BEST

1. A
PRESENTATION
ON
POWER TRANSFORMER
PRESENTED BY:
HIMANSHU SHARMA : ( 1228231006)
JP INSTITUTEOF ENGINEERING& TECHNOLOGY,
MEERUT

3. POWER TRANSFORMER

A transformer is a static machine used for transforming power from one circuit
to another without changing frequency. This is a very basic definition of
transformer

4. Stages of Power Transformers
manufacturing are :
 Design & Drawing
 Winding Manufacturing
 Core Building
 Unlacing of Core
 Fitting Bottom insulation
 Core Coil Assembly
 Fitting of Top insulation
 Replacing of core
 Terminal Gear
Mounting
 Final Tanking
 Testing
 Dispatch

5. Design & Drawing :
 Phase 1Φ 3 Φ
 Rating
MVA KVA
 Voltage Class
11 kv
66Kv

6. continue
50 Hz
 Frequency
60 Hz
 Connection delta star
 Generating
 Purpose Substation
Distribution

7. Winding Used :
 R-S Coil : reverse section
winding.
 Helical coil : winded in shape of
spring.
 Spiral coil : simply wounded on
the base.
 Interleaved coil : winding current
rotates in same conductor
 Composite winding : more than
one conductor winded with each
other.

8. Helical winding
INTERLEAVED

9. Core of Transformer :
Material Used :
CRGO : Cold rolled grain oriented silicon steel is
used to build the core.
Purpose of using CRGO is to reduce the Hysteresis
losses. Laminations of these sheets minimizes eddy
current loss.

10. Unlacing of core :
This is basically the phenomena of removal of top end
frame of the core assembly so that the coils can be
mounted on the core.

11. Core – Coil Assembly :
 L.V Coil : primary coil for step down transformer, made in order to allow the
flow of large current through it .
 H.V Coil : Secondary coil for step down transformer, made in order to allow
high voltage and hence small current through it.
 T.V Coil : this is known as the tertiary voltage coil.

12. Replacing Of Core :
The top yoke is again attached to
The Rest of the Core, the sheets
Are attached one by one or in
Packets (generally 2 to 4 in
numbers) to the core limb in
erect position. Then the job is
dipped in oil and then heated to
remove any kind of moisture in
it. After that the job is
compressed i.e. pressure is
applied from the top to compress
the coil and achieve the required
CD of the coil as specified in
design.

13. Processing and DRY OUT :
The presence of the moisture brings about the
reduction in the electric strength of material and
also increases its volume.
Dry out is necessary in this condition.
The final drying out is commenced either when
the core and winding are placed or when they
are fitted in to there tank, all main connections
made and the tank placed in an oven and
connected to the drying system

15. Final Tanking:
Tanking means…..
assembling the core coil
assembling job into
transformer tank with
all necessary accessories
according to bill
of material
and design diagram.

16. Testing of Power Transformer
Tests during manufacture :
 Core plate checks
 Core frame insulation resistance
 Core loss measurement
 Winding copper checks
 Tank tests

17. Final Testing:
Routine Tests
 Voltage ratio and polarity.
 winding resistance.
 impedance voltage, short-circuit impedance and load loss
 dielectric tests.
(a) separate source AC voltage.
(b) Induced voltage.
 no-load losses and current.
 on-load tap changers, where appropriate.

18. Tests
TYPE Tests :
Temperature rise test.
noise level test.
lightning impulse tests.

19. EQIPMENTS USED FOR THE PROTECTION OF
POWER TRANSFORMER
 Lightning Arrester.
 Over Current Relay.
 Bocholt relay.
 Earth fault relay.
 Oil level indicator.
 Over fluxing relay.