Tasked with replacing two
ageing autotransformer
starters at the Kempton
Water Treatment Works of
Thames Water, Varicon (3D)
Drives selected Vacon NXS
AC variable speed drives for
the project. The drives are
used in conjunction with
high-lift pumps that provide
an auxiliary water feed to the
low-pressure main.

The NXS drives are robust
and offer protection against
supply network disturbances.

Trip-free operation is
guaranteed by sophisticated
motor control principles and
motor/drive protection
features.

For this project, Varicon
used Vacon drives with
ratings of 160kW. IP21
chassis versions were preinstalled
in enclosures prior
to delivery to minimise the
time needed on site
for installation,
wiring and
commissioning.

Stop/start and
manual speed control
facilities were provided in the
plant control room. Provision
was made for future automatic
control of pump speeds from
a 4-20 mA flow signal.