1. STUDY OF TRANSFORMER
SUBMITTED TO:- submitted by:-
Padmadhar Garg
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2. Transformer
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3. Transformer
A transformer is a
device that
transfers electrical
energy from one
circuit to another
through inductively
coupled electrical
conductors
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4. If a load is connected to the secondary
circuit, electric charge will flow in the
secondary winding of the transformer and
transfer energy from the primary circuit to
the load connected in the secondary
circuit
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5. The secondary induced voltage VS, of
an ideal transformer, is scaled from
the primary VP by a factor equal to
the ratio of the number of turns of
wire in their respective windings:
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6. By appropriate selection of
the numbers of turns, a
transformer thus allows an
alternating voltage to be
stepped up — by making NS
more than NP — or stepped
down, by making it less.
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7. Type Of Transformer:
1. Shell Type Transformer
2. Core Type Transformer
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8. TRANSFORMERS RULES
Transformer is
based on two
principles:
Firstly,that an
electric current can
produce a
magnetic.
Secondly,
electromegnetic
induction
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9. An ideal step-
down transformer
showing magnetic
flux in the core.
The primary and
secondary coils
are wrapped
around a core of
very high magnetic
permeability,such
as iron.
PRACTICAL CONSIDERATION
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10. Induction law
Faraday’s law states that:
Vs=Ns.dΦ/dt
where VS is the instantaneous
voltage.
NS is the number of turns in the
secondary coil.
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11. Since the same magnetic flux passes
through both the primary and
secondary coils in an ideal
transformer,the instantaneous voltage
across the primary coil
Vp=Np.dΦ/dt
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12. Taking the ratio of the two equationsTaking the ratio of the two equations
forfor VSVS andand VPVP gives the basicgives the basic
equation for stepping up or steppingequation for stepping up or stepping
down the voltagedown the voltage
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13. If Ns>Np, Vs>Vp
Such transformer voltage across
secondary is greater than primary
voltage called step up transformer.
Voltage cross secondary less than
primary voltage called step down
transformer.
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14. Types of Transformers:
A wide variety of transformer designs are used
for different applications.
Some important types are given as:
Power transformer
Distribution transformer
Instrument transformers
Auto-transformer
 Resonant transformer
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15. Ideal Transformer
The primary and secondary winding should
have zero resistance.It means there is no
ohmic power loss and no resistive voltage
drop.
There is no stray capacitance through the
actual transformer.It has inter-turn capacitance
and capacitance between turns and ground but
their effect is negligible at 50 Hz.
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16. Continue…
• There is no leakage flux so that all the flux is
confined to the core and links both the
windings.
• The core has infinite permeability so that zero
magnetizing current is needed to establish the
requisite amount of flux in the core.
• The core loss (the hysteresis as well as current
loss) is considered zero.
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17. DISTRIBUTION TRANSFORMER
• TRANSFORMER WHICH IS USED FOR THE
PURPOSE OF DISTRIBUTION OF POWER.
• 11KV/433V is the standard voltage rating.
• STANDARD KVA ratings are
25,63,100,160,200,250,315,400,500,630,750 ,
1000 , 1250,1500,2000,2500 KVA.
IS-2026 is the NATIONAL I S STANDARD.
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18. Transformers in MNIT
Location Rating
Girls Hostel 500KVA
Boys Hostel 500+500KVA
Design centre 500KVA
Admin. Block 500KVA
Canteen 500KVA
Pump house 100KVA
Colony I 315KVA
Colony II 250KVA
Sports 250KVA
Workshop 250KVA
Electrical Dept. 500KVA
Hostel Canteen 315KVA
Hostel 5 500KVA
Hostel 6 315KVA
Hostel 5 160KVA
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19. Transformer testing
I. Short Circuit Test
II. Open Circuit Test
III. Sumpner’s Test
IV. Polarity Test
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20. Transformer Losses
There are mainly two kinds of losses in a
transformer namely
• I. Core Loss (constant loss)
• II. Ohmic Loss (variable loss)
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21. Transformer Efficiency
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22. Transformer Rating
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23. Efficiency Calculation:
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25. TRANSFORMER AUDIT FORM
transformer_basic_audit_form.pdf
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26. MAINTENANCE PROCEDURE
• OIL :
1. Oil level checking. Leakages to be attended.
2. Oil BDV & acidity checking at regular
intervals. If acidity is between 0.5 to 1mg
KOH, oil should be kept under observation.
3. BDV, Color and smell of oil are indicative.
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27. CONTINUE…
1. Sludge, dust, dirt ,moisture can be removed
by filtration.
2. Oil when topped up shall be of the same
make. It may lead to sludge formation and
acidic contents.
• Insulation resistance of the transformer
should be checked once in 6 months.
• Megger values along with oil values indicate
the condition of transformer.
• Periodic Dissolved Gas Analysis can be
carried out. 27

28. • Periodic checking of any loose connections of
the terminations of HV & LV side.
• Breather examination. Dehydration of Silica gel
if necessary.
• Conservator to be cleaned from inside after
every three years.
• Regular inspection of OIL & WINDING
TEMPERATURE METER readings.
• Cleanliness in the Substation yard with all nets,
vines, shrubs removed.
CONTINUE…
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29. THANKS!!!
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