Installation manual

Danaher Motion Kollmorgen System Operation
SERVOSTAR
®
S and SERVOSTAR
®
CD Series 76
Foldback
The SERVOSTAR offers two types of FoldBack protection for both the motor
and the drive. The drive’s microprocessor monitors the current feedback signal
and develops a RMS value of this signal for the purpose of providing a value
that represents the current in the motor. The system is similar to an “I-squared-T
accumulator.
Drive FoldBack
This FoldBack algorithm monitors current feedback and, if the feedback exceeds
the continuous current rating of the drive/motor combination (ICONT), will
decrease the system’s current to the ICONT level. For example, under a step
command input condition, the FoldBack algorithm will allow maximum peak
current (IMAX) output from the drive for 2 seconds (or ½ second for Cx units).
After two seconds, the drive enters “FoldBack mode” (FOLD = 1) and begins an
exponentially FoldBack to the system’s continuous current. It will take
approximately six seconds for the exponential decay to drop from the system’s
peak current to its continuous level.
For drive currents that exceed ICONT, but are below IMAX, the
system period before FoldBack occurs is extended beyond two
seconds. Two seconds is the shortest time period that will elapse
before the drive enters FoldBack and only occurs when
maximum peak current (IMAX) is drawn.
This FoldBack feature is designed to protect the drive
electronics, not the motor. The Configurable Output, O1, (pin
12) can be configured to indicate a drive FoldBack condition.
Motor FoldBack
This FoldBack algorithm is designed to provide motor protection in cases where
the drive’s continuous current rating is above the motor’s continuous rating.
This combination is often desired in applications where maximum peak motor
torques are required. However, the possibility exists that the drive could source
current on a continuous basis indefinitely to the motor and would force it
beyond its thermal capability. Unlike the drive FoldBack, you have complete
configurability over this feature (MFOLD, MFOLDD, MFOLDDIS, MFOLDR,
MFOLDT).