Efficiency drive
January 1st 2008 A local government building in the
Finnish city of Tampere has
networked variable speed fan
drives into its heating and
ventilating system during a major
refit of the 40-year old building.
The Finnish climate makes
environmental control within large
or public buildings a critical issue,
so estates managers are keen to
be able to monitor performance of
the entire building from a central
location. To achieve this, many
buildings are being upgraded with
suitable network controls.
The Tampere Authorities use the
Mitsubishi F700 series drives in
many building management
projects. In the case of the Nekala
2 building which covers 15 000m2
over two floors, F740s in a variety
of sizes were chosen, each
individually matched to the motor
and duty cycle with which they are
paired. The drives are linked via a
PLC, which monitors and controls
speed, current and alarms and
collects operational data for high
level management functions such
as energy optimisation and
maintenance planning.
The FR-F700 has both optimum
excitation control, for improved
motor efficiency during constant
speed operation and acceleration
periods, and optimum torque
patterns which match the power
delivered to that required at any
instant. The speed of optimisation
is effectively instant, so the drive is
always giving maximum
performance and efficiency to the
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