Voltage Temperature Monitoring System (VTMS) for a BTS Room

Abstract

Although Cellular communication is getting more and more popular in our
country present days, but its network improvement is hampered by the crysis of
electricity. The recent decision of present Government is that they will not
provide any electricity from the grid to any new BTS rooms of any Celluler
operator companies like Grammen Phone, Robi, Airtel etc. These companies have
to develop their own power stations either by using generators or by developing
solar plants. Now a days most of the BTS rooms, that the cellular operators are
installing with a generator and 48 volt battery backup. So for the
synchronisation of the operation of PDB, Generator and battery, they require a
device called Voltage Temperature Monitoring System or VTMS. It is a
Microcontroller based controlling unit which controlls the operation of
generator and battery when PDB in not available in the BTS room.

Full text

International Journal of Instrumentation and Control Systems (IJICS) Vol.2, No.4, October 2012
DOI : 10.5121/ijics.2012.2401 1
Voltage Temperature Monitoring System (VTMS)
for a BTS Room
Sadeque Reza Khan
1
, Siddique Reza
2
and Arifa Ferdousi
3
1
Dept. of Electronic and Communication Engineering, NITK, India
sadeque_008@yahoo.com
2
Dept. of Computer Science and Engineering, MIST, Dhaka University, Dhaka,
Bangladesh
remond_007@yahoo.com
3
Dept. of Computer Science and Engineering, Varendra University, Rajshahi, Bangladesh
arifaferdousi@yahoo.com
ABSTRACT
Although Cellular communication is getting more and more popular in our country present days, but its
network improvement is hampered by the crysis of electricity. The recent decision of present Government is
that they will not provide any electricity from the grid to any new BTS rooms of any Celluler operator
companies like Grammen Phone, Robi, Airtel etc. These companies have to develop their own power
stations either by using generators or by developing solar plants. Now a days most of the BTS rooms, that
the cellular operators are installing with a generator and 48 volt battery backup. So for the synchronisation
of the operation of PDB, Generator and battery, they require a device called Voltage Temperature
Monitoring System or VTMS. It is a Microcontroller based controlling unit which controlls the operation of
generator and battery when PDB in not available in the BTS room.
Keywords
BTS; Microcontroller; LCD; LM35DZ; ADC.
1. INTRODUCTION
In the history of Bangladesh, power crisis has reached to the worst-ever level, especially during
the hot summer days, when country's average temperature is 31 to 35 degree Celsius [1].
Bangladesh has been facing electricity shortage for many years. The distribution system in
Bangladesh is facing tremendous pressure from industrial and residential users to maintain a
regular supply [2]. In last few years this problem was not serious but in the year of 2010-11 the
problem has exceeded the common people's patient. Power outage/failure is a common
phenomenon now-a-days and people are facing severe electrical load shedding, voltage
fluctuation throughout the day and this problem is more severe in the rural areas, although only
30% of the total population enjoys the electricity facilities [3]. One of the major steps that our
Goverment has taken to solve this electricity problem is that they will not provide any power
from the grid to any new BTS and for new BTS, operators must have to develop their own power
system by using generators or renewable energy [4], i.e. solar energy [5]. But many important

International Journal of Instrumentation and Control Systems (IJICS) Vol.2, No.4, October 2012
2
devices and chip components of a BTS demand for stable temperature and voltage without
instantaneous breakdown and wide range of fluctuation [6]. Early detection of overheating and
proper handling of such situation in a BTS room is really essential [7] to avoid deterioration and
faulty components. To solve the power problem, now-a-days most of the BTS rooms are installed
with a diesel generator [8] and 48 volt battery backup. So they alternate the source like they use
generator for 6 hours and battery for next 6 hours to fullfil their power requrements with the help
of a controlling device called VTMS. And temperature is also maintained in a certain level by
tracking the temperature with VTMS which provides an alarm for an overheating environment of
BTS. So Voltage and Temperature Monitoring System (VTMS) is a micro-processor based digital
programmable device, designed with integrated systems [9] [10]. It is used to control the whole
power distribution environment by monitoring 48 volt battery voltage level and temperature of a
BTS room, synchronizing and maintaining the supply among PDB, Generator and 48 volt battery
supply and also by generating some important alarm as per required.
2. PROPOSED SYSTEM
The system contains a temperature sensor, a multi turn 5 kilo ohm resistor to adjust the battery
voltage level and some relays to generate different alarms and also to sense the mains fail and low
fuel condition. The whole system is controlled by a PIC microcontroller 16F877A. It senses
whether the PDB is available or not if not then takes different decisions, synchronize the
operation of generator and battery and give some alarms as per logic provided. The overall
system is shown in Fig 1.
Figure 1. System overview

International Journal of Instrumentation and Control Systems (IJICS) Vol.2, No.4, October 2012
3
3. SYSTEM DESIGN
The design steps and working principles of the system is organized into two different units like
Hardware unit and Software unit. Hardware unit includes controller unit, power supply section,
reset section, display section, sensor unit, and battery voltage monitoring system and alarm
section. Software unit includes the compiler to build the assembly program used in PIC
microchip.
3.1 Hardware design
3.1.1 Controller unit
The control module is built with the microcontroller IC. The central controller is Microchip
PIC16F877A. Microcontroller is one of the ways of the evolution of microprocessor. It consists
of a microprocessor, RAM, EEPROM or EPROM, I/O capacities, ADC, timer, interrupt [11]
controller and embedded controller. The microcontroller chip has the versatility to sense inputs
and control outputs in the devices. PIC 16F877A is an upper range and 16 series low cost 8 bit
microcontroller [12] [13]. It consists of 33 I/O (Bi directional lines) with 25mA current in per pin.
It also has 5channel built-in A/D converter [14] and serial communication [15].
3.1.2 Power supply section
All the BTS rooms contain rectifier which provides 48 volt DC . So it is necessary to convert this
48 volt DC to 5 volt DC which is not generally possible wihout any SMPS(Switch Mode Power
Supply) [16] [17] [18]. So a small power supply is developed for these BTS room products and it
is common part for all controller of BTS. It can also be defined as a small version of SMPS.
Figure 2. Power supply section of VTMS
3.1.3 Reset section
It is the most important part of this whole controller. Because it is working as an external
watchdog timer [19] for the microcontroller. BTS room is full of thermal noise [20]. So the

International Journal of Instrumentation and Control Systems (IJICS) Vol.2, No.4, October 2012
4
possility of getting hung is so much, that it is necessary to set up a portion in the main circuit to
watch the microcontroller periodically. So, if the main controller gets hung then the reset circuit
will recover it from this condition. The main work is done here by CD4047 IC [21] wihch is a
CMOS monostable/astable multivibrator [22] [23]. This IC is edge triggerd which is the most
significant quality of it.
3.1.4 Display section
For display section a 4x20 line LCD (Liquid Crystal Display) is used. LCD is now a very
common choice for graphical and alphanumeric displays. Generally LCD is a high contrast
control module with a 4-bit or 8-bit data bus and built in temperature control module [24] [25].
\
Figure 3. 4X20 Line LCD
3.1.5 Sensor section
LM35DZ is used here as a temperature sensor to measure the room temperature. It is a linear
device or it provides linear data. The LM35 series are precision integrated-circuit temperature
sensors, whose output voltage is linearly proportional to the Celsius (Centigrade) temperature
[26] [27] [28]. The calculation of temperature from the sensor is shown in equation 1.
Temperature = Voltage level in ADC0 (AN0)/2 …………………………………………..Eqn.1
Figure 4(a). LM35DZ[5] Figure 4(b). Connection Diagram of LM35DZ[5]
3.1.6 Battery voltage monitoring system
Battery voltage level monitoring [29] is one of the important part of this device. So we can
monitor the battery voltage level of a BTS room by the given circuit. For the precise adjustments

International Journal of Instrumentation and Control Systems (IJICS) Vol.2, No.4, October 2012
5
of voltage a 5kohm multiturn is used. Multiturn trimmers are suitable for applications that
require fine resistance adjustment [30] [31]. Battery voltage and its decimal value calculation are
provided in equation 2 and equation 3 and total battery voltage calculation is provided in equation
4.
Figure 5(a). Battery Voltage Monitoring section Figure 5(b). 5kohm multiturn
Battery Voltage (Integer) = Voltage level in ADC1 (AN1)/16
………………………………………… Eqn.2
Decimal value of Battery Voltage (Integer) = {(ADC1 MOD 16) * 10}/16
…………………………... Eqn.3
Total Battery voltage = Battery Voltage (Integer) + Decimal point (.)+ Decimal value
(Integer) ….. Eqn.4
3.1.7 Mains fail and Low fuel sense
For mains fail and low fuel sensing this controller uses two extra relays and also some security
section which keeps the microcontroller away from noise and any other unwanted circumstance.
Both those relays are controlled from the ATS (Auto Transfer Switch) and Fuel tank switch
shown in Fig 6.
Figure 6. Mains fail and Low fuel sense

International Journal of Instrumentation and Control Systems (IJICS) Vol.2, No.4, October 2012
6
3.1.8 Auto Bypass
It is a special feature of VTMS. If because of any unexpected reasons the controller shuts down,
it will automatically turn the generator on for the safety purpose of BTS room.
3.1.9 Alarm section:
This whole device is designed with six alarms. They are : (1) Mains fail, (2) Low fuel , (3) Genset
on load, (4) High temerature, (5) Genset Fault and (6) Service hour alarm. These six alarms are
given by the main controller to the alarm box of the BTS room through a relay contact which is
shown in Fig 7.
Figure 7. Alarm Section
3.2 Software design
3.2.1 MPLAB v 8.40
In this system MPLAB v8.40 is used to develop the program for PIC microchip. This compiler
consists of Hitech C as well. So this compiler can be used to program in C language. Here the
program is divided into fifteen macros. The main macro controls the whole program. There are
eight macros to show some certain lines in the LCD. Two macros are used to measure the ADC
value of temperature and battery voltage. Other three macros are designed to maintain the overall
operation of the controller. Other three macros are used to display some special conditions like
the setting option and the preset values.

International Journal of Instrumentation and Control Systems (IJICS) Vol.2, No.4, October 2012
7
3.2.2 Flow Chart
Flow chart shows whole logic of VTMS controller. This full logic is implemented in the main
controller IC.

International Journal of Instrumentation and Control Systems (IJICS) Vol.2, No.4, October 2012
8
4. RESULT:
The result shows the complete controller in fig 8(a). This is the complete product and it is also
tested in the real time environment. Fig 8(b) shows the ports to connect the wires coming from
alarm box and also from generator. This figure shows the multiturn of battery voltage monitoring
section is kept in such a way that battery voltage can be calibrated for showing in the LCD. This
figure also shows the temperature sensor position. In fig 8(c) the LCD output is shown and in fig
8(d) the indicator LED and their names are shown.
Figure 8(a). VTMS full product Figure 8(b). VTMS Connection Ports and
Temperature Sensor
Figure 8(c). VTMS LCD display Figure 8(d). Fault indicator LED
5. CONCLUSION:
The reason and the actual motivation toward this work is to build a quality product which
provides a full support to control the operation of the generator and bring synchronization
between the battery and generator according to the PDB supply in BTS room. For the safety of
the equipment of BTS room it is also necessary to control the temperature which is monitored by
using VTMS. So it is a complete package for a BTS room to not only maintain the proper power
system for BTS but also monitor the temperature for the safety of sophisticated equipments of
BTS room. The manufacturing cost of VTMS is estimated to be 29 USD which is really cost
effective.

International Journal of Instrumentation and Control Systems (IJICS) Vol.2, No.4, October 2012
9
REFERENCES
[1] Worst ever power crisis in Bangladesh, 28 November, 2011[online]. Available:
http://www.weeklyblitz.net/1497/worst-ever-power-crisis-in-bangladesh.
[2] Meah, K., Sadrul Ula, A.H.M., Kearns, J., Vaisakh, K., Short and medium term solutions for the
current electricity crisis in Bangladesh: Power and Energy Society General Meeting, 2010 IEEE, pp:
1 – 8.
[3] Ziauddin Ahmed, Electricity Crisis of Bangladesh: Result of Organizational Inefficiency? : Energy
and Environment Research, 2011, pp: 12-23.
[4] Chowdhury, S.A. Roy, V. Aziz, S., Renewable energy usage in the telecommunication sector of
Bangladesh: Prospect and progress, in: 1st International Conference on the Renewable energy usage
in the telecommunication sector of Bangladesh: Prospect and progress, 2009, pp: 1-5.
[5] Sarker, M.J. Islam, S. Zaidi, Bringing Solar power solution to the telecom sector of Bangladesh:
International Conference on Emerging Trends in Electrical and Computer Technology (ICETECT),
2011, pp: 190-195.
[6] Nazlia Omar, Mohd. Faizal Ismail, Rozli Zulkifli, Rosilah Hassan, Development of a Real-Time
Temperature and Voltage Monitoring System for Semiconductor Devices: European Journal of
Scientific Research, 2009, pp: 168-177.
[7] Chiueh, H., Choma, J. and Draper, J., Implementation of a Temperature Monitoring Interface Circuit
for PowerPC Systems: Proceedings of the 43rd Midwest Symposium on Circuits and Systems,
Lansing MI, USA. 2000 , pp: 98-101.
[8] R.Surendra, B.Karunaiah, Murali Mohan K V, POWER MANAGEMENT OF CELL SITES:
International Journal of Computer Technology and Application, 2012, pp: 5-8.
[9] Voltage & Temperature Monitoring System, 30 October, 2011, [online]. Available:
http://liveoutsource.com/pages/voltage-and-temperature-monitoring-system.
[10] Voltage & Temperature Monitoring System, 30 October, 2011, [online]. Available:
http://www.powertech-bd.com/voltage_temperature.html.
[11] Chin-Pao Hung, Wei-Ging Liu, Hong-Jhe Su, Jia-Wei Chen, and Bo-Ming Chiu, PIC-Based Multi-
Channel PWM Signal Generation Method and Application to Motion Control of Six Feet Robot Toy:
INTERNATIONAL JOURNAL OF CIRCUITS, SYSTEMS AND SIGNAL PROCESSING, 2009,
pp: 73-81.
[12] PIC16F87XA Data Sheet: 28/40/44-Pin Enhanced Flash Microcontrollers, © 2003, Microchip
Technology Incorporated.
[13] PIC Tutorial Hardware- PIC Vietnam, 30 October, 2011, [online]. Available:
http://www.picvietnam.com/download /Nigel%tutorial.pdf
[14] B. Murmann, A/D Converter Trends: Power Dissipation, Scaling and Digitally Assisted
Architectures: www.ieee-cicc.org/best_paper.
[15] Chetan Patil, Development of a Simple Communication Protocol for Microcontrollers (SSCPM):
International Journal of Scientific and Research Publications, 2011, pp: 1-6.
[16] SMPS, 15 December 2011, [online]. Available: http://en.wikipedia.org/wiki/SMPS
[17] Richard Francis, Marco Soldano, A New SMPS Non Punch Thru IGBT Replaces MOSFET in SMPS
High Frequency Application: presented at APEC 03, International Rectifier.
[18] Xiang Luo, Du, Y., Xinghua Wang, Transient responses of switching mode power supplies under a
lightning surge: Industry Applications Society Annual Meeting (IAS), 2011 IEEE, pp: 1-8.
[19] Meenakshi Bheevgade, and Rajendra M. Patrikar, Implementation of Watch Dog Timer for Fault
Tolerant Computing on Cluster Server: World Academy of Science, Engineering and Technology 38
2008, pp: 265-268.
[20] Kenji Natori and Nobuyuki Sano, Scaling limit of digital circuits due to thermal noise: Journal of
Applied Physics, 1998.
[21] HEF4047B, “MSI Monostable/astable multivibrator” 21 January 2012, [online]. Available:
ics.nxp.com/products/hef/datasheet/hef4047b.pdf
[22] Del Re, S., De Marcellis, A., Ferri, G., Stornelli, V., Low voltage integrated astable multivibrator
based on a single CCII: Research in Microelectronics and Electronics Conference, 2007, pp: 177-180.

International Journal of Instrumentation and Control Systems (IJICS) Vol.2, No.4, October 2012
10
[23] Tuwanut, P. Koseeyaporn, J. Wardkein, P, A Novel Monostable Multivibrator Circuit: TENCON
2005 2005 IEEE Region 10, pp: 1-4.
[24] Matrix multimedia E-Blocks, 2011, [online]. Available: http://www.matrixmultimedia.com/E-Blocks
hardware .php
[25] LCD MODULE 4x20 - 3.73mm, 21 January 2012, [online]. Available: http://www.lcd-
module.de/eng/pdf/doma/dip204-4e.pdf
[26] LM35DZ, 10 December 2011, [online]. Available: http://www.alldatasheet.net/datasheet-
pdf/pdf/8875/NSC/LM35DZ.html
[27] Cuihong Liu, Wentao Ren, Benhua Zhang, Changyi Lv, The application of soil temperature
measurement by LM35 temperature sensors: International Conference on Electronic and Mechanical
Engineering and Information Technology (EMEIT), 2011, pp: 1825-1828.
[28] Mark Muyskens, An Integrated-Circuit Temperature Sensor for Calorimetry and Differential
Temperature Measurement: Journal of Chemical Education, 1997.
[29] S. N. Patil, Sangmeshwar S. Kendre, Dr. R. C. Prasad, Battery Monitoring System using
Microcontroller: International Journal of Computer Applications, 2011, pp: 11-14.
[30] Multiturn vs. Single-turn, 10 December 2011, [online]. Available:
http://www.bourns.com/pdfs/bourns_mt_vs_st_apno.pdf
[31] Kuhn W.B., Ibrahim N.M., Analysis of current crowding effects in multiturn spiral inductors: IEEE
Transactions on Microwave Theory and Techniques, pp: 31- 38.
AUTHORS
Sadeque Reza Khan received B.Sc. degree in Electronics and Telecommunication
Engineering from University of Liberal Arts Bangladesh and continuing his M.Tech in
VLSI from National Institute of Technology Kernataka (NITK), India. Currently he is in
study leave from his Institution where he was working as a lecturer in the department of
Electrical and Electronic Engineering in Prime University, Bangladesh. His research
interest includes VLSI, Microelectronics, Control System Designing and Embedded
System Designing.
Siddique Reza Khan is a Computer Science Engineer from Military Institute of
Science and Technology (MIST) under Dhaka University. His Research field covers
Artificial Intelligence and Robotics. He also seeks some of his interest in control
system designing.
Arifa Ferdousi received B.Sc. and M.Sc. degree in ICE from University of Rajshahi,
Bangladesh, in the year of 2007 and 2009 respectively. Currently she is working as a
lecturer in the department of CSE in Varendra University, Rajshahi, Bangladesh. Her
research interest includes electronics system designing, OFDM, Advanced LTE Wi-Max
and Bangla speech recognition system using Neural Network. She is the member of
Bangladesh Electronic Society (BES).