presentation on all products with detailed ccv and ct
TRANSCRIPT
Instrument TransformersBangalore Site
January 2006
Deepak.VProducts Profile and Details
> Instrument Transformers - (ITR)- RMK Site - December 20053 3
A Competitive Site in an International Group
> Instrument Transformers - (ITR)- RMK Site - December 20054 4
4 Units, 874 Employees *
AREVA T&D Instrument Transformers Manufacturing Unit
Brazil
Mexico
France
India
* 2005 figures
A Competitive Site in an International Group
> Instrument Transformers - (ITR)- RMK Site - December 20055 5
CODENSACOLOMBIA
245 KV
EDELCAVENEZUELA
800 KV
SEGBAARGENTINA
525 KV
UTEURUGUAY
525 KV
FURNASBRAZIL800 KV
TRANSELEC CHILE 525 KV
AREVA T&D Instrument Transformers Empower Satisfied Partners Worldwide
BPAUSA
525 KV
HYDRO QUEBECCANADA
800 kV
AEPUSA
800 kV
BC HYDROCANADA525 KV
APSUSA
525 KV
CFEMEXICO420 kV
GUIZHOU E.P.C.CHINA525 kV
PLNINDONESIA525 kV
TNBMALAYSIA275 KV
PGCIL/NTPC/SEB INDIA420 kV
EVNVIETNAM550kV
KEGOCKAZAKHSTAN500 kV
POWERNETAUSTRALIA550 KV
RAO EESRUSSIA800 kV
ZHEJIANGCHINA525 kV
ONEMOROCCO
245 KV
SONELGAZALGERIA
245 KV
CIEIVORY COAST
245 KV
ESKOMS. AFRICA
420 KV
STEGTUNISIA245 KV
EEAEGYPT245 KV
REESPAIN420 KV
EDFFRANCE420 KV
NGTUK
420 KV
ELIABELGIUM
420 KV
E -ONGERMANY
420 KV
ENELITALY420 KV
> Instrument Transformers - (ITR)- RMK Site - December 20056 6
AREVA T&D Instrument Transformers are installed in the four corners of the world :
AREVA T&D Instrument Transformers
> Instrument Transformers - (ITR)- RMK Site - December 20057 7
Bangalore Site
> Instrument Transformers - (ITR)- RMK Site - December 20058 8
AREVA T&DInstrument Transformers India Private Limited
Built area : 16,350 sq.m
People : 250
Workers : 173
Engineers & Employees : 77
Activities
HV Instrument Transformers
Line Traps
Condenser Bushings
Bangalore
India - Bangalore Site
> Instrument Transformers - (ITR)- RMK Site - December 20059 9
AREVA T&DInstrument Transformers India Private Limited
India - Bangalore Site
HV Instrument Transformers
Current Transformers (Paper-oil) up to 765 kV
Capacitor Voltage Transformers (Paper/Film/Oil) up to 765 kV
Line Traps up to 1mh / 3150A & 800kV
Condenser Bushings up to 420 kV
> Instrument Transformers - (ITR)- RMK Site - December 200510 10
An History of Innovative Excellence
1976 - WSI is created (Line Traps and Capacitor Voltage Transformers)
1977 - Started Bushings manufacture
1983 - WSI started Current Transformers production (420 kV)
1991 - ISO-9001 Certification
2000 - WSI Bangalore unit sold to ALSTOM group
2002 - Commercialization of mixed dielectric technology (CCV) for Capacitor Voltage Transformers as per AREVA T&D design
2005 - IS0-14001:2004 certification for environmental system
2005 - Plant becomes part of AREVA T&D
2005 - Top core Current Transformers (CTH) transferred from AREVA T&D
Bangalore Site at a Glance
> Instrument Transformers - (ITR)- RMK Site - December 200511 11
A leader and a Pioneer
30 years of operating experience in India
First manufacturer in India for 3600 Amps Current Transformers
Only manufacturer of Wall-to Wall and Oil-Oil bushings in India
First manufacturer of 400 kV (8800pF) Capacitor Voltage Transformers in India
First manufacturer of 1mH / 3150 Amps Line Traps in India
Over 25,000 Current Transformers and Capacitor Voltage Transformers in operation
Over 40,000 Line Traps on site
Bangalore Site at a Glance
> Instrument Transformers - (ITR)- RMK Site - December 200512 12
We are un-compromising about our quality production process techniques, safety and efficiency
State-of-the-art facility for oil treatment and impregnation
Optimized flow of materials and components
“Dust-free” room for Capacitor Voltage Transformers winding
Current Transformers taping carried out in high pressure room
In-house testing capability
World-class Manufacturing
> Instrument Transformers - (ITR)- RMK Site - December 200513 13
We are un-compromising about our quality production process techniques, safety and efficiency
Only qualified, skilled/trained and experienced personnel
Training programs to maintain high performances
Safe & pleasant work environment to encourage efficient, quality work
Technical & commercial interactions between Bangalore and other global AREVA T&D Units
Our experts regularly participate in technical conferences
People Power
> Instrument Transformers - (ITR)- RMK Site - December 200514 14
We have embarked on a total quality process
Reliable quality management system
Continuous improvement through effective communication
Innovation & investment in the products, processes, services, environment and human resources
ISO-9001:2000 certification
ISO-14001:2004 certification
Quality First
> Instrument Transformers - (ITR)- RMK Site - December 200515 15
Bangalore Site - Product LinesOverview
> Instrument Transformers - (ITR)- RMK Site - December 200516 16
Instrument Transformers in IndiaProduct Lines
Hair pin / eye bolt design current transformers
ITT and IT type
Designed according to our Indian customers’ most exacting requirements
Extensive field experience
Low maintenance
Designed to withstand 600 multiple chopped impulse
Flexible design
These CTs are installed throughout India and are highly respected by network managers and substation personnel alike
HV Instrument Transformers
> Instrument Transformers - (ITR)- RMK Site - December 200517 17
Instrument Transformers in IndiaProduct Lines
Top Core design current transformers
CTH type up to 765 kV
Reinforced security design
Top core design with metal head
High quality paper-oil insulation. Oil expansion by stainless steel bellows
Stable accuracy over a long period of time
Extensive experience in highly active seismic regions
Compact construction
Single, double or triple ratio at the primary side
Top-of-the-range Current Transformers (CTH type) : the next wave of Bangalore production
HV Instrument Transformers
> Instrument Transformers - (ITR)- RMK Site - December 200518 18
Instrument Transformers in IndiaProduct Lines
Capacitor Voltage Transformers (Paper/Film/Oil)
CCV type up to 765 kV
Optimized design for high reliability and longevity; maintenance free
Superior transient response
Optimized insulation technology (mixed PPR / Paper), high grade synthetic oil
Effective protection against ferroresonance
Operations as coupling capacitor for power line carrier transmission
Stability of capacitance and accuracy over many yearsThis range is manufacturing in India using the most
modern insulation impregnation technology and equipment
HV Instrument Transformers
> Instrument Transformers - (ITR)- RMK Site - December 200519 19
Instrument Transformers in IndiaProduct Lines
up to 800 kV
can operate within the 30 kHz to 500 kHz frequency range
Flexible mounting options
High short-circuit withstand capability
Light weight
Reliable open-style design (OSD)
Excellent cooling capabilities
Extremely reliable tuning devices
Maintenance free
Over 40,000 Line Traps on site
Line Traps
> Instrument Transformers - (ITR)- RMK Site - December 200520 20
Instrument Transformers in IndiaProduct Lines
Oil-to-air
Oil-impregnated paper (OIP)
External shell : porcelain envelope
Partial discharges < 5pC at 1.5 Un / 3
Specially treated mineral oil
Power factor tap, air draining plug & oil side shield provided
Prismatic oil sight glass with option of MOLG above 145 kVFlange of aluminum alloy casting
High creepage bushings on requestSuitable for connecting outdoor equipment to high voltage
transformers
High voltage Condenser Bushings up to 420 kV
> Instrument Transformers - (ITR)- RMK Site - December 200521 21
Basics of Instrument Transformer
> Instrument Transformers - (ITR)- RMK Site - December 200522 22
Magnetic circuit (core)
Instrument TransformerSensing function
U1 U2
Voltage sensor
Secondary Windings
Primary Windings
> Instrument Transformers - (ITR)- RMK Site - December 200523 23
Instrument TransformerSensing function
I2
I1
Current sensor
> Instrument Transformers - (ITR)- RMK Site - December 200524 24
I2
Instrument TransformerSensing function
I2
Current sensorMultiple secondary
I1
> Instrument Transformers - (ITR)- RMK Site - December 200525 25
K : Transformation
ratio
PrimaryU1
Secondary
U2
Voltage Transformer :
Kn
n
U
U
2
1
2
1 1n
2n
Definition of an Instrument Transformer
> Instrument Transformers - (ITR)- RMK Site - December 200526 26
PrimaryI1
Secondary I2
Current Transformer :
Kn
n
I
I
I.nI.n
1
2
2
1
2211
Ampere-TurnsConservation
Law
1n
2n
Definition of an Instrument Transformer
K : Transformation
ratio
> Instrument Transformers - (ITR)- RMK Site - December 200527 27
K.Us
Instrument Transformer Error
Secondary
Primary
Up
Us
K
:Ratio error
Up (theoretically = k.US)
: Phase error
Voltage Transformer :Voltage Transformer :
s
p
U
Uk
> Instrument Transformers - (ITR)- RMK Site - December 200528 28
Secondary
PrimaryIp
Is
K
TC : K=Ip
Is
K.Is :Ratio error
Ip
: Phase error
Current transformer :Current transformer :
Instrument Transformer Error
> Instrument Transformers - (ITR)- RMK Site - December 200529 29
Reminder
6eff
eff
10SBn2E
SBfn444E
....
...., Volts,W/m²,m²
at 50 Hz,Gauss, cm²
EMF Equation
Electrodynamical Forces
L
D
I1
F FI2
A]m,[N, 10.D
L.I.I.2F 721
> Instrument Transformers - (ITR)- RMK Site - December 200530 30
Magnetization curve
Double logarithmic graph
Indu
ctio
n [G
auss
]
102
103
105
104
18.000 Gauss
Magnetic field [AT/cm]10-3 10-2 10-1 1
Compared to reference curves
1 Tesla = 104 Gauss
> Instrument Transformers - (ITR)- RMK Site - December 200531 31
Induction [B]
Magnetic field [H]
Hc
Br
Br : Remanent InductionHc : Coercive field
Reminder
Hysteresis cycle
> Instrument Transformers - (ITR)- RMK Site - December 200532 32
Reminder
R cuivre
I0
L0
RCF
Iw
Equivalent scheme of a coil with sinusoidal current
U
IwRH
I
U
I
I0
wiii0
A
> Instrument Transformers - (ITR)- RMK Site - December 200533 33
Current TransformersTop Core Design - CTH range
> Instrument Transformers - (ITR)- RMK Site - December 200534 34
1. Top cover
2. Oil level indicator
3. Oil expansion device
4. Metal box LV screen and cores
5. Bar-type or wound type primary
6. Paper-oil insulation
7. Porcelain insulator
8. LV screens
9. Secondary terminal box
10. Base
Full Range of HV Technologies
Current Transformers (Paper/Oil) up to 765 kV - CTH range
> Instrument Transformers - (ITR)- RMK Site - December 200535 35
Current Transformers -- CTH 72.5 to 765 kV
Performance:
Un: 72.5 kV to 765 kV
In: up to 4800 A
In short circuit: up to 80 kA1” [Isc dyn : 200 kA peak]
Secondary cores : up to 8
Characteristics:
High quality paper-oil insulation
Top core design with metal head
Oil expansion by stainless steel bellows
Secondary cores : in aluminium box
Single, double or triple ratio at the primary side
Low maintenance
Linking the Power Chain
> Instrument Transformers - (ITR)- RMK Site - December 200536 36
Linking the Power Chain
Current Transformers -- CTH 72.5 to 765 kV
Special accuracy classes: TPS, TPX, TPY, TPZ, PR
Explosion-proof design
Extensive experience in highly active seismic regions
Compact construction
Built for long life
Compliance with IEC, ANSI / IEEE or equivalent standards
> Instrument Transformers - (ITR)- RMK Site - December 200537 37
Reinforced Security Design:
Limit the consequences of an internal failure by limiting the projections of parts, porcelain, and insulating oil.
CT Specific Design:
Reduced oil volume
Internal ground conductors with sufficient cross section for handling the fault current
Tank head designed to prevent the transmission, inside the porcelain insulator, of the over-pressure wave that originates in the head at the time of the fault
Reinforced Security Design
> Instrument Transformers - (ITR)- RMK Site - December 200538 38
Failure Test at KEMA Laboratory
Characteristics of the test:
No load voltage: 10 kV RMS
Fault current: 40 kA RMS -- Fault duration: 200 ms
Time to fire the head: 9 ms
Fault energy: 8.9 MJ
Test results:
The CT is still at original position.
Limited oil fire
Top cover is perforated (500 mm dia).
Porcelain insulator intact
CT internal examination shows no arc inside the bushing. Grounding and secondary wiring are not affected.
Before the fault Just after the fault
CTH 525
> Instrument Transformers - (ITR)- RMK Site - December 200539 39
Current Transformers - CTH
For years, tens of thousands of CTH have been installed all over the world
> Instrument Transformers - (ITR)- RMK Site - December 200540 40
Current TransformersEye Bolt Design - IT range
> Instrument Transformers - (ITR)- RMK Site - December 200541 41
1. Oil filling plug
2. Dome
3. Nitrogen filling valve
4. Collar
5. Primary terminal
6. Porcelain insulator
7. Insulated primary
8. Cover plate for tank
9. Tank
10. Secondary cores
Full Range of HV Technologies
Current Transformers (Paper/Oil) up to 245 kV - IT range
Eye bolt design
IT 245 Cross section
> Instrument Transformers - (ITR)- RMK Site - December 200542 42
Eye Bolt DesignTechnical data
Rated voltage : 123 to 245 kV
Technology : Eye-Bolt
Expansion device : Nitrogen
Primary reconnection : 1-2
Rated primary current : 1200 Amp (1440 max)
Short circuit current : 40 kA 1”
Total weight (kg)
kV 72.5 145 245
kg 700 750 1200
IT range
> Instrument Transformers - (ITR)- RMK Site - December 200543 43
Eye Bolt DesignActive Part Manufacturing
IT range
Primary conductor (1,2 or 4 turns)
Primary steel pipe
Paper insulation
Seconday cores
> Instrument Transformers - (ITR)- RMK Site - December 200544 44
Eye Bolt DesignActive Part Manufacturing
IT range
> Instrument Transformers - (ITR)- RMK Site - December 200545 45
Eye Bolt DesignVacuum Treatment
IT range
Oven
Active part
Target :Remove all the water trapped in
the paper (and in other materials) during insulation
process
Duration :Up to 3 weeks
> Instrument Transformers - (ITR)- RMK Site - December 200546 46
Current TransformersHair-Pin Design - ITT / IT range
> Instrument Transformers - (ITR)- RMK Site - December 200547 47
1. Dome
2. Nitrogen filling valve
3. Primary terminal
4. Collar
5. Porcelain insulator
6. Primary conductor with insulation
7. Adaptor cylinder
8. Secondary cores
9. Base
10. Oil drain plug
Full Range of HV Technologies
Current Transformers (Paper/Oil) up to 420 kV - ITT 245
- IT 400
Hair-Pin design
IT 400 Cross section
> Instrument Transformers - (ITR)- RMK Site - December 200548 48
Hair-Pin DesignTechnical Data
Rated voltage : 245 to 420 kV
Technology : Hair-Pin
Expansion device : Nitrogen
Rated primary current : up to 3000
Short circuit current : - 40 kA 1” (245 kV)
- 60 kA 1” (420 kV)
Total weight (kg)
kV 245 420
kg 1400 2300
ITT range
> Instrument Transformers - (ITR)- RMK Site - December 200549 49
Classe Ratio errorat In
Phasedisplacementat In
Compositeerror atfL.IN
5 P 1 % 60 min. 5 %10 P 3 % 10 %
Current TransformersProtection accuracy
classesCEI 600 44-1CEI 600 44-1
Accuracy classes (Protection)Accuracy classes (Protection)Maximum current error in % of IP
Accuracy limit primary current = fL.IN
Burden :SN
> Instrument Transformers - (ITR)- RMK Site - December 200550 50
Factors for Protection
Parameters
1. ALF ( accuracy limiting factor)
2. Composite error
Over Current and Earth Fault Protection
> Instrument Transformers - (ITR)- RMK Site - December 200551 51
Factors for Protection
1. Accuracy Limiting Factor
What is Accuracy Limiting factor ?
It is the factor of over current above the rated current which determines the capability of CT to maintain the error at such a condition.
2. Composite error
It is the error of the CT when this over current is applied.
> Instrument Transformers - (ITR)- RMK Site - December 200552 52
Composite error : Under steady-state conditions, the r.m.s. value of the difference between:a) the instantaneous values of the primary current, andb) the instantaneous values of the actual secondary current multiplied by the rated transformation ratio
CEI 600 44-1CEI 600 44-1
T
psnp
c dtiIKTI 0
2.1100
Current TransformersProtection accuracy classes
Kn is the rated transformation ratio;Ip is the r.m.s. value of the primary current;ip is the instantaneous value or the primary current;is is the instantaneous value of the secondary current;T is the duration of one cycle.
> Instrument Transformers - (ITR)- RMK Site - December 200553 53
Factors for Protection
1. Accuracy Limiting Factor/composite error
For e.g if the class designation is 5P20
20 is the Accuracy limiting factor which signifies that when 20 times the rated primary current is applied the compositeerror of 5P( +/- 5%) is maintained.
Typical Class designations are
5P10, 5P20, 10P10, 10P20 etc.,
> Instrument Transformers - (ITR)- RMK Site - December 200554 54
Factors for Protection
Parameters
1. Knee Point Voltage requirement(Vk)
2. Exciting current ( Io)
3. Resistance of CT (Rct)
Transformer and Busbar Differential Protection
> Instrument Transformers - (ITR)- RMK Site - December 200555 55
Current TransformersSaturation curve
10 20 30 40
InductionB [T]
Primary currentIp/In
Protection CT
18500 gauss
Metering CT
8000 gauss
> Instrument Transformers - (ITR)- RMK Site - December 200556 56
Factors for Protection
1. Knee Point Voltage(Vk):
Knee point voltage is point beyond which an application of 10% of voltage increases the exciting current by 50%.
The typical equations for Vk ( based on relay used)
Vk > 24 In (Rc t+2RL)- for Transformer Differential
Where In: Relay rated currentRL = Total lead ResistanceRc t = CT secondary resistance
> Instrument Transformers - (ITR)- RMK Site - December 200557 57
Current TransformersType Tests
IEC 600 44-1IEC 600 44-1
Type tests
a) short-time current tests
b) temperature rise test
c) lightning impulse test
d) switching impulse test
e) wet test for outdoor type transformers
f) determination of errors
> Instrument Transformers - (ITR)- RMK Site - December 200558 58
Current TransformerRoutine tests
CEI 600 44-1CEI 60-1
CEI 600 44-1CEI 60-1
Routine tests
The following tests apply to each individual transformers:
a) verification of terminal markings
b) power-frequency withstand test on primary winding
c) partial discharge measurement
d) power-frequency withstand test on secondary windings
e) power-frequency withstand tests, between sections
f) inter-turn overvoltage test
g) determination of errors
The order of the tests is not standardized, but determination of
errors shall be performed after the other tests.
> Instrument Transformers - (ITR)- RMK Site - December 200559 59
Typical ( Maximum) lead lengths based on voltage level of substations
Voltage Level in kV Lead Length in Meters
400 1000
220 800
132 500
> Instrument Transformers - (ITR)- RMK Site - December 200560 60
Typical Burdens - Analog and Digital Meters( Current Transformer Circuit )
METERS/LOADS TYPICAL VABURDEN( ANALOG TYPE )
TYPICAL VA BURDEN( DIGITAL TYPE )
AMMETER 1 0.5
WATTMETER &VARMETER
1 0.1
ENERGY METER 1 0.1
PF METER 1 0.1
TRANSDUCER 1
TOTAL 5 1.8
> Instrument Transformers - (ITR)- RMK Site - December 200561 61
Typical Burden Calculation 400kV Current Transformer Metering core
The max burdens of all the meters/load = 5 VA (approx) considering analog meters and max lead length for 400kV switchyard = 1000 meters
The control cable size is 2.5 sq.mm. Always 2 runs of cable are used. Resistance of 2.5sq.mm cable is 8.5 ohms per kilometre for 2 runs of cable it is 4.25 Ohms
Therefore the burden of the lead length is = 2* isec2 * r * 1kM
= 2 *1*1* 4.25
= 8.5 VA
The optimum total burden will be = 5 + 8.5 = 13.5VA
Therefore realistic burden required is 15 or 20VA
> Instrument Transformers - (ITR)- RMK Site - December 200562 62
Burden of numerical relay recommended = 2.5 VA ( inclusive of lead length ). The maximum lead length for 220/132kv switchyard = 500 meters
The control cable size is 2.5 sq.mm. Always 2 runs of cable are used. Resistance of 2.5sq.mm cable is 8.5 ohms per kilometre for 2 runs of cable it is 4.25 Ohms
Therefore the burden of the lead length is = 2* isec2 * r * 500/1000
= 2 *1*1* 4.25*0.5
= 4.25 VA
the optimum total burden = 2.5 +4.25 = 7 VA
Therefore realistic burden required for class 5P cores is 15 VA
NOTE: FOR 400KV CT's ONLY CLASS PS CORES NOTE: FOR 400KV CT's ONLY CLASS PS CORES ARE USED. HENCE THIS CALCULATION IS ARE USED. HENCE THIS CALCULATION IS OMITTED FOR 400KV CT’s.OMITTED FOR 400KV CT’s.
Typical Burden Calculation 220kV Current Transformer Protection core
> Instrument Transformers - (ITR)- RMK Site - December 200563 63
List of utilities who have reduced burdens for metering of 0.2 accuracy Cl
CUSTOMER 400KV CT 220KV CT 132KV CT
APTRANSCO 20 ( 40 ) 20 ( 40) 15 ( 30)
PGCIL 20 ( 40) 20 ( 40) 20 ( 40 )
MSEB 20 ( 40) 20 ( 40 )
KPTCL 20 ( 30) 20 ( 30) 20 ( 30 )
RRVPNL 30 ( 40)
VALUES WITHIN BRACKET INDICATES PREVIOUS VALUES SPECIFIED
> Instrument Transformers - (ITR)- RMK Site - December 200564 64
Capacitor Voltage TransformersCCV range
> Instrument Transformers - (ITR)- RMK Site - December 200565 65
1. Oil level indicator (optional)2. Expansion device3. Capacitor units4. Insulating oil5. Porcelain insulator6. Sealing7. Electromagnetic unit8. Low voltage terminals box/
HF terminal9. Series inductance10. Medium voltage transformer11. Damping circuit against ferroresonance effects
Capacitor Voltage Transformers (Paper/Film/Oil) up to 765 kV
CCV range
Full Range of HV Technologies
123
4
5
7
89
11
6
10
> Instrument Transformers - (ITR)- RMK Site - December 200566 66
Accurate Measurement of HV
Capacitor Voltage Transformers Coupling Capacitors CCV / CC 72.5 to 765 kV
Line protection
HF transmission
Compliance with IEC, ANSI or equivalent standards
Reduce the slope of the RRRV (Rate of Rise of Recovery Voltage (Ik >40 kA)
Performance:
72.5 to 765 kV
Cn from 2.500 to 20.000 pF
Thermal capacity up to 1000 VA
> Instrument Transformers - (ITR)- RMK Site - December 200567 67
Accurate Measurement of HV
Capacitor Voltage TransformersCoupling Capacitors CCV / CC 72.5 to 765 kV
Characteristics:
Capacitor elements are made of paper-polypropylene and aluminum foils, insulated with synthetic dielectric oil
Up to four secondary windings
Carrier accessories (transmission from 30 up to 500 kHz) on request
Oil expansion by metallic bellows
> Instrument Transformers - (ITR)- RMK Site - December 200568 68
Accurate Measurement of HV
Capacitor Voltage TransformersCoupling Capacitors CCV / CC 72.5 to 765 kV
Advantages:
Built-in safety features
Hermetically sealed for long life
Mineral & synthetic oil-filled, PCB free
Non-corrosive hardware
High reliability and longevity due to optimized design
Operation as coupling capacitors for power line carrier transmission
Superior transient response
Compact design : smaller diameter porcelain that results in less oil and less weight
> Instrument Transformers - (ITR)- RMK Site - December 200569 69
Capacitor Voltage Transformers - CCV Range
Thousands of installed units attest to their reliability
> Instrument Transformers - (ITR)- RMK Site - December 200570 70
Capacitor Voltage TransformerDefinitions
Element Pack(or pack)
Element Pack(or pack)
Pile of elements : ± 10 to 25 kV
> Instrument Transformers - (ITR)- RMK Site - December 200571 71
Capacitor Voltage TransformerDefinitions
Assembly of elements in an insulating container: ± 245 kV.Can be connected to a HV line
Capacitor Unit(or unit)
Capacitor Unit(or unit)
HV Power line
Ground
> Instrument Transformers - (ITR)- RMK Site - December 200572 72
Capacitor Voltage TransformerDefinitions
Capacitor STACK(or stack)
Capacitor STACK(or stack)
Assembly of elements to reach higher voltage levels : ± 800 kV
HV Power line
Ground
In general, the termCAPACITOR
stands for a capacitor elementas well as a capacitor stack.
> Instrument Transformers - (ITR)- RMK Site - December 200573 73
Capacitor Voltage Transformer
Definitions
Capacitor Voltage Divider( or CVT )
Capacitor Voltage Divider( or CVT )
Connecting an MV inductive voltage transformer to a tap.
HV Power line
Ground
> Instrument Transformers - (ITR)- RMK Site - December 200574 74
IntermediateVoltage :
10 to 20 kV/3
Capacitor Voltage TransformerBasics
S1
S2
P1
P2
C1
C2
> Instrument Transformers - (ITR)- RMK Site - December 200575 75
Lµ = Inductance equivalent to magnetic losses of the magnetic circuit.
Rw = Resistance equivalent to the watt losses of the magnetic circuit.
Lfs = Secondary leakage inductance of the magnetic VT.
Rs = Resistance of the secondary winding
Capacitor Voltage TransformerMagnetic Transformer
Ce La LfsRa Rs
Lμ Rw ZcUsU’P =Vp . C1
k . (C1+C2)
Equivalent DiagramEquivalent Diagram
> Instrument Transformers - (ITR)- RMK Site - December 200576 76
RMK - CVT
Capacitor stack
Inductive VT
> Instrument Transformers - (ITR)- RMK Site - December 200577 77
CCV 72.5 to 765 kV
Capacitor elements
Capacitor column
Insulating oil
Insulator flange
Secondary terminal box
Inductance
MV Transformer
Oil expansion device
Damping circuit
RMK - CVTRMK - CVT
> Instrument Transformers - (ITR)- RMK Site - December 200578 78
P
Capacitor Voltage TransformerDiagram
P
GROUND
GS HF
HV Terminal
C1
C2
N
4a
4n
111214
1a
1n
111214
2a
2n
111214
3a
3n
111214
MCB
S S S SGS MV D
L
HFDC
C
> Instrument Transformers - (ITR)- RMK Site - December 200579 79
PLC System
> Instrument Transformers - (ITR)- RMK Site - December 200580 80
Capacitor Voltage TransformerNew Capacitor Elements
All Paper Dielectric design Mixed dielectric design(New)
Paper PPR film + paper
Copper tabs forconnection
Aluminum foilfolded for contactwith next element
> Instrument Transformers - (ITR)- RMK Site - December 200581 81
Capacitor Voltage TransformerNew Capacitor Elements
No more soldering
Improved contact between elements
No copper tabs
Improvements in the new designImprovements in the new design
Aluminum foil :
> Instrument Transformers - (ITR)- RMK Site - December 200582 82
Capacitor Voltage TransformerNew Insulating "Oil"
Comparison between NEW JARYLEC and MINERAL OILSI.NO. Property Unit Mean value
Before treatment After treatmentmineral oil Jarylec mineral oil Jarylec
1 Colour transparent slightly yellow transparent slightly yellow2 Density at 29.50C g/cm3 0.89 0.99 0.89 0.99
3 Kinematic viscosity at 270C Cst 27 4.2 27 4.2
4 Interfacial tension at 270C N/m 0.04 0.036 0.04 0.036
5 Flash point 0C 140 144 140 144
6 Pour point 0C -6 <-50 -6 <-507 Acidity mgKOH/g 0.03 <0.01 0.03 <0.018 Breakdown voltage kV 30 >70 >60 >80
9Dielectric dissipation factor (tan) at
900°C<0.005 <0.004 <0.002 <0.001
10 Water content ppm 50 <100 15 511 Resistivity 1000C hmxcm 0.15x1012 >9x1014 0.35x1014 >9x1014
Very high breakdown voltage
High volume resistivityVery low viscosityfor better impregnation
Low loss angle
> Instrument Transformers - (ITR)- RMK Site - December 200583 83
Capacitor Voltage TransformerNew Insulating "Oil"
Nature of the dielectric (impregnated)all paper/mineral oil Paper +PPR/Jarylec
under rated voltage 12.2 V/m 25 V/munder power frequency voltage 40 V/m 80 V/m
Maximal gradient
dielectricThicknesselementsN
columnUGradients
.)(
)(
The elements as per the new design can withstand double gradients.
Higher gradients allowed
> Instrument Transformers - (ITR)- RMK Site - December 200584 84
Capacitor Voltage TransformerNew Insulating "Oil"
Maximalvoltage for "All paper"/mineral oil Paper + PPR/Jarylecan element 1050 V 1500 V
Nature of the dielectric
columntheinelementsofNumber
UU m
elementi .....
7.0/max
The elements as per the new design can withstand a higher voltage
Improved gradient results in smaller capacitorsSAME HEIGTH BUT SMALLER DIAMETER
> Instrument Transformers - (ITR)- RMK Site - December 200585 85
During HF communication, earthing of signals or entry into magnetic part must be avoided.
Capacitor Voltage TransformerPLC system
P2
C1
C2
Line trap
InductivePart
HV line
Draining coil and grounding switchcould already be included in HF generator.
HF
> Instrument Transformers - (ITR)- RMK Site - December 200586 86
cos.
.
1-.sin..
2V
VA3440.=
s
minutos)(en
ea CLR
Phase error :
sin.
.
1-.+cos..
2V
VA100.=%)(en
s ea CLR
Ratio error :
Reduce nominal secondary burden
Capacitor Voltage TransformerMagnetic Transformer
Accuracy at nominal frequencyAccuracy at nominal frequency
Good quality of windings
Good tuningHigh intermediate voltage
> Instrument Transformers - (ITR)- RMK Site - December 200587 87
Ce La Rp
Lµ Rw
Rs
Rpam
Lam
Ram
ZcVsVi
Primary Short Circuit & Transient Response
Primary Short Circuit & Transient Response
Capacitor Voltage TransformerDamping Circuit
> Instrument Transformers - (ITR)- RMK Site - December 200588 88
• In steady state, the CVT secondary voltage is a reliable representation of the primary voltage.
• In case of sudden change in the primary voltage (like a short circuit), the voltage output will be distorted (high error) during a few cycles.
• The above transient error will depend on:• The burden connected to the CVT• The moment of the voltage interruption.
• The transient response will be improved by adding a damping circuit connected on the secondary
Capacitor Voltage TransformerDamping Circuit
Primary Short Circuit & Transient ResponsePrimary Short Circuit & Transient Response
> Instrument Transformers - (ITR)- RMK Site - December 200589 89
Short-circuit at zero crossing
Primary voltage
Secondary voltage
t
Vs
Vi
t
Capacitor Voltage TransformerDamping Circuit
Primary Short Circuit & Transient ResponsePrimary Short Circuit & Transient Response
> Instrument Transformers - (ITR)- RMK Site - December 200590 90
Capacitor Voltage TransformerDamping Circuit
Short-circuit at zero crossing
Primary voltage
Secondary voltage
t
Vs
Vi
t
5%
10%
Secondary error
t
0 100 200 300 [ms]
Necessary to add a damping circuitNecessary to add a damping circuit
20 msIEC 186 error limits
IEC today :max 10% after 20ms
Primary Short Circuit & Transient ResponsePrimary Short Circuit & Transient Response
> Instrument Transformers - (ITR)- RMK Site - December 200591 91
R R-L-C R-L-RHow to solve transient problems :
• High burden
• jeopardize accuracy
• High burden
• jeopardize accuracy
• Efficient• Easy to design
• Expensive
• Efficient• Easy to design
• Expensive
• Efficient• Sophisticated design
• Economical
• Efficient• Sophisticated design
• Economical
Capacitor Voltage TransformerDamping Circuit
Primary Short Circuit & Transient ResponsePrimary Short Circuit & Transient Response
> Instrument Transformers - (ITR)- RMK Site - December 200592 92
Primary Short Circuit & Transient ResponsePrimary Short Circuit & Transient Response
-200
-100
0
100
200
30
0
35
0
40
0
45
0
50
0
55
0
60
0
Tension secondaireSecondary Voltage
-2
-1
0
1
2
3
4
5
6
7
30
0
35
0
40
0
45
0
50
0
55
0
60
0
% Erreur secondaire (transitoire)% error at secondary
R-L-RR-L-R
Capacitor Voltage TransformerDamping Circuit
-200-150-100-50
050
100150200
30
0
35
0
40
0
45
0
50
0
55
0
60
0
Tension primairePrimary Voltage
> Instrument Transformers - (ITR)- RMK Site - December 200593 93
a) After clearance of a short-circuit at the secondary terminals (fuse blown) , the CVT being energizedat 120% of the rated voltage, the crest value of the secondary voltage must return to less than 10% error after 10 cycles.
b) After short-circuit clearance, at 150% of the rated voltage, the ferroresonnance must be eliminated within less than 2 seconds
Ferroresonance according IEC 186
Capacitor Voltage TransformerFerroresonance
> Instrument Transformers - (ITR)- RMK Site - December 200594 94
Capacitor Voltage TransformerFerroresonance
L1
L2
ZN2
N1
Ith
C2
C1
SGC
CSecondary Short CircuitSecondary Short Circuit
L
R2
R1
D
FerroresonanceDamping deviceon inductive PT
L'1
L'2
RL SGL
FerroresonanceDamping deviceon inductance
"Transformer type"compensating
inductance
> Instrument Transformers - (ITR)- RMK Site - December 200595 95
Secondary current
Secondaryvoltage
Withoutdampingdevice
Short-circuit
Fuseoperation
Capacitor Voltage TransformerFerroresonance
Primary voltage
> Instrument Transformers - (ITR)- RMK Site - December 200596 96
-100-80-60-40-20
020406080
100
35
0
40
0
45
0
50
0
55
0
60
0
65
0
70
0
75
0
Secondarycurrent
-600
-400
-200
0
200
400
600
350
400
450
500
550
600
650
700
750
Secondary voltage
Withdampingdevice
Capacitor Voltage TransformerFerroresonance
-250-200-150-100-50
050
100150200250
35
0
40
0
45
0
50
0
55
0
60
0
65
0
70
0
75
0
Primaryvoltage
10 cycles : error < 10%
> Instrument Transformers - (ITR)- RMK Site - December 200597 97
Voltage TransformersMetering Accuracy Classes
Accuracy classes - Multiple windingsSame conditions except, accuracy to be garanteed with- Other windings loaded between 0% to 100%
IEC 600 44-2IEC 600 44-2
REMEMBER : with multiple secondaries, the maximum possible burden will generally be limited by :- the possible burden in the highest accuracy class with 1 winding- the difference between the different burdens- the mutual influence of the secondaries
Ex.: Accuracy VA max Total VA to be sharedClass if 1 secondary between the 2 windings 0.2 250 VA 250 x 0.8 = 200 VA0.5 800 VA max. total simultaneous
> Instrument Transformers - (ITR)- RMK Site - December 200598 98
ExcessiveFrequencyVariations
Nominal burdenOVER-ESTIMATEDReal load < 25% VAN
Nominal burdenUNDER-ESTIMATEDReal load > 100% VAN
Capacitor Voltage TransformerTypical Error Curve
Typical graph of variation of errors with VA & frequencyTypical graph of variation of errors with VA & frequency
Phase error
Ratio error
f
25% VA
f+f
f -f100% VA
+20’- 20’
+0.5
- 0.5
> Instrument Transformers - (ITR)- RMK Site - December 200599 99
Voltage transformersProtection accuracy
classes
IEC 600 44-2IEC 600 44-2
Accuracy classes (Protection)Maximum error in % of VP
- Voltage between 5 % and fT x VNP
- Burden between 25% and 100% of SN
- Maximum error doubled for VNP=2%
Accuracyclass
Voltage(ratio)error
Phasedisplacement[minutes]
Cl 3P 3 % 120
Cl 6P 6 % 24O
> Instrument Transformers - (ITR)- RMK Site - December 2005100 100
Capacitor Voltage TransformersRoutine tests (IEC 60044-5)
Routine tests
The following tests apply to each individual transformer:
a) Verification of terminal markings
b) Power-frequency withstand tests on primary windings
c) Partial discharge measurement
d) Power-frequency withstand tests on secondary
windings
e) Power-frequency withstand tests between sections
f) Determination of errors.
G) Ferroresonance test
h) Sealing test
> Instrument Transformers - (ITR)- RMK Site - December 2005101 101
Capacitor Voltage TransformersType tests (IEC 60044-5)
a) Temperature-rise test
b) Short-circuit withstand capability test
c) Lightning impulse test
d) Switching impulse test
e) Wet test for outdoor type transformers
f) Determination of errors.
> Instrument Transformers - (ITR)- RMK Site - December 2005102 102
Typical Burdens - Analog and Digital Meters (Voltage
Transformer Circuit )
METERS/LOADS TYPICAL VABURDEN( ANALOG TYPE )
TYPICAL VA BURDEN( DIGITAL TYPE )
VOLTMETER 5 1
WATTMETER&VARMETER
4 0.1
ENERGY METER 1 0.1
PF METER 4
ELECTRONICSYNCHROSCOPE
6
FREQUENCYMETER
7 1
TRANSDUCER 1
TOTAL 28 12.2
> Instrument Transformers - (ITR)- RMK Site - December 2005103 103
MAXIMUM BURDEN IMPOSED ON THE CAPACITOR VOLTAGE TRANSFORMER METERING WINDING IN A 400KV SUBSTATION
The max burdens of all the meters/load = 28 VA (approx) when analog meters are considered and max lead length for 400kv switchyard = 1000 meters
The control cable size is 2.5 sq.mm. Always 2 runs of cable are used. Resistance of 2.5sq.mm cable is 8.5 ohms per kilometre for 2 runs of cable it is 4.25 Ohms
Therefore the burden of the lead length is = 2* isec2 * r * 1km
= 2 * (28/63.5)2* 4.25*1
= 1.70 VA
The optimum total burden = 28 +1.7 = 29.7 VA
Therefore realistic burden required is 50 VA
> Instrument Transformers - (ITR)- RMK Site - December 2005104 104
Line Traps
> Instrument Transformers - (ITR)- RMK Site - December 2005105 105
Features of AREVA T&D Line Traps Design
High short-circuit withstand capability
Light weight
Reliable open-style design (OSD)
Mounting flexibility
Excellent cooling
Extremely reliable tuning devices
Self-resonance frequency greater than 500 kHz
Maintenance-free design
No surface cracking
> Instrument Transformers - (ITR)- RMK Site - December 2005106 106
Corona Ring
Protective Device
Tie Rod
Main Coil
Tuning Device
PedestalBird Barrier
Crossarm
Terminal
Terminal
Lifting Lug
Line TrapsConstruction
Main Components
> Instrument Transformers - (ITR)- RMK Site - December 2005107 107
Line TrapsMounting Arrangements
Vertical pedestal Horizontal pedestal Suspension
> Instrument Transformers - (ITR)- RMK Site - December 2005108 108
Line TrapsMounting Arrangements
Lifting lug bolted to the central tie rod
Eyebolt to the bottom crossarm
One to four-point suspension
Suspension mounting
> Instrument Transformers - (ITR)- RMK Site - December 2005109 109
Line TrapsMounting Arrangements
Vertical pedestal mounting type “A”
Aluminum pedestal
Small or medium sized LT can be mounted directly on a single post insulator or CCVT
> Instrument Transformers - (ITR)- RMK Site - December 2005110 110
Line TrapsMounting Arrangements
Vertical pedestal mounting type “B”
Aluminum pedestal
Large sized LT: 3 insulator column pedestal
Number of columns can be adapted
> Instrument Transformers - (ITR)- RMK Site - December 2005111 111
Line TrapsMounting Arrangements
Aluminum or stainless steel pedestal
Horizontal mounting (for OSD)
> Instrument Transformers - (ITR)- RMK Site - December 2005112 112
Line TrapsMain Components
Easily accessible and exchangeable:
can be replaced without removing the
line trap from the line.
Factory fixed or field adjustable.
For single-frequency, double-
frequency,
or wide-band tuning
Areva tuning device can be used in all
existing LT
Tuning Device Options
> Instrument Transformers - (ITR)- RMK Site - December 2005113 113
Line TrapsMain Components
Connected across the main coil and the tuning device to prevent the LT from being damaged by transient over-voltages.
Surge Arrester
> Instrument Transformers - (ITR)- RMK Site - December 2005114 114
Bird Barrier
Line TrapsMain Components
Temperature and UV resistant fiberglass reinforced plastic grid with square shaped 15 X 15 mm openings
Cooling of the line traps remains unchanged.
Bird Barrier
> Instrument Transformers - (ITR)- RMK Site - December 2005115 115
Line TrapsBasic Design Parameters
Standard
System voltage
Rated frequency
Rated inductance
Rated current
Blocking range
Minimum blocking impedance or resistance
Short-circuit requirements
Type of mounting
Site conditions
> Instrument Transformers - (ITR)- RMK Site - December 2005116 116
Condenser Bushings
> Instrument Transformers - (ITR)- RMK Site - December 2005117 117
Full Range of HV Technologies
Condenser bushings - Oil to air- Oil impregnated paper (OIP)
Suitable for connecting outdoor equipment to HV transformers as per ANSI or IEC standard
Air side : porcelain envelope
Partial discharge < 5pC at 1.5Un /
Specially treated mineral oil
Power factor tap, air draining plug and oil side shield provided
Prismatic oil sight glass with option MOLG above 145kV
Flange of aluminum alloy casting
Extensive field experience
High creepage bushing on request
Dielectric dissipation factor < 0.40%
3
Up to 420 kV
> Instrument Transformers - (ITR)- RMK Site - December 2005118 118
Full Range of HV Technologies
In addition to bushings for power transformers, AREVA T&D also manufactures wall bushings, oil-oil bushings and high current bushings.
> Instrument Transformers - (ITR)- RMK Site - December 2005119 119
1. Top terminal
2. Cable bolt
3. Oil filling plug
3a . Nitrogen filling plug
4. Expansion bowl
5. Oil sight glass
6. Springs
7. Gaskets
8. Central metal tube
9. Oil impregnated core
10. Porcelain - Upper
11. Fixing flange
12. Test tap
13. Air releasing screw
14. Porcelain -Lower
15. Base plate / stress shield
16. Upper arcing horn
17. Lower arcing horn
18. Top shield cover
19. Bolt and nut
Full Range of HV Technologies
Condenser Bushings
> Instrument Transformers - (ITR)- RMK Site - December 2005120 120
Assembled Bushings