Rockwell Automation SP600 AC Drive User Manual Version 1.0 - Manual (Page 31)

About the Drive 2-17
2.4.23 Flying Start
The flying start feature (enabled in parameter 169) is used to start
into a rotating motor as rapidly as possible and resume normal
operation with a minimal impact on load or speed. This action will
prevent an overcurrent trip and significantly reduce the time for the
motor to reach its desired frequency. Since the motor is "picked up"
smoothly at its rotating speed and ramped to the proper speed, little
or no mechanical stress is present.
2.4.24 Voltage Class
The voltage class (see parameter 202 in chapter 12) identifies the
general input voltage to the drive. This general voltage includes a
range of actual operating voltages. A 400 volt class drive will have
an acceptable input voltage range of 380 to 480 VAC. There are
also the 200 volt class drives with a range of 200 to 240 volts
operation.
While the hardware remains the same for each class, other
variables, such as factory defaults and power unit ratings, will
change. In most cases, all drives within a voltage class can be
reprogrammed to accommodate a motor within its voltage class.
This can be done by resetting the Voltage Class parameter (202) to
a different setup within the voltage class.
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.).
2.4.25 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.