ABB UZE User manual
On-load tap-changers, type UZE and UZF,
with motor-drive mechanism, type BUF 3
Installation and commissioning guide
1ZSE 5492-115 en, Rev. 5
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 rst consulting ABB.
Follow local and international wiring regulations at all times.
Use only factory authorized replacement parts and procedures.
WARNING, CAUTION and NOTE
WARNING
A WARNING provides information which, if disregarded, could cause injury or death.
CAUTION
A CAUTION provides information which, if disregarded, could cause damage to the equip-
ment.
NOTE: A NOTE provides additional information to assist in carrying out the work de-
scribed.
Safety precautions
WARNING
Unused transformer oil is slightly 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 on-load 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 very easily set on re. Used transformer oil may well be carcino-
genic.
Avoid contact with the oil as much as possible and use oiltight protective gloves
when handling the oil.
First aid:
Skin contact: Wash the hands. Use skin cream to counteract drying.
In the eyes: Rinse the eyes in clean water.
Swallowing: Drink water or milk. Avoid vomiting. Call a doctor.
Collect used oil in oil drums.Waste and cleaning up: Should be absorbed by an ab-
sorber. Treat it as hazardous to the environment.
Upon re: The re should be extinguished by using powder, foam or carbon acid.
WARNING
The motor-drive mechanism must not be installed in any explosive atmosphere. The
electrical equipment creates sparks which can cause an explosion.
Before any work is carried out on the on-load tap-changer:
Make sure that the transformer is disconnected and that earthing is properly carried
out. Obtain a signed certicate from the engineer in charge.
Before starting any work in the on-load tap-changer the protective motor switch and
the LOCAL/REMOTE switch must be set at ”0”.
Before starting any work inside the motor-drive mechanism, the auxiliary power must
be switched off.
N.B. The motor, contactors and heating element may be energized from separate
sources.
During drying of the transformer
CAUTION
The on-load tap-changer must not be included in the vapour phase drying process of the
transformer. For permissible pressure and temperature at the rear during drying process, see
chapter 3.
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 tighten-
ing torque and nally with the recommended tightening torque as described in section 1.7
Tightening Torque, in this guide.
During oil lling
WARNING
When oil that has been used in a selector switch compartment is pumped out, con-
ducting tubes and hoses that are earthed should be used to avoid the risk of explo-
sion due to the gases produced by the arcs during service.
CAUTION
Do not ll oil into the on-load tap-changer if the transformer tank is under vacuum and the
on-load tap-changer is not.
Do not ll oil into the transformer tank if the on-load tap-changer is under vacuum and the
transformer tank is not.
The oil level in the oil conservator of the on-load tap-changer should never be above the oil
level in the oil conservator of the transformer.
After oil lling
CAUTION
Do not energize the transformer earlier than three hours after oil lling in atmospheric pres-
sure. This waiting period is needed to allow airbubbles to disappear.
During service
WARNING
Small amounts of explosive gases will always come out from the breathing devices
(dehydrating breather or one-way breather). Make sure that no open re, hot surfaces
or sparks occur in the immediate surrounding of the breathing devices.
If a failure in power supply occurs during operation, the operation will be completed
when the power returns.
The hand crank must not be inserted during electrical operation.
If the on-load tap-changer is not in 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 ”Pressure Relay” in the Re-
pair Guide.
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.
Contents
1. Introduction _______________________________________________________9
1.1 Required tools _________________________________________________10
1.2 Required material _______________________________________________10
1.3 Oil____________________________________________________________11
1.4 Oil conservator _________________________________________________11
1.5 Filter unit for continuous oil ltration________________________________13
1.6 Weights _______________________________________________________13
1.7 Tightening torque _______________________________________________13
2. Receiving _________________________________________________________14
2.1 Unpacking_____________________________________________________14
2.2 Inspection upon receiving ________________________________________14
2.3 Temporary storage before assembly _______________________________14
3. Drying ____________________________________________________________15
4. Installation on the transformer ________________________________________16
4.1 Attaching the on-load tap-changer to the transformer ________________16
4.1.1 Welding ___________________________________________________16
4.1.2 Bolting ____________________________________________________16
4.1.3 Assembly of accessories_____________________________________18
4.1.4 Retightening _______________________________________________18
4.2 Connection of the regulating winding of the transformer_______________18
4.3 Connection to the oil conservator _________________________________20
5. Pressure relay _____________________________________________________21
5.1 General _______________________________________________________21
5.2 Installation _____________________________________________________21
5.3 Checking when commissioning the transformer _____________________22
6. Oil lling __________________________________________________________23
6.1 Filling methods and restrictions ___________________________________23
6.1.1 Retightening _______________________________________________23
6.2 Filling at atmospheric pressure ____________________________________23
6.3 Filling under vacuum ____________________________________________24
6.4 Correct oil level _________________________________________________24
7. Electrical connection and testing _____________________________________25
7.1 General _______________________________________________________25
7.2 Connecting and testing __________________________________________25
7.3 Electrical tests on transformer ____________________________________26
7.4 After energizing_________________________________________________26
7.5 Resistance measurement ________________________________________26
8. Transport _________________________________________________________27
8.1 Oil level during transport _________________________________________27
8.1.1 Transformer lled with oil _____________________________________27
8.1.2 Transformer drained _________________________________________27
9. Commissioning ____________________________________________________28
9.1 Reassembly ___________________________________________________28
9.2 Oil lling _______________________________________________________28
9.2.1 Dehydrating breather ________________________________________28
9.3 Electrical connection and testing __________________________________28
9.3.1 Motor protection____________________________________________28
9.3.2 Counter ___________________________________________________28
9.3.3 Position transmitter and other multi-position switches ____________28
9.3.4 Light______________________________________________________28
9.3.5 Heater ____________________________________________________29
9.3.6 Pressure relay ______________________________________________29
9.4 Putting into operation ___________________________________________29
APPENDIX A. Welding and mounting instruction __________________________30
A1 Introduction ______________________________________________________30
A1.1 Required tools ________________________________________________30
A2 Receiving ________________________________________________________31
A2.1 Temporary storage before assembly ______________________________31
A3 Welding and mounting instruction ____________________________________31
A3.1 Welding of the ange and frame for the motor-drive mechanism ______31
A3.2 Installing the on-load tap-changer and the motor-drive
mechanism in the tank ______________________________________________33
A3.2.1 Installation of the on-load tap-changer ________________________33
A3.2.2 Installation of the motor-drive mechanism _____________________35
A3.3 Mounting of ttings for motor-drive mechanism cabinet______________37
A3.4 Welding of the ange and mounting of the pressure relay ____________38
A4 Welding instruction for inclined assembly______________________________39
A4.1 Welding of ange and frame for motor-drive mechanism _____________39
A4.2 Mounting of the on-load tap-changer _____________________________40
9
1ZSE 5492-115 en, Rev. 5
fm_00069
1 Introduction
1. Introduction
The on-tank concept of on-load tap-changer, realized by ABB in the UZ range, is unique.
The design offers advantages in installation and maintenance. The whole device is delivered
installed in a tank that is simply mounted onto the transformer tank together with the motor-
drive mechanism.
In the event of an on-load tap-changer being delivered without a tank, the transformer
manufacturer will supply the tank. Appendix A includes a welding and mounting instruction.
It is easy to access all parts of the on-load tap-changer for maintenance and repair. After
draining the oil, you simply unbolt and open the front cover to access any part you may
need to inspect or replace.
Lifting eye
Connection to oil conservator
On-load tap-changer tank
Oil valve
Pressure relay
Terminals for
conductors
Attachment ange to
transformer tank
Cover for access to conductors,
UZFonly
Fig. 1. General arrangement of on-load tap-changer.
10 1ZSE 5492-115 en, Rev. 5
UZE requires the transformer conductors to be accessed from the rear of the on-load tap-
changer.
UZF has an inclined rear wall and a top cover that is removable to provide access to the
transformer conductors.
WARNING
The cover for access to conductors on top of UZF tank may be opened after draining
the transformer main tank.
UZE models are available for use without a separate oil conservator. For example, when
used on sealed tank transformers.
1.1 Required tools
■Normal set of screwdrivers
■Normal set of open-end wrenches
■Hexagonal wrench, 8 mm
■Dynamometric wrench (5-85 Nm)
■Air pump with pressure gauge and connection to male thread R 1/8” (0-100 kPa)
■Flexible tube with connection, internal thread R 1/8”
■Tool for opening of oil drums
■Clamping blocks, (only for installation)
■Small brush (width 10 mm, only for installation)
1.2 Required material
■Equipment for oil lling for connection to the oil valve. For dimensions see the dimension
drawing.
■Equipment for connection between the on-load tap-changer and the transformer when
lling under vacuum.
■Sealing tape
■Glue (ABB 1 3401-608), 0.5 kg (contact adhesive on nitrile rubber base, only for instal-
lation)
■Oil as per section 1.3
■Maintenance Guide, 1ZSE 5492-123
■Circuit diagram for the motor-drive mechanism
1 Introduction
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