“Design of a PLC System for health monitoring of DC drive

through SMS”

A PROJECT REPORT

Submitted in partial fulfillment of the

requirement for the award of the

Degree of

BACHELOR OF TECHNOLOGY

IN

ELECTRICAL AND ELECTRONICS ENGINEERING

by

(Abhishek Sharma- 10BEE1009)

Under the Guidance of

Mr. Guru K Prasad Prof. Nilanjan Tewari

External Guide Internal Project Supervisor

SCHOOL OF ELECTRICAL ENGINEERING VIT University

CHENNAI-600127, Tamil Nadu, India

MAY 2014

CERTIFICATE

This is to certify that the project work titled “Design of a PLC System

for health monitoring of DC drive through SMS” submitted by

“Abhishek Sharma” is in partial fulfillment of the requirements for the

award of BACHELOR OF TECHNOLOGY DEGREE, is a record of bona fide

work done under my /our guidance. The contents of this project work, in

full or in parts, have neither been taken from any other source nor have

been submitted to any other Institute or University for award of any

degree or diploma and the same is certified.

Guru K Prasad Nilanjan Tewari

External Guide Internal Project Supervisor

ABB India Ltd.

(Organization stamp)

The thesis is satisfactory / unsatisfactory

Internal Examiner External Examiner

Approved by

Dean

School Of Electrical Engineering

IF THE CANDIDATE HAS DONE HIS /HER PROJECT OUTSIDE THE

VIT UNIVERSITY A CERTIFICATE TO THAT EFFECT MUST BE

ATTACHED HERE ON THE ORGANIZATION’S LETTER HEAD DULY

STAMPED and SIGNED

I would like to dedicate this project to my project guides, my parents and my

abled professors who have given their best efforts in making it possible.

ACKNOWLEDGEMENTS

I would like to thank VIT for imparting me knowledge and skills required for my

current endeavors. I also want to thank ABB India Ltd., Bangalore for providing me the

opportunity to intern at Peenya premises and providing me all possible technical assistance

during the training period. I would like to especially thank my mentor- Mr. Guru K Prasad for

his timeless help, apt guidance and motivation despite of health adversaries. I feel fortunate to

have Mr. Ramdas and Mr. Harish for my help from Discrete Motion PLC department. I

would take this opportunity to thank them for all technical assistance I received from them. I

want to pay my special thanks to Mr. Vadiraj (Low Voltage Drives department) for arranging

the drive and providing technical input. Without the support of above mentioned people, it

would have been impossible to complete the project on time.

In addition, I would like to heartily thank Prof. Nilanjan Tewari for his unparalleled

guidance, availability, technical assistance and encouragement. Finally but most importantly,

I thank my parents, respected dean- Prof. Hemamalini, program chair- Prof. Senthil Kumar

and entire SCHOOL OF ELECTRICAL ENGINEERING for providing me this chance and

for supporting me throughout the course.

(Abhishek Sharma)

10BEE1009

ABSTRACT

Control has been a necessary part of every process involved in a day to day life. Use of

analog controllers is conventional but they are difficult to design and reduce flexibility in

operation of system. Hence, digital control systems are gaining prominence for industrial

control applications. One of the applications of digital control is monitoring of industrial

process or systems. There are various options available for implementation of control but the

PLC (Programmable Logic Controller) emerges as the most viable option for industrial

applications. In this project a PLC system is designed to regularly monitor the health of a

remotely located DC drive used for applications like pumping, nuclear waste processing,

manufacturing automation, etc. Assigning this task to an employee is costly, monotonous and

inefficient way. Thus by automating the monitor and operations process, this project aims to

obviate the need of humans in monitoring and responding to any inadvertent contingency.

This project was proposed to monitor speed, efficiency, torque, output power, input power,

and ripple factor of a DC drive. The system also detects over-current fault, temperature

related fault, overvoltage and under-voltage faults. In this condition the drive is stopped and

the user is notified of the type of fault occurred through an SMS on his mobile phone. The

user is also informed of runtime, average value of torque, current, voltage, speed and

efficiency daily. In the second review further extension to this project was proposed. The

extension included control of the DC drive system through SMS. However due to lack of

time for testing, the desired results were not achieved.

LIST OF TABLES

Table 1 Drive runtime data when current is kept constant 26

Table 2 Drive runtime data when applied voltage is kept constant 28

LIST OF FIGURES

Fig. 1 AC500 PM573 ETH Programmable logic controller 2

Fig. 2 Sectional view of DC550 DC drive 3

Fig. 3 AI561 analog input module 4

Fig. 4 Maestro Heritage GSM modem with attachments 4

Fig. 5 Process flow in the RTU 7

Fig. 6 Process flow at base data station 8

Fig. 7 Command flow for GSM modem 9

Fig. 8 Block design: send value of torque 9

Fig. 9 Block design: send value of speed 10

Fig. 10 Block design: send value of drive efficiency 10

Fig. 11 Block design: send value of input power 11

Fig. 12 Block design: send value of output power 11

Fig. 13 Block design: motor speed calculation 12

Fig. 14 Block design: motor torque calculation 12

Fig. 15 Block design: output power calculation 13

Fig. 16 Block design: input power calculation 13

Fig. 17 Block design: Efficiency calculation 14

Fig. 18 Block design: Overvoltage and under voltage fault monitoring 14

Fig. 19 Block design: Overcurrent fault monitoring 15

Fig. 20 Block design: Overheat fault monitoring 15

Fig. 21 Control builder plus configuration for COM ports 16

Fig. 22 Hardware overview of the project 17

Fig. 23 Hardware setup 18

Fig. 24 Result: Message received “voltage fluctuation out of range” 21

Fig. 25 Result: Message received “overcurrent fault occurred” 22

Fig. 26 Result: Message received “Drive is running at speed (RPM) 600 23

Fig. 27 Result: Message received “Drive efficiency is 91” 23

Fig. 28 Result: Message received “Motor torque is 33.5” 24

Fig. 29 Result: Data received on hyper terminal by data center 25

Fig. 30 Voltage v/s speed variations keeping current constant 27

Fig. 31 Voltage v/s Efficiency variations keeping current constant 27

Fig. 32 Current v/s Torque keeping operating voltage constant 28

Fig. 33 Current v/s Speed keeping operating voltage constant 29

Fig. 34 Efficiency v/s Current keeping operating voltage constant 29

Fig. 35 Speed – Torque curve of the motor 30

LIST OF ABBREVIATIONS

DC - Direct current

ETH - Ethernet

PLC - Programmable logic controller

RTU - Remote terminal unit

DM - Discrete motion

I/O - Inputs/Outputs

I/P - Input

O/P - Output

SCADA - Supervisory control and data acquisition

ANN - Artificial network

GPRS - Global radio packet service

NOTATIONS

is the armature current

is the developed torque

and are motor parameters

is armature resistance

is armature voltage

is efficiency of the system

TABLE OF CONTENTS

LIST OF TABLES (if any) viii to ----

LIST OF FIGURES ---- to ----

LIST OF ABBREVIATIONS -----to ----

NOTATION -----to ----

CHAPTER 1 Introduction Page Nos

1.1 Objective and goal of the project 1

1.2 Literature survey 1

1.3 Hardware description

1.3.1 PM 573 ETH PLC 2

1.3.2 ABB DCS550 drive 2

1.3.3 AI 531 four input analog module 3

1.3.4 Maestro Heritage GSM modem 4

CHAPTER 2 Background

2.1 Compatibility and developments 5

2.2 Mathematical Formulae 5

2.2.1 Motor torque developed 5

2.2.2 Angular speed 5

2.2.3 Output power 6

2.2.4 Input power 6

2.2.5 Efficiency 6

CHAPTER 3 Design and methodology

3.1 Methodology 7

3.1.1 Process components of remote terminal unit (RTU) 7

3.1.2 Base data station process components 8

3.1.3 RS232 based AT command parsing for GSM modem 8

3.2 Software design 9

3.2.1 Design of the block to send value of torque 9

3.2.2 Design of block to send motor speed 10

3.2.3 Design of block to send drive efficiency 10

3.2.4 Design of block to send input power 11

3.2.5 Design of block to send output power 11

3.2.6 Design of block to calculate motor speed 12

3.2.7 Design of block to calculate motor torque 12

3.2.8 Design of block to calculate output power 13

3.2.9 Design of block to calculate input power 13

3.2.10 Design of block to calculate efficiency 13

3.2.11 Design of block for voltage fault monitoring 14

3.2.12 Design of block for overcurrent fault monitoring 15

3.2.13 Design of block for temperature monitoring 15

3.3 COM port setting for RS232 communication 16

3.4 Hardware design 16

3.5 Variable declaration and initialization 18

CHAPTER 4 Results and discussions

4.1 Hardware results 20

4.1.1 Results for fault monitoring 20

4.1.2 Drive runtime information – Mobile phone 22

4.1.3 Data collection results – Hyperterminal 25

4.1.4 Graphical results 26

CHAPTER 5 Conclusion and scope of improvement

5.1 Conclusion 30

5.2 Applications of the developed system 31

5.3 Scope of improvement 31

CHAPTER 1

INTRODUCTION

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1.1 Objectives and goal of the project

Current projects aims at software design and hardware implementation of a

programmable logic control (PLC) system for health monitoring of a direct current (DC)

drive through simple message service (SMS). This system is designed to monitor the

various operational parameters of DC drive including speed, efficiency, torque, output

power, input power, and ripple factor. The proposed system can be used to monitor a

group of remotely located drives operating continuously without much changes in

operational schedule.

The design is primarily proposed to counter the problems like ignorance of human

supervisor and high operational cost. It also ensures fault monitoring and enables

economic optimization of the system. By automating the monitoring system better

performance can be achieved and incipient damage to the operating system can be

achieved. The proposed design holistically acts as a remote terminal unit (RTU) and

keeps sending the runtime information to user and data center.

1.2 Literature Survey

Programmable logic controllers have been incessantly used in industrial applications for

control and monitoring. SCADA based systems are used in modern power systems for

power flow polling and contingency/fault monitoring. R. Isermann [1] has proposed a

model for condition monitoring of actuators, machineries, drives, plants, sensors and fault

tolerant systems. This work also proposes various models for fault diagnosis of DC

drives. The current project utilizes the mathematical model developed in this worked for

calculation of various parameters displayed in results. Singh and Nandanwar [2] presents

a microcontroller based approach for performance monitoring of DC motor. The main

drawback of this system is the limited and small amount of memory and processing

capability available on chip. Also, microcontrollers are incapable of real-time data

processing and efficient handling of analog data. Thus, digital signal processors (DSP)

emerge as viable option. However, DSPs have limitations related to communication with

other units and number of inputs and outputs. Therefore, PLC appears to be the most

viable option with high clock speed, inherent ability for analog data and real-time data

processing, multiple modes of communication (Profibus, Modbus, serial, parallel and

ethernet) and easily expandable I/O cards. All these advantages make PLCs highly

suitable for supervisory control and monitoring of industrial installations. Ionnides [3] has

also used PLC for designing monitoring control system for induction motor. Current work

tries to combine the above work and adopts a new approach for data transmission using

SMS to increase the range and effectiveness of data transfer to the terminal unit.

1.3 Hardware Description

1.3.1 PM 573 ETH PLC

AC 500 series of PLCs are currently being used by ABB in various installations. The PLC

used in this project is PM573 with onboard Ethernet for communicating with a PC or OPC.

The I/Os can be extended by adding available modules as required.

Fig. 1 AC500 PM573 ETH Programmable logic controller

1.3.2 ABB DCS 550-20 drive

ABB DCS 550 is an ideal solution and a replacement of analog devices for OEM machine

manufacturers. It has compact design to suit installations with limited space. It is compatible

with a wide range of available motors because of its integrated three phase field exciter

ranging up to 35 A. It also has a “winder” with commissioning assistant for easy adaption to

various applications. It offers great integration in automation through various fieldbus

interfaces including EtherCAT, PROFINET. It can be adaptively programmed with Drive

AP, ABB’s graphical PC-tool for easy implementation of additional functions. In addition to

this, it has various start-up assistants and auto-tune functions for fast commissioning along

with a large control panel for straight forward and self-explanatory operation. Besides this it

has a rugged design for rough environments and which ensures high reliability.

Fig.2 Sectional view of DC550 DC drive

1.3.3 AI 531 four analog input module

This Analog Input Module AI531 is used as a remote expansion module with PM573 for

acquiring the analog values of current and frequency from DCS550. It has four configurable

inputs (I0-I3) in one group. It can be interfaced using TU515 for connecting with the PLC.

These inputs are not electrically insulated from each other. Following figure displays the

AI561 module.

Fig. 3 AI561 analog input module

1.3.4 Maestro Heritage GSM modem

The Heritage GPRS modem from Maestro Wireless Solutions combines a base unit offering

GSM/GPRS/EDGE technologies in an Industrial grade design with pluggable boards catering

for diverse Machine to Machine applications. It is OpenAT Compatible, which means it can

be programmed using Wavecomm AT commands. It also supports expansion boards

including Industrial Grade I/Os, Ethernet and GPS. The following figure displays Maestro

Heritage GSM modem with its attachments.

Fig. 4 Maestro Heritage GSM modem with attachments

CHAPTER 2

BACKGROUND

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2.1 Compatibility and developments

The system developed in this project derives its technical grounds from the research

publications mentioned in chapter 1.2. The developed system is designed to support DCS550

and DCS800 series of DC drives developed and marketed by ABB Ltd. The various inputs

and outputs of the system have been parameterized to support multiple drives with a wide

range of motors. The software configured system developed in this project is versatile and

highly adjustable according to the need of time. In the following section, extracts from

previous publications regarding derivations have been mentioned.

2.2 Mathematical formulae

The formulae utilized in this project have been derived to minimize the number of inputs and

reduce the computational complexity. For the same reason, a time domain based approach

has been adopted. These calculations can be altered for different motor and drive

combinations.

2.2.1 Motor Torque developed

This formula have been used to find out the motor torque developed.

------------------ (2.1)

Where, and are motor parameters

is the armature current

is the developed torque

2.2.2 Angular Speed

To calculate the angular speed, following relation has been used.

-------------------

(2.2)

Where, and are motor parameters

is the armature current

is armature resistance

is armature voltage

2.2.3 Output Power

The output power is calculated by using the relation:

------------------- (2.3)

Where T is torque

2.2.4 Input Power

Following relation is used to determine the input power:

-----------------------

(2.4)

Where V is armature voltage

is armature current

2.2.5 Efficiency

Efficiency of the system is governed by the relation:

-------------------------- (2.5)

Where is efficiency of the system

CHAPTER 3

DESIGN & METHODOLOGY

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In this section the software design of the project and the algorithm based on which the design

is concurred are discussed. Later, the hardware design is discussed and a complete overview

of the project is provided.

3.1 Methodology

Current project follows a simple design methodology. It is a hardware-software correlated

design hence the hardware required to accomplish the project is also dependent on the

software design. The following flow charts depicts the flow of information and instructions in

the system.

3.1.1 Process components of remote terminal unit (RTU)

The following figure depicts the components of the process performed by the RTU in a

stepwise pattern.

Fig. 5 Process flow in the RTU

First the data is acquired from the drive through AI531 analog input module. It can be done

using either parallel communication or MODBUS communication. In this project parallel

communication is supposed. This data is sampled and used for real time data processing. The

value of variables thus received are then used for calculations of various parameters like

torque, angular speed, etc. The value of these parameters can be sent out either using RS 485

or RS 232 or using Ethernet interface. However, in this project a novel approach is proposed

for sending the data through SMS and GSM based interface. For this the PLC communicates

with the modem through a modified RS232 interface. This enables flexibility with distance

and maintenance.

3.1.2 Base data station process components

The following figure depicts the process flow at the base data station in a step wise pattern.

Fig. 6 Process flow at base data station

In addition to the user, base station receives the operation data continuously where it may be

stored for retrospection. The base station receives this data through COM2 port of the PLC

through serial communication or through MODBUS. These values are then processed and

stored at the data center for viewing later and analyzing the performance of the system.

3.1.3 RS232 based AT command parsing for GSM modem

The GSM modem receives the AT commands through serial communication via COM1 port

of the PLC. Simultaneous communication with the GSM modem and the data center is

possible since the field bus used in both these interactions are different. The GSM modem

receives the commands, parses them and follow the instructions provided to send the SMS to

the user. The following figure shows the order in which instructions are passed to the GSM

modem.

Fig. 7 Command flow for GSM modem

3.2 Software Design

The above algorithm is now implemented for parametric calculations and fault monitoring.

The software design has been accomplished using Codesys and ABB control builder is used

for configuring the PLC to perform according to the user’s wish. In the following sub

sections, design of individual blocks have been discussed and displayed.

3.2.1 Design of the block to send value of torque

Using the previously discussed mathematical formulae, a block is developed to send the

motor torque in SMS. The software design of this block is provided in Fig. 8.

Fig. 8 Block design: send value of torque

Above block checks for the value of voltage and current to be in range. If the values are in

range, it sends the value of calculated torque to the user’s mobile phone.

3.2.2 Design of block to send motor speed

Using the previously discussed mathematical formulae, a block is developed to send the

motor speed. The software design of this block is provided in Fig. 9.

Fig. 9 Block design: send value of speed

Above block checks for the value of voltage and current to be in range. If the values are in

range, it sends the value of calculated motor speed to the user’s mobile phone.

3.2.3 Design of block to send drive efficiency

Using the previously discussed mathematical formulae, a block is developed to send the drive

efficiency in SMS. Software design of this block is provided in Fig. 10.

Fig. 10 Block design: send value of drive efficiency

Above block checks if the value of voltage and current are in allowable range or not. If the

values are in range, it sends the value of calculated motor efficiency to the user’s mobile

phone.

3.2.4 Design of block to send input power

From the set of formulae provided previously, a block is designed to send input power.

The software design of this block is provided in Fig. 11.

Fig. 11 Block design: send value of input power

Above block checks for the value of voltage and current to be in range. If the values are in

range, it sends the value of input power to the user’s mobile phone.

3.2.5 Design of block to send output power

From the set of formulae provided previously, a block is designed to send the value of output

power. The software design of this block is provided in Fig. 12.

Fig. 12 Block design: send value of output power

Above block checks for the value of voltage and current to be in range. If the values are in

range, it sends the value of input power to the user’s mobile phone.

3.2.6 Design of block to calculate motor speed

Using the previously discussed mathematical formulae, a block is developed to calculate

motor speed and pass it on to the communication block. The software design of this block is

provided in Fig. 13.

Fig. 13 Block design: Motor speed calculation

This block calculates the value of speed from input current and input voltage of the drive.

3.2.7 Design of block to calculate motor torque

From the set of formulae provided previously, a block is designed to calculate the value of

torque developed by the motor. Fig. 14 shows the software design of the block created for

this purpose.

Fig. 14 Block Design: Motor torque calculation

This block calculates the value of torque from input current and drive parameters and passes

on the value to the communication block which dispatches the message to the user’s mobile

phone.

3.2.8 Design of block to calculate output power

Using the mathematical formulae discussed in chapter 2, a block is developed to calculate

output power and pass it on to the communication block. The software design of this block is

provided in Fig. 15.

Fig. 15 Block design: Output power calculation

This block calculates the value of output power from calculated torque and speed. It works

regardless of whether it is a normal condition or a fault condition.

3.2.9 Design of block to calculate input power

From the set of formulae provided in chapter 2, a block is designed to calculate the value of

input power of the motor. Fig. 16 shows the software design of the block created for this

purpose.

Fig. 16 Block design: Input power calculation

This block calculates the value of input power from input voltage and input current. It works

regardless of whether it is a normal condition or a fault condition.

3.2.10 Design of block to calculate Efficiency of the system

Using the mathematical formulae discussed in chapter 2, a block is developed to calculate the

drive efficiency and pass it on to the communication block. The software design of this block

is provided in Fig. 17.

Fig. 17 Block Design: Efficiency calculation

This block calculates the value of efficiency from input power and output power. It works

regardless of whether it is a normal condition or a fault condition.

3.2.11 Design of block for overvoltage and under voltage fault monitoring

From the set of formulae provided in chapter 2, a block is designed to calculate the value of

input power of the motor. Fig. 18 shows the software design of the block thus created.

Fig. 18 Block design: Overvoltage and under voltage fault monitoring

This block continuously checks whether the value of voltage is in specified limits. When the

limits of voltage are crossed, the block stops the drive and alerts the user of the fault by

sending an SMS to his mobile phone.

3.2.12 Design of block for overvoltage and under voltage fault monitoring

Using the mathematical formulae discussed in chapter 2, a block is developed to calculate the

drive efficiency and pass it on to the communication block. The software design of this block

is provided in Fig. 19.

Fig. 19 Block design: Overcurrent fault monitoring

The above block continuously checks whether the value of current is under specified limit.

When the limit of current is crossed, the block stops the drive and alerts the user of the fault

by sending an SMS “Overcurrent fault” and value of current to his mobile phone.

3.2.13 Design of block for temperature monitoring

The software design of this block is provided below.

Fig. 20 Block design: Overheat fault monitoring

The above block continuously checks whether the temperature of the drive is under specified

limit. When the limit of temperature is crossed, the block stops the drive and alerts the user of

the fault by sending an SMS “Temperature exceed the normal temperature” and value of

current to his mobile phone.

3.3 COM port setting for RS232 communication

Following is the setting done for COM1 and COM2 for extending RS232 communication

with the GSM modem. The data format used is 8N1 with no flow control. This enables the

PLC to communicate with GSM modem and to pass on the AT commands through serial

communication. This way a master-slave setup is established and exchange of data is

enabled. The connection is made through DB9 male to male connector.

Fig. 21 Control builder plus configuration for COM ports

3.4 Hardware design

Hardware design of this system can be broken into two parts:

Control system design

Communication System design

For communication design SMS_ALERT library was designed to be used for controlling

GSM modem serially through the PLC. Control system design on the other hand consists of a

network of DC drive, PLC and sensors. In the following section, hardware overview of the

project is provided and images of the real setup are provided. The following diagram denotes

the hardware overview of the project.

.

Fig. 22 Hardware overview of the project

The DCS550 drive is interfaced with the analog module which connected to the PLC through

TU515 base module. The outputs of the drive is output current and voltage. In the first phase,

data acquisition is done through the AI531 four input analog modules. Once these values are

acquired, they are passed on to the PLC and parametric calculations are carried out.

In the second phase these values are prepared and dispatched for communication through the

modem. The signal originating from the modem is wirelessly received by the Base

Transceiving Station (BTS). From the BTS, this data is passed on to Base Switching Circuit

(BSC) which searches the location of intended receiver. From the BSC the data is passed on

to the Main Switching Circuit (MSC) which has the info of the mobile subscriber. This way

MSC decides the destination BSC of the SMS. Now the message is transmitted through the

message center after IMSI check of the receiver. When the IMSI of the TU matches with the

IMSI details encrypted in the com signal, the incoming message is accepted. After receiving

the information packet, the decoder located on the mobile device decodes the message into a

readable data. This data is also simultaneously sent to the data center which records all the

information and events for retrospection. The hardware setup of the project is displayed in

Fig. 23.

Fig. 23 Hardware setup

3.5 Variable declaration and initialization

PROGRAM PLC_PRG

VAR

voltagefluct: SMS_ALERT; // Declaration of various SMS alerts

torque_send: SMS_ALERT;

overcurrentalert: SMS_ALERT;

Efficiency_send: SMS_ALERT;

Speed_send: SMS_ALERT;

ip_send: SMS_ALERT;

op_send: SMS_ALERT;

overheatalert: SMS_ALERT;

Vref: REAL:=100; // Input and references declaration

Iref: REAL:=20;

In_voltage: REAL:=100;

In_current:REAL:=29;

Ke: REAL:= 0.95; // motor constants declaration

Kf: REAL:=0.88;

Ra: REAL:=0.5;

Speed:REAL;

Torque: REAL; // motor calculaton declaration

In_power: REAL;

Output_power:REAL;

Efficiency: REAL;

temp: REAL;

fs: R_TRIG; // trigger and timer declaration

fs1: R_TRIG;

fs2: R_TRIG;

time1: TON;

timestart: TON;

time2: TON;

timeelapsed: TIME;

Complete: BOOL; // done flag declaration

Complete1: BOOL;

Complete2: BOOL;

Complete3: BOOL;

complete4: BOOL;

Phone_number_invalid: BOOL;

Com_port_invalid: BOOL; // invalid results declaration

Phone_number_invalid1: BOOL;

Com_port_invalid1: BOOL;

Phone_number_invalid2: BOOL;

Com_port_invalid2: BOOL;

END_VAR

VAR_OUTPUT

Drive_Stop: BOOL; // emergency output declaration

END_VAR

CHAPTER 4

RESULTS AND DISCUSSIONS

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In this chapter, results obtained after hardware implementation are displayed. In

addition to it the generated trends are generated from the data obtained and plots

are displayed.

4.1 Hardware results

The project is proposed for monitoring DC drives located at remote areas. The same system

was designed and implemented and following results were concurred. The results were at par

with the design objectives and the system developed is compatible with 57X, 58X series of

PLC and has compatibility with DCS550 and DCS800 series of DC drives. The user and the

data center can receive the various parameters sent by the RTU.

4.1.1 Results for fault monitoring

In this section, results for fault monitoring of DC drive including results for Overvoltage and

under-voltage fault monitoring, overcurrent fault monitoring and temperature monitoring

blocks are discussed. Following images display the message received on mobile phone and

hyper terminal in case an under voltage or an overvoltage fault occurs in the system.

Fig. 24 Result: Message received “voltage fluctuation out of range”

As seen from Fig. 24, when the voltage fluctuations go out of range, i.e. when the drive

speeds up or down beyond the recommended values, it is stopped and an error message is

received by the user. This informs the user of possible fault related to voltage and thus

mitigates any possible damage to the system.

Similarly, when the armature current exceeds the max possible allowable value of current of

the drive, it is protected by braking the power supply to the drive and informing the user by

an SMS as shown in Fig. 25. This way over current protection is offered by the system for the

drive. Similar to these two faults, temperature of the drive is also monitored by a digital

temperature sensor which checks whether the operating temperature is in the permissible

limits. If the operating temperature crosses the reference (set value) of maximum allowable

temperature, the system disconnects the drive and informs the user by sending an SMS

“Drive temperature exceeded”.

Fig. 25 Result: Message received “overcurrent fault”

4.1.2 Drive runtime information – Mobile phone

In the following section, results for displaying runtime information to the user as a summary

for the day are provided. When no contingency occurs i.e. when the voltage and current do no

exceed the preset values, a message regarding drive’s speed, efficiency, input power, output

power and torque is sent out to the user.

As seen in Fig. 26 the drives running speed is displayed along with the instance at which the

value was recorded. This keeps the user aware of the drive speed constantly through a simple

message. The system can be programmed to send hourly, daily or every minute update of the

drive speed to the user. In the background, the available block diagram for this particular

function is provided. In a separate block calculations are done and passed on to the

communication block. The SMS_ALERT block then sends the SMS to the user’s mobile

phone as well as to the data center which uses Hyper terminal for view ASCII data being sent

through RS232 based serial communication.

Fig. 26 Result: Message received “Drive is running at speed (RPM) 600

Similarly in Fig. 27 the result displaying the drive efficiency are provided. The system

calculates the drive efficiency and sends it to the user and hyperterminal from where trends

can be generated.

Fig. 27 Result: Message received “Drive efficiency is 91”

Fig. 28 displays the information about the generated torque received by the user through

SMS. The same information is also sent to hyper terminal for generating trends if required.

The following figure displays the data “summary” as received by the data center through

COM2 communication port.

This summary consists of input power, output power, speed and torque of the motor attached

to the drive. The drive can be programmed to give either 0-10V TTL logic or 400mA current

based logic for providing to I/Os.

Fig. 28 Result: Message received “Generated torque is 33.5”

This sums up the hardware results as obtained on the user’s mobile phone. In the following

sections the results obtained on the hyperterminal and graphical results obtained through this

data are displayed.

4.1.3 Data collection results – Hyperterminal

The following section, screenshots of how the summary (runtime data) is received by the data

center are provided. Using MS Excel, a macro was created to import the data in a datasheet

which is later used to generate trends at the data center.

Fig. 29 above, displays the summary received by the hyper terminal continuously in a time

period of two seconds. It also displays the number to which the message regarding summary

is sent along with the instant of sending

Fig. 29 Result: Data received on hyper terminal by data center

All the results were verified both through the hyperterminal as well as mobile phone. The

system is tested to perform well with AC500 PM57X and PM58X series along with DCS500

or DCS800 drives.

4.1.4 Graphical results

In this section, various plots obtained are displayed and discussed. These trends are plotted in

MS excel after data collection through macro. These are helpful in evaluating drive

performance and fault monitoring. The data simulated from the drive are provided in Table 1.

Table 1 Drive runtime data when current is kept constant

Graph shown in Fig. 30 is obtained by keeping the drive current constant and varying the

voltage of the drive using a potentiometer. The corresponding values of current speed is

calculated and are plotted against the values of operating voltage.

Voltage Current Speed Input power Output power efficiency

20 20 58 400 200 50

25 20 87 500 300 60

30 20 117 600 400 66.66

35 20 146 700 500 71.4

40 20 175 800 600 75

45 20 204 900 700 77.7

50 20 234 1000 800 80

55 20 263 1100 900 81.8

60 20 292 1200 1000 83.3

65 20 321 1300 1100 84.6

70 20 351 1400 1200 85.7

75 20 380 1500 1300 86.7

80 20 409 1600 1400 87.5

85 20 438 1700 1500 88.2

90 20 468 1800 1600 88.9

95 20 497 1900 1700 89.5

100 20 526 2000 1800 90

Fig. 30 Voltage v/s speed variations keeping current constant

As evident from Fig. 30, when the drive operating speed is increased in a step size of 5 volts,

the speed of the motor increases linearly.

In Fig. 31, trend for voltage and efficiency are provided. The set voltage range is 20-

120 volts and maximum allowable current is set at 20 amperes. For current trends, the value

of current was set at 20 amperes and voltage is varied in a range of 20-120 volts. Maximum

efficiency achieved was 91 percent at 100 volts.

Fig. 31 Voltage v/s Efficiency keeping current constant

Now, the operating voltage is kept constant and drives operating data is recorded. The

recorded data is displayed in Table 2.

Voltage

(V)

Current

(Amps)

Torque

(N-m)

I/P power

(watts)

O/P power

(watts)

Speed

(rpm)

Efficiency

(%)

100 4 13.68 400 392 2865 98

100 8 54.72 800 768 1403 96

100 12 123.12 1200 1128 916 94

100 16 218.88 1600 1472 672.5 92

100 20 342 2000 1800 526 90

Table 2 Drive runtime data when applied voltage is kept constant

From the data in Table 2 various characteristics are derived. Some of these characteristics are

discussed in following section.

Fig. 32 displays a plot between current and torque. It is evident from Fig. 32 that the value of

motor torque has a quadratic relation with the armature current.

Fig. 32 Current v/s Torque keeping operating voltage constant

Fig. 33 Current v/s Speed plot keeping operating voltage constant

Fig. 33 displays the relation between armature current and motor speed. It displays and

inverse quadratic relations. This means when the current is increased (implies that load is

increased), the speed of the motor decreases to make the generated torque equal to the load

torque.

Fig. 34 Efficiency v/s Current plot keeping operating voltage constant

While keeping the operating voltage constant, efficiency is calculated for different values of

current. This is an inverse linear relation as displayed in Fig. 34. As the load on the system

increases the efficiency of the system decreases due to higher losses.

Fig. 35 Torque- speed curve of the motor

In Fig. 35, torque speed characteristics of the system are displayed. As seen from Fig. 35, the

motor speed is inversely proportional to the motor torque. All the data analyzed in this report

was collected from DCS550 DC drive and through simulation in Codesys.

CHAPTER 5

CONCLUSION AND SCOPE FOR IMPROVEMENT

----------------------------------------------------------------------------------------------------------------

5.1 Conclusion

The proposed system is designed to mark up the objectives. The system is tested to work with

PM 573 and PM 583 PLCs. The designed system is also expected to work appropriately with

DCS550 and DCS800 series of DC drives by ABB. The system successfully monitors for any

fault condition and intimates the user in case of any fault.

The developed system works successfully according to the objectives laid at the beginning of

the project. It increases the flexibility, connects remote areas where equipment is installed

and saves time and labor. The system offers low computational complexity, high chances of

integrity and provides sufficient supervision and monitoring. All these factors makes it a

popular choice in industrial automation. However, the effectiveness of this system can be

enhanced by making a few additions. Such possible amendments and scope of this project are

proposed in the following section.

5.2 Applications of the developed system

Current project finds its applications in myriad directions. Nuclear power plants, mining

industries, chemical industries, water pump house, industrial automation, remotely located

transmission towers and transformers are a few applications of this project. By making subtle

changes in the software, it can be adjusted to suit any need of supervisory control and

monitoring.

5.3 Scope of improvement

The RTU developed in this project is not completely wireless. It uses COM2 serial

communication interface to interact with the data center. This limits the range in

which the RTU can be installed since serial communication suffers major attenuation

when data is required to be sent at large distances. By using a 3G router, GPRS based

connectivity can be established between RTU and data center. Thus, the range can be

maximized and losses can be mitigated.

The current system does not monitors any mechanical faults or incipient faults which

may lead to an electrical fault. These mechanical faults can be monitored using the

machine learning based approach adopted by Abhishek et al. [4]. However, a few

improvements to the system are required to train the system to perform in various

possible conditions.

Current work only focuses on development of an individual RTU. Based on this

system a SCADA system can be developed for remote monitoring.

A SMS based control system can be developed based on this work which enables the

user to also control the drive wirelessly by sending an SMS.

The designed system can be upgraded to enable fault diagnosis. Current system is

only limited to fault monitoring and detection. However, a more challenging task is to

diagnose where the fault has occurred in the circuit and how the fault can be cleared.

For this wavelet transform methods, ANN based methods and mathematical models

can be developed.

REFERENCES

[1] Ioannides, M.G., “Design and implementation of PLC-based monitoring control system

for induction motor”, IEEE Transactions on Energy Conversion, Vol.19(3), 469-476, 2004

[2] Singh, Nandawar., “Design of a PLC system for fault monitoring using microcontrollers”,

AIJSER, Vol. 5(2), 230- 233, 2009

[3] Isermann, R., “Model-based Condition monitoring: Actuators, Drives, Machinery, plants,

sensors and fault tolerant systems”, Vol. XVI, 49-63, 2011

[4] Abhishek Sharma, V. Sugumaran, S. Babu Devasenapati, “Misfire Detection in an IC

engine using vibration signal and decision tree algorithm”, Measurement, Vol. 50, 370-380,

2014

AUTHOR’S BIOGRAPHY

Abhishek Sharma is a final year student in Bachelor of Technology (Electrical and

Electronics Engineering) at Vellore Institute of Technology, Chennai. His particular research

interests are in Control systems and application specific VLSI system design. He has also

published two international journal research papers and two IEEE conference papers (indexed

in IEEE Xplore). Currently he is pursuing his undergraduate thesis project at ABB India Ltd.,

Bangalore as an intern.