Fault analysis and Control of Induction

Motor using MODBUS protocol

Mrs. J. Priyadarshini ,

Assistant professor,

Department of Electrical and Electronics

Engineering,

Sri Krishna College of Technology,

Coimbatore, India.

Abstract:-All types of large industries uses induction

motors for driving process equipment participating in

their respective production line up. It is must to control

the parameters like speed, on off switch and starting

torque of these motors. Normally large industries have

larger area in which more number of induction motors

are used. If the controlling processes of the motors is

automated using MODBUS, DELTA PLC and DELTA

VFD whose settings are set accordingly by the users

then the work and burden of the operators get reduced.

In this paper the system is designed using MODBUS,

where a slave device is placed in the land slots which

acquire the data and send it to one main master device.

The slave and master communicates through RS485

network using MODBUS protocol which is cheap and

yet effective. So that user can monitor and control each

and every node from the master itself. Through this we

can able to control the speed, direction, start and stop

torque of various induction motors.

Keywords:- MODBUS, PLC, HMI, VFD ,Induction

motors, master bus, slave bus.

I. INTRODUCTION

Nowadays industries are occupying larger area in

which more number of induction motors are placed in

around an industries. It is difficult to control the

motor which is far away from the industry. In our

project, an automated method is used to control the

parameters of the motor using MODBUS protocol

where HMI act as a master and Delta PLC and Delta

VFD act as slaves. With VFD Induction motors are

connected. Here Master can give the command to the

slave and slave can only respond to the master.

Master gives the command which is transmitted

through D+ transmitter and slave respond to the

command and send information through D-

receiver[1].This designing system can indicate the

abnormalities of the motors. The usual abnormal

conditions encountered by the motors occurred in

voltage (undervoltage, overvoltage, unbalance in 3-

P.Kanagaraj, M.Karthiga, G. Karthikeyen, J.K.Kavya

UG Scholar,

Department of Electrical and Electronics

Engineering,

Sri Krishna College of Technology,

Coimbatore, India.

phase , single phasing, voltage surges) and frequency

(low frequency and high frequency). Abnormalities

are occurred due to environmental conditions like

high/low temperature, high humidity, hazardous

atmosphere or surroundings , exposure to steam or oil

vapour. The major impact of the listed abnormal

condition is overheating of the motor along with

several effects. This can be avoided because this

system will indicate the problems and it will try to

correct those problems automatically. Controlling the

parameters are based upon the nature of application

and the type of duty they are expected to perform.

Critical factors like speed, locked-rotor torque and

load applications are taken into consideration during

MODBUS control. The locked-rotor torque which is

the maximum torque that motor can produce during

startup from steady state condition specially designed

for conveyors[2].

The PLC correlates the operational

parameters to the speed requested by the user and

monitors the system during normal operation and

under trip condition[4].

Variable frequency drive uses power

electronics vary the frequency of input power to

motor, thereby controlling the speed[6].

II. BLOCK DIAGRAM

A. Master-slave

A MODBUS system comprises of a master and slave,

where the “master” communicates with one or

multiple “slaves.” The master typically is a

Programmable Logic Controller (PLC), PC,

Programmable Automation Controller (PAC),

Distributed Control System (DCS) or Remote

Terminal Unit (RTU). The slaves are mostly field

devices, all of which connect to the network in a

multi-drop configuration shown in the figure.

D+ -TRANSMITTER D- -RECEIVER

D+ MODBUS IN RS485 STANDARD

D-

. . ………………

Figure 1: Block diagram of MODBUS based industrial automation

B. MODBUS ASCII

All messages are coded in hexadecimal using 4-bit

ASCII characters. MODBUS ASCII marks the start

of each message with a colon character ": " (hex 3A).

The end of each message is terminated with the

carriage return and line feed characters (hex 0Dand

0A).

C. HMI

It is the space where interactions between humans

and machines occur. This interaction will lead to

effective operation and control of the machine from

the human end, at the time the machine

simultaneously feeds back information that aids the

operators' decision making process. User interface is

the one in which operator needs to provide minimal

input to achieve the desired output, and also that the

machine minimizes undesired outputs to the human.

D. PLC

A Programmable logic controller (PLC) is an

industrial computer control system that continuously

Figure 2: model connection of MODBUS multidrop system

monitors the state of input devices and makes

decisions based upon custom program to control state

of output devices. Almost any production line,

machine function, or process can be highly enhanced

using this type of control system. It has an ability to

change and replicate the operation while collecting

and communicating important information. Another

advantage of a PLC system is that it is modular, (i.e)

input and output devices are used according to their

applications.

E. VFD

A Variable Frequency Drive (VFD) is a type of

motor controller that drives an electric motor by

varying the frequency and voltage supplied to the

electric motor. Frequency (or hertz) is directly related

to speed the motor (RPMs). In other words, the faster

the frequency, the faster the RPMs go. If any of the

application does not require an electric motor to run

at full speed, the VFD can be used to ramp down the

frequency and voltage to meet the requirements of

the electric motor’s load.

III. MASTER- SLAVE PARAMETERS

A. Delta HMI -Features

A full 65,536 color display is available on all models

with a whole 2D drawing technique. The screen

resolution is enhanced for more realistic images and

for more colorful and vivid displays.

HMI APPLICATION PROGRAM USING

DOP SOFT HMI

D+ D-

(MASTER)

D+ D- DELTA VFD

(SLAVE 2)

D+ D- DELTA PLC

(SLAVE 1)

PLC PROGRAM

USING WPL SOFT 3 PHASE SUPPLY

D+ D- DELTA VFD

(SLAVE

247)

INDUCTION

MOTOR

1. Specifications

4.7″ (480 x 272 pixels) 16:9 TFT LCD 65536 colors

1 set of COM port, supports RS232 / RS422 / RS485

Touch screen complies with IP65

Supports horizontal / vertical display

Editing software, DOP Soft is compatible with

operating systems: Windows XP, Windows Vista,

Windows 7.

B. Delta PLC DVP 14SS2

The DVP-SS2 Series is Delta Electronics' second

generation of slim line industrial PLCs. The DVP-

14SS211R features high speed counters, a flexible

serial port, real-time monitoring and an expansion

bus that allows matching modules to be mounted on

the right side of the PLC without external wiring. The

DVP-14SS211R supports PID loops with automatic

tuning for process control applications. The transistor

outputs allow high speed pulse generation for servo

or stepper motor motion control applications.

1. Specification Power: 20.4 to 28.8 VDC

Digital input: 8 inputs,24 VDC sink

Digital output: 6 relay outputs

Output rating: 1.5A each outputs

Communication port: RS-232 and RS-485

Program capacity: 8 k steps

IO points: Up to 238 via expansion modules

Software up/down counter: Any input, up to 10 KHz

on a single input

Software quadrature inputs: 2-X4/X5 (5KHz) and X6/X7 (5KHz)

Hardware up/down counters: 2-X0 and X2, both 20KHz

Hardware quadrature inputs: 2-X0/X1 and X2/X3, both

10 KHz

C. Delta VFD

1. Specification

Terminal

symbols

Terminal

functions

Factory settings

MI0 Multi-function input 0 Refer to Pr.04-04

to Pr.04-06 Multi-function

input terminals

MI1 Multi-function input 1

MI2 Multi-function input 2

MI3 Multi-function input 3

RA Multi-function relay

output (N.O.)a

120Vac, 3A

24Vdc, 3A Refer to Pr.03-03 RC Multi-function Relay

common

+10V Potentiometer power

source

+10V 20Ma

AVI Analog voltage/input current

0 to +10v/4 to 20mA

Figure 3: circuit diagram of VFD

IV. WORKING PROCESS

A. ASCII Standard

In ASCII format, the messages are readable. In

MODBUS ASCII, messages are encoded with

hexadecimal value, represented with comprehensive

ASCII characters. The characters used for this

encoding are 0…9 and A…F. For every byte of

information, two communication-bytes are used

because every communication-byte can only define 4

bits in the hexadecimal system. The MODBUS

messages on a serial connection are not broadcast in

plain format. They are constructed in a way that

allows receivers an easy way to detect the beginning

and end of a message. The characters start and end a

frame when in ASCII mode. To flag the start of a

message, a colon ‘:’ is used and each message is

ended with a CR/LF combination.

B. Properties of MODBUS ASCII

MODBUS ASCII

Characters ASCII 0…9 and A…F

Error check LRC

Frame start Character ‘:’

Frame end Character CR/LF

Gaps in message 1 sec

Start bit 1

Data bit 7

Parity Even/odd None

Stop bits 1 2

C. VFD conversion process

The first stage of a Variable Frequency AC Drive, or

VFD, is the Converter. The converter is comprised of

six diodes. They allow current to flow in only one

direction; the direction shown by the arrow in the

diode symbol. For example, whenever A-phase

voltage is more positive than B or C phase voltages,

then that diode will open and allow current to flow

and vice versa. The same is true for the 3 diodes on

the negative side of the bus. Thus, we get six current

“pulses” as each diode opens and closes.

1. AC ripple: We can get rid of the AC ripple

on the DC bus by adding a capacitor. This

capacitor absorbs the ac ripple and delivers a

smooth dc voltage. The AC ripple on the DC

bus is typically less than 3 Volts. Thus, the

voltage on the DC bus becomes

“approximately” 650VDC. The actual

voltage will depend on the voltage level of

the AC line feeding the drive, the level of

voltage unbalance on the power system, the

motor load, the impedance of the power

system, and any reactors or harmonic filters

on the drive.

Figure 4:Six pulse waveform with

motor connection

D. Delta PLC memory map

Two types of memory variables in Delta PLCs; the

input relays and the output relays.

1. Input Relays: Single bit variables and can be

extended to 128 points. They are indicated

with X sequence in Octal numbering mode.

2. Output Relays: Similar to input relays. They

are indicated with Y sequence in Octal

numbering mode.

E. WPL Soft Installation and setup

1. Start-up your computer to Windows

95/98/2000/NT/ME/XP system.

2. Insert WPL Soft CD into the CD-ROM disk

or download installation program from

http://www.delta.com.tw/product/em/plc/plc

_main.asp .

3. Click “START”, and then click on “RUN

4. Designate the location where WPL Soft is to

be installed

5. The program show the dialog box explaining

the WPL Soft copyright. Please click

"Next" to proceed with the installation

V. IMPLEMENTATION OF PLC AND HMI

PROGRAM

An experimental test has been conducted using the

program compatible with the PLC. The following

screenshots are the results of PLC and HMI programs

which defines the working process of the system.

A. HMI output screens

Figure 5.1: output screen for conveyor control

Figure 5.2: output screen for process1

Figure 5.3: Output screen drive status

B. PLC output screens

Figure 6.1: Output screen PLC 1

Figure 6.2: Output screen PLC2

CONCLUSION

By using PLC and HMI connected through

MODBUS protocol the cost effective automation

system for controlling the induction motors are

developed and it is very user friendly for the operator

or control engineer to trouble shoot the process if any

error occurs and can also be kept track of what is

happening in the process. The main factor holding the

project up straight is the modification and

development which could be made possibly with

available resources in the industry.

REFERANCE

[1] K. Shashi Raj , Nayanan .D.K , Dr.S.S

Manvi “MODBUS based Multinode

Irrigation Automation”, International

Journal of Advanced Networking and

application., pp. 1467-1472, April 2014.

[2] S. Takiyar , B.K. Chauhan , “Hybrid Method

for customized Control of Induction Motor”,

International journal of Computer and

Electrical Engineering, pp.505-599 August

2013.

[3] Yasar birbir , H. Selcuk Nogay , “Design

and Implementation of PLC based

Monitoring Control System for Three-Phase

Induction Motors Fed by PWM Inverter”,

Turkey,2008 .

[4] P.Gandhi , D. Adhyaru , “Critical data

reliability issues with MODBUS protocol in

smart grid application”. Inst.of technol.,

Nirmal Univ ., Ahmadabad , India.Jan 2015.

[5] Feng Lei-Hua, “Application of

communication optimization strategy based

on cascade PLC MODBUS in Fire Water

system oh hydropower station”, Sch. Of inf.

Sci. & Eng., Central South Univ., Changsha,

China. Oct.2009.

[6] B. Madivalappa , M.S. Aspalli, “Speed

control of three phase induction motor by

variable frequency drive” PDACE,

Gulberga, Karnataka, India. Volume 3, issue

12.

[7] Francesco Basile, Pasquale Chiacchio,

Diego Gerbasio , “On the Implementation of

Industrial Automation Systems Based on

PLC”, IEEE transactions on automation

science and engineering, vol. 10, no. 4,

october 2013.

[8] K. Madhanamohan , R.K. Praveen , T.R.

Nirmalraja , H. Goutha , R. Sabarinathan ,

A. Logeesan , “Industrial Automation

System”, International Journal of

Mechanical Engineering and Research,

ISSN No. 2249-0019, Volume 3 , pp. 543-

552 Number 5 (2013).