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What is transformer : an electrical device that converts AC electric energy at one voltage or current level to another voltage or current level at the same frequency
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150 kV
G
20 kV
Step Stepup up Transforme Transforme rr
Interconnecti Interconnecti on on Transformer Transformer
20 20/ /150 150kV kV
150 150/ /20 20kV kV
0.4 kV
Distribution Distribution Transforme Transforme rr Load 20 20/ /0.4 0.4kV kV
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Basic Principle of Transformer: - consist of two inductive coils (primary and secondary) which are electrically separated but magnetically linked - mutual induction between the two circuit - if one coil is connected to a source of alternating voltage, alternating flux is set up in the laminated core which is linked with the other coil. Then it produces mutually induced emf. - If the second coil circuit is closed, a current flows in it and so electric energy is transferred.
Φ V 1
N 1
N 2
V 2
E = 4,44. f .φ m .N I1 N = I2 N
2 1
E1 V = 1 E2 V2 6
ΔU
Up
I
I
p
s
Np
Us
Ns
»SIEC = Up x (Is x Ns/Np) »SANSI = Us x Is »Cooling capacity = »IEC 60076 = max. load loss + no load loss 100% excitation + sun rad.
»ANSI C57 = max. load loss + no load loss (100% + ΔV) excit.+
sun rad.
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There are two type transformer based on its insulation : The party active is immersed in the tank by dielectric liquid The party active is immersed in the tank by air or gas
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The expansion of dielectric takes place in an expansion tank placed above the tank
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Expansion of the dielectric is absorbed by compensating on the radiator fins
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The oil volume expansion is compensated with inert gas layer between the surface of the dielectric and the top of the tank.
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HV 60° oblique winding patented by AREVA three dimensional computerized control automatic and vertical winding machine
micro ordinat eur
fully automated casting and mixing under vacuum 12
¾ No liquid dielectric ¾ no danger for environment due to oil leakage ¾ no loss of dielectric strength due to oil leakage ¾ no need for oil dams or containment systems ¾ no fluids to be targeted for regulation in the future resulting in costly change-outs ¾ Excellent Fire resistance ¾ self-extinguishing, ¾ fire retardant, ¾ not explosive, ¾ no release of toxic or corrosive products and opaque smokes in the event of fire ¾ Excellent response to service conditions ¾ High short circuit withstand ratings ¾ Resistant to mechanical and thermal stress caused by over-loads, over-voltages and harmonics ¾ Low partial discharge, therefore high life expectancy
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- Core - Winding - Cooling medium - Insulation structure
- Cooling equipment - Termination - Control/Protection
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Tank cover. Internal connection bushings Tap changer barrel and lead outs connection Core & coil assembly Yoke clamping Pedestal Tank wall + base. 15
TTransformer ransformer for for Hazardous Hazardous Area Area
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Basic description : X
Definition : Those areas where fire or explosion hazards may exist due to flammable gases or vapors, flammable liquids, combustible dust or ignitable fibers
X For hazardous areas with risks of explosion, specific electrical equipment is required. X Application fields: Based on decades of filled tested experience in electrical generation and distribution for both offshore and onshore installations
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•
Arcs and sparks produced by the normal operation of equipment, like motor starters, contactors and switches, can ignite a hazardous location atmosphere
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The high temperatures of some heat-producing equipment, such as lamps and lighting fixtures, can ignite flammable atmospheres if they exceed the ignition temperature of the hazardous material. The National Electrical Code requires special marking of heat-producing equipment with temperatures above 100°C (212°F)
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Electrical equipment failure is another way an explosion could be set off. A burn out of a lamp socket or shorting of a terminal could spark a real disaster in a hazardous location
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Zone 0
: an area in which an explosive gas atmosphere is continuously present or present for long periods
Zone 1
: an area in which an explosive gas atmosphere is likely to occur in normal operation
Zone 2
: an area in which an explosive gas atmosphere does not normally exist
Type of Area Continuous Hazard Intermittent Hazard Hazard under abnormal conditions
IEC ZONE 0 ZONE 1 ZONE 2
NEC DIVISION 1 DIVISION 1 DIVISION 2
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SEALING FITTING
EXPLOSION PROOF TERMINAL BOX
20 CONDUIT CABLES
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Standard Applicable
IEC 76, ANSI C-57 and AS 2734 Information required with enquiry and order: A.General Information - dry type or oil immerse - single or 3 phase - frequency - indoor or outdoor - type of cooling - rated power and voltage - tapping (if needed); on load or off load - highest voltage level - method of earthing
- BIL and power frequency - connection - Accessories B. Special information - impedance - altitude and ambient temp. - special installation space - tests required : lightning impulse etc. C. Paralel operation
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Part active : this is the main part of transformer, consist of core magnetic and winding
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Bushing Cooling Device : oil (for oil immersed transformer), radiator, fan Protection Device : Bucholz relay, protection relay for OLTC RS 2001, pressure relief device, pressure vacuum gage & bleeder
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Accessories : Oil Level Indicator (OLI), Oil Temperature Indicator (OTI), Winding Temperature Indicator (WTI), etc
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Valve : oil sampling valve, butterfly valve, screw end globe type valve
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- Magnetic core - Low voltage winding - High voltage winding - Active part clamping
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1 3
4
5
2
LV Winding Gradins HV Winding
1 Top yoke 2 Bottom yoke 3 Left outer limb 4 Center limb 5 Right outer limb
Choice of gradins used must be as close as possible to the circle section 24
• There are two kinds of magnetic core stacking : 1. Flat yoke : The silicon steels of the yoke are arranged with the same distance to each other
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2. Non flat yoke : The silicon steels of the yoke are arranged like stairs
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There are three kinds of wire used for winding: 1. Round wire (email)
Current density (δ) limitation used : Copper wire : 1.4 <= δ <= 4.4 A/mm2
2. Rectangular (meplate) 3. Foil (Bande)
Aluminium wire : 0.6 <= δ <= 2.4 A/mm2
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Winding Temperature Indicator
Function : To measure the winding temperature
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Winding Temperature Indicator 1. Case 2. Locking Glass Ring 3. Fixing Rear Flange 4. Air Hole 5. Capillary Output 6. Dial 7.Microsw. Setting Dial
9. Microsw. Setting Pointer 10. Junction Box 11.Glass or polycarbo-nate window 12. Potentiometer for heating resistance adjustment
8. Max. indicating pointer
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Oil Temperature Indicator
Function : To measure the oil temperature inside power transformer tank
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Oil Temperature Indicator 1. Case 2. Locking Glass Ring 3. Fixing Rear Flange 4. Air Hole 5. Capillary Output 6. Dial 7.Microsw. Setting Dial
8. Max. indicating pointer 9. Microsw. Setting Pointer 10. Junction Box 11.Glass or polycarbo-nate window
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Oil Level Indicator
Function : to measure the level reached by the oil in a transformer conservator
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Pressure Vacuum Gauge
Function : To check the vacuum pressure inside the tank
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Sudden Pressure Relay
Function : To minimize the damage on the equipment caused by excessive gas pressure that occurred from internal arcing in oil filled transformers.
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Pressure Relief Device
Function : An equipment to relieve large volumes of gas or insulating fluid rapidly when the pressure inside a transformer reaches a predetermined limit.
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1. Measurement of Winding Resistance 2. Measurement of voltage ratio 3. Measurement of no-load loss and no-load current 4. Short duration induced AC withstand voltage test (induced overvoltage test) 5. Measurement of short-circuit impedance and load loss 6. Separate-source AC withstand voltage test ( Applied protential test)
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1. Lightning impulse test 2. Temperature rise test
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1. Measurement of partial discharge 2. Measurement of sound levels
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Carefully examined to detect any signs of damage in transport: • Damaged or deformed packing blocks • Dielectric stains or leaks • Broken pieces of wooden crate • Cracked or spilled bushings • Broken or damaged wiring • Low nitrogen pressure on pressure gauge • No dielectric oillevel reading on gauge • Damaged tank body • Bent or broken fittings 41
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! USE THE LIFTING AND JACKING POINTS SHOWN ON THE GENERAL ARRANGEMENT DRAWING !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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¾ Purpose: To condition oil before filling of transformer
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9 Check the list of components
9 Check the condition of parts 9 Any operation involving opening a passage into the inside of the transformer must be done in the shortest time and good weather 9 Installation, erection, and commissioning of transformer may only be carried out by qualified, skilled personel and only in accordance with the instruction manual.
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Tools should be ready for Erection : DESCRIPTION
QUANTITY
Crane 5 ton
1 unit
Sling wire for crane 5 ton
1 set
Oil filtering/purely and vacuum machine 1500 - 3000 lt./hours equipment with horse
1 unit
Torque wrench
1 set
Spanner : 8mm, 13mm, 22mm, 30mm etc
1 set
Adjustable wrench
1 set
Screw driver (plus & minus)
1 set
Multi tester
1 unit
Megger
1 unit
Oil tester
1 unit
REMARK Lifting and assembling
Filling & treatment oil if necessary
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Tightening Torques
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¾ Take a sample, to ensure it meets the requirements for dielectric strength ¾ DO NOT pour dielectric directly into the transformer ¾ Oil should flow in through a valve located below the level of the dielectric already in the transformer
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1. Inject N2 gas through N2 injection valve 2. 3.
Control N2 gas pressure (± 6 psi.) For leakage test, the voltage regulator is applied by 6-psi pressure for 24 hours
4. After the test the pressure is down to 2 psi on pressure vacuum gauge
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¾ Protective Accesories and Setting Values NAME OF PROTECTIVE ACCESSORIES
No
SET VALUES ALARM
NOTE TRIP OK
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1
Sudden Pressure relay
OK
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Oil temperature indicator
85o
95o
Adjustable
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Winding temperature indicator 95o
105o
Adjustable
70o
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Adjustable
Min level
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7 psi
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Winding temperature
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Fan (future)
• start 70o /stop 60o C
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Oil level indicator for main tank
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Pressure relief device
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¾ Inspection and checking before operation No.
CHECK ITEMS
DESCRIPTION
SPECIFIED
1
Out line drawing
Specification
Compliance with drawing and specification
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Oil level
Main tank
Level gauge to read correctly for existing level and oil temperature
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Valve position
1. Valves 2. Radiator valves
REMARK
Open and close position
3. Other valves 4
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Off load tap changer
Electrical tests
Manual operation through all tap position
As specified
1. Insulation resistance of windings
1 MΩ/kV
2. Ratio and polarity
Acc. to specification
3. Dielectric strength of oil
See CT606MO 1. Wired properly and comply with wiring 2. Contacts open or close as specified.
4. Alarm, tripped, control circuits, and auxiliary circuit
As reference
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¾ Inspection and checking before operation (Cont’d) No.
CHECK ITEMS
DESCRIPTION
SPECIFIED
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Earthing
Tank and Marshalling kiosk
It should be connected to earth
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Bushing
1.
Porcelain
Clean
2.
Spark Gap
3.
Connected
Proper continuity and tightness
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Other
Cleans rust
Cleans
REMARK
Clean and touch point
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Efficient protection should prevent the transformer from any incident. ¾ Setting of Protective Devices Most of the protective devices, ordered wtih the transformer are installed and pre-adjust at the factory. The choice of the protective device thet is not directly installed on the transformer must take into account the effect of switching transient voltages and currents caused by energising the transformer. ¾ Inrush Current Energising a transformer gives rise to high over current. This inrush current is between 3 – 5 times the rated current of the transformer. This current reduces accordingly to an exponential law whose time constant depend on the winding resistance and the secondary load. 52
NORMAL OPERATION ¾ All radiators valves must be opened, and all other valves closed ¾ The tap changer secured in correct position.
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EMERGENCY OPERATION ¾ Over load Can be operated under permissible load, which is given according to IEC publication 354 ¾ Over excitation 150
50/60 Hz at No Load
140 130 120 110 100 0 1
2
3
5
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10
20
30
50
70
100
200
300
500
700
time (sec) PERMISSIBLE OVER-VOLTAGE CHARACTERISTIC
¾ Maximum duration of short circuit in second is 2 second at LV and HV 54 feeder.
¾ Maintenance Check-List NO
ITEMS
CONTENTS NOTES 1.
Check and record oil indicator Record ambient temperature, load (MW, MVAR)
JUDGING STANDARD Reading in proper range considering load and ambient temperature
ACTION IN CASE OF ABNORMAL Watching temperature variation
1.
Winding and Oil temperature indicator
2.
2.
Oil level indicator
Check oil level gauges.
Difference within 10° between oil level indicator reading and temperature indicator reading
Watching oil level variation
3.
Noise
Check for abnormal sounds
Without abnormal sound compared with other units
Stop operation
Without loosening of nuts and bolts
Refastening
1. 4.
Loose connections
2.
Check for loose connections such as those found in main circuits, grounding circuits, auxiliary circuits and others.
Check valves for looseness
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¾ Maintenance Check-List (Cont’d) NO
5.
6.
ITEMS
Oil leakage
Cooling equipment can not operate
CONTENTS NOTES
JUDGING STANDARD
ACTION IN CASE OF ABNORMAL
Check for oil leaks in connections such as those of valves, meter especially in gaskets joints and welded parts
Without oil leakage
Refastening
1.
Check for leaks
Without oil leakage
Stop & repair
2.
Check for abnormal rotating sounds and vibration
Without abnormal sound compared with other units
Stop & repair
3.
Check valve status
Shall be open
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Bushing
Evaluate the extent of the porcelain contamination by appropriate method
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Instrument
Check indicators and relays
Without much dust
Cleaning
Without oil leakage
Stopping and coating the anti-oil leak paste
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¾ Maintenance Check-List (Cont’d) NO 9.
ITEMS
CONTENTS NOTES
JUDGING STANDARD
ACTION IN CASE OF ABNORMAL
Hazardous Area
Sealing Fitting
Bar properly seal
Find leakage, reseal
10.
Paint Work
Check to see if paint is chipped or pitting
Check to see if rust is showing
Clean off rust and touch-up painting
11.
Oil strength
Take oil sample and test every 2 years
Should not be less than 30kV/2.5 mm
Filter oil, or add new oil, or change all oil
12.
Other
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¾Elimination of Leakage Leakage can occur in: • HV or LV bushings • Transformer Instrumentation • Tank sealing gaskets • Pipework device • Valves • Radiator and on tank 58
¾ Leakage on HV and LV bushings Cause → Cracked insulator → Defective seal
Solution → Tightening → Replace the defective seal Note: It is important for all seal and gasket replacement operations to be carried out in a dry palce 59
¾ Safety precautions: • The tap-changer is to be operated off-load. Before operating ensure that the transformer is de-energized. • Installation, erection, and commissioning of transformers may only be carried out by qualified, skilled personel and only in accordance with the instruction manual. • When handling the transformer, use the lifting and jacking points shown on the general arrangement drawing for lifting the complete unit (see outline drawings). • If possible the transformer should be placed at least 0.5 m from the walls, to avoid excessive and harmful temperature rises. 60
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