Oltc Fundam Iran 06
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OLTC Fundamentals
© ABB - 1
By Mats Carlsson
On-Load Tap-Changers EETC Alexandria Zone November 2006
© ABB Power Technologies - 2 Components 2003-05-12
Outline
ABB Components introduction
Tap-changers
Bushings
Life cycle support
Power Transformer Components
Bushings
© ABB Power Technologies - 3 Components 2003-05-12
TapChangers
The High Voltage Valley in Ludvika, Sweden
High Power Laboratory
© ABB Power Technologies - 4 Components 2003-05-12
High Voltage Laboratory
Swedish Transmission Research Institute
Transformer Tapchangers High Power Capacitors
HV Shunt Reactors
HV Circuit Breakers
HV Instrument Transformer s HV Surge Arresters Transform er Bushings HV Thyristor Converters
Power Transformer s
Components Ludvika, Sweden
© ABB Power Technologies - 5 Components 2003-05-12
KEY FIGURES 2005
Revenue
~100 MUSD
External ABB sales ~50%
Employees
~300
No of Bushings
>10000
No of Tap Changers
>2000
Export share
95%
R&D expenditure
~10%
Tap-changer historical overview (2) 1910 First tap-changer produced (type HM)
1927 HA
1953 HF
1963 UCB (in-tank)
1964 UZB (on-tank)
1965 UCC
1978 UCG
1978 UZE
1983 UCL
1987 UZF
© ABB Power Technologies - 6 Components 2003-05-12
1991 UBB
ABB is the largest manufacturer of bushings
© ABB Power Technologies - 7 Components 2003-05-12
Resin impregnated (RIP) with composite or porcelain insulators 36 - 550 kV
Oil impregnated (OIP) with porcelain insulators 36 - 800 kV
Conformance: IEC, IEEE & Regional Standard Variants
© ABB Power Technologies - 8 Components 2003-05-12
Transformer components – in challenging applications!
HVDC transformers
Phase-shifters e.g. 1630 MVA & 400 kV
Subjects
Tap-changer types Principles of operation Transition resistor Switching time Contact life Maintenance
News! Tie-in resistor
Tests
Development
© ABB Power Technologies - 9 Components 2003-05-12
On-load tap-changers ABB (ASEA) has manufactured tap-changers since 1910.
© ABB Power Technologies - 10 Components 2003-05-12
More than 45 000 units of the modern design are today in operation worldwide.
On-load tap-changers Design philosophy: Highest reliability
Easy maintenance
Longest lifetime
© ABB Power Technologies - 11 Components 2003-05-12
On-load tap-changers
Longest lifetime by using first class materials and by thorough tests. Typical contact life is 350 000 through 500 000 operations. Highest reliability by using few parts and making simple designs
Easiest maintenance by same reasons as above
© ABB Power Technologies - 12 Components 2003-05-12
© ABB Power Technologies - 13 Components 2003-05-12
On-load tap-changers
ABB Tap-Changer Reliability Reported unscheduled service interruptions due to the tap-changer 0,06%
0,05%
Amount
0,04%
0,03%
0,02%
© ABB Power Technologies - 14 Components 2003-05-12
0,01%
0,00% 1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
Year
An average of 5000 years between these stops!
2004
Failures of Tap Changers from 1996-2005 Failures during service.
© ABB Power Technologies - 15 Components 2003-05-12
Year failure was repo
1996 1997 1998
The figures include all failures, independent of age and types of tap-changers, which have led to a service interruption of the transformer, caused by fault in the tap-changer.
© ABB Power Technologies - 16 Components 2003-05-12
On-load tap-changers
On-load tap-changers
© ABB Power Technologies - 17 Components 2003-05-12
WHAT IS AN ON-LOAD TAP-CHANGER?
On-load tap-changers
© ABB Power Technologies - 18 Components 2003-05-12
A device for changing the tapping connection of a winding while the transformer is on load
© ABB Power Technologies - 19 Components 2003-05-12
On-load tap-changers
© ABB Power Technologies - 20 Components 2003-05-12
On-load tap-changers
On-load tap-changers
© ABB Power Technologies - 21 Components 2003-05-12
Current is interrupted Must not happen!
On-load tap-changers
One loop of the regulating winding is short-circuited
© ABB Power Technologies - 22 Components 2003-05-12
Must not happen!
© ABB Power Technologies - 23 Components 2003-05-12
On-load tap-changers Transition Resistors
© ABB Power Technologies - 24 Components 2003-05-12
On-load tap-changers Transition Resistors
On-load tap-changers Resistor type
Reactance type
Electronic types
Others
© ABB Power Technologies - 25 Components 2003-05-12
On-load tap-changers
© ABB Power Technologies - 26 Components 2003-05-12
Reactance type is mainly used in ANSI-standard countries, most often to regulate on the LV side of the transformer.
On-load tap-changers
© ABB Power Technologies - 27 Components 2003-05-12
Electronic types belongs to the future
On-load tap-changers
Resistor types most common today.
© ABB Power Technologies - 28 Components 2003-05-12
Can be diverter switch type or selector switch type.
On-load tap-changers Diverter switch type consists of separate diverter switch and tap selector
Selector switch type consists of a combined diverter switch and tap selector unit
© ABB Power Technologies - 29 Components 2003-05-12
Types of Switching A.
Linear Switching
Selector Switch
Coarse Winding
A.
Plus/Minus Switching
K
© ABB Power Technologies - 30 Components 2003-05-12 Regulating Winding
10
K 9
9
A. Selector Switch
B
C
Most common (~70%) Additive (+) & subtractive (-) Change Over Selector
Coarse/Fine Switching
A
Not very common (~20%) Simple design trafo & oltc Smallest regulating range Smallest losses
Least common (~10%) Coarse winding insertion Change Over Selector Small losses
Principle Circuits of OLTC Transformers (1) For two-winding power transformers, the most popular arrangments is the regulation at the neutral end of the winding.
© ABB Power Technologies - 31 Components 2003-05-12
This solution provides the most economical tap winding arrangement with generally graded insulation combined with a compact three-phase neutral point OLTC. OLTC in Y or Star Connected Windings
Principle Circuits of OLTC Transformers (2)
© ABB Power Technologies - 32 Components 2003-05-12
3-Pole Line-End Arrangment
2-Pole + 1-Pole Line-End Arrangment
3-Pole Mid-Winding Arrangment
OLTC in Delta-Connected Windings
On-load tap-changers MVA Transformer Ratings
> 80
80
80
50
60
150
150
300
HVDC
1000
---------------------------------------------------------------------------------------------------------------1
© ABB Power Technologies - 33 Components 2003-05-12
USB 200
UZF 650
UZE 650
L (m)
UB 2 B3 UCG.N/ 50 3 UCG.N/C C 1050 UCL.N/III UCD.N/II 1050 Short I 1050 UCG.N/II 1050 4 I 1050
All are of Jansen type, i.e. spring operated switches and of resistive type.
UCC. N 1050
© ABB Power Technologies - 34 Components 2003-05-12
Tap-changers, diverter switch type Diverter
Tap selector
© ABB Power Technologies - 35 Components 2003-05-12
7 5
6 4
Transformer regulating winding
© ABB Power Technologies - 36 Components 2003-05-12
Italy, Terna
400 kV, 1630 MVA
Weight 820,000 kg
Footprint 13x15x10 m
On-load tap-changers
© ABB Power Technologies - 37 Components 2003-05-12
Two-phase UC-type Tap-Changer mounted on special transformer
On-load tap-changers
Top section with mounting flange Shielding rings Diverter switch Connectors between diverter switch ant tap selector
© ABB Power Technologies - 38 Components 2003-05-12
Tap selector with preselector
On-load tap-changers
© ABB Power Technologies - 39 Components 2003-05-12
Switching sequence for Diverter-Switch type Tap-Changer
© ABB Power Technologies - 40 Components 2003-05-12
Tap-changers, diverter switch type
7
5 6
4
© ABB Power Technologies - 41 Components 2003-05-12
Tap-changers, diverter switch type
7
5 6
4
© ABB Power Technologies - 42 Components 2003-05-12
Tap-changers, diverter switch type
7
5 6
4
© ABB Power Technologies - 43 Components 2003-05-12
Tap-changers, diverter switch type
7
5 6
4
© ABB Power Technologies - 44 Components 2003-05-12
Tap-changers, diverter switch type
7
5 6
4
© ABB Power Technologies - 45 Components 2003-05-12
Tap-changers, diverter switch type
7
5 6
4
© ABB Power Technologies - 46 Components 2003-05-12
Tap-changers, diverter switch type
7
5 6
4
© ABB Power Technologies - 47 Components 2003-05-12
Tap-changers, diverter switch type
7
5 6
4
On-load tap-changers
© ABB Power Technologies - 48 Components 2003-05-12
Animation Switching sequence for Diverter-Switch type Tap-Changer
Features for the UC tap-changer Extensive More
service experience
than 9000 units in service
Excellent
Quick
service record
and easy maintenance
Shaft
outside diverter switch housing
Open
design, no special tools needed
Reliable
© ABB Power Technologies - 49 Components 2003-05-12
Few
parts
Simple No
and robust design
on-line filtration needed
© ABB Power Technologies - 50 Components 2003-05-12
UC tap-changers
Completely clean cover
Bevel gear for shaft system outside cover
Lift our diverter switch without removing shafts!
Operate motor-drive and tap selector when diverter switch is removed
Operate diverter switch as desired!
© ABB Power Technologies - 51 Components 2003-05-12
UC tap-changers
Diverter switch electrically connected and mechanically coupled without screws
Kept on place by springs on top, pressed by the cover
© ABB Power Technologies - 52 Components 2003-05-12
UC tap-changers
Easiest possible maintenance
No dismantling of diverter switch needed for inspection & cleaning
© ABB Power Technologies - 53 Components 2003-05-12
UC tap-changers
No need to bring diverter switch down from transformer for maintenance
Transformer outage less than one day for maintenance
ABB tap-changers in furnace transformers
UCG top section with shaft, bevelgear & motor-drive
© ABB Power Technologies - 54 Components 2003-05-12
mechanism
ABB tap-changers in furnace transformers The cover has been removed.
© ABB Power Technologies - 55 Components 2003-05-12
(Six minutes passed)
ABB tap-changers in furnace transformers
Note that the shaft system is not
© ABB Power Technologies - 56 Components 2003-05-12
dismantled
ABB tap-changers in furnace transformers
Tube for draining, guiding and oil sampling Springs for fixing diverter switch
© ABB Power Technologies - 57 Components 2003-05-12
Mounting information
ABB tap-changers in furnace transformers
© ABB Power Technologies - 58 Components 2003-05-12
Hook to lift...
© ABB Power Technologies - 59 Components 2003-05-12
ABB tap-changers in furnace transformers
Lift...
ABB tap-changers in furnace transformers
© ABB Power Technologies - 60 Components 2003-05-12
Continue to lift...
ABB tap-changers in furnace transformers
Dvierter switch lifted out.
© ABB Power Technologies - 61 Components 2003-05-12
(Ten minutes passed)
ABB tap-changers in furnace transformers
Drive disc with
© ABB Power Technologies - 62 Components 2003-05-12
slot for drive pin
UC Tap-changer Maintenance (overhaul) Bottom in tap selector cylinder
© ABB Power Technologies - 63 Components 2003-05-12
Notch for driving pin
Driving pin
ABB tap-changers in furnace transformers
Operate the diverter switch
© ABB Power Technologies - 64 Components 2003-05-12
from one side...
ABB tap-changers in furnace transformers
© ABB Power Technologies - 65 Components 2003-05-12
...to the other without caring about the position...
ABB tap-changers in furnace transformers
No harm if you
operate the motordrive.
You don’t have to
note the tap position
© ABB Power Technologies - 66 Components 2003-05-12
number.
ABB tap-changers in furnace transformers
© ABB Power Technologies - 67 Components 2003-05-12
Put the spare or overhauled diverter switch back...
ABB tap-changers in furnace transformers
© ABB Power Technologies - 68 Components 2003-05-12
Fork for guiding
ABB tap-changers in furnace transformers
Switch not yet in proper
© ABB Power Technologies - 69 Components 2003-05-12
position
ABB tap-changers in furnace transformers
© ABB Power Technologies - 70 Components 2003-05-12
Before operated to correct position
ABB tap-changers in furnace transformers
© ABB Power Technologies - 71 Components 2003-05-12
Operate the hand crank till you see and hear that...
ABB tap-changers in furnace transformers
… that it falls down to it’s proper position. Everything is © ABB Power Technologies - 72 Components 2003-05-12
now mechanically and electrically connected.
ABB tap-changers in furnace transformers
When the tapchanger is operated to correct position you can put the cover on.
© ABB Power Technologies - 73 Components 2003-05-12
(Less than 20 minutes passed)
UC tap-changers
© ABB Power Technologies - 74 Components 2003-05-12
Simple, open design with very few parts offers highest reliability and easiest maintenance!
© ABB Power Technologies - 75 Components 2003-05-12
Diverter Switch
Upgrade your old transformer Plug & play concept
Interchangeability in old transformers
For all UCGs since 1978
© ABB Power Technologies - 76 Components 2003-05-12
Tap-changer with vacuum interrupter technology Proven experience
© ABB Power Technologies - 77 Components 2003-05-12
Vacuum bottles, based on 25 years of ABB experience and millions of successfully delivered units provide for an extremely reliable product
© ABB Power Technologies - 78 Components 2003-05-12
Tap-changer with vacuum interrupter technology
Tap-changer with vacuum interrupter technology Reduced life-cycle cost and increased transformer availability
Very limited maintenance during the entire transformer life time
No arcing in oil
No carbonization
Reduced down time
No need for an oil-filter unit
Designed for maintainability
External shaft system remains
© ABB Power Technologies - 79 Components 2003-05-12
Tap-changer with vacuum interrupter technology Reliability
© ABB Power Technologies - 80 Components 2003-05-12
Redundant contactsystem for increased reliability
Vacuum more complex
Monoploy
Humidity – oil samples
Normally maintence after 5-7-15 years
Failures often happens after maintenance
© ABB Power Technologies - 81 Components 2003-05-12
Modular motor drive Improved service friendliness and flexibility Adding / changing of functionality in the field
Self diagnostic and event handling
Reduced number of parts
Transmission gear made from maintenance free elements
Shortened delivery time and increased flexibility in order process
© ABB Power Technologies - 82 Components 2003-05-12
© ABB Power Technologies - 83 Components 2003-05-12
CIGRÉ, August 28th - September 1st
© ABB Power Technologies - 84 Components 2003-05-12
Modular motor drive
On-load tap-changers Summary Extremely high reliability
Excellent service records
Easiest maintenance
Models for all applications available
New technology to be introduced during 2007
© ABB Power Technologies - 85 Components 2003-05-12
© ABB Power Technologies - 86 Components 2003-05-12
Comparison ABB - MR
2000
Criteria: Current, neutral point versions
USB
1500
UCC
1000
UCD
G& RMV-II
R
UCL
© ABB Power Technologies - 87 Components 2003-05-12
500
UCG, UZ UBB
M V
UCG short
MS
ABB
MR
ABB OLTC Benefits - Type UC In-Tank Operating shaft OUTSIDE the diverter housing requiring no disassemble before lifting diverter assembly = Time SAVINGS and REDUCED risk of reassembly error.
© ABB Power Technologies - 88 Components 2003-05-12
Design optimisation of diverter using FEWER parts = LESS statistical possibility for error on reassembly No disassembly of diverter required during overhaul* = Time SAVINGS and NO SPECIAL skills required by service technician
* Note: Contact inspection does not require disassembly but is required during contact replacement.
On-load tap-changers
GSA bushing VVAH cooler
© ABB Power Technologies - 89 Components 2003-05-12
UZF tap-changer
On-load tap-changers Active part of transformer prepared for UZE type tap changer.
Transformer tank with integrated tap-changer tank.
© ABB Power Technologies - 90 Components 2003-05-12
Benefits of using the on-tank UZ No oil filter is needed
Less cleats and leads (conductors), which can easily be made in parallel
No drive-shafts or bevel gears
The UZ is needed later in the production process
Short delivery time
© ABB Power Technologies - 91 Components 2003-05-12
On-load tap-changers Three-phase fully insulated phases or neutral point design
Tap-changer, motor-drive and shaft system integrated
Extremely simple excellent maintenance properties
© ABB Power Technologies - 92 Components 2003-05-12
On-load tap-changers UZF tapchanger
Three phase boards
Integrated motor-drive mechanism
© ABB Power Technologies - 93 Components 2003-05-12
Benefits of using the on-tank UZ BIL 650kV / 600A fully insulated
Up to 100 MVA transformers
No drive-shafts or bevel gears
The UZ require a smaller tfo
© ABB Power Technologies - 94 Components 2003-05-12
less oil
less sheet metal
less beams
less welding
less work
Benefits of using the on-tank UZ
The UZ require a smaller transformer tank
less oil
less sheet metal
less beams
less welding
less work
On-tank
In-tank
Smaller oil conservator
The UZ does not determine the height of the transformer
© ABB Power Technologies - 95 Components 2003-05-12
On-load tap-changers
© ABB Power Technologies - 96 Components 2003-05-12
Mobile transformer by Porter, USA, equipped with UZE type tap-changer
© ABB Power Technologies - 97 Components 2003-05-12
Tap-changers, selector switch type
I
© ABB Power Technologies - 98 Components 2003-05-12
Tap-changers, selector switch type
7
6
5
4
3
2
1 I
© ABB Power Technologies - 99 Components 2003-05-12
Tap-changers, selector switch type
7
6
5
4
3
2
1 I
© ABB Power Technologies - 100 Components 2003-05-12
Tap-changers, selector switch type
7
6
5
4
3
2
1 I
© ABB Power Technologies - 101 Components 2003-05-12
Tap-changers, selector switch type
7
6
5
4
3
2
1 I
© ABB Power Technologies - 102 Components 2003-05-12
Tap-changers, selector switch type
7
6
5
4
3
2
1 I
© ABB Power Technologies - 103 Components 2003-05-12
Tap-changers, selector switch type
7
6
5
4
3
2
1 I
© ABB Power Technologies - 104 Components 2003-05-12
Tap-changers, selector switch type
7
6
5
4
3
2
1 I
© ABB Power Technologies - 105 Components 2003-05-12
Tap-changers, selector switch type
7
6
5
4
3
2
1 I
© ABB Power Technologies - 106 Components 2003-05-12
On-Load Tap-Changer Type UB UBB type tap-changer
Selector switch type
Introduced in 1992
More than 5000 units in service
Uses the contact system from UZtype tap-changer
© ABB Power Technologies - 107 Components 2003-05-12
On-Load Tap-Changer Type UB Fibreglass cylinder
Fixed contacts mounted through cylinder wall with excellent tightening system
Fixed and moving contacts replaceable from inside the tap-changer
© ABB Power Technologies - 108 Components 2003-05-12
On-Load Tap-Changer Type UB
Pre-selector switch
Three fully insulated phases
Moving contacts
Current collectors
© ABB Power Technologies - 109 Components 2003-05-12
On-Load Tap-Changer Type UB
Central shaft
Shield
Current collectors
Neutral connection between phases
© ABB Power Technologies - 110 Components 2003-05-12
On-Load Tap-Changer Type UB
Moving contact system consisting of: Transition
Main
arcing contacts
Current
© ABB Power Technologies - 111 Components 2003-05-12
resistor contacts
contacts
On-Load Tap-Changer Type UB
Main arcing contacts by copperwolfram alloy
Current carrying contacts by silverplated brass
Contact tips by solid silver
© ABB Power Technologies - 112 Components 2003-05-12
On-Load Tap-Changer Type UB
© ABB Power Technologies - 113 Components 2003-05-12
Pre-selector contacts with four contact fingers
© ABB Power Technologies - 114 Components 2003-05-12
TIE-IN RESISTOR
Only for plus/minus and coarse/fine connections.
Used when the recovery voltage over the change-over selector exceed the max. value (between 25-40kV dependent on OLTC)
© ABB Power Technologies - 115 Components 2003-05-12
TIE-IN RESISTOR
© ABB Power Technologies - 116 Components 2003-05-12
Main Winding
Change-Over Selector
Tap Winding
Switch (only connected during change-over operations)
TIE-IN RESISTOR
© ABB Power Technologies - 117 Components 2003-05-12
Main Winding
Change-Over Selector
Tap Winding
Switch (only connected during change-over operations)
TIE-IN RESISTOR
© ABB Power Technologies - 118 Components 2003-05-12
Main Winding
Change-Over Selector
Tap Winding
Switch (only connected during change-over operations)
TIE-IN RESISTOR
© ABB Power Technologies - 119 Components 2003-05-12
Main Winding
Change-Over Selector
Tap Winding
Switch (only connected during change-over operations)
TIE-IN RESISTOR CONNECTION
Main Winding
Change-Over Selector
© ABB Power Technologies - 120 Components 2003-05-12
Tie-in Resistor Tap Winding
Switch (only connected during change-over operations)
TIE-IN RESISTOR CONNECTION
Main Winding
Change-Over Selector
© ABB Power Technologies - 121 Components 2003-05-12
Tie-in Resistor Tap Winding
TIE-IN RESISTOR CONNECTION
Main Winding
Change-Over Selector
© ABB Power Technologies - 122 Components 2003-05-12
Tie-in Resistor Tap Winding
Switch (only connected during change-over operations) Switch (only connected during change-over operations)
Calculation of Tie-In Resistor Needed to calculate the Tie-In Resistor value are:
Capacitance from the regulating winding to adjacent windings or earth. (Included influence from leads)
Voltage on the adjacent windings and the voltage over the regulating winding.
Transformer connection data and frequency. H1
Tank
HV
U
RW
© ABB Power Technologies - 123 Components 2003-05-12
C1
C2
+
-
© ABB Power Technologies - 124 Components 2003-05-12
Recommendation Letter
© ABB - 1
By Mats Carlsson
On-Load Tap-Changers EETC Alexandria Zone November 2006
© ABB Power Technologies - 2 Components 2003-05-12
Outline
ABB Components introduction
Tap-changers
Bushings
Life cycle support
Power Transformer Components
Bushings
© ABB Power Technologies - 3 Components 2003-05-12
TapChangers
The High Voltage Valley in Ludvika, Sweden
High Power Laboratory
© ABB Power Technologies - 4 Components 2003-05-12
High Voltage Laboratory
Swedish Transmission Research Institute
Transformer Tapchangers High Power Capacitors
HV Shunt Reactors
HV Circuit Breakers
HV Instrument Transformer s HV Surge Arresters Transform er Bushings HV Thyristor Converters
Power Transformer s
Components Ludvika, Sweden
© ABB Power Technologies - 5 Components 2003-05-12
KEY FIGURES 2005
Revenue
~100 MUSD
External ABB sales ~50%
Employees
~300
No of Bushings
>10000
No of Tap Changers
>2000
Export share
95%
R&D expenditure
~10%
Tap-changer historical overview (2) 1910 First tap-changer produced (type HM)
1927 HA
1953 HF
1963 UCB (in-tank)
1964 UZB (on-tank)
1965 UCC
1978 UCG
1978 UZE
1983 UCL
1987 UZF
© ABB Power Technologies - 6 Components 2003-05-12
1991 UBB
ABB is the largest manufacturer of bushings
© ABB Power Technologies - 7 Components 2003-05-12
Resin impregnated (RIP) with composite or porcelain insulators 36 - 550 kV
Oil impregnated (OIP) with porcelain insulators 36 - 800 kV
Conformance: IEC, IEEE & Regional Standard Variants
© ABB Power Technologies - 8 Components 2003-05-12
Transformer components – in challenging applications!
HVDC transformers
Phase-shifters e.g. 1630 MVA & 400 kV
Subjects
Tap-changer types Principles of operation Transition resistor Switching time Contact life Maintenance
News! Tie-in resistor
Tests
Development
© ABB Power Technologies - 9 Components 2003-05-12
On-load tap-changers ABB (ASEA) has manufactured tap-changers since 1910.
© ABB Power Technologies - 10 Components 2003-05-12
More than 45 000 units of the modern design are today in operation worldwide.
On-load tap-changers Design philosophy: Highest reliability
Easy maintenance
Longest lifetime
© ABB Power Technologies - 11 Components 2003-05-12
On-load tap-changers
Longest lifetime by using first class materials and by thorough tests. Typical contact life is 350 000 through 500 000 operations. Highest reliability by using few parts and making simple designs
Easiest maintenance by same reasons as above
© ABB Power Technologies - 12 Components 2003-05-12
© ABB Power Technologies - 13 Components 2003-05-12
On-load tap-changers
ABB Tap-Changer Reliability Reported unscheduled service interruptions due to the tap-changer 0,06%
0,05%
Amount
0,04%
0,03%
0,02%
© ABB Power Technologies - 14 Components 2003-05-12
0,01%
0,00% 1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
Year
An average of 5000 years between these stops!
2004
Failures of Tap Changers from 1996-2005 Failures during service.
© ABB Power Technologies - 15 Components 2003-05-12
Year failure was repo
1996 1997 1998
The figures include all failures, independent of age and types of tap-changers, which have led to a service interruption of the transformer, caused by fault in the tap-changer.
© ABB Power Technologies - 16 Components 2003-05-12
On-load tap-changers
On-load tap-changers
© ABB Power Technologies - 17 Components 2003-05-12
WHAT IS AN ON-LOAD TAP-CHANGER?
On-load tap-changers
© ABB Power Technologies - 18 Components 2003-05-12
A device for changing the tapping connection of a winding while the transformer is on load
© ABB Power Technologies - 19 Components 2003-05-12
On-load tap-changers
© ABB Power Technologies - 20 Components 2003-05-12
On-load tap-changers
On-load tap-changers
© ABB Power Technologies - 21 Components 2003-05-12
Current is interrupted Must not happen!
On-load tap-changers
One loop of the regulating winding is short-circuited
© ABB Power Technologies - 22 Components 2003-05-12
Must not happen!
© ABB Power Technologies - 23 Components 2003-05-12
On-load tap-changers Transition Resistors
© ABB Power Technologies - 24 Components 2003-05-12
On-load tap-changers Transition Resistors
On-load tap-changers Resistor type
Reactance type
Electronic types
Others
© ABB Power Technologies - 25 Components 2003-05-12
On-load tap-changers
© ABB Power Technologies - 26 Components 2003-05-12
Reactance type is mainly used in ANSI-standard countries, most often to regulate on the LV side of the transformer.
On-load tap-changers
© ABB Power Technologies - 27 Components 2003-05-12
Electronic types belongs to the future
On-load tap-changers
Resistor types most common today.
© ABB Power Technologies - 28 Components 2003-05-12
Can be diverter switch type or selector switch type.
On-load tap-changers Diverter switch type consists of separate diverter switch and tap selector
Selector switch type consists of a combined diverter switch and tap selector unit
© ABB Power Technologies - 29 Components 2003-05-12
Types of Switching A.
Linear Switching
Selector Switch
Coarse Winding
A.
Plus/Minus Switching
K
© ABB Power Technologies - 30 Components 2003-05-12 Regulating Winding
10
K 9
9
A. Selector Switch
B
C
Most common (~70%) Additive (+) & subtractive (-) Change Over Selector
Coarse/Fine Switching
A
Not very common (~20%) Simple design trafo & oltc Smallest regulating range Smallest losses
Least common (~10%) Coarse winding insertion Change Over Selector Small losses
Principle Circuits of OLTC Transformers (1) For two-winding power transformers, the most popular arrangments is the regulation at the neutral end of the winding.
© ABB Power Technologies - 31 Components 2003-05-12
This solution provides the most economical tap winding arrangement with generally graded insulation combined with a compact three-phase neutral point OLTC. OLTC in Y or Star Connected Windings
Principle Circuits of OLTC Transformers (2)
© ABB Power Technologies - 32 Components 2003-05-12
3-Pole Line-End Arrangment
2-Pole + 1-Pole Line-End Arrangment
3-Pole Mid-Winding Arrangment
OLTC in Delta-Connected Windings
On-load tap-changers MVA Transformer Ratings
> 80
80
80
50
60
150
150
300
HVDC
1000
---------------------------------------------------------------------------------------------------------------1
© ABB Power Technologies - 33 Components 2003-05-12
USB 200
UZF 650
UZE 650
L (m)
UB 2 B3 UCG.N/ 50 3 UCG.N/C C 1050 UCL.N/III UCD.N/II 1050 Short I 1050 UCG.N/II 1050 4 I 1050
All are of Jansen type, i.e. spring operated switches and of resistive type.
UCC. N 1050
© ABB Power Technologies - 34 Components 2003-05-12
Tap-changers, diverter switch type Diverter
Tap selector
© ABB Power Technologies - 35 Components 2003-05-12
7 5
6 4
Transformer regulating winding
© ABB Power Technologies - 36 Components 2003-05-12
Italy, Terna
400 kV, 1630 MVA
Weight 820,000 kg
Footprint 13x15x10 m
On-load tap-changers
© ABB Power Technologies - 37 Components 2003-05-12
Two-phase UC-type Tap-Changer mounted on special transformer
On-load tap-changers
Top section with mounting flange Shielding rings Diverter switch Connectors between diverter switch ant tap selector
© ABB Power Technologies - 38 Components 2003-05-12
Tap selector with preselector
On-load tap-changers
© ABB Power Technologies - 39 Components 2003-05-12
Switching sequence for Diverter-Switch type Tap-Changer
© ABB Power Technologies - 40 Components 2003-05-12
Tap-changers, diverter switch type
7
5 6
4
© ABB Power Technologies - 41 Components 2003-05-12
Tap-changers, diverter switch type
7
5 6
4
© ABB Power Technologies - 42 Components 2003-05-12
Tap-changers, diverter switch type
7
5 6
4
© ABB Power Technologies - 43 Components 2003-05-12
Tap-changers, diverter switch type
7
5 6
4
© ABB Power Technologies - 44 Components 2003-05-12
Tap-changers, diverter switch type
7
5 6
4
© ABB Power Technologies - 45 Components 2003-05-12
Tap-changers, diverter switch type
7
5 6
4
© ABB Power Technologies - 46 Components 2003-05-12
Tap-changers, diverter switch type
7
5 6
4
© ABB Power Technologies - 47 Components 2003-05-12
Tap-changers, diverter switch type
7
5 6
4
On-load tap-changers
© ABB Power Technologies - 48 Components 2003-05-12
Animation Switching sequence for Diverter-Switch type Tap-Changer
Features for the UC tap-changer Extensive More
service experience
than 9000 units in service
Excellent
Quick
service record
and easy maintenance
Shaft
outside diverter switch housing
Open
design, no special tools needed
Reliable
© ABB Power Technologies - 49 Components 2003-05-12
Few
parts
Simple No
and robust design
on-line filtration needed
© ABB Power Technologies - 50 Components 2003-05-12
UC tap-changers
Completely clean cover
Bevel gear for shaft system outside cover
Lift our diverter switch without removing shafts!
Operate motor-drive and tap selector when diverter switch is removed
Operate diverter switch as desired!
© ABB Power Technologies - 51 Components 2003-05-12
UC tap-changers
Diverter switch electrically connected and mechanically coupled without screws
Kept on place by springs on top, pressed by the cover
© ABB Power Technologies - 52 Components 2003-05-12
UC tap-changers
Easiest possible maintenance
No dismantling of diverter switch needed for inspection & cleaning
© ABB Power Technologies - 53 Components 2003-05-12
UC tap-changers
No need to bring diverter switch down from transformer for maintenance
Transformer outage less than one day for maintenance
ABB tap-changers in furnace transformers
UCG top section with shaft, bevelgear & motor-drive
© ABB Power Technologies - 54 Components 2003-05-12
mechanism
ABB tap-changers in furnace transformers The cover has been removed.
© ABB Power Technologies - 55 Components 2003-05-12
(Six minutes passed)
ABB tap-changers in furnace transformers
Note that the shaft system is not
© ABB Power Technologies - 56 Components 2003-05-12
dismantled
ABB tap-changers in furnace transformers
Tube for draining, guiding and oil sampling Springs for fixing diverter switch
© ABB Power Technologies - 57 Components 2003-05-12
Mounting information
ABB tap-changers in furnace transformers
© ABB Power Technologies - 58 Components 2003-05-12
Hook to lift...
© ABB Power Technologies - 59 Components 2003-05-12
ABB tap-changers in furnace transformers
Lift...
ABB tap-changers in furnace transformers
© ABB Power Technologies - 60 Components 2003-05-12
Continue to lift...
ABB tap-changers in furnace transformers
Dvierter switch lifted out.
© ABB Power Technologies - 61 Components 2003-05-12
(Ten minutes passed)
ABB tap-changers in furnace transformers
Drive disc with
© ABB Power Technologies - 62 Components 2003-05-12
slot for drive pin
UC Tap-changer Maintenance (overhaul) Bottom in tap selector cylinder
© ABB Power Technologies - 63 Components 2003-05-12
Notch for driving pin
Driving pin
ABB tap-changers in furnace transformers
Operate the diverter switch
© ABB Power Technologies - 64 Components 2003-05-12
from one side...
ABB tap-changers in furnace transformers
© ABB Power Technologies - 65 Components 2003-05-12
...to the other without caring about the position...
ABB tap-changers in furnace transformers
No harm if you
operate the motordrive.
You don’t have to
note the tap position
© ABB Power Technologies - 66 Components 2003-05-12
number.
ABB tap-changers in furnace transformers
© ABB Power Technologies - 67 Components 2003-05-12
Put the spare or overhauled diverter switch back...
ABB tap-changers in furnace transformers
© ABB Power Technologies - 68 Components 2003-05-12
Fork for guiding
ABB tap-changers in furnace transformers
Switch not yet in proper
© ABB Power Technologies - 69 Components 2003-05-12
position
ABB tap-changers in furnace transformers
© ABB Power Technologies - 70 Components 2003-05-12
Before operated to correct position
ABB tap-changers in furnace transformers
© ABB Power Technologies - 71 Components 2003-05-12
Operate the hand crank till you see and hear that...
ABB tap-changers in furnace transformers
… that it falls down to it’s proper position. Everything is © ABB Power Technologies - 72 Components 2003-05-12
now mechanically and electrically connected.
ABB tap-changers in furnace transformers
When the tapchanger is operated to correct position you can put the cover on.
© ABB Power Technologies - 73 Components 2003-05-12
(Less than 20 minutes passed)
UC tap-changers
© ABB Power Technologies - 74 Components 2003-05-12
Simple, open design with very few parts offers highest reliability and easiest maintenance!
© ABB Power Technologies - 75 Components 2003-05-12
Diverter Switch
Upgrade your old transformer Plug & play concept
Interchangeability in old transformers
For all UCGs since 1978
© ABB Power Technologies - 76 Components 2003-05-12
Tap-changer with vacuum interrupter technology Proven experience
© ABB Power Technologies - 77 Components 2003-05-12
Vacuum bottles, based on 25 years of ABB experience and millions of successfully delivered units provide for an extremely reliable product
© ABB Power Technologies - 78 Components 2003-05-12
Tap-changer with vacuum interrupter technology
Tap-changer with vacuum interrupter technology Reduced life-cycle cost and increased transformer availability
Very limited maintenance during the entire transformer life time
No arcing in oil
No carbonization
Reduced down time
No need for an oil-filter unit
Designed for maintainability
External shaft system remains
© ABB Power Technologies - 79 Components 2003-05-12
Tap-changer with vacuum interrupter technology Reliability
© ABB Power Technologies - 80 Components 2003-05-12
Redundant contactsystem for increased reliability
Vacuum more complex
Monoploy
Humidity – oil samples
Normally maintence after 5-7-15 years
Failures often happens after maintenance
© ABB Power Technologies - 81 Components 2003-05-12
Modular motor drive Improved service friendliness and flexibility Adding / changing of functionality in the field
Self diagnostic and event handling
Reduced number of parts
Transmission gear made from maintenance free elements
Shortened delivery time and increased flexibility in order process
© ABB Power Technologies - 82 Components 2003-05-12
© ABB Power Technologies - 83 Components 2003-05-12
CIGRÉ, August 28th - September 1st
© ABB Power Technologies - 84 Components 2003-05-12
Modular motor drive
On-load tap-changers Summary Extremely high reliability
Excellent service records
Easiest maintenance
Models for all applications available
New technology to be introduced during 2007
© ABB Power Technologies - 85 Components 2003-05-12
© ABB Power Technologies - 86 Components 2003-05-12
Comparison ABB - MR
2000
Criteria: Current, neutral point versions
USB
1500
UCC
1000
UCD
G& RMV-II
R
UCL
© ABB Power Technologies - 87 Components 2003-05-12
500
UCG, UZ UBB
M V
UCG short
MS
ABB
MR
ABB OLTC Benefits - Type UC In-Tank Operating shaft OUTSIDE the diverter housing requiring no disassemble before lifting diverter assembly = Time SAVINGS and REDUCED risk of reassembly error.
© ABB Power Technologies - 88 Components 2003-05-12
Design optimisation of diverter using FEWER parts = LESS statistical possibility for error on reassembly No disassembly of diverter required during overhaul* = Time SAVINGS and NO SPECIAL skills required by service technician
* Note: Contact inspection does not require disassembly but is required during contact replacement.
On-load tap-changers
GSA bushing VVAH cooler
© ABB Power Technologies - 89 Components 2003-05-12
UZF tap-changer
On-load tap-changers Active part of transformer prepared for UZE type tap changer.
Transformer tank with integrated tap-changer tank.
© ABB Power Technologies - 90 Components 2003-05-12
Benefits of using the on-tank UZ No oil filter is needed
Less cleats and leads (conductors), which can easily be made in parallel
No drive-shafts or bevel gears
The UZ is needed later in the production process
Short delivery time
© ABB Power Technologies - 91 Components 2003-05-12
On-load tap-changers Three-phase fully insulated phases or neutral point design
Tap-changer, motor-drive and shaft system integrated
Extremely simple excellent maintenance properties
© ABB Power Technologies - 92 Components 2003-05-12
On-load tap-changers UZF tapchanger
Three phase boards
Integrated motor-drive mechanism
© ABB Power Technologies - 93 Components 2003-05-12
Benefits of using the on-tank UZ BIL 650kV / 600A fully insulated
Up to 100 MVA transformers
No drive-shafts or bevel gears
The UZ require a smaller tfo
© ABB Power Technologies - 94 Components 2003-05-12
less oil
less sheet metal
less beams
less welding
less work
Benefits of using the on-tank UZ
The UZ require a smaller transformer tank
less oil
less sheet metal
less beams
less welding
less work
On-tank
In-tank
Smaller oil conservator
The UZ does not determine the height of the transformer
© ABB Power Technologies - 95 Components 2003-05-12
On-load tap-changers
© ABB Power Technologies - 96 Components 2003-05-12
Mobile transformer by Porter, USA, equipped with UZE type tap-changer
© ABB Power Technologies - 97 Components 2003-05-12
Tap-changers, selector switch type
I
© ABB Power Technologies - 98 Components 2003-05-12
Tap-changers, selector switch type
7
6
5
4
3
2
1 I
© ABB Power Technologies - 99 Components 2003-05-12
Tap-changers, selector switch type
7
6
5
4
3
2
1 I
© ABB Power Technologies - 100 Components 2003-05-12
Tap-changers, selector switch type
7
6
5
4
3
2
1 I
© ABB Power Technologies - 101 Components 2003-05-12
Tap-changers, selector switch type
7
6
5
4
3
2
1 I
© ABB Power Technologies - 102 Components 2003-05-12
Tap-changers, selector switch type
7
6
5
4
3
2
1 I
© ABB Power Technologies - 103 Components 2003-05-12
Tap-changers, selector switch type
7
6
5
4
3
2
1 I
© ABB Power Technologies - 104 Components 2003-05-12
Tap-changers, selector switch type
7
6
5
4
3
2
1 I
© ABB Power Technologies - 105 Components 2003-05-12
Tap-changers, selector switch type
7
6
5
4
3
2
1 I
© ABB Power Technologies - 106 Components 2003-05-12
On-Load Tap-Changer Type UB UBB type tap-changer
Selector switch type
Introduced in 1992
More than 5000 units in service
Uses the contact system from UZtype tap-changer
© ABB Power Technologies - 107 Components 2003-05-12
On-Load Tap-Changer Type UB Fibreglass cylinder
Fixed contacts mounted through cylinder wall with excellent tightening system
Fixed and moving contacts replaceable from inside the tap-changer
© ABB Power Technologies - 108 Components 2003-05-12
On-Load Tap-Changer Type UB
Pre-selector switch
Three fully insulated phases
Moving contacts
Current collectors
© ABB Power Technologies - 109 Components 2003-05-12
On-Load Tap-Changer Type UB
Central shaft
Shield
Current collectors
Neutral connection between phases
© ABB Power Technologies - 110 Components 2003-05-12
On-Load Tap-Changer Type UB
Moving contact system consisting of: Transition
Main
arcing contacts
Current
© ABB Power Technologies - 111 Components 2003-05-12
resistor contacts
contacts
On-Load Tap-Changer Type UB
Main arcing contacts by copperwolfram alloy
Current carrying contacts by silverplated brass
Contact tips by solid silver
© ABB Power Technologies - 112 Components 2003-05-12
On-Load Tap-Changer Type UB
© ABB Power Technologies - 113 Components 2003-05-12
Pre-selector contacts with four contact fingers
© ABB Power Technologies - 114 Components 2003-05-12
TIE-IN RESISTOR
Only for plus/minus and coarse/fine connections.
Used when the recovery voltage over the change-over selector exceed the max. value (between 25-40kV dependent on OLTC)
© ABB Power Technologies - 115 Components 2003-05-12
TIE-IN RESISTOR
© ABB Power Technologies - 116 Components 2003-05-12
Main Winding
Change-Over Selector
Tap Winding
Switch (only connected during change-over operations)
TIE-IN RESISTOR
© ABB Power Technologies - 117 Components 2003-05-12
Main Winding
Change-Over Selector
Tap Winding
Switch (only connected during change-over operations)
TIE-IN RESISTOR
© ABB Power Technologies - 118 Components 2003-05-12
Main Winding
Change-Over Selector
Tap Winding
Switch (only connected during change-over operations)
TIE-IN RESISTOR
© ABB Power Technologies - 119 Components 2003-05-12
Main Winding
Change-Over Selector
Tap Winding
Switch (only connected during change-over operations)
TIE-IN RESISTOR CONNECTION
Main Winding
Change-Over Selector
© ABB Power Technologies - 120 Components 2003-05-12
Tie-in Resistor Tap Winding
Switch (only connected during change-over operations)
TIE-IN RESISTOR CONNECTION
Main Winding
Change-Over Selector
© ABB Power Technologies - 121 Components 2003-05-12
Tie-in Resistor Tap Winding
TIE-IN RESISTOR CONNECTION
Main Winding
Change-Over Selector
© ABB Power Technologies - 122 Components 2003-05-12
Tie-in Resistor Tap Winding
Switch (only connected during change-over operations) Switch (only connected during change-over operations)
Calculation of Tie-In Resistor Needed to calculate the Tie-In Resistor value are:
Capacitance from the regulating winding to adjacent windings or earth. (Included influence from leads)
Voltage on the adjacent windings and the voltage over the regulating winding.
Transformer connection data and frequency. H1
Tank
HV
U
RW
© ABB Power Technologies - 123 Components 2003-05-12
C1
C2
+
-
© ABB Power Technologies - 124 Components 2003-05-12
Recommendation Letter
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