Rockwell Automation 150 MNL/SMC DIALOG+/APP-PROD GUIDE - Manual (Page 98)

4-16 Application Profiles for the SMC Dialog Plus Controller
Figure 4.15 Rock Crusher with Soft Start
Problem: Because of the remote location of a rock quarry, the
power company required a reduced voltage start on all
motors over 150 HP. The starting current on these larg
motors strained the capacity of the power system, causing
severe voltage dips. When the rock crusher became
overloaded, the current drawn by the motor increased.
Therefore, current monitoring capabilities within the soft
starter were required. Because the conveyor feeding the
rock crusher was controlled by a PLC, communications
between the soft starter and a PLC was necessary. The
rock crusher ran unloaded at times, and occasionally
stall or jam would occur.
Solution: The SMC Dialog Plus controller was installed, meeting
the power company requirements. The metering
capabilities of the SMC Dialog Plus controller allowed
the current drawn by the motor to be monitored. With the
built-in communications capabilities, the motor current
could then be communicated to the PLC. When the
motor current reached a specified limit, the conveyor
feeding the rock crusher could be slowed. By slowing
the conveyor, a jam condition in the rock crusher was
avoided. The Energy Saver feature of the controlle
reduced the voltage to the motor when the system was
running lightly loaded. The stall and jam detection
capabilities of the SMC Dialog Plus controller would
shut off the motor when a stall or jam condition occurred.
Motor: 250
480 Volts
Starts: Unloaded
Gearbox
Discharge
Motor