant torque is not usually possible without separately-motorized fan ventilation.

With a VFD, the stopping sequence is just the opposite as the starting sequence. The

frequency and voltage applied to the motor are ramped down at a controlled rate. When the frequency

approaches zero, the motor is shut off. A small amount of braking torque is available to help decelerate

the load a little faster than it would stop if the motor were simply switched off and allowed to coast.

Additional braking torque can be obtained by adding a braking circuit (resistor controlled by a

transistor) to dissipate the braking energy. With a four-quadrant rectifier (active-front-end), the VFD is

able to brake the load by applying a reverse torque and injecting the energy back to the AC line.

39

7.3. Emerson Commander SK AC Drive:

The VFD drive used in the project is a product manufactured by Emerson. The figure shown

below is Emerson commander sk ac drive. This is the AC drive used for controlling the speed of the

3-phase induction motor. In this drive we can adjust the voltage and frequency at a time, so the speed

of the 3-phase induction motor is increased or decreased according to the values given. The

Commander SK is an open loop vector AC variable speed inverter drive used to control the speed of

an AC induction motor. The drive uses an open loop vector control strategy to maintain almost

constant flux in the motor by dynamically adjusting the motor voltage according to the load on the

motor.

The AC supply is rectified through a bridge rectifier and then smoothed across high voltage

capacitors to produce a constant voltage DC bus. The DC bus is then switched through an IGBT

bridge to produce AC at a variable voltage and a variable frequency. This AC output is synthesized by

a pattern of on-off switching applied to the gates of the IGBTs. This method of switching the IGBTs is

known as Pulse Width Modulation (PWM).

Fig : 7.3. Emerson Commander SK AC Drive

40

Specifications:

The specifications of V/F AC drive are:

Model No.: SKA1200075

Voltage : (200-240)V

Current: 10.5A

Frequency: 50-60Hz

Driving capability: 3-phase

0-240V

0-1500rpm

4A

Description:

The V/F drive being used has 9 different configurations i.e., the V/F drive can be operated in 9

different modes. Each mode or configuration has some pre-defined operation. There are three physical

sizes comprising 15 different models. The input voltage ranges are single phase input, 200 to 240V,

three phase input, 200 to 240V, three phase input 380 to 480V and are power dependent.

The 9 different configurations are

41

Fig:7.4. Voltage Preset Mode

Each mode has a pre-defined operation. The mode we are using in this project is AV.PR (voltage

preset). In this mode three speeds can be preset. The figure below shows the basic terminals of the

AC drive in AV.PR mode. Using this V/F drive not only the speed but also the direction of rotation of

the motor can be controlled.

The switches B4,B5,B6 denotes enable, run forward and run reverse. The motor rotates in forward or

clockwise direction when both the switches B4 and B5 are closed or are in ON position. The motor

rotates in reverse direction or anti-clockwise direction when the switches B4 and B6 are closed or in

ON position. The switch B4 must be always ON or in closed position for ant operation to take place.

The drive consists of switches name T1-T4 and B1-B7. The connections are made according to the

one as shown in the fig below for the drive to operate in Av.PR mode. By operating or connecting the

switches T4 and B7 as shown in the table below, the speed of the induction motor can be set to a

preset value.

42

CHAPTER-8

MISCELLANEOUS COMPONENTS

8.1. Proximity Sensor

A proximity sensor is a sensor which is able to detect the presence of nearby objects without

any physical contact. A proximity sensor often emits an electromagnetic field or a beam of

electromagnetic radiation (infrared, for instance), and looks for changes in the field or return signal. The

object being sensed is often referred to as the proximity sensor's target. Different proximity sensor

targets demand different sensors. For example, a capacitive photoelectric sensor might be suitable for

a plastic target; an inductive proximity sensor always requires a metal target. The maximum distance

that this sensor can detect is defined "nominal range". Some sensors have adjustments of the nominal

range or means to report a graduated detection distance.

Proximity sensors can have a high reliability and long functional life because of the absence of

mechanical parts and lack of physical contact between sensor and the sensed object.

Proximity sensors are also used in machine vibration monitoring to measure the variation in

distance between a shaft and its support bearing. This is common in large steam turbines, compressors,

and motors that use sleeve-type bearings.

Fig: 8.1. Proximity sensor

43

8.2 Relay Module

The relay module is a separate hardware device used for remote device switching. With it you can

remotely control devices over a network or the Internet. Devices can be remotely powered on or off

with commands coming from Clock Watch Enterprise delivered over a local or wide area network.

You can control computers, peripherals or other powered devices from across the office or across the

world. The Relay module can be used to sense external On/Off conditions and to control a variety of

external devices. The PC interface connection is made through the serial port.

The Relay module houses two SPDT relays and one wide voltage range, optically isolated input. These

are brought out to screw-type terminal blocks for easy field wiring. Individual LED‟s on the front panel

monitor the input and two relay lines. The module is powered with an AC adapter.

Fig: 8.2. Relay module

44

CHAPTER-9

RESULT

The Solar Tracking System thus rotated the Solar Panel in discrete steps according to the preset delay

and in the preset speed. After completing the whole 44 steps, it rotated further forward without

stopping till it reached the original position. The voltage output of the Solar Panel has been recorded in

a multi meter as 6.41 V DC in the morning 7.30 am.

Fig: 9.1. Automatic Solar Tracking System

45

CHAPTER-10

10.1 Conclusion

The Automatic Solar Tracker thus, is able to trace the sun in discrete steps from morning to

evening without any manual intervention. This automation is achieved by the PLC thus rendering the

setup more accurate and reliable. The PLC programming is User-Friendly and easier to program as it

is Block-Programming. The V/f drive has made it easy to use the Induction Motor speed Control and

the direction control. Different preset speeds could also be achieved by this drive.

10.2 Future Scope

The Future scope of the setup is to incorporate a more reliable balancing technique than that of the

present one used. Along with that, a Cuk or Buck converter can be connected to the output of the

Solar panel. MPPT (max power point tracking) also used to generate high power.

46

REFERENCES

1]. “Introduction to Photovoltaic Systems” by Texas and “Design of a Solar Tracker System for

PV Power Plants” by Tiberiu Tudorache, Liviu Kreindler

2]. “DC-DC Converters via MATLAB/SIMULINK” by Mohamed Assaf, D. Seshsachalam and

“Analsis, Design and Modeling of DC-DC Converter using SIMULINK” by Saurabh Kasat.

3]. “Programmable Logic Controllers: Programming Methods and Applications” by John R.

Hackworth and Frederick D. Hackworth and “PLC Implementation of Supervisory Control” by

Prof. Tarun Kumar Dan.

4]. “Speed control of Induction Machines” by prof. Krishna Vasudevan, prof. g.sridara rao and

prof p. shasidara rao.

5]. “AC variable speed drive for 3 phase induction motors from 0.25kW to 7.5kW, 0.33hp to

10hp” is a Technical Data Guide for AC variable speed drive for 3 phase induction motors.

6]. (Rashid, 2003).

47

APPENDICES

DATA SHEET OF XD 26 PLC

48

49