Introduction - ABB UCL Installation And Commissioning Manual

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.
Horizontal drive shaft
and protective tubes
Bevel gear
Pressure relay
Vertical drive shaft
and protective tubes
Motor-drive mechanism
Fig. 1. On-load tap-changer system (single-unit shown).
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.
1ZSC000562-AAZ en | Installation and commissioning guide UCL/VUCL 9
Oil valve