This paper describes the various options of energy conservation methods to enhance the energy efficiency of transformers. The energy economics of using low loss core is also studied and given the results in this paper. The load management of distribution transformers have reduced the energy losses considerably in industries. In this paper, a detailed computer based evaluation of energy losses due to off-design operation and size mismatch of transformers, unbalanced secondary load, low power factor on the secondary are discussed for thermal power stations and process industries. Automation of transformer management is described as it can lead to considerable saving in energy. The energy conservation measures for distribution transformers have reduced the transformer losses by 10 – 15 % in industries.

1. Enhancing Energy Efficiency of Distribution Transformers through Energy Conservation Techniques
IRJPEE
Enhancing Energy Efficiency of Distribution
Transformers through Energy Conservation Techniques
Rajashekar P. Mandi
Director, School of Electrical and Electronics Engineering, REVA University, Bangalore, India
E-mail: dir.eee@reva.edu.in
This paper describes the various options of energy conservation methods to enhance the energy
efficiency of transformers. The energy economics of using low loss core is also studied and given
the results in this paper. The load management of distribution transformers have reduced the
energy losses considerably in industries. In this paper, a detailed computer based evaluation of
energy losses due to off-design operation and size mismatch of transformers, unbalanced
secondary load, low power factor on the secondary are discussed for thermal power stations and
process industries. Automation of transformer management is described as it can lead to
considerable saving in energy. The energy conservation measures for distribution transformers
have reduced the transformer losses by 10 – 15 % in industries.
Keywords: energy efficiency, all day efficiency, eddy current losses, winding losses, load factor,
INTRODUCTION
The present total installed power generation capacity in
India is 228.72 GW, out of which 44 % of the energy is
being used by industries. The estimated energy loss in
transformers is 520 MW in industrial system (CEA, 2013,
Growth of Electricity Sector in India from 1947 to 2013).
Electrical energy is the most popular form of energy being
used as the main driving force in industrial units and power
stations due to its versatility, easy to use & less pollution
(Energy conservation in India (1983), Energy conservation
bulletin, Tata Energy Documentation and Information
Centre, 1983). The electrical energy for industrial sector
accounts for about 50 % of total energy generated. Indian
industries consume about 25 % more electrical energy for
the same level of production as compared to the advanced
countries due to hesitation in technology up-gradation,
obsolete equipment, higher line losses, inadequate
capacitive power compensation, poor quality of power
supply, etc.
The electrical distribution network in many industries were
extended in an ad hoc manner to provide power supply to
new equipment with a minimum capital cost, resulting in
increased network losses and poor-quality power supply.
This had overloaded the transformers industries.
The transformers are the simple electrical equipment that
transfer the power from voltage level to other voltage i.e.,
either step up or step down. This equipment is robust and
sturdy which does not have any moving parts.
Transformers require least maintenance compared to
other electrical equipment. Due to the advancement in
transformer core technology, new low loss transformers
introduced.
The losses in transformers account for 3.6 % of total
auxiliary power in a typical 210 MW plant and are in the
range of 5 % to 16 % in process industries. Thus, due to
acute shortage in power, it is essential to conserve the
energy through minimizing the transformer losses by
design up-gradation, use of low loss material, improved
secondary load power factor, minimizing the voltage and
load unbalance, suppressing the harmonics, use of better
quality of oil, etc. (Rajashekar P. Mandi et al., 2012).
Transformer losses
These losses are mainly due to iron losses and winding
losses.
International Research Journal of Power and Energy Engineering
Vol. 3(2), pp. 104-111, November, 2017. © www.premierpublishers.org, ISSN: 3254-1213x
Conference Paper

2. Enhancing Energy Efficiency of Distribution Transformers through Energy Conservation Techniques
Mandi RP. 105
A. Iron losses
The iron losses account for 1.77 - 3.85% of total input
energy in an industry. These losses are mainly eddy
current and hysteresis losses. The increased iron losses
are due to idle charging, oversizing, use of inferior core
material and harmonics in the distribution system, etc.
Table I gives the core losses for different types of cores
used in transformers.
TABLE I. THE CORE LOSSES FOR DIFFERENT
GRADES OF TRANSFORMER CORES.
S/No Type/grade Thickness,
mm
Core loss at flux
density of 1.7 T,
W/kg
01 M4 0.27 1.22
02 MOH 0.30 1.01
03 ZH 100 0.27 0.96
04 ZDKH 0.23 0.84
05 Metal glass alloy
SA1
0.025 0.31
It can be seen from the table that the metal glass
(Amorphous) cores will reduce the core loss by about 75
% and the cost of the metal glass core transformer will be
1.6 to 2 times (Hitachi, ‘Catalogue on Hitachi Amorphous
Core Transformers’, Hitachi Industrial Equipment Systems
Co. Ltd., Singapore). The Iron losses are divided into a)
hysteresis losses & b) eddy current losses. Hysteresis
losses are those which are inherent to magnetic fields. An
empirical relation for hysteresis losses is given by
(Sawhney A.K., 1990):
)1(.. 6.1
max WfBkW hh 
where Kh is a constant dependent on the material used, f is
frequency in Hertz and Bmax is maximum flux density in
wb/m2.
Hysteresis losses mainly depend on applied voltage and
frequency. If the voltage and frequency is high, the
hysteresis losses will be more. But these losses mainly
depend on the type of material used. The present new
material (Amorphous) available in the market is having less
hysteresis loss.
Eddy current losses occur because the magnetic core
material itself consists of material that conducts electricity.
As voltages are induced in the material by alternating
magnetic fields, currents called eddy currents are
produced. An approximate expression for these losses is
given by:
)2(... 222
max WtfBkW eh 
where Ke is a constant dependent on the material and t is
thickness of material.
These eddy current losses are more for the harmonic
prone areas where the higher order frequencies are
available in the system voltage. The possibility of
transformer core failure is more in harmonic prone area.
These core losses play a major role in industrial system
and power stations where the loading on these
transformers will be less. All these transformers have to be
either idle charged or loaded at partially cause more losses
in core because core losses depend on the applied voltage
and frequency and not directly depend on the load carried
through transformers (Rajashekar P. Mandi and
Udaykumar R Yaragatti, 2014).
The suggested measures are:
i. The stand-by transformers may be de-energised on
primary side.
ii. Generally industrial distribution transformers are
designed based on the all day efficiency of transformer
and lower loading on these transformers cause more
core losses.
iii. The loading on transformer in industries is often in the
range between 10 - 30 % (low load factor). Wherever
more number of transformers are installed and are
working at low load factors, it is economical to shift all
the load on to a single or multiple transformers without
increasing the transformer load factor to above 65 - 70
%.
iv. The suppression of harmonics in the distribution will
reduce the eddy current and hysteresis losses.
B. Winding losses
The winding losses in the transformers are in the range of
0.25 - 1.65 % of total energy in an industry. The increased
winding losses are due to poor power factor, load
unbalance, winding temperature and harmonic currents on
the secondary (Say M.G., 1983).
The poor power factor will reduce the capacity of the
transformer. The improved secondary power factor will
reduce the winding losses and enhance the transformer
capacity. The unbalanced load on secondary causes the
reduction in transformer capacity. A load unbalance of 50
% will reduce the transformer capacity approximately by
14.5 %.
The increased winding temperature causes the increased
losses. The winding temperature may increase because of
inadequate cooling provided by oil i.e., sludge formation in
the oil, more acidity content of oil, presence of dissolved
gases in the oil, etc. Fig. 1 shows the local cooling
technique used by providing desert coolers in a sub-station
to maintain the transformer winding temperature below its
trip limit. Fig. 2 gives the view of transformer is cooled by
providing the water just below the transformer base. The
current harmonics increase the RMS value of the current,
which will increase the winding losses. These losses can
be tapped by suppressing the harmonics with the help of
filters.

3. Enhancing Energy Efficiency of Distribution Transformers through Energy Conservation Techniques
Int. Res. J. Power Energy Engin. 106
Fig. 1. View of Cooling of Transformer by using desert
coolers r base
Fig 2. View of cooling Transformer by using desert coolers
EXPERIMENTAL RESULTS AND DISCUSSIONS
The transformer efficiency and the factor affecting the
transformers efficiency are discussed below:
A. Voltage variation and unbalance
Unbalanced incoming voltage will reduce the capacity of
transformer and cause more unbalanced load. Due to low
incoming voltage, the efficiency of the transformer
decreases (G.L. Dua, 1996). Generally, distribution
transformers are provided with off-load tap changers to
maintain the voltage at transformer secondary. The off-
load tap changers are provided with either 5 taps or 7 taps.
In 7 tap changers, the middle tap 4th is 1:1 ratio, the higher
tap numbers i.e., 5 or 6 or 7 will increase the secondary
voltage when the primary voltage is lower than rated value
whereas lower taps i.e., 1 or 2 or 3 will reduce the
secondary voltage in-case of primary voltage is higher
than rated value. The voltage step between each tap is
2.5% of secondary rated voltage. Thus, 7 tap off load tap
changer will provide voltage variation of ±7.5%. The
sensitivity of efficiency to voltage is more pronounced at
lower power factors i.e., below 0.90. When the power
factor is above 0.90, the variation in efficiency offered by
voltage is less.
Case study 1: In a case study in an industry, the 500 kVA
transformer (provided with off load tap changer of 7 taps)
secondary voltage was measured during peak hour was
about 380 V and the transformer tap was middle at 4. The
computed transformer efficiency at an average load factor
of 52% was 98.58%. The transformer tap position was
increased to 7 by de-energising and again charged the
transformer. The voltage was improved to about 400 V on
secondary side with the same load factor of 52%. The
transformer efficiency is computed as 98.65% i.e., an
increase of about 0.07%. The reduction of power loss in
500 kVA transformer is 0.19 kW. The saving in transformer
winding loss by changing the transformer tap is computed
as:
)3(
100
1
22
1
2
WW
LF
V
V
L Ctaploss 





















Where V1 is the present transformer secondary voltage in
V, V2 is the voltage after changing the transformer tap in
V, LF is the load factor of transformer in % and Wc is the
transformer winding loss at full load in W.
The higher secondary voltage improved the illumination
level by about 10% and also enhanced the performance of
process end-use equipments.
B. Harmonics
The effects of harmonic currents are copper loss due to
circulating currents, increased core loss and interference
magnetically with communication circuits and protective
gear (Ramakrishnaiah R, 1996). The effects of harmonic
voltages are increased dielectric stresses, electrostatic
interference with communication circuits and resonance
between the inductance of the transformer windings and
the capacitance of a feeder to which they are connected
(Ned mohan and Girish R Kamath, 1997). The voltage total
harmonic distortion (THD) was measured about 7.4 % in
an industry. But as per IEEE 519-1992, the voltage THD
should be below 5 % and for special applications and
critical loads it should be below 3 % for the system voltage
up to 69 kV. The harmonics will reduce the capacity of
transformers up to about 50 % and these can be
suppressed by using harmonic filters (Rajashekar P.
Mandi and Udaykumar R Yaragatti, 2016).
C. Load unbalance
Generally, in an industry the load between 3-phases must
be balanced but due to various reasons like providing
power to single phase and two-phase loads, dissimilar
loading of 3-phases, difference in power factor in 3-
phases, etc., causes load unbalance in distribution
system. This un-balanced load on transformer secondary
increases the transformer loss as well as reduce the
capacity of transformer as compared to balanced load.

4. Enhancing Energy Efficiency of Distribution Transformers through Energy Conservation Techniques
Mandi RP. 107
Case study 2: In a case study in Thermal power plant, the
loading of lighting transformers is studied. Table II gives
the current in three phases, load unbalance at primary &
secondary side of transformer ( / Y connection) (100 kVA,
0.433/0.433 kV) in a power station. The load unbalance on
secondary is in the range of 5.08 % and 32.45 % and the
load unbalance at primary side is 18.44 % and 82.58 %.
The increased loss due to load unbalance is 548
kWh/month. The flow of unbalanced current in secondary
increased flow of current in primary windings. The
reduction in load unbalance below 3 % by distributing the
single-phase lighting loads equally on all three phases
reduces the energy losses in transformer and network
losses.
TABLE II. MEASURED CURRENT AND COMPUTED
LOAD UNBALANCE AT LIGHTING TRANSFORMERS.
Particular
Primary current,
A
Secondary
current, A
Load
unbalance,
R Y B R Y B %
Tr. No. 23 12.5 11.4 12.3 7.8 9.8 6. 8 20.2
Tr. No. 43 12.6 13.8 13.0 6.7 11.7 7.1 37.8
Tr. No. 33 34.5 28.5 37.1 35.2 25.2 32.3 18.4
Tr. No. 26 27.0 28.4 21.7 18.1 32.2 16.9 43.7
Tr. No. 27 23.5 29.0 24.2 17.8 26.1 22.8 19.9
Tr. No. 52 5.8 6.4 6.7 1.28 2.3 1.1 45.8
Tr. No. 29 52.4 44.9 45.8 48.9 49.8 33.3 24.3
Tr. No. 60 12.4 12.3 9.1 6.4 6.2 8.3 18.5
Tr. No. 74 8.0 10.2 7.7 1.1 8.2 7.8 81.1
Tr. No. 55 16.7 13.9 15.2 14.5 13.0 10.2 18.8
Tr. No. 35 15.1 12.2 12.0 12.1 13.1 3.2 66.2
D. Power factor
The power factor in industries was varying between 0.70
to 0.85. At poor power factor of secondary load, the
transformer efficiency is low. Fig. 3 gives the efficiency of
transformer with improvement in power factor for 500 kVA
transformers. The efficiency for 500 kVA transformer (load
factor: 35%) is increased from 97.6 % to 98.5 % by
improving the power factor from 0.70 to about 0.98. This
had reduced the energy consumption of 324 kWh/month
and the demand saving was 50 kVA. The investment is Rs.
1.50 lakhs (125 kVAR) and the payback period with
considering the total demand saving at network is 13
months which is economically feasible solution.
Fig. 3. Variation of efficiency with load factor.
Case study 3: In a case study at power station, the power
factor measured at secondary of Lighting transformers in
each phase are in the range of 0.06 and 0.93 (Table III).
The lower power factor causes more flow of current in the
transformer winding that increased the losses in
transformer. The installation of switchable single phase
capacitor banks (360 kVAR) at secondaries of
transformers lead to energy saving of 892 kWh/month and
network demand saving of 25 kVA. The investment of Rs.
4.00 lakhs had a payback period of 40 months.
E. Load factor & transformer management
The overloading of transformer increases the hot spot
temperature of winding. The rate of deterioration increases
exponentially with temperature rise. This will reduce the
transformer life drastically.
Case study 4: In a case study in an industry, there were
24 transformers of different ratings installed in six sub-
stations. Table IV gives the load factor and all-day
efficiency of transformers. The transformers are loaded
between 6.4 % and 39.6 %. The load factors were very
less. The de-energisation of low loaded and standby
transformers, and charging any one of the transformers in
each group reduced the energy consumption of 24.58
MWh/month in an industry. The changeover of transformer
charging may be programmed cyclically by PLC based
automatic controller or manual in 4-6-day cycle to avoid
increase of moisture content of transformer oil.

5. Enhancing Energy Efficiency of Distribution Transformers through Energy Conservation Techniques
Int. Res. J. Power Energy Engin. 108
Table IV. energy savings through transformer management
Sl. No. Particular
Present LF, %
Present
all day , %
Group New LF, %
New
all day , %
Energy saving, kWh/
month
01 S/S 1 TR.1 14.5 90.2 -
02 S/S 1 TR.2 06.3 88.1
03 S/S 1 TR.3 03.3 86.1 A 40.3 98.5 6,872
04 S/S 1 TR.4 10.6 90.3
05 S/S 1 TR.5 05.6 89.1
06 S/S 2 TR.1 06.4 89.1
07 S/S 2 TR.2 24.7 89.7
08 S/S 2 TR.3 17.7 90.1 B 44.0 98.3 3,241
09 S/S 2 TR.4 03.6 75.1
10 S/S 3 TR.1 15.8 90.2
11 S/S 3 TR.2 17.9 91.4 C 33.70 92.1 1,215
12 S/S 3 TR.3 07.1 87.2
13 S/S 3 TR4 09.1 90.3 D 40.2 97.8 2,029
14 S/S 3 TR.5 24.0 91.1
15 S/S 4 TR.1 Stand-by
16 S/S 4 TR.2 35.5 96.8 E 41.9 98.8 3,560
17 S/S 4 TR.3 06.4 85.3
18 S/S 5 TR.1 Stand-by
19 S/S 5 TR.2 39.6 95.3 F 39.6 95.3 2,133
20 S/S 5 TR.3 Stand-by
21 S/S 5 TR.4 33.1 94.8 G 40.8 97.8 3,638
22 S/S 5 TR.5 07.7 87.3
23 S/S 6 TR.1 Stand-by
24 S/S 6 TR.2 38.2 97.8 H 38.2 97.8 1,893
The transformer efficiency will be maximum when iron
losses are equal to winding losses. Generally, the iron
losses and winding losses will be equal at load factor of 45
to 55 % in case of distribution transformers. If the iron
losses and winding losses are equal at 50 % load factor.
Till the transformer load factor increases to 50 %, the iron
losses will be dominant and above 50 % load factor, the
winding losses will be dominant. In case if two
transformers are sharing the load, it is economical to
operate only one transformer while de-energizing other
transformer till the load factor transformer reaches to about
70 %. If the load factor is more than 70 %, it is economical
to operate both transformers in parallel to reduce winding
losses. In order to optimization of number of transformers
to be energized following relation is developed. The
number of transformers to be charged in a bunch of
transformer is computed and is given in Table V.
)4(2
2
i
C
r
T
P
P
n
P
P
X 
Where PT is the total demand in kVA, Pr is the rating of
transformer in kVA, Pi is the No-load losses in kW, Pc is
the Load losses of transformer in kW and n is the No. of
transformers present.
Table V. Transformers to be charged with different values of X
Numbers to be charged Value of X
1 X  2
2 2  X  6
3 6  X  12
4 12  X  20
5 30  X  30
It can be seen from the Table V that if X is between 2 and
6, the number of transformers to be charged is 2 numbers
to optimize the total transformer losses.
Case study 5: In a thermal power plant, there are two
station transformers (charged from the grid, 220 kV / 6.6
kV) of 50 MVA ratings for two 210 MW units and two unit
auxiliary transformers (charged from the individual 210
MW generator voltage, 15.7 kV / 6.6 kV) of 16 MVA rating
for 210 MW plant. The auxiliary load is about 18 to 19 MW.
During a cold start, the entire auxiliary load is handled by
the station transformers. Even if the load on the unit is
increased to full load, the auxiliaries will still be on the
station transformers. Our study indicated that when the
load on each unit is raised above 30 MW, the auxiliary load
can be shifted on to unit auxiliary transformers.

6. Enhancing Energy Efficiency of Distribution Transformers through Energy Conservation Techniques
Mandi RP. 109
F. Oil quality
As the temperature of the transformer oil increases, the
temperature and resistance of winding increases
correspondingly and the transformer efficiency decreases.
The temperature rise should be limited as per B.S.
171:1936. The important physical property i.e., Interfacial
tension, Chemical properties i.e., acidity, sludge content
and water content, and electrical properties i.e., dielectric
strength (breakdown voltage), dielectric dissipation factor
(Tan ) and resistivity are responsible for lower transformer
efficiency.
The electrical properties of transformer oil are important in
its function as an insulator, and their maintenance at an
acceptable level (Table VI) ensures satisfactory equipment
performance, reduces ohmic losses and limits discharge
inception within the oil. To keep higher transformer
efficiency, the oil should have high dielectric strength, high
resistivity and low dielectric dissipation factor. Sludging is
the slow formation of semi-solid hydrocarbons and are
deposited on windings and tank walls. The formation of
sludge is due to heat and oxidation. Experience shows that
sludge is formed more quickly in the presence of bright
copper surfaces. The transformer oil has to be heated in
the presence of oxygen to test the sludge formation. If the
sludge formation is less than the prescribed limit, the oil
has to be changed.
Table VI. Properties of transformer oil.
Particulars Units Limits
Sludge % 0.10
Acidity after oxidation ( max ) mg KOH/G 0.40
Flash point ( min. ) 0
C 140
Viscosity at - 15 0
C cSt 800
Viscosity at 27 0
C cSt 40
Pour point ( max. ) 0
C -30
Break down voltage with 2.5
mm standard gap
Upto 11 kV kV 25
11 - 33 kV kV 30
66 - 220kV kV 40
220kV kV 45
400kV kV 50
Water content ( max.) ppm 5.00
Acidity (neutralization value
(max.)
mg KOH/g 0.03
Dissipation factor (Tan ) (max.)
at 270
C - 0.005
at 900
C - 0.001
Oil density at 270
C kg/m3
890
Due to oxidation of transformer oil produces CO2, volatile,
water soluble organic acids and water. These combination
attack and corrode iron and other metal parts. Oil
conservators are desirable to avoid the condensation of
water soluble acids on the under surface of the tank lid
from which acidic droplets may fall back into the oil.
The deterioration of oil during its working life be retarded
by the use of oxidation inhibitors which are usually of the
phenolic or amino type, convert chain forming molecules
in the oil into inactive molecules, being gradually
consumed in the process. Inhibitors greatly prolong the
phase in the service life of the oil which precedes the onset
of deterioration and during which the acid and sludge
formations are substantially zero.
Modeling of transformers
The transformer losses consist of load losses (85 % of total
losses) and no-load losses (15 % of total losses) in the
ratio of 17 : 3 for a typical distribution transformer (Darshan
Sakpal, 1996)
Table VII gives the load losses in 2 MVA (11/0.433 kV)
transformer. The load losses are grouped into (a) I2 R loss:
Due to winding resistance & the current flowing through
the transformer winding and these losses from about 75 %
of load losses. (b) Stray losses: These are produced by the
leakage flux which cuts the conductors & metallic parts
such as frame, tank, clamping structures, etc., and due to
the circulating current through these metal parts.
Table VII. Load losses in a transformer
S/No Particular Loss, % of load loss
01 I2
R losses 75
02 Stray losses 25
2.1 Winding eddy current losses 6
2.2 Losses in tank, frame, etc.. 2.5
2.3 High current carrying lead
loss
2.5
2.4 Circulating current loss 14
The I2 R losses may be reduced by reducing the resistance
of winding i.e., by increasing the conductor cross section.
The stray losses can be minimized by reducing the
conductor size and increasing the number of conductors in
parallel, increasing the clearances of tank and metallic
parts with conductors and adequate arrangement of inlet
& outlet leads. The load losses also can be reduced by
transposing the conductors such that each conductor cut
the same leakage flux.
The no load losses are those independent of the load.
These are mainly due to eddy current and hysteresis
losses in core. The use of amorphous (metallic glass core)
in place of CRGO core will reduce the no load losses [13].
Table VIII presents the no load losses of transformers for
different core material. It can be seen from the table that
the loss reduction is about 70 % and 76%.
Table VIII. No-load losses for different cores
Rating, No-load losses, W Saving,
kVA CRGO Amorphous %
25 100 30 70
63 180 45 75
100 260 60 77

7. Enhancing Energy Efficiency of Distribution Transformers through Energy Conservation Techniques
Int. Res. J. Power Energy Engin. 110
Automation of Transformer network
In an industry where the distribution system is widely
spread over, it is emphasized to introduce the automated
distribution network control system [14] which contains
Power Monitoring Devices (PMD), power transducers,
CTs, PTs, Programmable logic controllers (PLC),
Supervisory Control and Data Acquisition (SCADA),
application software, etc.
The PMD works based on the input data from power
transducers that have the ability not only to gather and
analyze the power system data but also the added
functionality of remote status input and control outputs for
peripheral functions such as Alarm, Trip and Control
action.
These devices when integrated with PLCs and SCADA
based computer workstations, will provide very powerful
power monitoring control, protection of power automation
system and along with application software will supervise,
control, collect, analyze and archival of the data.
The application software can offer graphic-based data
displays that can be used for displaying real-time power
data parameters and graphics of the power monitoring
system. This can provide the evaluation of power/energy
input, losses, load factor, all day efficiency, etc., on hourly,
daily, monthly and yearly on the mean value basis. The
critical conditions can be stored and re-viewed whenever
required. The charging and de-energisation of
transformers can also be programmed.
CONCLUSION
Present all India electrical energy loss occurring on
account of transformers - size mismatch and internal
losses in industrial sector is ~ 520 MW. Energy loss due to
voltage variation and unbalance is varying between 1.5 -
6.5 % of total transformer load which can be reduced in the
range of 1.0 - 4.0 % by implementing energy conservation
techniques like installation of regulating transformer on HT
side and appropriate selection of transformer tapping. The
minimization of load unbalance on transformer
secondaries and operational optimization of transformer
reduces the energy losses from 1.5 - 6.5 % of transformer
load to 1.2 - 4.5 %. The improvement of power factor on
secondaries of 500 kVA transformer near to 0.96
enhanced the transformer efficiency from 94.25 - 97.75 %
to 95.5 - 98.7 %. Appropriate sizing of transformer and load
management as suggested in the paper, reduces the
energy loss from 5 - 16 % of the total energy handled by
transformer to 2.5 - 8.2 %. The implementation of overall
energy conservation measures reduces the all India
transformer loss by 35 % of the present loss which works
out to a saving of about 180 MW.
REFERENCES
CEA, 2013, Growth of Electricity Sector in India from 1947
to 2013, website: http//:www.cea.nic.in.
Darshan Sakpal (1996), Computer aided design for energy
efficient transformers, Electrical India, 29th Feb. 1996,
pp. 31-34.
Energy conservation in India (1983), Energy conservation
bulletin, Tata Energy Documentation and Information
Centre, 1983, pp. 13-38.
G.L. Dua (1996), Debut of ultra-energy efficient transformers
in India, Electrical India, 29th
Feb. 1996, pp. 17-18.
Hitachi, ‘Catalogue on Hitachi Amorphous Core
Transformers’, Hitachi Industrial Equipment Systems Co.
Ltd., Singapore, website: http://www.hitachi.com.sg. 4
J. McCarthy (1997), Power monitoring devices: trends in
power automation, Electrical India, 28th
Feb. 1997, pp. 19-
22.
Ned mohan and Girish R Kamath (1997). Active power
filters-Recent advance”, Sadhana, Vol.22, Part 6, pp.
723 - 732.
Rajashekar P. Mandi and Udaykumar R Yaragatti (2014).
Technological advances in distribution transformers.
Electrical Power & Review Magazine, Vol. 2, issues 11,
pp. 39-41.
Rajashekar P. Mandi and Udaykumar R Yaragatti (2016).
Power Quality issues in Electrical Distribution System
and industries. Asian Journal of Engineering and
Technology Innovation, Vol. 2016, issues 3, pp. 64-69.
Rajashekar P. Mandi, S. Seetharamu and Udaykumar R
Yaragatti (2012). Energy Efficiency Improvement of
Auxiliary Power Equipment in Thermal Power Plant
through Operational Optimization. Proc. of IEEE
International Conference on Power Electronics, Drives
and Energy Systems (PEDES), at National Science
Seminar Complex, CSIC, IISc, Bangalore.
Ramakrishnaiah R. (1990). Impact of harmonics and
voltage fluctuation in reactive power problems.
Electrical India. pp. 25 - 27.
Sawhney A.K. (1990). A course in electrical machine
design, Dhanpat Rai and Sons Publications, New Delhi,
pp. 331-451.
Say M.G. (1983), The performance and design of
alternating current machines, CBS Publishers and
Distributors, New Delhi, pp. 64-101.
Vijai Electricals Ltd., Catalogue on Amorphous Core
Transformers, Vijai Electricals Co. Ltd., Hyderabad,
website:http://www.vijaielectricals.com/kb_amorp.html.

8. Enhancing Energy Efficiency of Distribution Transformers through Energy Conservation Techniques
Mandi RP. 111
Accepted 23 October, 2017
Citation: Mandi RP (2017). Enhancing Energy Efficiency
of Distribution Transformers through Energy Conservation
Techniques. International Research Journal of Power and
Energy Engineering, 3(2): 104-111.
Copyright: © 2017. Mandi RP. This is an open-access
article distributed under the terms of the Creative
Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium,
provided the original author and source are cited.