New Danfoss VLT® Decentral Drive E cient, reliable and powerful

Power selector switch makes
drive systems more versatile
CONTROL TECHNIQUES has developed a
device for multi-way switching of drive
control cables via contactors which, it says,
could cut capital costs, make operations
more flexible, add redundancy at a low
cost, and improve efficiency.
The SPM power selector module is
designed to be used with CT’s modular
Unidrive SPM AC drives and allows
automatic re-routing of connections
between the control and power stages in
parallel drive systems. It also provides
automatic control of contactors.
The switch was developed originally for
the crane industry, with the aim of
eliminating the need for separate hoist
drives. CT says it can also make process
equipment and test rigs more versatile,
allowing operation over a wide power range,
and providing continuous operation in
the event of a fault, thus giving system
redundancy for critical operations.
For example, a gantry crane with dual
long-travel motors and a main hoist can
use just two drives instead of three – by
switching the drives between travel and
hoist duty – thus delivering significant
savings. Similarly, the power range can
be expanded by using up to 10
modules, again eliminating the need for
a separate hoist drive.
For test rigs operating over wide torque
and power ranges, the SPM power modules
can be switched out of circuit as the output
power demand is reduced and, conversely,
re-connected as power demand rises.
Matching the drives to the motors makes the
test rig more versatile, improves feedback
Flexible: Control
Techniques’ power
selector module
accuracy, and cuts losses, according to CT.
One master can work with a string of
modules which are switched in and out as
required. This also offers the option of
increasing the power at a later date by
adding more modules.
www.controltechniques.com
TECHNOLOGY
Actuator combines driving and guidance functions
Two-in-one: Haydon
Kerk’s motorised
SplineRail
THE US linear motion specialist Haydon
Kerk has developed a linear actuator that
combines the traditionally separate
functions of driving and guidance in a
single, coaxial component. The SplineRail
actuator uses a precision-rolled leadscrew,
supported by bearings and contained in a
concentric aluminium spline, to drive a
composite polymer nut/bushing.
When mounted vertically, the SplineRail
can be used to lift and rotate
simultaneously. With one motor driving
the screw and a second rotating the rail, a
compact, self-supporting pick-and-place
mechanism can be created.
Typical applications are expected to
include robotic assemblies, packaging and
assembly systems. The extruded aluminium
spline is said to offer good torsional
stability. Long, maintenance-free operating
lives are promised.
Screw leads will be available from 0.05–
1.2 inches (1.27–30.5mm) per revolution,
providing a wide range of performance
profiles, including self-locking threads that
can support a load without external power
or breaks. The SplineRail is powered by
single- or double-stack stepper motors.
www.haydonkerk.com