On-load tap-changers, type UC and VUC...On-load tap-changers, type UC and VUC Technical guide This...

1ZSE 5492-105 en, Rev. 7

On-load tap-changers, type UC and VUCTechnical guide

This Technical Guide has been produced to allow transformer manufacturers, and their designers and engineers, access to all the technical information required to assist them in their selection of the appropriate on-load tap-changer and motor-drive mechanism.

The technical information pertaining to on-load tap-changers and motor-drive mecha-nisms manufactured by ABB has been divided and is contained in separate documents, with one document for each type.

The information provided in this document is intended to be general and does not cover all possible applications. Any specific application not covered should be referred directly to the supplier, or its authorized representative.

ABB makes no warranty or representation and assumes no liability for the accuracy of the information in this document or for the use of such information. All information in this document is subject to change without notice.

Manufacturer’s declaration

The manufacturer ABB AB Components SE-771 80 LUDVIKA Sweden

Hereby declares that

The products On-load tap-changers, type UC and VUC with motor-drive mechanisms, types BUE and BUL

comply with the following requirements:

By design, the machine, considered as component on a mineral oil filled power transformer, complies with the requirements of

Machinery Directive 89/392/EEC (amended 91/368/EEC and 93/44/EEC) and 93/68/EEC (mark-ing) provided that the installation and the electrical connection be correctly realized by the manu-facturer of the transformer (e.g. in compliance with our Installation Instructions) and

EMC Directive 89/336/EEC regarding the intrinsic characteristics to emission and immunity levels and

Low Voltage Directive 73/23/EEC (modified by Directive 93/68/EEC) concerning the built-in motor and apparatus in the control circuits.

Certificate of Incorporation:

The machines above must not be put into service until the machinery into which they have been incorporated have been declared in conformity with the Machinery Directive.

Date 2008-03-15

Signed by .........................................................................

Folke Johansson

Title Manager of Division for Tap-Changers

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�1ZSE 5492-105 en, Rev. 7

ContentsGeneral information ..................................................................... 5

Design principles ......................................................................... 8On-load tap-changer ...................................................................................8Diverter switches .........................................................................................8

Conventional diverter switch ...................................................................8Diverter switch with vacuum interrupters ................................................8Tap selector ............................................................................................10Design differences over the UC range of on-load tap-changers ............10Diverter switch housing and top section ................................................12

Painting .............................................................................................12Operating mechanism ............................................................................12Transition resistors .................................................................................1�Special applications, load conditions and environments ........................1�Special designs .....................................................................................1�On-line oil filtration (for diverter switch with arc quenching in oil only) ...1�

Motor-drive mechanism ...............................................................................14Type BUE ...............................................................................................14Type BUL ................................................................................................14

Accessories .................................................................................................14

Tap-changer principles of operation ............................................ 15Switching sequence, UC ............................................................................15Switching sequence, VUCG ........................................................................16Type of regulation ........................................................................................18

Linear switching (type L) .......................................................................18Change-over selector for plus/minus switching (type R) ........................18Change-over selector for coarse/fine switching (type D) .......................18

Type of connection ......................................................................................19Three-phase star point (N) .....................................................................19Single-phase (E) .....................................................................................19Three-phase delta (B) ............................................................................19Three-phase delta fully insulated (T) ......................................................19Auto transformer (T) ...............................................................................19

Tap-changer characteristics and technical data .......................... 20Type designation .........................................................................................20

Maximum number of positions ...............................................................21Diverter switches .........................................................................................21Tap selectors ...............................................................................................22

Possible combinations of diverter switches and tap selectors ................22Enforced current splitting .............................................................................22

In position ...............................................................................................22During operation .....................................................................................2�

Rated phase step voltage ............................................................................24Coarse fine regulation leakage inductance switching ............................26

Contact life ...................................................................................................26Standards and testing .................................................................................28Rating plate .................................................................................................28Insulation levels ...........................................................................................28Withstand voltages ......................................................................................�1

UCG and VUCG with tap selector C .......................................................�1UCG and VUCG with tap selector I ........................................................�1UCG and VUCG with tap selector III unshielded version .......................�2UCG and VUCG with tap selector III shielded version ...........................�2

UCL with tap selector III unshielded version ..........................................��UCL with tap selector III shielded version ..............................................��UCD with tap selector III unshielded version ..........................................�4UCD with tap selector III shielded version ..............................................�4UCC with tap selector IV ........................................................................�5

Short-circuit current strength .......................................................................�6Highest phase service voltage across the regulating winding ....................�7Rated through-current .................................................................................�7Occasional overloading ...............................................................................�7Oil temperature ............................................................................................�8Coarse/fine regulation leakage inductance switching ..................................�9Tie-in resistor and tie-in resistor switch .......................................................40

Installation and maintenance ....................................................... 42On-load tap-changer ...................................................................................42

Installation ..............................................................................................42Drying .....................................................................................................42Weights ..................................................................................................42Oil filling .................................................................................................44Maintenance ...........................................................................................45Pressure .................................................................................................45

Accessories and protection devices ............................................................45Motor-drive mechanism ...............................................................................46

Design ....................................................................................................46Installation ..............................................................................................46Maintenance ...........................................................................................46Operating shafts .....................................................................................46

Dimensions ..................................................................................................48Type UCG/C and VUCG/C .....................................................................48Type UCG/I and VUCG/I .........................................................................49Type UCG/III and VUCG/III .....................................................................50Type UCL/III ............................................................................................52Type UCD/III ...........................................................................................55Type UCC/IV ...........................................................................................57Oil conservator .......................................................................................59

Appendices: Single-Phase Diagrams .......................................... 60Appendix 1: Single-phase diagrams for UCG/C .....................................60Appendix 2: Single-phase diagrams for UCG/I .......................................65Appendix �: Single-phase diagrams for UCG/III, VUCG/III, UCL/IIIand UCD/III .............................................................................................72Appendix 4: Single-phase diagrams for UCC/IV.....................................79

51ZSE 5492-105 en, Rev. 7

General informationWhen the on-load tap-changer operates, the insulating oil will be contam-inated. To avoid contamination of the transformer oil, the diverter switch has its own housing separate from the rest of the transformer. The tap selector, which is mounted beneath the diverter switch housing, consists of the fine tap selector and usually also of a change-over selector. The operating principle for the UC and VUC range of on-load tap-changers is called the diverter switch principle.

The UC types of on-load tap-changers are usually mounted inside of the transformer tank, suspended from the transformer cover. Power to oper-ate the on-load tap-changer is supplied from the motor-drive mechanism, which is mounted on the outside of the transformer. The power is trans-mitted by means of shafts and bevel gears.

The UC types of on-load tap-changers come in a wide range of models with a rating suitable for every application.

Transformer cover

On-load tap-changer

Oil conservator

Motor-drive mechanism

Shaft

Bevel gear

Shaft

Transformer tank

Fig. 1. Main parts, on-load tap-changers types UC and VUC.

Diverter switch

Tap selector

6 1ZSE 5492-105 en, Rev. 7

Cover

Lifting eye

Top section

Shielding-ring

Current terminal

Bottom section

Valve for use atprocessing

Connections fromthe tap selector

Plug-in contacts

Insulating cylinder

Diverter switch

Oil draining tube

Flange for connection to gas operated relay

Intermediate gear

Driving disc for thediverter switch

Locating pins

Fixed and movingcontacts

Transition resistors

Shielding-ring

Insulating shaft

Bevel gear withposition indicator

Buffer springs

Diverter switch housing

Fig. 2. On-load tap-changer type UCG.

71ZSE 5492-105 en, Rev. 7

Vacuum interrupters

Transition resistors

Spring drive mechanism

Plug-in contacts

Fig. 3. On-load tap-changer type VUCG.

8 1ZSE 5492-105 en, Rev. 7

Design principles

On-load tap-changerWhen the on-load tap changer operates, the oil is contaminated. UC with conventional arc quenching in oil contaminates the oil heavily while VUC with arc quenching in vacuum interrupters only contaminates slightly due to current commutation sparks and heat dissipation from the transition resistors. To avoid contamination of the transformer oil the on-load tap-changer is built in two separate sections, the diverter switch, which has its own housing, and the tap selector. The tap selector is mounted below the diverter switch housing and the complete unit is suspended from the transformer cover.

VUC and UC are of the diverter switch type. UC works according to the flag cycle principle and VUC works according to the unidirectional pen-nant cycle principle.

Diverter switchesTwo different types of diverter switches are available, the conventional type with arc quenching in oil and the new type with vacuum interrupters.

The diverter switches are equipped with plug-in contacts that automati-cally connect it to the bushings in the diverter switch housing when the switch is lowered into the housing. Guiding facilities keep the diverter switch in correct position when lowering it into the housing. Mechanical coupling to the motor-drive mechanism is automatically established when the driving pin enters the slot in the driving disc.

The design and dimensioning of the diverter switches offer high reliability and long life with a minimum of maintenance and easy inspection.

Conventional diverter switchThe diverter switch is of the high-speed, spring-operated type with resis-tors as transition impedance.

The diverter switch is designed as a system of moving and fixed contacts. Movement of the moving contact system is controlled by a self-locking polygon link system with a set of helical springs. The link system is robust and has been carefully tested. The fixed contacts are placed on the sides of the diverter switch, which are made of insulated board.

The current-carrying contacts are made of copper or copper and silver, and the breaking contacts of copper-tungsten.

Diverter switch with vacuum interruptersCombines all the advantages of the conventional type with improved breaking capacity, increased contact life and reduced maintenance.

It works according to the unidirectional pennant cycle, which gives the lowest complexity. A mechanical rectifier ensures operation in only the direction that gives the lowest breaking stresses and contact wear.

91ZSE 5492-105 en, Rev. 7

Fig. 4. Examples of diverter switches UCG and VUCG.

The load is commutated from one tap to the other by aid of the vacuum interrupters and auxiliary contacts. The auxiliary contacts are also able to break the load current in the unlikely event of a vacuum interrupter failure should occur.

In service position the current is transferred through the auxiliary contacts and the vacuum interrupters. All current carrying contacts are made of low resistance material.

The vacuum interrupters have a very long life time but yet mounted for easy replacement when needed, for instance in industrial applications when the number of operations might be extremely high.

The contact system is powered by a compact mechanical system with integrated driving springs, mechanical rectifier, robust mechanical sys-tem for vacuum interrupter actuating and geneva gears for operating the auxiliary contacts.

All manufactured conventional UCGs can be easily replaced by the vacuum diverter switch and gain benefit of the improvements made on this type.

10 1ZSE 5492-105 en, Rev. 7

Tap selectorAlthough the tap selector for the UC range of on-load tap-changer is available in various sizes, all have similar functions with different ratings.

The fixed contacts are mounted around the central shafts. The moving contacts are mounted on, and are operated by, the shafts in the center of the selector. The moving contacts are connected, via current collectors, to the diverter switch by means of paper insulated copper conductors.

Depending on the load current, the moving contacts have either one, two, or more contact arms in parallel with one, two or four contact fingers each. The fingers make contact at one end with the fixed contact, and at the other with the current collector. The moving contacts slide on the fixed contacts and the current collector rings, giving a wiping action which makes the contacts self cleaning. This arrangement promotes good con-ductivity and negligible contact wear.

Fig. 5. Tap selectors: size C and size III.

Design differences over the UC range of on-load tap-changersThe UC range of tap-changers consists of five diverter switches and four tap selectors.

The diverter switches, from the smallest to the biggest type, are UCG, VUCG, UCL, UCD and UCC. VUCG has arc quencing in vacuum, all oth-ers have arc quencing in oil.

The VUCG diverter switch fits without modification in all UCG tap-chang-ers as manufactured 1977 and later, which enables all UCG tap-changers to be easily upgraded to vacuum technology.

111ZSE 5492-105 en, Rev. 7

L (m)

3

2

1

UCG.N/CVUCG.N/CUCG.N/IVUCG.N/I650 kV

UCG.N/IIIVUCG.N/III650 kV

UCL.N/III650 kV

UCD.N/III650 kV

UCC.N650 kV

Fig. 6. On-load tap-changers type UC, size comparison.

The tap selectors, from the smallest to the biggest type, are C, I, III and IV. Tap selectors I and C can be combined with UCG and VUCG diverter switches. Tap selector III can be combined with all diverter switches ex-cept UCC. Tap selector IV can be combined with UCC only.

For correct selection, use this Technical Guide or the ABB selection pro-gram “Compas”.

UCG is available in two versions (standard and short) and manages 200 – �00 MVA star connected transformers and up to approximately 500 MVA Auto transformers.

UCL manages star connected transformers up to 500-600 MVA and Auto transformers up to 1000 MVA.

UCD and UCC manages star connected transformers >600 MVA and >1000 MVA respectively. For winding connections where three single-phase tap-changers are needed, each single phase of the UCD and UCC must have it-s own motor-drive mechanism.

In tap selectors I and IV the fixed contacts are mounted on insulating bars, whereas the C and III types use a complete, un-divided glass fibre reinforced epoxi cylinder.

12 1ZSE 5492-105 en, Rev. 7

Diverter switch housing and top section The top section forms the flange that is used for mounting to the trans-former cover, and for carrying the gear box for the operating shafts. The top section includes a connection for the conservator pipe, draining and filtering connections, an earthing terminal, the supervisory device, and the cover with its gasket. The top section is available in two designs, one for cover mounting and one for pre-mounting (yoke-mounting) on the transformer’s active part.

The diverter switch housings have high quality sealings that guarantee vacuum and overpressure-proof performance under all service condi-tions. In case of material ageing after extremely long service the sealings can be re-tightened.

The bottoms and heads of the cylinders are made of cast aluminium.

The driving shafts and bevel gears are placed beside the diverter switch cylinders, thereby providing easy access to the diverter switches.

The bottom section has locating holes for the diverter switch, bearings, brackets for the tap selector mounting and the current terminal for the diverter switch. There is also a draining valve in the bottom which should only be opened during the drying process of the transformer.

The top and bottom sections are fixed to a cylinder of glassfibre rein-forced plastic. The bushings through the cylinder wall are sealed by O-ring gaskets with elastic pressure. Each ready-made unit is tested under vacuum and the outside is exposed to helium and checked for leaks with the use of a helium gas detector.

Painting

The diverter switch housing top sections are finish coated with a blue-grey colour, Munsell 5,5 B 5,5/1,25, corrosion class C� acc. to SS-EN ISO 12944-2. For the motor drives, the painting can be chosen between primary coating corrosion class C� or finish coated with a blue-grey colour, Munsell 5,5 B 5,5/1,25, corrosion class C� acc. to SS-EN ISO 12944-2.

Operating mechanismThe bevel gear, mounted on the top section flange transfers the drive from the motor-drive mechanism, via the vertical shaft, to the intermedi-ate gear for the diverter switch and the tap selector.

From the intermediate gear, a drive shaft transfers the energy to the di-verter switch through an oil tight gland in the bottom of the diverter switch housing. When the diverter switch is lowered into the housing (after inspection), the drive is automatically re-connected by a system that en-sures that the drive shaft and the locating pin of the diverter mechanism is correctly aligned.

The intermediate gear also drives the geneva gear of the tap selector, via a free wheel connection. The geneva gear provides alternate movement to the two vertical shafts of the tap selector.

The external drive shaft, that does not need to be removed during main-tenance work, minimizes the risk for misalignment in the system. However a mechanical end limit stop for the tap selector is available on request.

Special shaft systems are also available on request.

1�1ZSE 5492-105 en, Rev. 7

Transition resistorsThe transition resistors are made of wire and located above the diverter switch contacts. The resistors are robust and designed to withstand the lifetime of the mechanism under normal service conditions.

Special applications, load conditions and environmentsPlease contact the supplier for advisory in the following cases:

For special applications such as:

Arc furnace

HVDC

Rectifiers

Shunt reactors

Series reactors

Phase shifters

Traction

Industrial applications in general

OLTCs working in parallel

In case of unusual load conditions such as overloads beyond IEC 60076-7, IEC 60�54 or IEEE C57.1�1-1995, extreme inductive or capacitive loads or loads beyond the given data in this document.

In case of service in extreme environments such as very high humid-ity, very high or low temperatures, indoors, etc.

Special designsOn request, the UC and VUC tap-changers are also available for regula-tion with bias winding and for Y/D regulation.

On-line oil filtration (for diverter switch with arc quenching in oil only)On-line oil filtration is not required in any application and does not extend lifetime of contacts, but can give benefits for OLTCs with arc quenching in oil in certain applications such as:

Arc furnace applications (prolongs mechanical life and maintenance interval and shortens maintenance time)

High voltage line end applications (maintains the high dielectric with-stand of the insulating liquid)

Whenever short outage time is important when carrying out maintenance

At any application with a high number of operations or high dielectric stresses.

The on-line oil filtration works with continuous low flow filtration giving the best filtration result, less risk of gas bubbles and requires less con-trol equipment. Filter cartridges are easily replaced without taking the transformer out of service. For further information about the oil filter, see manual 1ZSC000562-AAA.

The filtration reduces the number of particles and keeps the water level at a dielectric safe level.

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14 1ZSE 5492-105 en, Rev. 7

Motor-drive mechanismThe motor-drive mechanism provides the drive to allow the on-load tap-changer to operate. Energy is provided from a motor through a series of gears and out through a drive shaft. Several features are incorporated within the mechanism to promote long service intervals and reliability.

There are two sizes of motor-drive mechanisms that can be used. If there are any doubts about which type to select, please consult the supplier.

Type BUEThe BUE is for all on-load tap-changers types UC and VUC. For detailed operation descrip-tion, see Technical Guide for Motor-Drive Mechanisms type BUE.

Fig. 7a. Motor-drive mechanism type BUE

Type BULThe BUL is for on-load tap-changers types UCG, VUCG and UCL at star point or single-phase applications. However, when extra space is required for optional acces-sories the type BUE might have to be selected due to limited space in the BUL. For detailed operation descrip-tion, see Technical Guide for Motor-Drive Mechanisms type BUL.

Fig. 7b. Motor-drive mechanism type BUL

AccessoriesFor a list of accessories available for both the on-load tap-changers and the motor-drive mechanisms, consult the supplier.

151ZSE 5492-105 en, Rev. 7

Tap-changer principles of operation

Switching sequence, UC The switching sequence of the on-load tap-changer from position 6 to position 5, is shown in the figures below.

The sequence is designated the symmetrical flag cycle. This means that the main switching contact of the diverter switch, breaks before the transi-tion resistors are connected across the the regulating step. This ensures maximum reliability when the switch operates with overloads.

At rated load the breaking takes place at the first current zero after con-tact separation, which means an average arcing time of approximately 4-6 ms. The total time for a complete sequence is approximately 50 mil-liseconds. The tap change operation time of the motor-drive mechanism is approximately 5 s/step. (10 s for through-positions.)

Fig 8a. Position 6

Selector contact V con-nects tap 6 and selector contact H on tap 7. The main contact x carries the load current.

Fig. 8b

Selector contact H has moved in the no-load state from tap 7 to tap 5.

Fig. 8c

The main contact x has opened. The load cur-rent passes through the resistor Ry and the resistor contact y.

Fig. 8d

The resistor contact u has closed. The load current is shared be-tween Ry and Ru. The circulating current is limited by the resistance of Ry plus Ru.

Fig. 8e

The resistor contact y has opened. The load current passes through Ru and contact u.

Fig. 8f. Position 5

The main contact v has closed, resistor Ru is bypassed and the load current passes through the main contact v. The on-load tap-changer is now in position 5.

16 1ZSE 5492-105 en, Rev. 7

MVI

MC

RVITR

RC

x

v

MVI

MC

RVITR

RC

x

v

MVI

MC

RVITR

RC

x

v

Switching sequence, VUCGBy using an auxiliary contact system (MC, RC) in combination with the vacuum interrupters (MVI, RVI) only two vacuum interrupters are required per phase.

Fig. 9a shows the current path during normal operation, from x to the star point (could also be to the next phase). When commuting the load from x to v, the first part of the operation sequence is to open the main vacuum interrupter (MVI) and hence let the current flow through the transition resistor (TR), Fig. 9b. The main contact (MC) is then rotated (Figs. 9c and 9d) in order to connect to v. The main vacuum interrupter then closes, leading to an associated circulating current driven by the difference in voltage potential, Fig. 9e. In Fig. 9f, the transition resistor is disconnected when opening the resistor vacuum interrupters (RVI). The load current is now via the normal path from v to the star point. The resistor contact (RC) is then rotated and put in position according to Fig. 9g. Finally, the se-quence is completed and next service position is reached when the resis-tor vacuum interrupter is closed, see Fig. 9h.

Fig. 9a.

Fig. 9b.

Fig. 9c.

171ZSE 5492-105 en, Rev. 7

MVI

MC

RVITR

RC

x

v

MVI

MC

RVITR

RC

x

v

MVI

MC

RVITR

RC

x

v

MVI

MC

RVITR

RC

x

v

MVI

MC

RVITR

RC

x

v

Fig. 9d.

Fig. 9e.

Fig. 9f.

Fig. 9g.

Fig. 9h.

18 1ZSE 5492-105 en, Rev. 7

Change-over selector for plus/minus switching (type R)The change-over selector extends the regulating range to twice the voltage of the tapped winding, by connecting the main winding to different ends of the regulating winding.

Fig. 11

Change-over selector for coarse/fine switching (type D) In type D switching the change-over selector extends the regu-lating range to twice the voltage of the tapped winding, by con-necting or disconnecting the coarse regulating winding.

Fig. 12

Reversing Change-over selector

Change-over selector, coarse/fine

Type of regulation

Linear switching (type L) The regulating range is equal to the voltage of the tapped winding. No change-over selector is used.

Fig. 10

191ZSE 5492-105 en, Rev. 7

Type of connection

Three-phase star point (N)Only one unit is required for all three phases. The transformers neutral point is in the OLTC.

Single-phase (E)Only one unit is required

Three-phase delta (B)Two units required. Driven by a com-mon motor-drive. One unit common for two phases.

Three-phase delta fully insulated (T)Three units required. Driven by a common motor-drive.

Auto transformer (T)Several configurations of auto trans-formers exist. This example shows the tap-changer in auto-tap.

20 1ZSE 5492-105 en, Rev. 7

Tap-changer characteristics and technical data

Type designation

UC... Diverter switch with arc quenching in oil

VUC... Diverter switch with vacuum interrupters

Example UCGRE 650/700/C

Type of tap-changerUC... Diverter switch with arc quenching in oil

VUC... Diverter switch with vacuum interrupters

Type of switchingL Linear

R Plus/Minus

D Coarse/Fine

Type of connection N Three-phase star point (one unit)

E Single-phase (one unit)

T Three-phase fully insulated (three units)

B Three-phase delta (two units; single-phase and two-phase)

Impulse withstand voltage to earthUCG, VUCG: �80 kV, 650 kV, 750 kV, 1050 kV

UCL: �80 kV, 650 kV, 750 kV, 1050 kV

UCD, UCC: �80 kV, 650 kV, 1050 kV

Maximum rated through-current

See tables for diverter switches and tap selectors respectively. The lowest rating of the two determines the overall rating.

Tap selector sizeC tap selector for UCG and VUCG only

I tap selector for UCG and VUCG only

III tap selector for UCG, VUCG, UCL and UCD

IV tap selector for UCC

UCG . . XXXX/YYYY/Z

VUCG . . XXXX/YYYY/Z

UCL . . XXXX/YYYY/Z

UCD . . XXXX/YYYY/Z

UCC . . XXXX/YYYY

211ZSE 5492-105 en, Rev. 7

Maximum number of positions

Table 1. Maximum number of positions.

Type of switching Tap selector Max. number of positions

Linear C 14

I 18

III 22

IV 18

Plus/minus C 27

I �5

III �5

IV �5

Coarse/fine C 27

I �5

III �5

IV �5

Diverter switchesTable 2. Diverter switches.

Type Max. rated through-current

VUCG.N, B 700 A

VUCG.E, T 1600 A 1)

VUCG.N, B, short version 2) 600 A

VUCG.E, T, short version 2) 1000 A

UCG.N, B �00, 500, 600 A

UCG.E, T �00, 500, 600, 1200, 1500 1) A

UCG.N, B, short version 2) �00 A

UCG.E, T, short version 2) 900 A

UCL.N, B 600, 900 A

UCL.E, T 600, 900, 1800, 2400 1) A

UCD.N �) 1000 A

UCD.E �) 1600 A

UCC.N �) 1600 A

UCC.E �) 1600 A

1) See also section “Enforced current splitting”.2) Shorter diverter switch housings, see dimension drawings in this guide. See also limits in

Fig. 14.�) UCC and UCD requires one motor-drive mechanism for each OLTC unit. Thus, three-

phase delta requires two UCC/D.E and three phases fully insulated requires three UCC/D.E.

22 1ZSE 5492-105 en, Rev. 7

Tap selectorsTable 3. Tap selectors.

Type Connection Max. rated through-current Max impulse test voltage across range

C N, B 400 A �50 kV

E, T 400, 700, 1050, 1200 1) A �50 kV

I N, B 600 A �00 kV �)

E, T 600, 1200, 1500, 1600 A �00 kV �)

III N, B 1000 A 550 kV �)

E, T 1000, 1800, 2400 1) A 550 kV �)

IV 2) N, E 1600 A 500 kV

1) With enforced current splitting in position.2) UCC requires one motor-drive mechanism for each unit and is therefore not available in

connection B and T.�) Note that for certain positions, these values are lower. See Insulating levels.

Possible combinations of diverter switches and tap selectors

Diverter switch UCG, VUCG UCL UCD UCC

Tap selector C I III IV

Enforced current splittingIn certain applications, two or more poles of an on-load tap-changer, or more than one on-load tap-changer can work in parallel. However, it is im-portant to make this in a correct way. It differs between whether it should work in position (not during operation) only or if it should operate during operation.

In positionEnforced current splitting in position is used only between poles within one on-load tap-changer for operation in one phase. It is used when hav-ing a tap selector with a lower current rating than the diverter switch . By having the same number of conductors through the regulating winding as there are poles in the tap selector and connect each of them to one pole of the tap selector, the rating for one pole times the number of poles can be made use of. (Otherwise a certain reduction in current rating has to be done due to unequal current splitting between the poles. For instance, a 1050 A tap selector C can be used for 400 x �=1200 A when the condi-tions for enforced current splitting are fulfilled).

2�1ZSE 5492-105 en, Rev. 7

During operationEnforced current splitting during operation can be used when the diverter switch has a lower current rating than the tap selector or when two or more on-load tap-changers work in parallel in the same phase.

By having the same number of conductors in parallel through the wind-ings as there are poles or on-load tap-changers in parallel, parallel work-ing conditions can be made to work. However, the impedance between these parallel paths must be such that the current through any of the poles or any of the on-load tap-changers must not exceed the rating of any of them. The reason is that the poles in the diverter switch or the di-verter switches do not operate at exactly the same time.

To achieve this impedance, it is normally required that the parallel con-ductors are kept separated through both the regulating and the main winding. However, the impedance between them must be calculated by the transformer manufacturer in each case where enforced current split-ting during operation should be made use of.

See also IEC 60214-2, paragraph 6.2.9 for information.

24 1ZSE 5492-105 en, Rev. 7

Rated through-current (A)

Ste

p v

olt

age

(V)

500

0

1000

1500

2000

2500

3000

3500

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300

UCG.E,TShort version

UCG.N,B

UCG.N,BShort version

UCG.E,T

1400 1500


Ste

p v

olt

age

(V)

500

0

1000

1500

2000

2500

3000

3500

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500

VUCG.E,TShort version

1600

VUCG.N,B

VUCG.N,BShort version

VUCG.E,T

Rated phase step voltageThe maximum permitted step voltage is limited by the electrical strength and the switching capacity of the diverter switch. The rated phase step voltage is a function of the rated through current as shown in the dia-grams below.

For arc furnace transformers, only up to 75 % of the given step voltages below are allowed. In case the current during electrode short circuits exceeds twice the rated through-current, please contact the supplier for advice.

UCG and VUCG in short version have a 220 mm shorter diverter switch housing, see dimension drawings in this document. For short version, there might be restrictions in applications other than network.

Fig. 13. Rated phase step voltage for type UCG.

Fig. 14. Rated phase step voltage for type VUCG.

251ZSE 5492-105 en, Rev. 7

Rated through-current (A)S

tep

vo

ltag

e (V

)

500

0

1000

1500

2000

2500

3000

3500

0 200 400 600 800 1000 1400 1600

3500

4500

5000

UCL.N,B

UCL.E,T

1200 1800 2000 2200 2400 2600

UCL.N,BUCL.N,B


Ste

p v

olt

age

(V)

500

0

1000

1500

2000

2500

3000

3500

0 200 400 600 800 1000 1200 1400 1600

UCC.N

3500

4500

5000UCC.E

For higher valuescontact ABB


Ste

p v

olt

age

(V)

500

0

1000

1500

2000

2500

3000

3500

0 200 400 600 800 1000 1200 1400 1600

UCD.N

3500

4500

5000UCD.E

UCD.N

UCD.E

Fig. 15. Rated phase step voltage for type UCL.

Fig. 17. Rated phase step voltage for type UCD.

Fig. 16. Rated phase step voltage for type UCC.

26 1ZSE 5492-105 en, Rev. 7


No

.of

op

erat

ion

s

50000

0

100000

150000

200000

250000

300000

350000

400000

450000

500000

0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500

UCG.N,B100% load

80% average load

80% average load

UCG.E,T 100% load


No

.of

op

erat

ion

s

100000

0

200000

300000

400000

500000

600000

700000

800000

900000

1000 000

0 100 200 300 600 800 900 1000 1100

VUCG.N,B

400 500 700 1200 1300 1400 1500 1600 1700

VUCG.E,T

Coarse fine regulation leakage inductance switchingWhen operating from the ends of the fine or the coarse winding a high leakage inductande might appear causing a phase shift between the switched current and the recovery voltage. This value has to be given when ordering an OLTC so a proper dimensioning is possible.

The leakage inductance value can be given in our order data sheet or be calculated by us from active part dimensions and number of turns. For more information, see IEC 60214-2 or product information 1ZSC000498-ABB.

Contact lifeThe predicted contact life of the fixed and moving contact of the diverter switch, is shown as a function of the rated through current in the dia-grams below. It is based on the type test with 50000 switching operations, and a current corresponding to the maximum rated through current. The contact life is stated on the rating plate.

Fig. 18. Contact life for type UCG.

Fig. 19. Contact life for type VUCG.

271ZSE 5492-105 en, Rev. 7


No

.of

op

erat

ion

s50000

0

100000

150000

200000

250000

300000

350000

400000

450000

500000

0 250 500 750 1000 1250 1500 1750 2000 2250

UCL.N,B100% load

80% average load

80% average load

UCL.E,T 100% load

2500


No

.of

op

erat

ion

s

50000

0

100000

150000

200000

250000

300000

350000

400000

450000

500000

0 200 400 600 800 1000 1200 1400 1600

80% average load

UCC.N 100% load

UCC.E100% load


No

.of

op

erat

ion

s

50000

0

100000

150000

200000

250000

300000

350000

400000

450000

500000

0 200 400 600 800 1000 1200 1400

UCD.N 100% load

1600

UCD.E 100% load

Fig. 20. Contact life for type UCL.

Fig. 22. Contact life for type UCD.

Fig. 21. Contact life for type UCC.

28 1ZSE 5492-105 en, Rev. 7

Standards and testingThe on-load tap-changers made by ABB fulfil the requirements according to IEC 60214-1, 200�-02, and IEEE C57.1�1-1995.

The type tests include:

Contact temperature rise test

Switching tests

Short-circuit current test

Transition impedance test

Mechanical tests

Dielectric tests

The routine tests include:

Check of assembly

Mechanical test

Sequence test

Auxiliary circuits insulation test

Vacuum test

Final inspection

Rating plate

■■■■■■

■■■■■■

Insulation levelsLI is the lightning impulse (1.2/50 µs) to earth. pf is the power frequency test voltage to earth (60 s). The insulation levels are indicated as impulse withstand voltage – power frequency withstand voltage.

The tests were carried out according to IEC 60214-1, 200�-02, with a new on-load tap-changer and clean insulation transformer oil I -�0 °C ac-cording to IEC 60296. The withstand voltage value of the oil was higher than 40 kV/2.5 mm (IEC 60156).

Fig. 23. Example of rating plate

fm_00299

291ZSE 5492-105 en, Rev. 7

a2

a1

b1

b2e1

g1

b1

a2 a1

b1

b2e1

g1

b1

Fig. 24. Linear switching.

corresponding contact in adjacent phase

Linear

L

Insulation levels to earth

For UCG �80–150 kV, 650–275 kV, 750–�25 kV and 1050–460 kV

For UCL �80–150 kV, 650–275 kV, 750–�25 kV and 1050–460 kV

For UCC and UCD �80–150 kV, 650–275 kV and 1050–460 kV

Lightning impulse levels (LI) and power frequency levels (Pf) corresponds to the following Um-values acc. to IEC:

LI (kV) Pf (kV) Um (kV)

�80 150 72,5

650 275 145

750 �25 170

1050 460 �00

Fig. 25. Reversing switching.

corresponding contacts in adjacent phase

Reversing

R

�0 1ZSE 5492-105 en, Rev. 7

a2 a1 f1

d1

b2e1

g1

b1

c1

f2

d1

a1 Between electrically adjacent contacts in the tap selector, not connected.

a2 Between the ends of the fine regulating winding (across range). For coarse/fine switching in minus position, this means between the freely oscillating end of the coarse winding and any end of the fine winding.

b1 Between not connected taps of different phases in the fine selector

b2 Between open contacts of different phases in the diverter switch.

c1 Between ends of the coarse winding in coarse/fine switching

d1 Between not connected taps of different phases in the coarse selec-tor (coarse/fine switching)

e1 Between preselected tap and connected tap of one phase in the di-verter switch and in the tap selector.

f1 Between any end of the coarse winding and connected tap

f2 Between any end of the coarse winding and the middle of the fine winding.

g1 Connected tap to earth

Fig. 26. Coarse/Fine switching.

corresponding contacts in adjacent phase

Coarse/Fine

D

�11ZSE 5492-105 en, Rev. 7

Withstand voltages

UCG and VUCG with tap selector CAll values given as 1.2/50 µs impulse withstand voltage (kV) – power frequency withstand voltage (kV).

a1 is not valid since the contact locations are such that electrically adjacent contacts are never physically adjacent, see connection diagrams in this document.

Within one phase Between phases for neutral point

a1 a2 c1 f1 f2 e1 b2 b1 d1

- �50-140 400-150 400-150 400-150 100-20 100-20 400-150 400-150

UCG and VUCG with tap selector IAll values given as 1.2/50 µs impulse withstand voltage (kV) – power frequency withstand voltage (kV).

a1 is not given since the contact locations are such that electrically adjacent contacts are never physically adjacent, see connection diagrams in this document.

Type of switching

No. of positions


a2 c1 f1 f2 e1 b2 b1 d1

L -14 �00-125 - - - 100-20 100-20 �00-125 -

L 15-16 290-120 - - - 100-20 100-20 �00-125 -

L 17-18 250-95 - - - 100-20 100-20 �00-125 -

R -1� �00-125 - - - 100-20 100-20 �00-125 -

R 14-15 250-95 - - - 100-20 100-20 �00-125 -

R 16-27 �00-125 - - - 100-20 100-20 �00-125 -

R 28-�1 290-120 - - - 100-20 100-20 �00-125 -

R �2-�5 250-95 - - - 100-20 100-20 �00-125 -

D -1� �00-125 �50-140 �50-140 �50-140 100-20 100-20 �00-125 �50-140

D 14-15 250-95 �50-140 �50-140 �50-140 100-20 100-20 �00-125 �50-140

D 16-27 �00-125 �50-140 �50-140 �50-140 100-20 100-20 �00-125 �50-140

D 28-�1 290-120 �50-140 �50-140 �50-140 100-20 100-20 �00-125 �50-140

D �2-�5 250-95 �50-140 �50-140 �50-140 100-20 100-20 �00-125 �50-140

�2 1ZSE 5492-105 en, Rev. 7

UCG and VUCG with tap selector III unshielded versionAll values given as 1.2/50 µs impulse withstand voltage (kV) – power frequency withstand voltage (kV).

Type of switching

No. of positions


a1 a2 c1 f1 f2 e1 b2 b1 d1

L -14 �00-125 490-150 - - - 100-20 100-20 500-160 -

L 15-16 �00-125 420-150 - - - 100-20 100-20 500-160 -

L 17-18 �00-125 �50-140 - - - 100-20 100-20 500-160 -

R -11 �00-125 490-150 - - - 100-20 100-20 500-160 -

R 12-1� �00-125 420-150 - - - 100-20 100-20 500-160 -

R 14-15 �00-125 �50-140 - - - 100-20 100-20 500-160

R 16-27 �00-125 490-160 - - - 100-20 100-20 500-160 -

R 28-�1 �00-125 420-150 - - - 100-20 100-20 500-160 -

R �2-�5 �00-125 �50-140 - - - 100-20 100-20 500-160 -

D -11 �00-125 490-160 600-200 600-200 600-200 100-20 100-20 500-160 600-200

D 12-1� �00-125 420-150 600-200 600-200 600-200 100-20 100-20 500-160 600-200

D 14-15 �00-125 �50-140 600-200 600-200 600-200 100-20 100-20 500-160 600-200

D 16-27 �00-125 490-160 600-200 600-200 600-200 100-20 100-20 500-160 600-200

D 28-�1 �00-125 420-150 600-200 600-200 600-200 100-20 100-20 500-160 600-200

D �2-�5 �00-125 �50-140 600-200 600-200 600-200 100-20 100-20 500-160 600-200

UCG and VUCG with tap selector III shielded versionAll values given as 1.2/50 µs impulse withstand voltage (kV) – power frequency withstand voltage (kV).

Type of switching

No. of positions


a1 a2 c1 f1 f2 e1 b2 b1 d1

L -14 �00-125 550-180 - - - 100-20 100-20 550-180 -

L 15-16 �00-125 480-160 - - - 100-20 100-20 550-180 -

L 17-18 �00-125 400-150 - - - 100-20 100-20 550-180 -

L 19-22 �00-125 �50-125 - - - 100-20 100-20 550-180 -

R -11 �00-125 550-180 - - - 100-20 100-20 550-180 -

R 12-1� �00-125 480-160 - - - 100-20 100-20 550-180 -

R 14-15 �00-125 400-150 - - - 100-20 100-20 550-180 -

R 16-27 �00-125 550-180 - - - 100-20 100-20 550-180 -

R 28-�1 �00-125 480-160 - - - 100-20 100-20 550-180 -

R �2-�5 �00-125 400-150 - - - 100-20 100-20 550-180 -

D -11 �00-125 550-180 600-200 600-200 600-200 100-20 100-20 550-180 600-200

D 12-1� �00-125 480-160 600-200 600-200 600-200 100-20 100-20 550-180 600-200

D 14-15 �00-125 400-150 600-200 600-200 600-200 100-20 100-20 550-180 600-200

D 16-27 �00-125 550-180 600-200 600-200 600-200 100-20 100-20 550-180 600-200

D 28-�1 �00-125 480-160 600-200 600-200 600-200 100-20 100-20 550-180 600-200

D �2-�5 �00-125 400-150 600-200 600-200 600-200 100-20 100-20 550-180 600-200

��1ZSE 5492-105 en, Rev. 7

UCL with tap selector III unshielded versionAll values given as 1.2/50 µs impulse withstand voltage (kV) – power frequency withstand voltage (kV).

Type of switching

No. of positions


a1 a2 c1 f1 f2 e1 b2 b1 d1

L -14 �00-125 490-150 - - - 1�0-20 1�0-20 500-160 -

L 15-16 �00-125 420-150 - - - 1�0-20 1�0-20 500-160 -

L 17-18 �00-125 �50-140 - - - 1�0-20 1�0-20 500-160 -

R -11 �00-125 490-150 - - - 1�0-20 1�0-20 500-160 -

R 12-1� �00-125 420-150 - - - 1�0-20 1�0-20 500-160 -

R 14-15 �00-125 �50-140 - - - 1�0-20 1�0-20 500-160 -

R 16-27 �00-125 490-160 - - - 1�0-20 1�0-20 500-160 -

R 28-�1 �00-125 420-150 - - - 1�0-20 1�0-20 500-160 -

R �2-�5 �00-125 �50-140 - - - 1�0-20 1�0-20 500-160 -

D -11 �00-125 490-160 600-200 600-200 600-200 1�0-20 1�0-20 500-160 600-200

D 12-1� �00-125 420-150 600-200 600-200 600-200 1�0-20 1�0-20 500-160 600-200

D 14-15 �00-125 �50-140 600-200 600-200 600-200 1�0-20 1�0-20 500-160 600-200

D 16-27 �00-125 490-160 600-200 600-200 600-200 1�0-20 1�0-20 500-160 600-200

D 28-�1 �00-125 420-150 600-200 600-200 600-200 1�0-20 1�0-20 500-160 600-200

D �2-�5 �00-125 �50-140 600-200 600-200 600-200 1�0-20 1�0-20 500-160 600-200

UCL with tap selector III shielded versionAll values given as 1.2/50 µs impulse withstand voltage (kV) – power frequency withstand voltage (kV).

Type of switching

No. of positions


a1 a2 c1 f1 f2 e1 b2 b1 d1

L -14 �00-125 550-180 - - - 1�0-20 1�0-20 550-180 -

L 15-16 �00-125 480-160 - - - 1�0-20 1�0-20 550-180 -

L 17-18 �00-125 400-150 - - - 1�0-20 1�0-20 550-180 -

L 19-22 �00-125 �50-125 - - - 1�0-20 1�0-20 550-180 -

R -11 �00-125 550-180 - - - 1�0-20 1�0-20 550-180 -

R 12-1� �00-125 480-160 - - - 1�0-20 1�0-20 550-180 -

R 14-15 �00-125 400-150 - - - 1�0-20 1�0-20 550-180 -

R 16-27 �00-125 550-180 - - - 1�0-20 1�0-20 550-180 -

R 28-�1 �00-125 480-160 - - - 1�0-20 1�0-20 550-180 -

R �2-�5 �00-125 400-150 - - - 1�0-20 1�0-20 550-180 -

D -11 �00-125 550-180 600-200 600-200 600-200 1�0-20 1�0-20 550-180 600-200

D 12-1� �00-125 480-160 600-200 600-200 600-200 1�0-20 1�0-20 550-180 600-200

D 14-15 �00-125 400-150 600-200 600-200 600-200 1�0-20 1�0-20 550-180 600-200

D 16-27 �00-125 550-180 600-200 600-200 600-200 1�0-20 1�0-20 550-180 600-200

D 28-�1 �00-125 480-160 600-200 600-200 600-200 1�0-20 1�0-20 550-180 600-200

D �2-�5 �00-125 400-150 600-200 600-200 600-200 1�0-20 1�0-20 550-180 600-200

�4 1ZSE 5492-105 en, Rev. 7

UCD with tap selector III unshielded versionAll values given as 1.2/50 µs impulse withstand voltage (kV) – power frequency withstand voltage (kV).

Type of switching

No. of positions


a1 a2 c1 f1 f2 e1 b2 b1 d1

L -14 �00-125 490-150 - - - 200-20 200-20 500-160 -

L 15-16 �00-125 420-150 - - - 200-20 200-20 500-160 -

L 17-18 �00-125 �50-140 - - - 200-20 200-20 500-160 -

R -11 �00-125 490-150 - - - 200-20 200-20 500-160 -

R 12-1� �00-125 420-150 - - - 200-20 200-20 500-160 -

R 14-15 �00-125 �50-140 - - - 200-20 200-20 500-160 -

R 16-27 �00-125 490-160 - - - 200-20 200-20 500-160 -

R 28-�1 �00-125 420-150 - - - 200-20 200-20 500-160 -

R �2-�5 �00-125 �50-140 - - - 200-20 200-20 500-160 -

D -11 �00-125 490-160 600-200 600-200 600-200 200-20 200-20 500-160 600-200

D 12-1� �00-125 420-150 600-200 600-200 600-200 200-20 200-20 500-160 600-200

D 14-15 �00-125 �50-140 600-200 600-200 600-200 200-20 200-20 500-160 600-200

D 16-27 �00-125 490-160 600-200 600-200 600-200 200-20 200-20 500-160 600-200

D 28-�1 �00-125 420-150 600-200 600-200 600-200 200-20 200-20 500-160 600-200

D �2-�5 �00-125 �50-140 600-200 600-200 600-200 200-20 200-20 500-160 600-200

UCD with tap selector III shielded versionAll values given as 1.2/50 µs impulse withstand voltage (kV) – power frequency withstand voltage (kV).

Type of switching

No. of positions


a1 a2 c1 f1 f2 e1 b2 b1 d1

L -14 �00-125 550-180 - - - 200-20 200-20 550-180 -

L 15-16 �00-125 480-160 - - - 200-20 200-20 550-180 -

L 17-18 �00-125 400-150 - - - 200-20 200-20 550-180 -

L 19-22 �00-125 �50-125 - - - 200-20 200-20 550-180 -

R -11 �00-125 550-180 - - - 200-20 200-20 550-180 -

R 12-1� �00-125 480-160 - - - 200-20 200-20 550-180 -

R 14-15 �00-125 400-150 - - - 200-20 200-20 550-180 -

R 16-27 �00-125 550-180 - - - 200-20 200-20 550-180 -

R 28-�1 �00-125 480-160 - - - 200-20 200-20 550-180 -

R �2-�5 �00-125 400-150 - - - 200-20 200-20 550-180 -

D -11 �00-125 550-180 600-200 600-200 600-200 200-20 200-20 550-180 600-200

D 12-1� �00-125 480-160 600-200 600-200 600-200 200-20 200-20 550-180 600-200

D 14-15 �00-125 400-150 600-200 600-200 600-200 200-20 200-20 550-180 600-200

D 16-27 �00-125 550-180 600-200 600-200 600-200 200-20 200-20 550-180 600-200

D 28-�1 �00-125 480-160 600-200 600-200 600-200 200-20 200-20 550-180 600-200

D �2-�5 �00-125 400-150 600-200 600-200 600-200 200-20 200-20 550-180 600-200

�51ZSE 5492-105 en, Rev. 7

UCC with tap selector IVAll values given as 1.2/50 µs impulse withstand voltage (kV) – power frequency withstand voltage (kV).

Type of switching

Shielded (s)/unshielded (us)

No. of positions


a1 a2 c1 f1 f2 e1 b2 b1 d1

L us -16 200-80 �00-125 - - - 200-20 200-20 �00-125 -

L s -16 200-80 500-170 - - - 200-20 200-20 500-170 -

L us 17-18 200-80 �00-125 - - - 200-20 200-20 �00-125 -

L s 17-18 200-80 450-150 - - - 200-20 200-20 500-170 -

R us -1� 200-80 �00-125 �00-125 - - 200-20 200-20 �00-125 -

R s -1� 200-80 500-170 600-200 - - 200-20 200-20 500-170 -

R us 14-15 200-80 250-95 �00-125 - - 200-20 200-20 �00-125 -

R s 14-15 200-80 400-150 600-200 - - 200-20 200-20 500-170 -

R us 16-27 200-80 �00-125 �00-125 - - 200-20 200-20 �00-125 -

R s 16-27 200-80 500-170 600-200 - - 200-20 200-20 500-170 -

R us 28-�5 200-80 250-95 �00-125 - - 200-20 200-20 �00-125 -

R s 28-�5 200-80 400-150 600-200 - - 200-20 200-20 500-170 -

D us 16-27 200-80 �00-125 �00-125 �50-150 �50-150 200-20 200-20 �00-125 �50-150

D s 16-27 200-80 500-170 600-200 600-200 600-200 200-20 200-20 500-170 600-200

D us 28-�5 200-80 250-95 �00-125 �50-150 �50-150 200-20 200-20 �00-125 �50-150

D s 28-�5 200-80 400-150 600-200 600-200 600-200 200-20 200-20 500-170 600-200

�6 1ZSE 5492-105 en, Rev. 7

Short-circuit current strengthThe short circuit current strength is verified with three applications of 2 or � seconds duration, with-out moving the contacts between the three applications. Each application has an initial value of at least 2.5 times the rms value.

Table 4.

Diverter switch

Tap selector Max rated through-current, A rms

Type of connection

2 s duration, kA rms

3 sduration, kA rms

Peak value, kA

UCG C �00 N,B,E,T 7 6 18

C 400 N,B,E,T 7 6 18

C 500 E,T 10 10 25

C 600 E,T 10 10 25

C 700 E,T 15 15 �8

C 900 E,T 16 16 40

C 1050 E,T 16 16 40

I �00 N,B,E,T 71) 61) 18

I 500 N,B,E,T 71) 61) 18

I 600 N,B,E,T 71) 61) 18

I 900 E,T 17 17 4�

I 1200 E,T 17 17 4�

I 1500 E,T 18 18 45

III �00 N,B,E,T 71) 61) 18

III 500 N,B,E,T 71) 61) 18

III 600 N,B,E,T 71) 61) 18

III 900 E,T 10 10 25

III 1200 E,T 17 17 4�

III 1500 E,T 18 18 45

VUCG C 400 N,B,E,T 7 7 20

C 700 E,T 10 10 25

C 1050 E,T 16 16 40

I 600 N,B,E,T 81) 81) 22

I 1200 E,T 15 15 �8

I 1500 E,T 16 16 4�

III 700 N,B,E,T 81) 81) 22

III 1600 E,T 16 16 4�

UCL III 600 N,B,E,T 111) 111) �0

III 900 N,B,E,T 111) 111) �0

III 1800 E,T 24 24 64

III 2400 E,T 27 27 79

UCD III 1000 N,B,E,T 18 182) 45

III 1600 E,T 18 182) 45

UCC IV 1600 N,E 18 182) 45

1) In case of UC..E,T or VUC..E,T higher values are possible on request.2) Available for reinforced performance with 24 kArms and 60 kApeak.

�71ZSE 5492-105 en, Rev. 7

Highest phase service voltage across the regulating winding The table below show the highest permissible phase service voltage for the different types of connections.

Table 5. Highest permissible phase service voltage across the regulating winding.

Across the regulating winding (kV)

Across the coarse and fine winding (kV)

Contact shieldings: with without with without

Tap-changer, tap selector

UCC.N IV 52 �5 75 45

UCD.N III

UCL.N III

UCG.N III

UCC.E IV 68 45 80 60

UCD.E, III

UCL.T, E, B III

UCG.T, E, B III

UCG.N C, I - �5 - 40

UCG.T, E, B C, I - �5 - 45

VUCG.T, E, B III 68 45 80 60

VUCG.N C, I - �5 - 40

VUCG.T, E, B C, I - �5 - 45

Rated through-currentThe rated through-current of the on-load tap-changer is the current which the on-load tap-changer is capable of transferring from one tapping to the other at the relevant rated step voltage, and which can be carried continu-ously whilst meeting the technical data in this document. The rated through current is normally the same as the highest tapping current. The rated through-current is limited by the step voltage according to the curves in the diagrams, Figs. 1� - 17. The rated through-current determines the dimen-sioning of the transition resistors and the contact life. The rated through-current is stated on the rating plate, Fig. 2�.

Occasional overloadingIf the rated through-current of the tap-changer is not less than the high-est value of tapping current of the tapped winding of the transformer, the tap-changer will not restrict the occasional overloading of the transformer, according to IEC 60076-7, 2005-12, and ANSI/IEEE C57-91-1995.

To meet these requirements, the UC models have been designed so that the contact temperature rise over the surrounding oil does not exceed 20 K when loaded with a current of 1.2 times the maximum rated through cur-rent of the tap-changer.

The contact life stated on the rating plate is given with consideration that currents of maximum 1.5 times the rated through current occur during a maximum of � % of the tap-change operations. Overloading beyond these values, results in increased contact wear and shorter contact life.

For more information about overloading, read the appropriate parts of IEC 60214-2, 2004-10.

�8 1ZSE 5492-105 en, Rev. 7

Oil temperatureProvided that insulating oil of class “Transformer oil -�0 °C” according to IEC 60296, 200�-11, is used, the temperature of the oil surrounding the on-load tap-changer shall be between -25 and +105 °C for normal opera-tion, as illustrated below. The range for UC (not VUC!) can be extended to -40 °C provided that the viscosity does not exceed 2500 mm2/s (=cst).

Individual brands need to be evaluated from case to case because of dif-ferences in viscosity compared to transformer grade mineral oil and the subsequent difference in heat dissipation. Also dielectric strengths and influence form moisture needs to be considered. Switching in vacuum generally opens for use of a wider range of insulating fluids.

No operations allowed.

Emergency overloading. The on-load tap-changer will not restrict the occasional overloading of the transformer according to the standards stated in section Occasional overloading.

Normal operating range.

UC: When operating within this range, no overloading is allowed. VUC: Operation with de-energized transformer only.

UC: Operation with de-energized transformer only. VUC: No operation allowed.

1)

2)

�)

4)

5)

�91ZSE 5492-105 en, Rev. 7

Coarse/fine regulation leakage inductance switchingWhen changing from the end of the fine winding to the end of the coarse winding, a high leakage inductance can be set up with the two wind-ings in series. The critical moment occurs at switching the tap-changers mechanical mid-position, as the circulating current is passing through not only one loop but also the entire coarse and fine tap winding.

The leakage inductance that occurs from one loop, Fig. 28, is neglectible but can be substantial from the complete coarse and fine winding, Fig. 29.

This leakage inductance causes a phase shift between switching current and recovery voltage that makes the breaking more severe. The OLTC must be dimensioned accordingly. The leakage inductance shall be speci-fied in the ordering data sheet.

For certain winding configurations, such as coarse and fine windings lo-cated axially, this value might be that high that it requires a larger OLTC than would be needed otherwise. For more information, see product in-formation 1ZSC000498-AAR as well as IEC 60214-2, 2004-10, or consult the supplier for advice.

Main winding

Coarse winding

Fine winding

Fig. 28. Normal operation Fig. 29. Operation with high leakage inductance.

40 1ZSE 5492-105 en, Rev. 7

Tie-in resistor and tie-in resistor switchWhen the change-over selector operates, the tapped winding is discon-nected for a short time. The voltage of that winding is then determined by the voltage of and the capacitances to the surrounding windings or tank wall/core. For certain winding layouts, voltages and capacitances, the capacitive controlled voltage will reach magnitudes that are too high for the change-over selector. In these cases potential controlling resistors, so called tie-in resistors, should be connected according to Fig. �0.

The tie-in resistor is connected between the middle of the tapped wind-ing and the connection point on the bottom of the diverter switch housing, see single phase diagrams in this document. This means that power is continuously dissipated in the resistors that add to the no-load losses of the transformers. The resistors must also be dimensioned for the power dissipation.

The tie-in resistors are normally mounted separate from the OLTC but can be mounted under the tap selector provided that tie-in resistor switch is not used. Please contact the supplier for advice in such case!

The following limits apply to the change-over selectors of the different tap selectors:

Tap selector Max recovery voltage (kV rms) Max capacitive current (mA rms)

C �5 200

I �5 200

III �5 �00

IV �5 �00

The capacitive current is the current going through the change-over se-lector before it opens.

Diverter switch

Tie-in resistor switch

Tie-in resistor

Tap selector

Main winding

Regulating winding wIth change-over selector

Fig. 30. Tie-in resistor example.

411ZSE 5492-105 en, Rev. 7

HV

C1

RW

C2

+ -

U

In the figure above is a switch, the tie-in resistor switch, that connects the tie-in resistors only when they are needed. The switch is a part of the tap selector and is mounted on the bottom plate of the tap selector, see dimension drawings in this document.

This switch is used when the no-load losses must be kept low or/and when the continuous power in the tie-in resistors is too high. The tie-in resistor switch is available for all tap selectors except tap selector C.

When ordering, give the winding layout and information according to the example below and the supplier will calculate whether tie-in resistors are needed or not. If needed, the supplier will choose the correct tie-in resis-tors. If a tie-in resistor switch is needed for limiting the no-load losses, give that information in the ordering data sheet! If anything is unclear, contact the manufacturer.

Example

C1 = Capacitance between HV and RWC2 = Capacitance between tank and RWFrequency 50 Hz

Winding Phase voltage Connection

High voltage (HV) 1�2 kV (H1) Delta

Regulating winding (RW) (Voltage across)

1�.� kV (U) Plus/Minus

Tank

42 1ZSE 5492-105 en, Rev. 7

Installation and maintenance

On-load tap-changer

InstallationThe on-load tap-changers can be delivered for cover-mounting method or yoke-mounting method onto the transformer.

For detailed installation instructions, consult the appropriate Installation and Commissioning Guide.

DryingThe on-load tap-changer must be stored indoors and left in its plastic shipping cover until time for assembly. The OLTC should be subjected to drying before taken into service. The diverter switch should not partici-pate in the drying process. For further instructions refer to the Installation Guide.

WeightsThe tables below shows all the weights of the UC range of tap-changers.

Table 7. Weights for type UCG.On-load tap-changer type designation

Approximate weight in kg

Tap-changer without oil1)

Required oil Total

UCG.N �80-750/�00-600 425 185 610

1050/�00-600 4�5 2�0 665

UCG.T �80-750/�00-900 1025 �x185 1580

�80-750/1050-1500 1190 �x185 1745

1050/�00-900 1090 �x2�0 1780

1050/1050-1500 1225 �x2�0 1915

UCG.B �80-750/�00-600 760 2x185 11�0

1050/�00-600 780 2x2�0 1240

UCG.E �80-750/�00-900 �60 185 545

�80-750/1050-1500 410 185 595

1050/�00-900 �70 2�0 600

1050/1050-1500 425 2�0 6551) The weight of the diverter switch, approximately 90 kg, is included.

4�1ZSE 5492-105 en, Rev. 7

Table 8. Weights for type VUCG.On-load tap-changer type designation



Required oil Total

VUCG.N �80-750/400-600 450 185 6�5

�80-750/700 500 185 685

1050/400-600 460 2�0 690

1050/700 510 2�0 740

VUCG.T �80-750/400-1200 1100 �x185 1655

�80-750/1500-1600 1250 �x185 1805

1050/400-1200 1165 �x2�0 1855

1050/1500-1600 1�15 �x2�0 2005

VUCG.B �80-750/400-600 810 2x185 1180

�80-750/700 910 2x185 1280

1050/400-600 8�0 2x2�0 1290

1050/700 9�0 2x2�0 1�90

VUCG.E �80-750/400-1200 �85 185 570

�80-750/1500-1600 4�5 185 620

1050/400-1200 �95 2�0 625

1050/1500-1600 445 2�0 6751) The weight of the diverter switch, approximately 115 kg, is included.

Table 9. Weights for type UCL.On-load tap-changer type designation



Required oil Total

UCL.N �80/600, 900 480 260 740

650/600, 900 500 �00 800

1050/600, 900 510 �40 850

UCL.T �80/600, 900 12�0 �x260 2010

�80/1800 1�50 �x260 21�0

�80/2400 1440 �x260 2220

650/600, 900 1290 �x�00 2190

650/1800 1410 �x�00 2�10

650/2400 1500 �x�00 2400

1050/600, 900 1�20 �x�40 2�40

1050/1800 1440 �x�40 2460

1050/2400 15�0 �x�40 2550

UCL.B �80/600, 900 850 2x260 1�70

650/600, 900 890 2x�00 1490

1050/600, 900 910 2x�40 1590

UCL.E �80/600, 900 410 260 670

�80/1800 450 260 710

�80/2400 480 260 740

650/600, 900 4�0 �00 7�0

650/1800 470 �00 770

650/2400 500 �00 800

1050/600, 900 440 �40 780

1050/1800 480 �40 820

1050/2400 510 �40 8501) The weight of the diverter switch, approximately 120 kg, is included.

44 1ZSE 5492-105 en, Rev. 7

Table 10. Weights for type UCD.On-load tap-changer type designation



Required oil Total

UCD.N �80/1000 900 700 1600

650/1000 940 760 1700

1050/1000 960 860 1820

UCD.E �80/1000 840 700 1540

�80/1800 870 700 1570

�80/2400 900 700 1600

650/1000 880 760 1640

650/1800 910 760 1670

650/2400 940 760 1700

1050/1000 900 860 1760

1050/1800 9�0 860 1790

1050/2400 960 860 18201) The weight of the diverter switch, approximately 250 kg, is included.

Table 11. Weights for type UCC.On-load tap-changer type designation



Required oil Total

UCC.N �80/1600 1140 700 1840

650/1600 1180 760 1940

1050/1600 1200 860 2060

UCC.E �80/1600 1040 700 1740

650/1600 1080 760 1840

1050/1600 1100 860 1960) The weight of the diverter switch, approximately 250 kg, is included.

Oil filling For details of oil filling, consult the appropriate Installation and Commissioning Guide.

451ZSE 5492-105 en, Rev. 7

MaintenanceFor information about maintenance, the appropriate Maintenance Guide should be used.

PressureDuring drying, the on-load tap-changers should have no pressure dif-ference to the transformer. This is obtained by opening the VP-valve in the bottom, see the Installation and commissioning guide for further information.

During oil filling and testing, up to 200 kPa pressure difference to the at-mosphere is allowed. During service, max. 150 kPa pressure difference to the atmosphere is allowed.

The pressure difference to the transformer tank during oil filling and test-ing is allowed to be max 100 kPa. During service, the pressure is recom-mended to be as low as possible and not more than 50 kPa and then preferably higher in the transformer tank. For higher pressures, contact the supplier.

Accessories and protection devicesThe tap-changer can be equipped with various protection devices. The standard protection device is the pressure relay. An oil flow relay is also available.

Pressure relief device with alarm signal is also available as well as some other supervisory sensors.

For more information about accessories and protection devices see tech-nical description 1ZSC000562-AAD.

46 1ZSE 5492-105 en, Rev. 7

Motor-drive mechanism

DesignFor detailed design description, see separate Technical Guides for Motor-Drive Mechanisms types BUL or BUE, respectively.

InstallationThe motor-drive mechanism is fitted to the outside of the transformer tank, and connected to the on-load tap-changer by drive shafts and bevel gears.

For the correct installation procedure, consult the appropriate Installation Guide.

MaintenanceThe motor-drive mechanism should be visually inspected anually.

For the correct inspection and maintenance procedures, consult the ap-propriate Maintenance Guide.

Operating shaftsLength L1 (mm) L2 (mm) L3 and L4 (mm) Motor-drive

mechanism

Min/max 500/�100 525/�100 900/2700 BUE

500/�100 600/�100 – BUL

The minimum and maximum lengths refer to mechanical design only. For L2 vertical shaft see following pages. Other shaft arrangements are avail-able on request.

For standard shaft arrangements, the maximum angle (totally in two di-rections) is 4°. For larger angles, special couplings are needed.

471ZSE 5492-105 en, Rev. 7

Fig. A

L1

UCG.N, EVUCG.N, EUCL.N, EUCD.N, EUCC.N, E

Fig. B

L1

Fig. C

L3 L1

UCG.BVUCG.BUCL.B

Fig. D

L1 L3

Fig. E

L4 L3 L1

UCG.TVUCG.TUCL.T

Fig. F

L1 L3 L4

Fig. 31. Positioning of motor-drive mechanism.

For singel units (UC..E, N and VUC..E, N) the gear box of the tap-changer might be mounted in the angle given below.

48 1ZSE 5492-105 en, Rev. 7

Dimensions

Type UCG/C and VUCG/CDimensions in mm. The design, technical data and dimensions are sub-ject to alteration without notice. For more information, see the dimension drawings.

C/L Tap selector C/L Diverter switch

Section A – APlus/Minus andCoarse/Fine switching

Section A – ALinear switching

145

�5�

80

2�0

1�4

440

R210

570

570

615D=420

615

R210

818

194

�6

75

157

L2

2907)

L1H�2)

A A

205

D=600

D=470

�45

�90

�0

H2

70

4057)

1)

1)

D=420

��2

D=740

111

16O

H1

BUL

BUL

BUE2

BUE2

491ZSE 5492-105 en, Rev. 7

Type UCG/I and VUCG/IDimensions in mm. The design, technical data and dimensions are sub-ject to alteration without notice.

C/L Tap selector C/L Diverter switch



�6

1)

610

19475

157

L2

L1

H1

H2

D=600

D=470

1)

1)

�0

605�)

665

�90�)

500

500 410�)

420�) 5�0

��2

��97)

�90

145

�5�

818

2�016°

80

440

4)

70

�0

195

H�2)

205

D=740

1�4

AA

111

4057)

BUL

BUL

BUE2

BUE2

50 1ZSE 5492-105 en, Rev. 7

Type UCG/III and VUCG/IIIDimensions in mm. The design, technical data and dimensions are sub-ject to alteration without notice.

Model for mounting on transformer’s active part

Model for cover mounting

C/L Diverter switchC/L Tap selector

Section B - BLinear switching

Section B - BPlus/Minus andCoarse/Fine switching

H2

H1

BB

85

H1+106

�0

�85

586490�)

840�)

29�

9�6

490�)

490�) 580

245�)

580

4)

511ZSE 5492-105 en, Rev. 7

Tables UCG and VUCG


For tap selector size

Impulse withstand voltage to earth (kV)

H1 (mm)

H1, short version (mm)

H3 2) (mm)

H3 2), short version (mm)

C �80, 650, 750 1192 972 1400 1200

1050 1492 1272 1700 1500

I �80, 650, 750 1�17 1097 1400 1200

1050 1617 1�97 1700 1500

III �80, 650, 750 1�54 11�4 1400 1200

1050 1654 14�4 1700 1500

Tap selector

For on-load tap-changer type

Max rated through-current (A)

H2, size C (mm) H2, size I (mm) H2, size III (mm)

UCG.N, VUCG.N 400 959 - -

�00-600 - 1026 1160

UCG.E, UCG.T 5), VUCG.E, VUCG.T 5)

400 519 - -

�00-600 - 526 552

700 7�9 - -

900 - - 552

1050 959 - -

1200 - 756 856

1500 - 1026 856

UCG.B 6), VUCG.B 6) 400 Single-phase unit 519Two-phase unit 7�9

- -

�00-600 - Single-phase unit 526Two-phase unit 776

Single-phase unit 552Two-phase unit 856

1) Shielding rings are used only for insulation level 650-275 kV and higher.2) Space required for lifting the diverter switch, excluding the lifting equipment.�) Dimension without shielding ring.4) For tie-in resistor switch add �60 mm.5) UCG.T and VUCG.T consists of three single-phase units.6) UCG.B and VUCG.B consists of one single-phase and one two-phase unit arranged as shown in the dimension drawing

for UCL.B.7) Space required for protective equipment.

52 1ZSE 5492-105 en, Rev. 7

Type UCL/IIIDimensions in mm. The design, technical data and dimensions are sub-ject to alteration without notice.

Type UCL.N (three-phase, star point) and type UCL.E (single-phase)



�018)

4808)

5�1ZSE 5492-105 en, Rev. 7

Design for premounting on the active part of the transformer

Type UCL.B (three-phase, delta)

4)

4)

54 1ZSE 5492-105 en, Rev. 7

Tables UCL


Impulse withstand voltage to earth (kV) H1 (mm) H3 2) (mm)

�80 1415 1500

650 1615 1700

1050 1815 1900

For mounting on active part 5) H1+85 H�+100

Tap selector

For on-load tap-changer type Max rated through-current (A) H2, size III (mm)

UCL.N 600-900 1160

UCL.E, UCL.T 6) 600-900 552

1800 856

2400 1160

UCL.B 7) 600-900 Single-phase unit H22 = 552

Two-phase unit H21 = 856

1) Shielding rings are used only for insulation level 650-275 kV and higher.2) Space required for lifting the diverter switch, excluding the lifting equipment.�) Dimension without shielding-ring.4) For tie-in resistor switch add �70 mm.5) Model for mounting on transformers active part.6) UCL.T consists of three single-phase units.7) UCL.B consists of one single-phase unit and one two-phase unit.8) Space required for protective equipment.

551ZSE 5492-105 en, Rev. 7

Type UCD/IIIDimensions in mm. The design, technical data and dimensions are sub-ject to alteration without notice.

2046)

7886)

56 1ZSE 5492-105 en, Rev. 7

Tables UCD



�80 1594 1700

650 17�4 1900

1050 19�4 2200

Tap selector


UCD.N 1000 1160

UCD.E 1000 552

1800 856

2400 1160

1) Shielding rings are used only for insulation level 650-275 kV and higher.2) Space required for lifting the diverter switch, excluding the lifting equipment.�) Dimension without shielding ring.4) For tie-in resistor switch add �70 mm.5) When two or three units are fitted together (three-phase delta and three-phase fully insulated respectively) the distance

between the units (c) must be at least 1�40 mm from mechanical point of view. For final dimensioning, check the insulation distance required.

6) Space required for protective equipment.

571ZSE 5492-105 en, Rev. 7

Type UCC/IVDimensions in mm. The design, technical data and dimensions are sub-ject to alteration without notice.

58 1ZSE 5492-105 en, Rev. 7

Tables UCC



�80 1540 1700

650 1680 1900

1050 1880 2200

Tap selector


UCC.N 1200 1282

1600 1522

UCC.E 1600 1282

1) Shielding rings are used only for insulation level 650-275 kV and higher.2) Space required for lifting the diverter switch, excluding the lifting equipment.�) Dimension without shielding ring.4) For tie-in resistor switch add �40 mm.5) When two or three units are fitted together (three-phase delta and three-phase fully insulated respectively) the distance

between the units (c) must be at least 1�40 mm from mechanical point of view. For final dimensioning, check the insulation distance required.

591ZSE 5492-105 en, Rev. 7

Oil conservatorThe transformer manufacturer must provide a conservator for the tap-changer. Consider the below as a guideline for the design.

The breathing device should prevent moisture from getting into the tap-changer compartment and let gases from the arcings out.

The oil volume should be such that the oil level always is within the range of the oil level indicator at all predictable temperatures.

X corresponds to a height giving a max permissible pressure dif-ference between the tap-changer tank and the transformer tank of 50 kPa.

H corresponds to a height giving a max pressure difference be-tween the tap-changer and the atmosphere of 150 kPa.

The oil level for the tap-changer should be equal or below the oil level of the transformer. Temporary during service the value is al-lowed to be negative.

Vacuum proof conservator if the tap-changer should be oil filled under vacuum with the conservator mounted.

Note that separate oil conservators for the transformer and the tap-changer (also for the vacuum tap-changer) are recommended. Both oil and air side should be separated. For transformers with common con-servator for both the transformer and the tap-changer a filter should be mounted in the pipe from the tap-changer to the conservator.

1.

2.

�.

4.

5.

6.

60 1ZSE 5492-105 en, Rev. 7

Appendices: Single-Phase DiagramsThe basic connection diagrams illustrate the different types of switching and the appropriate connections to the transformer windings. The dia-grams illustrate the connections with the maximum number of turns in the transformer winding, with the tap-changer in position 1.

The tap-changer can also be connected in such a way that position 1 gives a minimum effective number of turns in the transformer winding with the tap-changer in position 1.

Appendix 1: Single-phase diagrams for UCG/C

Linear Plus/Minus Coarse/Fine4 steps

Number of loops:

4

Number of tap positions:

5

5 steps

Number of loops:

5


6

611ZSE 5492-105 en, Rev. 7


Number of loops:

6


7

7 steps

Number of loops:

7


8

8 steps

Number of loops:

8 4 4 + 4


9 9 9

62 1ZSE 5492-105 en, Rev. 7


Number of loops:

10 5 5 + 5


11 11 11

12 steps

Number of loops:

12 6 6 + 6


13 13 13

13 steps

Number of loops:

13


14

6�1ZSE 5492-105 en, Rev. 7


Number of loops:

8 8 + 8


17 17

18 steps

Number of loops:

10 9 + 10


19 19

20 steps

Number of loops:

10 10 + 10


21 21

64 1ZSE 5492-105 en, Rev. 7


Number of loops:

12 11 + 12


23 23

24 steps

Number of loops:

12 12 + 12


25 25

26 steps

Number of loops:

14 13 + 14


27 27

651ZSE 5492-105 en, Rev. 7

Appendix 2: Single-phase diagrams for UCG/I


Number of loops:

4


5

5 steps

Number of loops:

5


6

6 steps

Number of loops:

6


7

66 1ZSE 5492-105 en, Rev. 7


Number of loops:

7


8

8 steps

Number of loops:

8 4 4 + 4


9 9 9

10 steps

Number of loops:

10 5 5 + 5


11 11 11

671ZSE 5492-105 en, Rev. 7


Number of loops:

12 6 6 + 6


13 13 13

14 steps

Number of loops:

14 7 7 + 7


15 15 15

16 steps

Number of loops:

16 8 8 + 8


17 17 17

68 1ZSE 5492-105 en, Rev. 7


Number of loops:

17


18

18 steps

Number of loops:

10 9 + 10


19 19

20 steps

Number of loops:

10 10 + 10


21 21

691ZSE 5492-105 en, Rev. 7


Number of loops:

12 11 + 12


23 23

24 steps

Number of loops:

12 12 + 12


25 25

26 steps

Number of loops:

14 13 + 14


27 27

70 1ZSE 5492-105 en, Rev. 7


Number of loops:

14 14 + 14


29 29

30 steps

Number of loops:

16 15 + 16


31 31

32 steps

Number of loops:

16 16 + 16


33 33

711ZSE 5492-105 en, Rev. 7


Number of loops:

18 17 + 18


35 35

72 1ZSE 5492-105 en, Rev. 7

Appendix �: Single-phase diagrams for UCG/III, VUCG/III, UCL/III and UCD/III


Number of loops:

4


5

5 steps

Number of loops:

5


6

6 steps

Number of loops:

6


7

7�1ZSE 5492-105 en, Rev. 7


Number of loops:

7


8

8 steps

Number of loops:

8 4 4 + 4


9 9 9

10 steps

Number of loops:

10 5 5 + 5


11 11 11

74 1ZSE 5492-105 en, Rev. 7


Number of loops:

12 6 6 + 6


13 13 13

14 steps

Number of loops:

14 7 7 + 7


15 15 15

16 steps

Number of loops:

16 8 8 + 8


17 17 17

751ZSE 5492-105 en, Rev. 7


Number of loops:

18 10 9 + 10


19 19 19

20 steps

Number of loops:

20 10 10 + 10


21 21 21

21 steps

Number of loops:

21


22

76 1ZSE 5492-105 en, Rev. 7


Number of loops:

12 11 + 12


23 23

24 steps

Number of loops:

12 12 + 12


25 25

26 steps

Number of loops:

14 13 + 14


27 27

771ZSE 5492-105 en, Rev. 7


Number of loops:

14 14 + 14


29 29

30 steps

Number of loops:

16 15 + 16


31 31

32 steps

Number of loops:

16 16 + 16


33 33

78 1ZSE 5492-105 en, Rev. 7


Number of loops:

18 17 + 18


35 35

791ZSE 5492-105 en, Rev. 7

Appendix 4: Single-phase diagrams for UCC/IV


Number of loops:

8 4


9 9

10 steps

Number of loops:

10 5


11 11

12 steps

Number of loops:

12 6


13 13

80 1ZSE 5492-105 en, Rev. 7


Number of loops:

14 7


15 15

16 steps

Number of loops:

16 8 8 + 8


17 17 17

17 steps

Number of loops:

17


18

811ZSE 5492-105 en, Rev. 7


Number of loops:

10 9 + 10


19 19

20 steps

Number of loops:

10 10 + 10


21 21

22 steps

Number of loops:

12 11 + 12


23 23

82 1ZSE 5492-105 en, Rev. 7


Number of loops:

12 12 + 12


25 25

26 steps

Number of loops:

14 13 + 14


27 27

28 steps

Number of loops:

14 14 + 14


29 29

8�1ZSE 5492-105 en, Rev. 7


Number of loops:

16 15 + 16


31 31

32 steps

Number of loops:

16 16 + 16


33 33

34 steps

Number of loops:

18 17 + 18


35 35

ABB ABComponentsVisiting address: Lyviksvägen 10Postal address: SE-771 80 Ludvika, SWEDENTel: +46 240 78 20 00Fax: +46 240 121 57E-mail: [email protected]/electricalcomponents 1Z

SE

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