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Painting
The diverter switch housing top sections are finish coated with
a blue-grey color, Munsell 5,5 B 5,5/1,25, corrosion class C3
according to SS-EN ISO 12944-2 and SS-EN ISO 9223. For
corrosion classes such as C4 or C5, or higher, please contact
ABB for further information.
Operating mechanism
The bevel gear, mounted on the top section flange transfers
the drive from the motor-drive mechanism, via the vertical
insulated shaft, to the intermediate gear for the diverter switch
and the tap selector.
From the intermediate gear, a drive shaft transfers the energy
to the diverter 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 easily
re-connected by a simple procedure that ensures that the
drive shaft and the guide pin of the diverter mechanism are
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, which does not need to be removed
during maintenance work, minimizes the risk of 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.
Transition resistors
The transition resistors are made of wire and located above
the diverter switch contacts. The resistors are robust and
designed to last the lifetime of the mechanism under normal
service conditions.
Special applications, load conditions, and environments
Please contact ABB for advice in the following cases:
– For non-network applications. (Limitations in number of
operations per time might be given.)
– In case of unusual load conditions such as overloads
beyond IEC 60076-7, 2005-12, or IEEE C57.91-2011,
extreme inductive or capacitive loads or loads beyond the
given data in this document.
– Current measurement in phase before neutral point.
– Applications for reactors.
Insulating liquids
All data in this guide is based on the use of mineral oil
according to IEC 60296, 2012-02. Other liquids, such as
esthers and HMWH are accepted under certain conditions.
Please consult ABB for advice.
Special designs
On request, the VUC tap-changers are also available for
regulation with bias winding and for Y/D regulation.
Motor-drive mechanism
The motor-drive mechanism provides the drive to allow the
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.
Accessories
For a list of accessories available for both the tap-changers
and the motor-drive mechanisms, contact ABB.
1ZSC000562-AAX en, Rev. 1 | Technical guide VUC 11
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