Rockwell Automation 150 MNL/SMC DIALOG+/APP-PROD GUIDE - Manual (Page 85)

Application Profiles for the SMC Dialog Plus Controller 4-3
Figure 4.2 Tumbler with Dual Ramp Start
Problem: A tumbler used in a nail finishing process was breaking
the drive chain because of uncontrolled acceleration from
the across-the-line start. In addition, a reversing starte
was needed to position the drum to the top position for
loading the product. Because of the lack of controlled
acceleration, numerous jogs were used to position the
drum. The stopping time was not a concern in this
application. When in maintenance mode, the tumble
started unloaded, reaching full speed very quickly. A
second starting ramp, for unloaded conditions, was
desired. Additionally, single phasing of the motor was a
frequent problem, causing premature motor failure.
Solution: The SMC Dialog Plus controller was installed after the
reversing contactor to control the starting torque of th
motor. This decreased the snapping of the drive chain on
start up, which in turn increased the life of the chain and
reduced the downtime on the tumbler. In addition, the
SMC Dialog Plus controller made it easier to jog the
drum into position for loading and unloading. (The SMC
Dialog Plus controller slowed the acceleration rate to
prevent overshoot.) When in maintenance mode, the
Dual Ramp Start feature of the SMC Dialog Plus
controller was utilized to provide a soft start specifically
for no load conditions. This improved the productivity of
the loading and unloading process. Further, the SMC
Dialog Plus controller quickly detected a phase failure
during either the starting or running modes. The
controller would shut off with a “line fault” condition and
prevent restarting the motor until the line had been
corrected. This provided additional protection to the
motor and system.
Tumbler Drum
Loading Door
Motor
Drive Chain
480 Volts
25 HP