
1ZSC000562-AAX en, Rev. 1
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Technical guide VUC
31
Motor-drive mechanism
Design
For detailed design description, see separate Technical guides
for motor-drive mechanisms types BUE or BUL, respectively.
Installation
The motor-drive mechanism is fitted to the outside of the
transformer tank, and connected to the tap-changer by drive
shafts and bevel gears. For the correct installation procedure,
consult the appropriate Installation and commissioning guide.
Maintenance
The motor-drive mechanism should be visually inspected
annually. For the correct inspection and maintenance
procedures, consult the appropriate Maintenance guide.
Operating shafts
Length
L1 (mm)
L2 (mm)
L3 and L4
(mm)
Motor-drive
mechanism
Min/max
500/3100
425/3100
900/2700
BUE2
500/3100
400/3100
–
BUL2
Table 18.
The minimum and maximum lengths refer to mechanical
design only. For L2 vertical shaft, see the dimension drawings
on the following pages. Other shaft arrangements are
available on request.
For standard shaft arrangements, the maximum angle (totally
in two directions) is 4°. For larger angles, order design is
required.
For single units (VUC..E, N) the gear box of the tap-changer
might be mounted in the angle given in Fig. 48. The angle is
given when ordering.
Fig. 48. Mounting angle, single unit.
Permitted range
0°
a
-10°
190°
Depending on the application, load and environment, it is
recommendable to perform one maintenance (cleaning and
inspection) during the transformer life. The figure of 15 years
stated on the rating plate is provided as a guideline.
For more details, see the appropriate Maintenance guide.
Pressure
During drying, the tap-changers diverter switch housing
should have no pressure difference to the transformer. This is
obtained by opening the vapor phase (VP) valve in the bottom
of the tap-changer diverter switch housing, see the Installation
and commissioning guide for further information.
During oil filling, up to 200 kPa pressure difference between
the tap-changer diverter switch housing and the atmosphere
is allowed. During service, max. 70 kPa pressure difference
between the tap-changer diverter switch housing and the
atmosphere is allowed.
The pressure difference to the transformer tank during oil
filling and testing is allowed to be max. 100 kPa. During
service, it is recommended that the pressure difference
be as low as possible and not more than 50 kPa and
preferably higher in the transformer tank. For higher pressure
differences, contact ABB.
Accessories and protection devices
The 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 technical description 1ZSC000562-AAD.