Rockwell Automation SP600 User Manual Version 3.0 - Manual (Page 27)

About the Drive 2-13
As an example, consider a 480 volt drive. This drive comes with
factory default values for 480 V, 60 Hz, with motor data defaulted for
U.S. motors (HP rated, 1750 RPM, etc.) By setting the Voltage
Class parameter to "low voltage" (this represents 400 V in this case)
the defaults are changed to 400 V, 50 Hz settings with motor data
for European motors (kW rated, 1500 RPM, etc.).
2.3.24 Motor Cable Lengths
The length of cable between the drive and motor may be limited for
various application reasons. The primary areas of concern are:
• Reflected wave
• Cable charging
The reflected wave phenomenon, also known as transmission line
effect, produces very high peak voltages on the motor due to
voltage reflection. While Reliance Electric drives have patented
software that limits the voltage peak to 2 times the DC bus voltage
and reduce the number of occurrences, many motors have
inadequate insulation systems to tolerate these peaks.
Caution should be taken to understand the effects and restrictions
when applying the drive to extended motor lead length applications.
Proper cable type, motor and drive selection is required to minimize
the potential risks.
2.3.25 Economizer Mode
Economize mode consists of operating the drive in sensorless
vector control mode with an energy saving function (E-SVC). When
the drive is in this mode and operating at steady state output
frequency, the output voltage is automatically adjusted as the load
is increased or decreased. This is done so that minimum current is
supplied to the motor thereby optimizing its efficiency. By adjusting
the output voltage, the flux producing current is reduced, but only if
the total drive output current does not exceed 75% of motor rated
current. In this mode the flux current is not allowed to be less than
50% of the selected flux current parameter value.
2.3.26 Fan Curve
When Torque Perf Mode (53) is set to Fan/Pump V/Hz the
relationship between frequency and voltage is a square function
where the voltage is proportional to frequency. The fan curve
provides the option to generate voltage that is a function of the
stator frequency squared up to the motor nameplate frequency.
Above base frequency, the voltage is a linear function of frequency.
At low speed, the fan curve can be offset by the Run Boost (70)
parameter to provide necessary starting torque.