SATURATION IN INSTRUMENT TRANSFORMER
A Thesis
by
AALOKA GOGATE
Submitted to the College of Graduate Studies Texas A&M University-Kingsville in partial fulfillment of the requirements for the degree of
MASTER OF SCIENCE
December 2014
Major Subject: Electrical Engineering ii
ABSTRACT
Saturation in Instrument Transformer
(December 2014)
Aaloka Gogate, B.E., University of Pune
Chairman of Advisory Committee: Dr. Amit Verma
In a power system, high voltages and currents are used for transmission and distribution of power over long distances from generation plant to end users. Instrument transformers transform these high currents and voltages to standardized low and easily measurable values for their easy monitoring and control. This ensures reliable and continuous supply of energy at all times. One of the integral components of the transformer is its magnetic core. This core saturates at fault conditions, causing problems in monitoring and the control of the system. Studying properties of these different magnetic materials helps in understanding saturation phenomenon. In this thesis, different materials were tested to study their saturation with the help of hysteresis curves and better material with higher saturation level was selected for protection application. Higher saturation level ensures that transformers will work reliably in faulty conditions, thus protecting the system.
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TABLE OF CONTENTS
Page CHAPTER I. INTRODUCTION ...... 1
CHAPTER II. INSTRUMENT TRANSFORMERS ...... 3
Current Transformer ...... 3 Voltage Transformer ...... 4
CHAPTER III. MATERIALS USED FOR TRANSFORMER CORES ...... 6
CHAPTER IV. SATURATION IN TRANSFORMER ...... 8
What is saturation? ...... 8 Factors affecting saturation ...... 9 Effect of saturation on current transformers...... 10 Effect of saturation on voltage transformers ...... 11
CHAPTER V. RESULTS ...... 13
Procedure ...... 13
Selection of material ...... 13 Testing ...... 14
Calculation of saturation voltage ...... 20
CHAPTER VI. CONCLUSION ...... 25
CHAPTER VII. FUTURE SCOPE ...... 26
REFERENCES ...... 27
VITA ...... 30
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LIST OF FIGURES Page Figure 1: Types of current transformers
(a) Wound CT (b) Bar-type CT (c) Toroid CT ...... 4
Figure 2: A hypothetical sketch of grain orientation and domain alignment ...... 7
Figure 3: A hypothetical sketch of alignment of domains in
(a) Absence of External Field (b) Presence of External Field ...... 9
Figure 4: Core materials
(Dimensions: 60 x 40 x 25) mm used for studying B-H characteristic ...... 13
Figure 5: A photograph of side view of toroid core ...... 14
Figure 6: A circuit diagram for core testing
showing connections between core, autotransformer, ammeter and voltmeter ...... 14
Figure 7: Core testing panel
(Sr. No. GM/TE/90, Gilbert & Maxwell‟s Electrical Pvt. Ltd., India) ...... 15
Figure 8: B-H curve for M4 material with knee point at 1.44T ...... 19
Figure 9: B-H curve for MOH material with knee point at 1.54T ...... 19
Figure 10: B-H curve for ZDKH material with knee point at 1.58T ...... 20
Figure 11: B-H curve for ZDMH material
showing more linear graph compared to other materials with knee point at 1.61T .....20
Figure 12: A toroid core of voltage transformer with dimensions used for calculating saturation voltage ...... 21
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CHAPTER I
INTRODUCTION
In a power system, high voltages and currents are used for transmission and distribution of power over long distances from generation plant to end user i.e. consumer. Proper monitoring and control of these voltages and currents is necessary for reliable and continuous supply of energy.
Measuring these large values of voltages with regular meters is not feasible. Also, manufacturing large meters for monitoring is impossible, both economically and structurally. Instrument transformers play an important role in monitoring and the control of these values maintaining regular flow of power [1]. Instrument transformers transform high currents and voltages to standardized, low and easily measurable values. These values are accurate representations of the transmission line values in both magnitude and phase [2].
Another important issue is the protection of the system. When a fault occurs on the system, the circuit breaker should open the circuit in order to protect the system from dangerous fault currents. Circuit breakers get the signals from relays that are connected to the secondary side of instrument transformers. Output of the instrument transformer accurately represents the transmission line values. The signals obtained from instrument transformers provide the important information for circuit-breaker operation, under fault conditions. Proper functioning of circuit breakers is important for network reliability and security [3].
One of the integral components of the transformer is its magnetic core. This core saturates at fault conditions, causing problems in monitoring and the control of the system [4]. Saturation is a condition where the transformer fails to transform the voltages and currents proportionally, leading to protection problems. In metering, though saturation helps in protecting measuring devices during fault conditions, accurate measurement of voltage and current values is not
1 possible. In protection application, the accurate representation of the high current level is of extreme importance for correctly operating the fault clearing system. Saturation results in false signals to be sent to relays, which cause a delay in operating time of relays or sometimes even complete failure of operation. Proper selection of a transformer with appropriate dimension, adequate burden on secondary and use of suitable core material may avoid such condition.
Various materials are used for manufacturing cores based on different designs, applications, cost, size and weight of the material. Studying properties of these different magnetic materials will help in understanding saturation phenomenon.
Saturation is not only limited to transformers but also observed in synchronous machines like generators and synchronous motors. This thesis is focused on studying saturation in transformers.
The different materials used for a transformer‟s core are tested to study the saturation with the help of hysteresis curves and better material with higher saturation level is selected for protection application. Higher saturation level ensures that transformers will work reliably in faulty conditions, thus protecting the system [5].
2
CHAPTER II
INSTRUMENT TRANSFORMERS
The task of instrument transformers is to transform high currents and voltages proportionally and in-phase into small current or voltage values for measuring or protection purposes. So, they are either used to measure and record the transmitted power or to feed protection devices. They isolate the connected measuring or protection equipment electrically from the live parts of switchgear. They are designed specifically for use with electrical equipment, such as voltmeter, ammeter, wattmeter, watt-hour meter and protection relay.
There are two types of instrument transformers: Current transformer, and Voltage transformer.
These will be seen in following sections.
CURRENT TRANSFORMER (CT):
The main purpose of a current transformer is to translate the primary current in a high voltage power system to a signal level that can be handled by delicate electronic devices. The devices connected on the secondary side of the transformer are measuring devices, energy integrating instruments, or protective relays. A CT has few turns on its primary winding which is connected in series with the line whose current is to be measured, and a secondary winding has large number of turns to which low range ammeter (0-5A) or relays are connected for measuring or control purpose[6]. Different designs of current transformer based on application are as follows:
(a)Wound current transformers – The primary winding of transformer is connected in series with the conductor whose current is to be measured. The current in the secondary depends upon the turns ratio of transformer.
3
(a) (b) (c)
Fig 1: Types of current transformers (a) Wound CT (b) Bar-type CT (c) Toroid CT (figures (a),
(b) and (c) taken from references [7], [8] and [9] respectively).
(b)Bar-type current transformers – In this, the bus-bar is used as the primary winding. They are insulated from the live parts of switchgear. The transformer is bolted to the current carrying device.
(c)Toroidal current transformers – These do not contain a primary winding. Instead, the line carrying the current runs through a window in the toroidal transformer. Some current transformers are a „split core‟ type transformers that allow it to be opened and installed without disconnecting the circuit.
VOLTAGE TRANSFORMER (VT):
Voltage transformers are used to measure the voltage in the high voltage transmission line and switchgear during normal and fault conditions, thus isolating control circuits from high voltage networks. They transform the voltages to standardized levels for control equipment such as relays and meters. Voltage is stepped down as the number of primary turns is more than the number of secondary turns. The primary side of transformer is connected across the line and low range voltmeter is connected across the secondary winding terminals. In case of protection
4 application, relays are connected to the secondary of the transformer to protect the system from high voltage.
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CHAPTER III
MATERIALS USED FOR TRANSFORMER CORES
The working of transformer depends significantly on its core. The core plays an important role of magnetically transforming energy from one circuit to another. Magnetic properties of each of the material used for manufacturing the core will affect the performance of the core and in turn the overall performance of the transformer. Different materials used for the manufacturing of the core are cold rolled grain oriented steel (CRGO), high permeability (HI-B) Silicon steel, Mu-
Metals (alloys of Ni-Fe) and nanocrystalline materials. When voltage is applied at the primary, some part of primary input is used for magnetizing the core. That part is not transferred to secondary side of the transformer contributing to core loss in terms of heat. This leads to errors in transformer operation. The magnetizing current should be as low as possible for better performance of transformer, which depends on the internal structure of the core. For this, it is important to study grain orientation and alignment of domains in the core [10].
The arrangement and size of grains and the positioning of domains in the core decide the exciting current in the core. The grain is composed of domains. These domains are randomly oriented electrical charges in the absence of electrical field.
In CRGO materials, cold rolling elongates the grain in one direction, and narrows it in the other direction. This helps in reducing losses. The size of the grain in CRGO steel is made bigger to reduce the hysteresis loss. The CRGO has a grain size between 2 mm to 5mm.The grain size of high permeability material is 5 mm to 20 mm. In CRGO, the direction of rolling of the steel is parallel to the alignment of grains. This results in less core loss in the direction of rolling. The
CRGO steel has about 3.2% of silicon, which reduces the eddy current loss.
A hypothetical sketch of grain orientation and positioning of domains is shown in figure below:
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Grain Domains
Fig 2: A hypothetical sketch of grain orientation and domain alignment (figure from reference [11])
To prevent ageing of the steel, CRGO steel is decarbonized and has no more than 0.06% of carbon in its chemical composition. Mu-metals are alloys of iron with varying amount of nickel from 30% to 80%. Nanocrystalline material (FeCuNbSiB) is an alloy of iron, copper, niobium, silicon, and boron with grain size of 10 nm each [11].
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CHAPTER IV
SATURATION IN TRANSFORMER
As discussed in the previous chapter, materials used for manufacturing cores of transformers decide the core saturation level. The saturation level is different for different materials. Before studying saturation in different materials, it is important to study the saturation phenomenon and its effects on CT and VT.
WHAT IS SATURATION?
Domains in the core are responsible for creating alternating flux in the core when external magnetic field is applied i.e. when primary is energized with an AC source. This flux links with secondary producing required output depending on the number of turns of the winding.
Production of flux depends on the domain alignment. In the absence of the external magnetic field, the domains in the core are aligned randomly. The magnetic fields of domains cancel each other resulting in net magnetic field of the material to be zero.
As soon as the external field is applied, the microscopic magnetic dipoles in the iron core start aligning their magnetic field in parallel to applied field. This develops large magnetic field in the core. The stronger the external field, the more the domains align. A point is reached where all the domains are lined up and further increase in applied field does not produce any increase in developed magnetic field, and this is when saturation occurs.
Saturation is a non-linear phenomenon where an increase in applied external magnetic field cannot increase the magnetization of the core further. After reaching the knee point, an increase in magnetic field intensity causes no change in magnetic flux density. The following sketch shows a hypothetical dipole arrangement based on external field:
8
Fig 3: A hypothetical sketch of alignment of domains in (a) Absence of External Field
(b) Presence of External Field (Figure from reference [11]).
If the magnetic field is further increased, it adds to the core losses, heating up the core and damaging it [4].
FACTORS AFFECTING SATURATION
There are various factors which are responsible for causing the saturation condition.
1) Remnant Flux:
Presence of magnetic flux even when the external magnetic field is removed is called remnant flux. Some of the tiny molecular magnets do not return to a completely random pattern when external field is removed. Some dipoles remain in the same aligned position, which results in early saturation. Hence, this residual flux is not desirable for good performance of transformer
[12].
2) Burden on secondary side:
Accuracy Limit Current is the maximum value of current up to which current transformers operate with considerable accuracy. Ratio of accuracy limit current to rated current is known as
Accuracy Limit Factor (ALF) and is given by,
ALF = {(ALV) / [ISec. Rated x (ZCT + ZExt.)]}
9 where,
ALF = Accuracy Limiting Factor for the protection core
ALV = Accuracy Limit Voltage in Volts
I Sec = Rated Secondary current of the protection core, in Ampere
ZCT = Internal Impedance of the CT Secondary winding, in Ohm
Z Ext. = External connected burden impedance, including connecting lead impedance, in Ohms
Here, ALV, Isec. & ZCT are fixed at the time of designing the CT. From the above equation, it is clear that accuracy limit factor and external connected burden are inversely proportional to each other. The lower the connected burden, the higher the ALF and vice-a-versa. The increase in external burden will reduce the ALF causing early saturation. In this case, saturation results in failure of operation of relays. Relays connected to secondary of transformer will not be able to detect high current resulting in damage to the system components. Also, saturation will not take place at a desired level if the external burden on the secondary is below rated burden. Therefore, connecting external burden both below and above rated burden can cause saturation problem in transformer [13].
3) Material used for Transformer Core:
Saturation depends on the internal structure of the material used for core. This structure is different for different materials. Hence, core material that has less number of grains and larger grain dimension will saturate at higher values of flux density, giving better results [5].
EFFECT OF SATURATION ON CURRENT TRANSFORMERS
Saturation greatly affects the performance of current transformers. Based on the application, current transformers are used either for metering or protection. In metering application, metering
10 devices are connected to the secondary side of CT and are used for accurately measuring the current values. The main purpose is to get accurate readings without damaging the device. In case of fault, the current in the primary becomes very high compared to the rated current. The measuring devices are not designed to withstand these high values. The reading shown by measuring CTs is accurate until the current in the primary becomes 125% of the rated value, after which the CTs should saturate in order to protect the measuring device connected on the secondary side of CT. Saturation helps in isolating the device from heavy inrush current. It acts as a` barrier for the flow of current to secondary side, thus protecting the device [3].
On the contrary, when CTs are used for protection purpose, saturation is not desirable. Relays are connected to the secondary side of the protection CT. In case of fault, relays send signals to the circuit breaker, which opens the circuit, thereby protecting the system from high values of current and preventing any damage to the system. If saturation occurs during faulty conditions,
CT will not produce a proportional current in the secondary side, and hence, the relay will fail to send signals to circuit breaker. This will result in damage to the whole system due to high inrush currents flowing through the system, affecting the reliability and stability of the system [14].
EFFECT OF SATURATION ON VOLTAGE TRANSFORMERS
As power demand increases in many parts of the world, power transmission needs to be improved as well. The construction of more power lines may not be the best way as cost for construction of transmission lines is high, and they take considerable time to construct and are subject to severe environmental constraints. The series compensation helps in increasing power transmission through the existing lines. For this, capacitance is injected in transmission line that is used to transfer maximum power to the load [15].
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The capacitance used for series compensation interacts with non-linear inductance. This causes
Ferroresonance. This non-linear inductance is the result of transformer core saturation.
Ferroresonance is an electrical phenomenon that can cause damage to the electrical equipment of power systems by its characteristic steady state over voltages and over currents. High voltage due to Ferroresonance will result in transformer noise, and if it is very high, it will result in a flash over. Ferroresonance is capable of producing sustained over-voltages with peak magnitudes, which is harmful and unsafe for the function of most devices [16].
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CHAPTER V
RESULTS
The experiment to test different transformer core materials to study saturation characteristics was performed at Gilbert and Maxwell‟s Electrical Pvt. Ltd., India.
Saturation was studied by plotting hysteresis curve based on data obtained from the test.
PROCEDURE
1) Selection of material:
The core materials used for testing were different grades of Cold Rolled Grain Oriented (CRGO) steel namely M4, MOH, ZDKH and ZDMH. The size of the core used for testing was (60 x 40 x
25) mm with weight 0.3 kg each. The different cores used for experimental results are shown below:
M4
MOH
ZDKH
ZDMH
Fig 4: Core materials (Dimensions: 60 x 40 x 25) mm used for studying B-H characteristic,
(Gilbert & Maxwell‟s Electrical Pvt. Ltd., India).
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Fig: 5 A photograph of side view of toroid core with dimensions (60 x 40 x 25) mm, (Gilbert &
Maxwell‟s Electrical Pvt. Ltd., India).
2) Testing:
The experimental set-up for testing is as shown in figures 7 and 8:
Fig 6: A circuit diagram for core testing showing connections between core, autotransformer,
ammeter and voltmeter.
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Ammeter (0- 2) A Ammeter (0-20) A
Selector Switch
Voltmeter (0-2) V Voltmeter (0- 20) V
Autotransformer Input 230 V AC
Core
Fig 7: Core testing panel (Sr. No. GM/TE/90, Gilbert & Maxwell‟s Electrical Pvt. Ltd., India)
a. The core testing panel (figure 8) has autotransformer, current and voltage terminals as
well as ammeter and voltmeter.
b. From the selected core types, each core, with suitable number of turns wound around it,
was tested.
c. Auto-transformer was used to gradually apply voltage to the core.Voltage was applied in
increasing intervals of 0.001V. The increase in voltage was observed using panel
voltmeter.
15
d. For each value of voltage, corresponding value of current was observed using ammeter.
e. Initially, voltage and current followed linear relationship. But after a particular point,
small increase in voltage produced large currents in the core, showing non-linear
behavior.
f. This non-linear relationship constituted that the core was saturated.
g. Same procedure was followed for all the core materials.
From the values of voltages and currents obtained from the experiment, the corresponding value of magnetic flux density and magnetic field intensity was found out by using following formulae.
Magnetic Flux Density (B) is given by [19],
…………. (1)
Where,
B: Magnetic field density in Tesla
V: Voltage applied in Volt f: Frequency in Hertz = 50 Hz n: Number of turns of winding
A: Area of core
For the above equation, Area of Core is given by
…………. (2)
Where,
OD: Outer Diameter in cm
ID: Inner Diameter in cm
SF: Stacking Factor
Now, Magnetic Field Intensity (H) is given by
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…………. (3)
Where,
H: magnetic field strength in AT/m
I: Current in Ampere n: Number of turns of winding
L: Mean Length of Flux in meter
Here, Mean Length of Flux (L) can be obtained by,
…………. (4)
Where,
OD: Outer Diameter in cm
ID: Inner Diameter in cm
With the help of above formulae, calculations are done to find values of B and H for corresponding values of voltages and currents.
For M4 material,
1) To find B,
Area of core with dimension (60 x 40 x 25) is
A= [{(6-4)/2} x 2.5]/0.975 …………. (From equation (2))
= 2.5641 cm²
= 0.00025641 m²
Value of B for voltage =0.06 V
B= 0.06/ (4.44 x 50 x 1 x 0.00025641) …………. (From (1))
B= 0.06/0.0569
B= 1.05T …………. (5)
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2) To find H,
Value of L for core of dimensions 60 x 40 x 25 is found out as follows:
Inner Diameter (ID) = 40mm= 4cm
Outer Diameter (OD) = 60 mm=6cm
L= π [(OD + ID)/2] …………. (From (4))
L= π [(6 + 4)/2]
= π (10/2)
= 5π
= 15.7079 cm
= 0.157079 m
Value of H for current = 1.53A
H = (1.53 x 1)/ 0.157079 …………. (From (3))
H = 9.74032 AT/m …………. (6)
(5) and (6) give the values of B and H for corresponding values of voltage and current. Similarly, calculations are done for each of the current and voltage reading for all the materials. Figure 8, figure 9, figure 10 and figure 11 depict B-H curves of M4, MOH, ZDKH and ZDMH materials respectively.
It can be observed from the graphs above that the curve is more linear with higher saturation level for ZDMH material than other materials making it more accurate over other materials. For the same amount of magnetic flux density, the amount of magnetic field intensity required is much less in ZDMH when compared with other materials. Knee points of the materials are
1.44T, 1.54T, 1.58T and 1.61T for M4, MOH, ZDKH and ZDMH respectively. After the knee point, the core starts to saturate.
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B (Tesla) 2 1.5 1 0.5 0 0 200 400 H (AT/m)
Fig 8: B-H curve for M4 material with knee point at 1.44T.
B (Tesla) 2 1.5 1 0.5 0 0 200 400 600 H (AT/m)
Fig 9: B-H curve for MOH material with knee point at 1.54T.
Proper protection can be ensured if transformer operates below the knee point i.e. in the linear region.
19
B (Tesla) 2 1.5 1 0.5 0 0 200 400 H (AT/m)
Fig10: B-H curve for ZDKH material with knee point at 1.58T
B (Tesla) 2 1.5 1 0.5 0 0 200 400 600 H (AT/m) Fig 11: B-H curve for ZDMH material showing more linear graph compared to other materials
with knee point at 1.61T.
CALCULATION OF SATURATION VOLTAGE:
For the values of magnetic flux densities where saturation starts to occur, saturation voltage of transformer with different core materials can be found out. Saturation voltage was found out considering an example of voltage transformer with specifications given below:
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Given:
Voltage Transformer (VT)
VT ratio 415/110 V
Core Size 110 x 70 x 30 (mm)
Number of turns on primary (N1) = 2430
Number of turns on secondary (N2) = 650
Cross sectional area of primary winding= 0.3973 mm2 =0.3973 x 10-6 m2
Fig 12: A toroid core of voltage transformer with dimensions used for calculating saturation
voltage (figure taken from reference [18]).
Calculation:
From Biot-Savart‟s Law [16],
…………. (7)
…………. (8)
Where,
µ: Permeability of Steel= 5 x 10-3 H/m
I: Total current in the primary winding in Ampere (A)
N: Number of Turns on primary
21
L: Mean Length of Flux path
Now, from equation (8)
(Where, N1=number of primary turns) …………. (9)
For the above equation,
…………. (10)
Where,
L: Mean length of magnetic flux
OD: Outer diameter
ID: Inner diameter
L= π [(11+7)/2]
= π [18/2]
= π (9)
= 28.274cm
= 0.2827m …………. (11)
For M4 material B=1.4 T,
Hence, from (9), (11) current in the winding is
I= (BL)/ (µ N1
I= (1.4 x 0.2827)/ (5 x 10-3 x 2430)
I= (0.3957)/ (12.15)
I= 0.03256 A …………. (Current per turn)
To get the total current in the primary winding,
I total = I (per turn) x Number of primary turns
22
I total = 0.03256 x 2430
I total = 79.1208 A …………. (12)
Now,
Resistance of the winding is given by
…………. (13)
Where,
ρ: resistivity of copper= 1.68 x 10 -8 Ωm l: length of primary winding in m
A: Cross sectional area of primary winding = 0.3973 x 10-6 m2 …………. (Given)
For above equation,
…………. (14)
Where,
Perimeter of core limb= 2 π r = 2 π (0.02) = 0.0628m l = 0.0628 x 2430 l = 152.68m
From equation (13), Resistance of primary winding is
R= (1.68 x 10 -8 x 0.0628)/ 0.3973 x 10-6
R= 645.61 x 10-2 Ω …………. (15)
To get saturation voltage, multiply equations (12) and (15)
…………. (16)
For M4,
-2 Vsat = 79.1208 x 645.61 x 10
Vsat = 510.81 V …………. (17)
23
Similarly,
For MOH,
-3 I total= (1.54x 0.2827)/ (5 x 10 )
= 87 A …………. (18)
-2 Vsat = 87 x 645.61 x 10 (from (15) and (18))
Vsat = 561.68 V …………. (19)
For ZDKH,
-3 I total= (1.58x 0.2827)/ (5 x 10 )
= 89.3 A …………. (20)
-2 Vsat = 89.3 x 645.61 x 10 (from (15) and (20))
Vsat = 576.52 V …………. (21)
For ZDMH,
-3 I total= (1.61x 0.2827)/ (5 x 10 )
= 91 A …………. (22)
-2 Vsat = 91 x 645.61 x 10 (from (15) and (22))
Vsat = 587.50 V …………. (23)
(17), (19), (21) and (23) show that as the magnetic flux density goes on increasing, saturation voltage increases.
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CHAPTER VI
CONCLUSION
Saturation of transformer core causes problems in protection application, affecting the performance of the transformer. In this, the secondary fails to produce proportional output with respect to the primary input, affecting the overall reliability and stability of the system.
The experimental results show that the different core materials exhibit different saturation characteristics, which are studied using saturation curves. The material with higher saturation level, i.e. with more linear portion, gives better results for protection application. The material with higher value of magnetic flux density gives higher saturation voltage. Higher saturation voltage will ensure better performance of transformer during faulty conditions, maintaining system stability.
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CHAPTER VII
FUTURE SCOPE
The external burden connected to the secondary side of the transformer affects the performance of the transformer. This can be studied by considering a transformer at various load conditions, and the effects can be analyzed using simulation. Also, behavior of transformer can be observed for different core materials at different values of external burden.
The time required for the transformer to go into saturation is different in different designs of transformer. The time to saturation can be studied based on core material, dimensions of the core, fault current and/or application.
Also, the combination of high grade and low grade material can be devised, which gives better results than low grade material and has lower cost than high grade material.
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VITA Name: AALOKA GOGATE Permanent Mailing Address: 301, Samruddha Apts., Rambaug Colony, Paud Road, Pune-411038 Education: Degree: Bachelor of Science in Electrical Engineering, University of Pune Graduated: June 2011 Major Field of Specialization: Electrical Engineering Professional Experience: Gilbert & Maxwell‟s Electricals Pvt. Ltd. (Graduate Research Intern) June 2014 – September 2014
S. S. Enterprises Pvt. Ltd. (Trainee Engineer Intern) September 2012-December 2012
Vihanta Energy Technologies Pvt. Ltd. (Electrical Engineer Intern) September 2011- February 2012
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