ABB UZE Istruzioni per il montaggio
On-load tap-changers, type UZE and UZF,
with motor-drive mechanism, type BUF 3
Repair guide
1ZSE 5492-128 en, Rev. 4
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 for service and repair
work on on-load tap-changers.
Do not repair an on-load tap-changer or motor-drive mechanism with a serious mechani-
cal or electrical fault without first consulting ABB.
Before you start any work, make sure that the personnel doing the job have read and fully
understood the Repair documents provided with the unit.
To avoid damaging the unit, never exceed the operating limits stated in delivery docu-
ments 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.
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
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.
The relevant technical documents should be read and understood before any work is
started, and the procedures in this document should be followed at all times.
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.
The hands or tools must be kept away from the contacts when making a manual or
electrical operation. The contact arm is operated by a spring battery and can cause
severe damage.
CAUTION
ABB recommends that only service engineers with appropriate skills regarding on-load tap-
changers carry out the repairs.
ABBrecommends that only maintenance engineers trained by ABB carry out contact re-
placement.
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 surroundings 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 this
Guide.
During oil handling
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 absorber. Treat it as hazardous to
the environment.
Upon re: The re should be extinguished by using powder, foam or carbon acid.
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.
The oil in the selector switch compartment may be hot. Be cautious!
There is always a cushion of explosive gases over the oil surface. This is sucked into
the on-load tap-changer tank during draining of the oil. No open re, hot surfaces or
sparks may be present when the front cover is opened.
CAUTION
Take care to avoid ingestion of moist air when oil is drained. If the ambient air is moist, let
incoming air pass through a dehydrating breather with slow air ow to obtain proper dehy-
dration.
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.
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 1.6
Tightening Torque, in this guide.
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.
Contents
1. Introduction _______________________________________________________9
1.1 General _______________________________________________________9
1.2 Repair categories _______________________________________________9
1.3 Serial number __________________________________________________9
1.4 Spare parts list _________________________________________________10
1.5 Maintenance guide______________________________________________11
1.6 Tightening torque _______________________________________________11
2. Trouble-shooting ___________________________________________________12
2.1 On-load tap-changer ____________________________________________12
2.2 Pressure relay __________________________________________________12
2 Trouble-shooting _____________________________________________13
2.3 Motor-drive mechanism__________________________________________14
2.3.1 Control system _____________________________________________14
2.3.2 Power system______________________________________________16
2.3.3 Miscellaneous ______________________________________________16
3. Repairs and adjustments ____________________________________________19
3.1
Replacement of gasket between insulating board and selector switch unit
19
3.1.1 General ___________________________________________________19
3.1.2 Tools required ______________________________________________19
3.1.3 Material and spare parts required______________________________19
3.1.4 Procedure _________________________________________________20
3.2
Replacement of gaskets between barrier board of steel and
selector switch unit _________________________________________________ 22
3.2.1 General ___________________________________________________22
3.3 Replacement of front cover and top cover gaskets ___________________22
3.3.1 General ___________________________________________________22
3.3.2 Tools required ______________________________________________22
3.3.3 Material and spare parts required______________________________23
3.3.4 Procedure _________________________________________________23
3.4 Changing the end stops in motor-drive mechanism __________________23
3.4.1 General ___________________________________________________23
3.4.2 Tools required ______________________________________________23
3.4.3 Material and spare parts required______________________________24
3.4.4 Procedure _________________________________________________24
3.5 Replacement of maintaining contact _______________________________26
3.5.1 Tools required ______________________________________________26
3.5.2 Spare parts required ________________________________________26
3.5.3 Procedure _________________________________________________26
3.6 Replacement of pressure relay ____________________________________26
3.6.1 General ___________________________________________________26
3.6.2 Tools required ______________________________________________26
3.6.3 Spare parts required ________________________________________27
3.6.4 Procedure _________________________________________________27
9
1ZSE 5492-128 en, Rev. 4
1 Introduction
1. Introduction
1.1 General
The UZ range of on-load tap-changers manufactured by ABB has been developed over
many years to provide maximum of reliability. The simple and rugged design gives a service
life equal to the service life of the transformer. Minimum maintenance is required for trouble-
free operation. The only parts requiring maintenance are contacts that might need replace-
ment during the service life, the insulating oil and the motor-drive mechanism.
The design allows excellent access to all parts, making inspection and maintenance quick
and simple.
The on-load tap-changer type UZE/UZF is placed in a oil lled tank separated from the
transformer tank. The motor-drive mechanism is attached to the side of the on-load tap-
changer tank.
1.2 Repair categories
Repairs on the UZ range of on-load tap-changers fall into two categories:
■Repairs. Repairs are to replace worn or end-of-service-life parts.
■Modications. Modications are only issued by ABB to improve the already very high
standard of reliability and to assist in prolonging the service life of the equipment.
The modications fall into two areas:
■Immediate, where the modication should be completed at the earliest possible oppor-
tunity.
■Routine, where the modication should be completed during a routine service.
1.3 Serial number
Before consulting ABB for technical advice to assist with repairs or to order spare parts to
complete the repairs, the on-load tap-changer serial number must be known. The serial
number can be found on the rating plate (gure 2 shows the location of the rating plate).
If the on-load tap-changer serial number cannot be obtained, the transformer serial number
should be used (only if the transformer is manufactured by ABB in Ludvika, Sweden).
NOTE: One of these serial numbers must be quoted in all correspondence and telefax
messages, and during any telephone conversations with ABB. Failure to use the serial
number may cause delays.
10 1ZSE 5492-128 en, Rev. 4
fm_00069
1.4 Spare parts list
The Repair Guide does not contain information about spare parts and how to order them.
For information about spare parts, please see the Spare Parts List 1ZSE 5492-132, On-
Load Tap-Changers, types UZE and UZF with Motor-Drive Mechanism, type BUF 3.
The Spare Parts List also contains several exploded views, which can be very handy when
making repairs.
1 Introduction
Lifting eye
Connection to oil conservator
On-load tap-changer tank
Oil valve
Pressure relay
Terminals for
conductors
Attachment ange to
transformer tank Front cover
Moulding
Change-over
selector
Fixed contact
Moving contact
system
Transition
resistor
Cover for access to conductors,
UZF only
Fig. 1. On-load tap-changer.
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