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2
5.22 I
T F
OLDBACK
The S200 incorporates an RMS output current protection algorithms sometimes called Foldback
2
or I
t (I-squared-t). There are two algorithms; One to protect the motor and one to protect the
drive. The purpose of the Foldback algorithm is to prevent excessive rms current from being
delivered which could cause damage to the motor or the drive.
2
The motor's I
T Filter sets the break frequency in Hz for the I
from transient thermal overload caused by very high peak currents compared to the motor's
continuous current capability. Typically set to between 4 and 10 times faster than the motor's bulk
thermal time constant published in the data sheet. Given a desired time constant set the I^2T
Filer (I2TF0) value to:
I2TF0 = 1/[(2π)*(Motor Thermal Time Constant in sec)]
The user can lower the value but not raise it above this calculation.
2
The I
T algorithm monitors the current delivered over time. In the event that the RMS value is
exceeded the S200 Position Node will take action. The Drive I
take one-of-two actions. First, and by default, the I
announce the fault condition. An F20b03 on the 7-Segment display while the Base Unit Led will
flash a code of 3 for Drive exceeded ratings. For the Motor I
segment display while the base unit will flash a code of 4. Alternately, the user can configure the
action to be a reduction in output current versus an actual fault. Under this condition the drive will
automatically clamp the current level of 2/3 DiPeak. It may be obvious that if the current limits are
not set to greater than 67% there can never be an I
This can be configured in the Drive Setup\Fault Thresholds tab.
Version 2.0.2 and early S200 OC Tools is recognized to have an error in its
construction. The Drive I
Motor I2t should be. The GUI is reverse. Please do not change the Drive
I2t Filter value. A new GUI will be posted at Danaher Motion.com with the
fix.
NOTE
28
2
T filter used to protect the motor
2
T condition can be configured to
2
T detection will shut down the drive and
2
T a code of F20b04 will be on the 7-
2
T fault.
2
T should not be configurable by the user while the
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