Rockwell Automation 150 MNL/SMC DIALOG+/APP-PROD GUIDE - Manual (Page 84)

4-2 Application Profiles for the SMC Dialog Plus Controller
Figure 4.1 Compressor with Soft Start
Problem: A compressor OEM shipped its equipment into overseas
markets. There were many different voltage and
frequency requirements to meet because of the
compressor’s final destination. Due to power company
requirements and mechanical stress on the compressor,
reduced voltage starter was required. This made ordering
and stocking spare parts difficult. Energy savings was
desired because this is typically one of the larger motors
in the plant and it frequently runs lightly loaded. Also,
because of the size of the motor, the incoming line
voltage unbalance was causing excessive heating in th
motor.
Solution: The SMC Dialog Plus controller was installed and set for
an 18-second Soft Start, which reduced the voltage to the
motor during starting and met the power company
requirements. By reducing the voltage, the starting
torque was also reduced, minimizing the shock to the
compressor. Panel space was saved because the SMC
Dialog Plus controller has a built-in overload feature.
The Phase Rebalance feature automatically adjusted the
voltage output to balance the three-phase currents drawn
by the motor. In addition, the Energy Saver feature
optimized the voltage to the motor while it was running
unloaded.
Inlet Valve
Turn Valve
Ports
208-480 Volts
50-250 HP
50/60 Hz
Motor
Air Filter