ISRASE First International Conference on Recent Advances in Science & Engineering-20014 (ISRASE-2014)
Automation system for Stator winding thermal
monitoring of AC Motor using Android
Ranjith N
Nagaraj P
VLSI EMBEDDED SYSTEM
Lecturer, VLSI EMBEDDED SYSTEM
UTL TEHNOLOGIES LTD,Bangalore.
UTL TEHNOLOGIES LTD,Bangalore.
Raju A S
Dr. Siva Yellampalli
Professor, Medical Electronics
Professor, VLSI EMBEDDED SYSTEM
SSIT, Tumkur-572105.
UTL TEHNOLOGIES LTD, Bangalore
Abstract— In this paper, the automation system is designed and develop for monitoring and control electrical appliance
ie. Induction Motor to control the temperature rise in the stator winding insulation, which uses the power line
communication method for the data transfer through the AC wires, which adopts the Direct spread spectrum modulation
methods for the data transfer and offer less data corruption and the ARM LPC2148 microcontroller is master device
which monitor and safe guard the device from the break down due the thermal effect caused in the stator windings.
The developed automation system is tested on single phase squirrel cage induction motor on mechanical load and
temperature rise for various load is noted and motor is switched off when it’s temperature rises above 1100C.
Keywords—Motor, PLC, Modulation, Wi-Fi, DCSK, Android.
I.
INTRODUCTION
Automation or automatic control is used for various Control systems for operating equipment such as machinery, processes
in factories, boilers and heat treating ovens, switching in telephone networks, steering and stabilization of ships or aircraft and
other applications with minimal or reduced human intervention [1]. Some processes have been completely automated.
Automation essentially involves leveraging the power of technology to reduce the dependency on human presence and
decision making for any process [2]. It leverages different electronic equipment (either standalone or interlinked with appropriate
applications) to control different parameters of any process.
In these days energy scarcity is more, it is prudent to save energy in every way possible. It is paramount to make such
systems as easy to use as possible so that people can use their Appliances in a smarter way to save energy [3]-[4]. It also enables
people to be more energy conscious by enabling them to have a real time status of electric appliances [5]-[6].
Aim of this project is to simplify the process of human-machine interaction by the proposed embedded system which using
Power line communication modem, which uses the existing power line for the communication, the PLC modem uses DSS
Modulation technique for transmitting and receiving which is known for its extreme robustness.
The Spread spectrum modulation is a method in which a signal is transmitted on a bandwidth considerably larger than the
frequency content of the original information [7]-[8].The PLC modem can be configured with various Communication parameters
through a programmable interface and PLC is an excellent system from the aspect of economy and convenience[9], because new
transmission line to be installed is not needed, and connection to the network is possible just connecting PLC modem to outlet
(Plug & Play)[10].
The automation of Induction motors should be done for the robust operation because of their wide application in industrial,
commercial and residential systems, and their ruggedness, simplicity and relatively low cost. Approximately 65% of the
electricity consumed in industry is used to drive electrical motors [11]. Squirrel cage induction Motors are the most important AC
machines in industry which is a Low cost, high reliability, low inertia and high transient torque capacity these are the advantages
of these motors.
Induction motors are reliable but we cannot avoid the possibility of failure also. These failure conditions are taking place
because of its component failure. If the failure occurs in the machine that failure is to be diagnose as early as possible. If these
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failure conditions are not diagnosed on time, the failure component will affect whole motor operation badly and will become
more catastrophic [12]. Consequently, large revenue losses and maintenance will be needed. Below figure gives the different
types of Induction motor faults.
Figure 1: Different Faults in IM
The percentage failure component of induction motor as per the survey was taken by Institution of Electrical & Electronics
Engineers (IEEE) and Electric Power Research Institute (EPRI) is as shown below [13].
Data as Per IEEE
Bearing Faults
44%
Rotor faults
8%
Stator Faults
26%
Others Faults
22%
22%
44%
8%
26%
Bearing Faults
Data as Per EPRI
49% Stator Faults
Rotor Faults
9%
9%
Other Faults
36%
14%
14%
41%
36%
Figure 2
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The stator winding temperature rises due to Motor windings (copper losses), Friction of the bearings, Rotor and Stator losses
(core losses), Unbalanced Load/ Motor Overload, Unbalanced Supply voltages, Impaired cooling capability [14].
The 35%–45% of motor failures are caused due to the stator insulation breakdown [15]-[16]. The main cause for the stator
insulation breakdown is the temperature rise in the motor. The Automation of the AC induction motor is required to control the
temperature and for the reliable operation of motor without any failure of the insulation which is provided for the stator windings,
thus the cost encured for the repair and the total system shutdown time due to Induction motor failure can be reduced.
II. SYSTEM DESIGN
A. BLOCK DIAGRAM
Figure 3: System design
The main aim of the project is to design and develop an automation system for controlling electrical appliance that is AC
Induction Motor using power line communication and monitoring the temperature rise and protect it from the Stator Insulation
Breakdown.
The experimental setup is as shown in the block diagram. The control messages are sent over Cell Phone WI-Fi network to
the PC with Wi-Fi network which then couples the messages to the power lines using the power line communication modem and
data is sent to the master (ARM7) device. The power lines are used as physical media to transmit data over 220V/50Hz signal to
control appliances/equipment and to monitor. In this thesis, the embedded system developed is used to monitor the temperature of
stator windings and when this crosses the certain limit, the data is sent back to the PC and this will send the data to the cell phone
which having android GUI for display of the Temperature and the user can get to know the temperature details, the data transfer
from PC to Mobile is done by development of the socket application program and the data is displayed on the android developed
GUI.
If the temperature exceeds the critical limits the Induction motor is automatically switched off by the microcontroller and
data is send to the modem which couples to lines using PLC Modem which employees DSSS (Direct sequence spread spectrum)
modulation technique to transmit the data, The receiver unit consists of PLC modem which couples the data to PC through RS232
data communication which in turn send the data to Android GUI .
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The PLC Modem can be connected anywhere in the power line network for the data transfer action. The Microcontroller unit
controls the flow of electricity to the device by using the relay unit to switch off the Induction motor for cooling or the Load can
be shared between other motors.
III.
INDUCTION MOTOR
The most commonly used type of motor in today world is the induction motor with over 90% of those being squirrel cage
induction motors.
The automation of Induction motors should be done for the robust operation without fail, The Temperature rise due to the
various issues in the motor will affect the insulation provided for the windings, so automation should be done to control the
temperature rise in the induction motor.
Figure 4: Induction Motor
Table 1: Insulation Class
Insulatio
n Class
Ambient
Temperatu
re
( Celsius)
Rated
Temperatu
re
Rise(
Celsius)
Hot Spot
Temperatur
e
( Celsius)
A
40
60
105
B
40
80
130
F
40
105
155
H
40
125
180
The table 1 gives the different insulation class adopted for the stator winding insulation and there rated as well as hotspot
temperature limits.
B. PLC MODEM
Power Line Communication is a technology which uses power lines as physical media for data transmission. PLC offers a no new
wires solution because the infrastructure has already been established.
The Sunrom PLC Modem provide bi-directional half-duplex data communication over the mains of any voltage up to 250v a.
c., and for frequency of 50 or 60 Hz. It does not require any protocol to function and protocol independent
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Figure 5
The Figure 5 gives the SUNRON PLC modem connection details for the communication purpose which capable of providing
9600 baud rate.
The SUNROM PLC is a system on chip solution optimally designed to provide the best performance over the Power Line
medium. The PLC modem can be configured with Serial communication parameters through a programmable interface. The Line
Coupler couples the data to the Power line which operates at the 230V and other side the Power Supply operation is 5volts which
provides direct interface to the microcontroller.
VI. ANDROID GUI & JAVA SOCKET API
Android is a Linux-based operating system designed primarily for touch screen mobile devices such as smart phones and
computers .Android GUI is developed using the android ADK which is an open source development kit provide the graphical user
development environment.
The developed android apps is executed on the cell phone for the display of data which is received from the hardware,
The figure below give the screen shots of the apps running on the cell phone.
Figure 6: ANDROID GUI
JAVA API : The Java object programming language is used to develop the socket communication API to read the data form the
hardware and to port the data to hardware, also the data communication between the android mobile GUI for the control of
operation of harware and to check the status of the Motor temperature.
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VII.
EXPERIMENTAL SETUP OF AUTOMATION SYSTEM
Mechanical
loading
system
LM35 Placed in the
stator slots
Experimental setup for the Active stator winding Temperature
monitoring and control System
Figure 8: Project circuit setup
The Experimental setup is as shown above, in which the sensor is placed in the Stator winding slots by making special
arrangements and directly the temperature rise is monitored by the master unit (LPC2148 microcontroller) and Motor is switched
off when the temperature is raised above the set value, and the message is send to the android mobile through Personnel computer
with WI-FI which is used to monitor and control the motor temperature.
VIII. APPLICATION & FUTURE WORK
The load on the induction motor varies in the size and type of function also, and range of operation, nature of surroundings,
and the type of motors used various application , some applications need multiple motors to work in tandem or in parallel. The
reasons for using multiple motors may vary from lack of space for big motors resulting in the use of several coupled motors of
smaller ratings in tandem, to process requirement of parallel motors. Process such as Mills, conveyor belts, roller tables, cranes,
etc., cannot work with just one motor. They need more than one motor working in parallel to drive the common mechanical load.
In such applications, load sharing is naturally required, and it is very much important, so naturally the reliable of operation of
such motor is done by using above automated system to overcome the thermal breakdown of the stator winding.
B.FUTURE WORK
The load sharing can be done by designing an special gear mechanism for the belt to be driven by other induction motor
running in parallel. Also an database can be developed for the storing the load variation data with respect to the time and the
corresponding speed variation which give the complete database of the load and the motor for the analysis for preventive
maintenance purpose and by special designing the stator slots for the passing the coolant we can pump the coolant to extract the
heat from the stator windings, this may reduce the heat developed in the stator and gives reliable operation of Motor.
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IX.
RESULTS
In this paper, the Induction Motor which has been used, and tested with the automation system, have the below Specification
1. Single Phase Motor
2. Rating
--- 0.37kw / 0.5hp
3. Voltage
--- 230Volts
4. Frequency
--- 50Hz
5. Insulation Type --- Class F
6. RPM
--- 2800
7. Rated Current --- 2.5A
The Temperature rise of the stator winding is measured by using the PLC based Automated system proposed above by
loading the Induction motor (Mechanical Loading) and Temperature rise is noted as shown below.
As per the data collected below if the Induction Motor is run for the period of time, the temperature is increased in stator
winding.
Sl/No
1
2
3
4
5
Load
(A)
1.4
1.8
2
2.2
2.7
Table2: Load versus Temperature rise
Temperature
of the stator
Speed
Temperature
with
Load
(N)
of Stator
applied up to
5min
2964
45
48
2895
49
53
2934
55
58
2729
56
63
2674
60
73
As the motor used is Class- F type of insulation which has the Rated Temperature rise of 1050C and HOT Spot 1550C, if it
reaches the hot spot it may affect the Insulation failure.
The Temperature rise can be controlled and monitor by PLC based Automated System Proposed above which is used to
switch of the relay when reached above 1100C and displayed as temperature crossed on Android Phone as shown in below figure
9.
Figure 9: Output on Android Mobile
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VI. Conclusion
The Thermal protection of ac motors is a crucial part of AC Induction motor for preventing catastrophic motor breakdown,
prolonging motor’s lifetime, and avoiding the extraordinary financial losses due to unexpected industrial process downtime
caused by motor failures.
The drawback of conventional overload relays and microprocessor-based thermal relays and thermal protection technique of
the ac line-started, soft-starter-connected, and inverter-fed ac motors has an error in the stator winding temperature estimation of
3°C and this system uses the indirect techniques to measure the temperature.
The proposed embedded system uses the sensor for the measurement of temperature of the stator winding of Induction Motor,
which measure directly the temperature rise in stator winding, the temperature reading by the sensor is having 0.5 0C accuracy
which reduces the error in reading also the response time and the hardware cost can be brought to minimum by implementing the
PLC based embedded system presented above.
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