Rockwell Automation 150 MNL/SMC DIALOG+/APP-PROD GUIDE - Manual (Page 31)

2-12 SMC-2 Smart Motor Controller
Applications (cont.)
Figure 2.14 Tumbler with Soft Start
Problem: A tumbler used in a nail finishing process was breaking
the drive chain due to the 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. Due to lack of controlled
acceleration, numerous jogs were used to position the
drum. The stopping time was not a concern in this
application. In addition, single phasing of the motor was
a frequent problem, causing premature motor failure.
Solution: The SMC-2 controller was installed after the reversing
contactor to control the starting torque of the motor. This
prevented the snapping of the drive chain on the start up
which increased the life of the chain and reduced th
downtime on the tumbler. In addition, the SMC-2
controller made it easier to jog the drum into position for
loading and unloading. (The SMC-2 controller slowed
the acceleration rate to prevent overshoot.) This helped
improve the productivity of the loading and unloading
process. In addition, the SMC-2 controller could quickly
detect the phase failure during starting. The controller
would prevent starting until the line had been corrected.
This added additional standard protection to the motor
and system.
Tumbler Drum
Loading Door
Motor
Drive Chain
480 Volts
50 HP