kt ntpc power transformers
TRANSCRIPT
-
7/28/2019 KT Ntpc Power Transformers
1/63
WELCOMETRANSFORMERS AND
ACCESSORIES
KARAN TRIPATHI
-
7/28/2019 KT Ntpc Power Transformers
2/63
CONTENTS Principles of Transformers
Materials used in transformers
Magnetic circuit
Winding and insulation
Tap Changers Accessories
Drying and Impregnation
Structural Design. DGA
Transformer Testing
Loading and life of Transformer.
-
7/28/2019 KT Ntpc Power Transformers
3/63
Principles of Transformers
A transformer is a static piece of apparatus usedfor the transferring power from one circuit to the
other without change in frequency. It can raise or
lower the voltage with a corresponding decreaseor increase in current.
Primary winding
Secondary winding
Linkage of the two by Mutual Inductance
-
7/28/2019 KT Ntpc Power Transformers
4/63
Voltage transformation ratio
E1 = 4.44* f *N1* m
E2= 4.44* f *N2* m
E2 / E 1 = N1/N2
-
7/28/2019 KT Ntpc Power Transformers
5/63
LOW VOLTAGE WINDING DESIGN
Since voltage is less ,hence turns will also be less.
Phase Current = MVA/(3*line voltage in kV) if winding
is star connected.Phase Current = MVA/(3*line voltage in kV) if winding is
Delta connected.
This indicates current in Low voltage winding shall be high.
-
7/28/2019 KT Ntpc Power Transformers
6/63
-
7/28/2019 KT Ntpc Power Transformers
7/63Directed Oil Flow Arrangement
k l
-
7/28/2019 KT Ntpc Power Transformers
8/63
8
Leakage Flux
Flux entering the tank
-
7/28/2019 KT Ntpc Power Transformers
9/63
9Flux enters the Shunt
LV Wi di
-
7/28/2019 KT Ntpc Power Transformers
10/63
To carry high current thearea of cross section of
the conductors should be
high. This is
accomplished by
adopting more no. of
conductors per turn.
Helical winding which isspring like, suits most forthe LV windings.
LV Windings
HELICAL WINDING
-
7/28/2019 KT Ntpc Power Transformers
11/63
HIGH VOLTAGE WINDING
Large no. of turns
Less current.
Disc coils are the best choice for the HVwindings where a single disc can have turns ashigh as 25 nos.
-
7/28/2019 KT Ntpc Power Transformers
12/63
l d f
-
7/28/2019 KT Ntpc Power Transformers
13/63
Materials used in transformers1. CONDUCTORS:
P.I.C.C.
C.T.C.
Bunched P.I.C.C.
Glued C.T.C.
l d f
-
7/28/2019 KT Ntpc Power Transformers
14/63
Materials used in transformers1. Insulators:
1. Paper Insulation2. Perma-wood
3. Transformer oil.
4. Solid Polymer Insulation.
M i l d i f
-
7/28/2019 KT Ntpc Power Transformers
15/63
Materials used in transformers1. Core:
o The material used for core making is lowreluctance magnetic steel containing
silicon.This is called CRGO i.e cold rolled
grain oriented steel.
o The grain orientation is technology which
ensures that the flux flow through the
laminations with minimumresistance,resulting in low core loss.
-
7/28/2019 KT Ntpc Power Transformers
16/63
M i l d i f
-
7/28/2019 KT Ntpc Power Transformers
17/63
Materials used in transformers1. Core:
YOKE BOLT:BOLTS USED IN YOKES TO CLAMPTHE LAMINATIONS TOGETHER.
TOP YOKE LEVEL(TYL)/BOTTOM YOKE
LEVEL(BYL): EDGE OF THE TOP OR BOTTOMYOKE IN THE WINDOW.
PIN PAD ASSEMBLY: THE ARRGMT. TO TOJOIN CLAMP PLATE WITH END FRAME ISCALLED PIN PAD ASSY.
-
7/28/2019 KT Ntpc Power Transformers
18/63
Ch
-
7/28/2019 KT Ntpc Power Transformers
19/63
Tap Changers
1. On Load Type (OLTC)
2. Off Load Type (OFTC)
Used for variation in terminal voltage inHV side.
Voltage in the system can be varied bychanging turns ratio of the transformer.
Tap changer can be used for adding orcutting out turns of primary or secondarywinding of transformer.
Provision for manual and DM movement.
TAP SELECTION SWITCHDIVERTER SWITCH
-
7/28/2019 KT Ntpc Power Transformers
20/63
-
7/28/2019 KT Ntpc Power Transformers
21/63
-
7/28/2019 KT Ntpc Power Transformers
22/63
SWITCHING CYCLE OF DIVERTER & SELECTOR SWITCH
-
7/28/2019 KT Ntpc Power Transformers
23/63
Accessories
BUSHINGS
PRESSURE RELIEF VALVE (PRV) SUDDEN PRESSURE RELAY (SPR) COOLING BANK RTD BUCCHOLZ RELAY BREATHER MAGNETIC OIL GAUGE (MOG) AIRCELL OIL / WINDING TEMP INDICATORS (OTI) / (WTI)
AIR CELL LEAKAGE DETECTORS (ACLD) OIL PUMPS OIL FLOW INDICATORS (OFI) OIL SURGE RELAY (OSR)
Bushings (HV)
-
7/28/2019 KT Ntpc Power Transformers
24/63
Bushings (HV)
-
7/28/2019 KT Ntpc Power Transformers
25/63
POLLUTION LEVELS CREEPAGE DISTANCE
I. Light ( areas without industries,agricultural or mountain areas ) 16mm/kV
II. Medium ( areas with industriesnot producing pollution smoke,
Low density of house areas not exposed
to the coast)
20 mm/kV
III. Heavy (Areas with high density ofindustries, high density of
Heating plants producing pollution,
areas close to the sea.)
25mm/kV
IV. Very Heavy(Areas close to
the coast and exposed to sea spray,
desert areas, areas exposed to strong
winds carrying salt and sand etc )
31mm/kV
Example: for 145 kV Bushing with heavy pollution level minimum creepagedistance works to be.
145 kVX 25mm/kV = 3625mm
-
7/28/2019 KT Ntpc Power Transformers
26/63
Major Partsof
Condenser Bushing
Top Cap
1. Condenser Core
2. Porcelain.3. Oil level Gauge
4. Top cap.
5. Test Tap.
6. Mounting Flange.
7. Oil side Stress Shield.
-
7/28/2019 KT Ntpc Power Transformers
27/63
d l
-
7/28/2019 KT Ntpc Power Transformers
28/63
Tan delta test cap
-
7/28/2019 KT Ntpc Power Transformers
29/63
Bushings (LV)
-
7/28/2019 KT Ntpc Power Transformers
30/63
Bushings (LV)
LOW CURRENT HIGH CURRENT
Pressure Relief Valve
-
7/28/2019 KT Ntpc Power Transformers
31/63
Pressure Relief Valve
Sudden Pressure Relay (SPR)
-
7/28/2019 KT Ntpc Power Transformers
32/63
Protection and detection of Devices calibrated to quickly alarmor trip during dangerous sudden pressure changes rapidpressure rise changes (see response curves below) Actuation only occurs based on rate of pressure rise and will
not occur under normal pressure variations caused bytemperature change and vibration Can be subjected to full vacuum or 20 PSI positive pressurewithout damage Standard operation from -40 to 180F ( -40 to 82C) Special units available for operation at -67F (-55C)
Sudden Pressure Relay (SPR)
D i d I i
-
7/28/2019 KT Ntpc Power Transformers
33/63
Drying and Impregnation
St t l D i
-
7/28/2019 KT Ntpc Power Transformers
34/63
Structural Design
TRANSFORMER TANK IS AN ENCLOSURE WHICH
CONTAINS INSIDE IT THE LIVE PARTS SUCH AS COREAND WINDING ASSEMBLY, ELECTRICALCONNECTIONS AND INSULATING OIL.
CONVENTIONAL TYPE TANK BELL TYPE TANK.
Bell type tank design
OIL TESTS
-
7/28/2019 KT Ntpc Power Transformers
35/63
OIL TESTS
Moisture Content
Break down value (BDV)
Dissolved gas analysis (DGA)
Inter facial tension (IFT) Acidity/Neut. Number.
Visual Inspection.
Tan delta and resistivity.
-
7/28/2019 KT Ntpc Power Transformers
36/63
-
7/28/2019 KT Ntpc Power Transformers
37/63
-
7/28/2019 KT Ntpc Power Transformers
38/63
-
7/28/2019 KT Ntpc Power Transformers
39/63
-
7/28/2019 KT Ntpc Power Transformers
40/63
-
7/28/2019 KT Ntpc Power Transformers
41/63
-
7/28/2019 KT Ntpc Power Transformers
42/63
-
7/28/2019 KT Ntpc Power Transformers
43/63
-
7/28/2019 KT Ntpc Power Transformers
44/63
DUVAL TRIANGLE
-
7/28/2019 KT Ntpc Power Transformers
45/63
DUVAL TRIANGLE
-
7/28/2019 KT Ntpc Power Transformers
46/63
-
7/28/2019 KT Ntpc Power Transformers
47/63
Loading and Life of Transformer
-
7/28/2019 KT Ntpc Power Transformers
48/63
Loading and Life of Transformer
-
7/28/2019 KT Ntpc Power Transformers
49/63
-
7/28/2019 KT Ntpc Power Transformers
50/63
-
7/28/2019 KT Ntpc Power Transformers
51/63
-
7/28/2019 KT Ntpc Power Transformers
52/63
-
7/28/2019 KT Ntpc Power Transformers
53/63
-
7/28/2019 KT Ntpc Power Transformers
54/63
31.3C
45.9C
35
40
45
NORMAL THERMAL IMAGE OF A TRANSFORMER
ABNORMAL THERMAL IMAGE OF A TRANSFORMER
-
7/28/2019 KT Ntpc Power Transformers
55/63
SP01: 46.8C
SP02: 48.2C
SP03: 47.7C
ABNORMAL THERMAL IMAGE OF A TRANSFORMER
Bl k d di
-
7/28/2019 KT Ntpc Power Transformers
56/63
Blocked radiator
LINE-01: 22.4C
LINE-02: 34.3C
I fl f P i h i f h
-
7/28/2019 KT Ntpc Power Transformers
57/63
Influence of Paper moisture content on the ageing rate of thePaper (Fabre, CIGRE 1960)
100
30
10
10.1 0.3 1 3 10
AgeingRate
Moisture content in weight %
At 4.5 % papermoisture and 90C top oil temp.,
flash over will
occur.
-
7/28/2019 KT Ntpc Power Transformers
58/63
THANK YOU
HV Winding terminal
-
7/28/2019 KT Ntpc Power Transformers
59/63
HV Winding terminal
5 Limb core
-
7/28/2019 KT Ntpc Power Transformers
60/63
5 Limb core
Windings and OLTC
-
7/28/2019 KT Ntpc Power Transformers
61/63
Windings and OLTC
Directed oil flow in windings
-
7/28/2019 KT Ntpc Power Transformers
62/63
Directed oil flow in windings
-
7/28/2019 KT Ntpc Power Transformers
63/63