ABB UCL User manual

On-load tap-changers, type UCL and VUCL
Installation and commissioning guide
1ZSC000562-AAZ en

Original instruction
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 ABB 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.
This document must not be copied without our written permission, and the contents
thereof must not be imparted to a third party nor be used for any unauthorized
purpose. Contravention will be prosecuted.

Recommended practices
ABB recommends careful consideration of the following
factors when installing on-load tap-changers:
Before you install or commission a unit, make sure that the
personnel doing the job have read and fully understood the
installation and commissioning guide provided with the unit.
To avoid damaging the unit, never exceed the operating limits
stated in delivery documents and on rating plates.
Do not alter or modify a unit without first consulting ABB.
Follow local and international wiring regulations at all times.
Use only factory authorized replacement parts and
procedures.
Safety warnings
The following warnings and notes are used in the manual:
WARNING
WARNING indicates an imminently hazardous
situation, which if not avoided will result in death or
serious injury. This signal word is to be limited to the
most extreme situations.
WARNING also indicates a potentially hazardous
situation, which if not avoided could result in death or
serious injury.
CAUTION
CAUTION indicates a potentially hazardous situation,
which if not avoided may result in minor or moderate
injury. It may also be used to alert of unsafe practices.
CAUTION may also indicate property-damage-only
hazards.
INFO provides additional information to assist in
carrying out the work described and to provide
trouble-free operation.
Safety precautions
WARNING
Unused transformer oil is harmful. Fumes from
unused warm oil may irritate the respiratory organs
and the eyes. After long and repeated contact with
transformer oil, skin becomes very dry.
Used tap-changer oil from diverter switch housings
and selector switch housings contains harmful
substances. Fumes are irritating to the respiratory
organs and the eyes and are highly flammable. Used
transformer oil may well be carcinogenic.
Avoid contact with the oil and use oil-tight protective
gloves when handling the oil.
First aid:
Skin contact: Wash your hands. Use skin cream to
counteract drying.
In the eyes: Rinse your eyes in clean water.
Swallowing: Drink water or milk. Avoid vomiting. Call
a doctor.
Collect used oil in oil drums.
Waste and clean-up: Should be absorbed by an
absorber. Treat it as hazardous to the environment.
In the event of fire: Any fires should be extinguished
with powder, foam or carbonic acid extinguishing
agents.
WARNING
Be aware of the risk for slipping caused by oil spillage,
for instance when working on the transformer cover.
WARNING
The motor-drive mechanism must not be installed in
an explosive atmosphere. The electrical equipment
creates sparks that can cause an explosion.
WARNING
Before any work is carried out on the tap-changer:
Make sure that the transformer is disconnected and
that grounding is properly conducted. Obtain a signed
certificate from the engineer in charge.

WARNING
Before carrying out work on the tap-changer, put
the LOCAL/REMOTE switch on the motor-drive
mechanism to position 0. It is also advisable to shut
the door of the motor-drive mechanism and pad lock
it when work is carried out on the tap-changer. The
key should be kept by the operator. This is done
to avoid an unexpected start of the motor-drive
mechanism.
WARNING
Before starting any work inside the motor-drive
mechanism, the auxiliary power must be switched off.
NOTE: The motor, contactors and heating element
may be energized from separate sources.
During drying of the transformer
CAUTION
The diverter switch should not be installed during
drying, since the process removes grease needed for
operation.
CAUTION
While drying with hot air and vacuum, the maximum
permitted pressure difference for the diverter switch
housing is 100 kPa at the maximum permitted
temperature of 135 °C (275°F).
CAUTION
During drying with the vapor phase process, the cover
of the diverter switch housing and the bottom valve
should be left open. The valve is opened with the
special bottom valve key – a long hexagonal rod. The
maximum permitted temperature is 135 °C (275 °F).
CAUTION
Use the special bottom valve key only (delivered with
the tap-changer) to operate the bottom valve through
the oil draining tube. The use of a stiffer tool may
damage the valve.
CAUTION
To avoid seizing, do not operate the tap-changer
during the drying process or afterwards until it is filled
with oil.
Mounting of gaskets
CAUTION
Sealing surfaces and gaskets must be clean and
undamaged. Diametrically opposed bolts in sealing
joints must be tightened alternately several times,
beginning with a low tightening torque and finally with
the recommended tightening torque as described in
Section 1.8 Tightening torques in this guide.
During oil filling
WARNING
When oil that has been used in a diverter switch
housing is pumped out, grounded conducting
tubes and hoses should be used to avoid the risk of
explosion due to the gases produced by arcs during
service.
CAUTION
Do not fill the diverter switch housing with oil if the
transformer tank is under vacuum and the diverter
switch housing is not.
CAUTION
Do not fill the transformer tank with oil if the diverter
switch housing is under vacuum and the transformer
tank is not.
After oil filling
CAUTION
Do not energize the transformer earlier than three
hours after oil filling at atmospheric pressure. This
waiting period is needed to allow air bubbles to
dissipate.

During service
WARNING
Small amounts of explosive gases may be emitted
from the breathing devices (dehydrating breather or
one-way breather). Make sure that no open fires, hot
surfaces or sparks occur in the immediate vicinity of
the breathing devices.
WARNING
If a power supply failure occurs during operation, the
operation will be completed when the power returns.
WARNING
The hand crank must not be inserted during electrical
operation.
WARNING
If the tap-changer is not at its exact position and the
hand crank is pulled out, the motor-drive mechanism
will start and go to the exact position if the power
supply is on.
CAUTION
After a pressure relay trip, follow the instructions in
the chapter “Trip or alarm from supervisory devices” in
the user's manual.
CAUTION
The pressure relay is a calibrated monitoring
instrument. It must be handled with care and
protected against careless handling or any kind of
mechanical damage. Do not open the pressure relay
package until just prior to installation on the tap-
changer.

Content
1. Introduction ..........................................................................................................................9
1.1 Type designation...........................................................................................................11
1.2 Required tools ..............................................................................................................12
1.3 Required material..........................................................................................................12
1.4 Oil.................................................................................................................................12
1.5 Oil conservator..............................................................................................................12
1.6 Oil lter unit for continuous oil ltration...........................................................................13
1.7 Weights ........................................................................................................................13
1.8 Tightening torques ........................................................................................................13
2. Receiving..............................................................................................................................14
2.1 Unpacking ....................................................................................................................14
2.2 Inspection on receipt.....................................................................................................14
2.3 Temporary storage before assembly..............................................................................14
3. Installation in the transformer ................................................................................................15
3.1 Cover-mounting ............................................................................................................16
3.1.1 UCL/VUCL with tap selector size III ........................................................................16
3.2 Yoke-mounting .............................................................................................................19
3.2.1 Mounting when the transformer ratio measurement is carried out before drying......20
3.2.2 Mounting when the transformer ratio measurement is carried out after drying.........22
3.2.3 Mounting on transformer cover (after the drying process) .......................................23
3.3 Connection to terminals ................................................................................................25
3.4 Transformer ratio measurement.....................................................................................27
3.4.1 Transformer ratio measurement before drying.........................................................27
3.4.2 Transformer ratio measurement after drying............................................................27
4. Drying...................................................................................................................................28
4.1 Precautions before processing......................................................................................28
4.2 Precautions after processing.........................................................................................28
4.3 Installation of diverter switch .........................................................................................28
5. Final assembly......................................................................................................................30
5.1 Mounting of motor-drive mechanism.............................................................................30
5.2 Mounting of external drive shafts...................................................................................34
5.2.1 Mounting of vertical drive shaft ...............................................................................34
5.2.2 Mounting of horizontal drive shaft for one unit.........................................................36
5.2.3 Mounting of horizontal drive shaft for two units .......................................................38
5.2.4 Mounting of horizontal drive shafts for three units ...................................................40
5.2.5 Before operation.....................................................................................................40
5.3 Supervisory equipment .................................................................................................40
5.4 Assembly of accessories...............................................................................................40
5.5 Connection to the oil conservator..................................................................................40
5.6. Connection of tube for oil sampling for VUC.................................................................41

6. Oil lling and draining............................................................................................................42
6.1 Filling methods and restrictions .....................................................................................42
6.2 Before lling ..................................................................................................................42
6.3 Filling at atmospheric pressure......................................................................................42
6.4 Filling under vacuum .....................................................................................................42
6.4.1 Oil conservator lled under vacuum ........................................................................42
7. Electrical connection and testing ..........................................................................................44
7.1 General.........................................................................................................................44
7.2
Connecting and testing the motor-drive mechanism and the tap-changer ..........................44
7.3 Electrical tests on the transformer .................................................................................44
7.4 After energizing.............................................................................................................44
8. Transport ..............................................................................................................................45
8.1 Dismantling before transport .........................................................................................45
8.1.1 Dismantling preparations ........................................................................................45
8.1.2 Removal of the vertical drive shaft...........................................................................45
8.1.3 Removal of horizontal drive shaft for one unit..........................................................45
8.1.4 Removal of horizontal dri
ve shafts for two units....................................................... 45
8.1.5 Removal of horizontal drive shafts for three units ....................................................45
8.1.6 Accessories............................................................................................................46
8.2 Oil level during transport ...............................................................................................46
8.2.1 Transformer lled with oil.........................................................................................46
8.2.1.1 Conservator mounted .....................................................................................46
8.2.1.2 Conservator unmounted .................................................................................46
8.2.2 Transformer drained ...............................................................................................46
8.2.2.1 Conservator mounted .....................................................................................46
8.2.2.2 Conservator unmounted .................................................................................46
9. Commissioning.....................................................................................................................47
9.1 Connection to the oil conservator..................................................................................47
9.2 Mounting the motor-drive mechanism and the drive shafts............................................47
9.2.1 Mounting of the motor-drive mechanism.................................................................47
9.2.2 Mounting of the external drive shafts ......................................................................47
9.2.3 Mounting of the vertical drive shaft .........................................................................48
9.2.4 Mounting of horizontal drive shaft for one unit.........................................................49
9.2.5 Mounting of horizontal drive shafts for two units .....................................................50
9.2.6 Mounting of horizontal drive shafts for three units ..................................................51
9.2.7 Before operation.....................................................................................................51
9.3 Supervisory equipment .................................................................................................51
9.4 Accessories ..................................................................................................................51
9.5 Oil lling ........................................................................................................................51
9.6 Electrical connection and testing...................................................................................51
9.6.1 Motor protection.....................................................................................................51
9.6.2 Disk brake ..............................................................................................................52
9.6.3 Counter ..................................................................................................................52
9.6.4 Position transmitter and other position switches .....................................................52
9.6.5 Light.......................................................................................................................52
9.6.6 Heater ....................................................................................................................52
9.7 Putting into operation....................................................................................................52

1ZSC000562-AAZ en | Installation and commissioning guide UCL/VUCL 9
1. Introduction
The arrangement of on-load tap-changers types UCL and
VUCL, and of the tap-changer system, are shown in Figs.1
and 2. The tap-changer may consist of one, two or three units
driven by the same motor-drive mechanism. The tap-changer
is delivered in three main parts: diverter switch housing, tap
selector and motor-drive mechanism.
The tap-changer is available in designs for cover-mounting or
for yoke-mounting. Cover-mounting means that the diverter
switch housing is lowered through the hole in the transformer
tank and then bolted straight onto the transformer cover,
followed by mounting of the tap selector. Yoke-mounting
means that the tap-changer is temporarily put on a fork
located on the active part of the transformer. Yoke-mounting
allows the transformer manufacturer to connect the windings
to the tap-changer before drying and without having the
transformer cover-mounted. The transformer cover is then
lowered onto the tank, and the tap-changer is lifted and
bolted to the cover. Use the appropriate instruction for cover-
mounting or yoke-mounting in Chapter 3.
After the transformer drying process, the motor-drive
mechanism and bevel gear are fitted to the transformer tank
and the drive shafts are fitted to complete the assembly of the
motor-drive mechanism, bevel gear and tap-changer before
oil filling and testing.
Position numbers in this guide, for example SA11 (see
Chapter 5), correspond to those on the packing list for the
tap-changer.
All instructions are for one tap-changer unit. When there is
more than one unit on the transformer, carry out the same
procedures for each unit.
Fig. 1. On-load tap-changer system (single-unit shown).
Horizontal drive shaft
and protective tubes
Bevel gear
Vertical drive shaft
and protective tubes
Motor-drive mechanism
Pressure relay
Oil valve

10 Installation and commissioning guide UCL/VUCL | 1ZSC000562-AAZ en
Vertical drive
shafts and
protective tubes
Rating plate
Bevel gear
Horizontal drive shafts
and protective tubes
Shielding caps
(only for insulation
level above 380 kV)
Type of connection, N or E
Hand crank
(inside the cover)
Motor-drive
mechanism
Bevel gear
Shielding rings
(only for insulation
level above 380 kV)
Not used for selector, size C
Unit -1
Fig. 2. Example of on-load tap-changer systems.
Type of
connection, T
Type of connection, B
Unit -1 Unit -2
Unit -1 Unit -2 Unit -3