Rockwell Automation SP600 AC Drive User Manual Version 1.0 - Manual (Page 25)

About the Drive 2-11
2.4.12 Drive Protection Current Limit
There are six ways that the drive protects itself from overcurrent or
overload situations:
• Instantaneous overcurrent trip
• Software instantaneous trip
• Software current limit
• Heatsink temperature protection
• Overload protection (see Drive Overload Protection, section
2.4.13)
• Thermal manager
2.4.13 Drive Overload Protection
The drive thermal overload protects the drive power stage while
maintaining performance as long the drive temperature and current
ratings are not exceeded.
The drive monitors the temperature of the power module based on a
measured temperature and a thermal model of the IGBT. As the
temperature rises, the drive may lower the PWM frequency to
decrease the switching losses in the IGBT. If the temperature
continues to rise, the drive may reduce current limit to try to
decrease the load on the drive. If the drive temperature becomes
critical, the drive generates a fault.
If the drive is operated in a low ambient condition, the drive may
exceed rated levels of current before the monitored temperature
becomes critical. To guard against this situation, the drive thermal
overload also includes an inverse time algorithm. When this scheme
detects operation beyond rated levels, current limit may be reduced
or a fault may be generated.