Rockwell Automation 150 MNL/SMC DIALOG+/APP-PROD GUIDE - Manual (Page 103)

Application Profiles for the SMC Dialog Plus Controller 4-21
Figure 4.20 Centrifuge with Current Limit Start and
SMB Smart Motor Braking Option
Problem: A centrifuge required a reduced voltage start because of
power company restrictions. The high torque during
starting was causing damage to the gearbox. A shorte
stopping time than the present fifteen minute coast-to-
rest was desired. The long stop time caused delays in the
production process. A Wye-Delta starter with a
mechanical brake was currently in use. A zero speed
switch was used to release the brake. The mechanical
brake required frequent maintenance and replacement,
which was costly and time consuming. Both the
mechanical brake and zero speed switches were worn out
and required replacement.
Solution: The SMC Dialog Plus controller with the SMB Smart
Motor Braking option was installed. The controller was
set for a 28-second, 340% current limit start, meeting the
power company requirements and reducing the starting
torque stress to the gearbox. The SMB Smart Moto
Braking option allowed the centrifuge to stop in
approximately one minute. The SMC Dialog Plus
controller with SMB Smart Motor Braking option did not
require additional mounting space or panel wiring. Th
controller was mounted in a panel that was considerably
smaller than the previous controller. Additionally, the
controller did not require frequent maintenance and could
sense zero speed without a feedback device.
480 Volts
75 HP
Centrifuge
Gearbox Motor