Rockwell Automation 150 MNL/SMC DIALOG+/APP-PROD GUIDE - Manual (Page 108)

4-26 Application Profiles for the SMC Dialog Plus Controller
Figure 4.25 Cooling Tower Fan with Dual Ramp Start
Problem: A chain-driven fan that moderates the temperature of
water in a chemical process was started across-the-line.
The system required frequent inspection and
maintenance because of problems with the chain drive.
In the winters, ice would form on the blades. Also, the
air density varied between winter and summer, which
affected the starting time. A controlled start was
required.
Solution: The SMC Dialog Plus controller was installed to provid
a controlled acceleration, thereby minimizing the
mechanical shock encountered during an across-the-line
start. Maintenance inspection was also reduced. In th
winter, when a longer start was required, the controlle
could quickly be switched to the second ramp of the Dual
Ramp Start feature.
Air Flow
Fan
Chain
Motor
480 Volts
50 HP