Parker AC890PX Series, Engineering Reference

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D-66
A p p e n d i x D : P r o g r a m m i n g
AC890PX AC Drive
INVERSE TIME
SETUP::MOTOR CONTROL::INVERSE TIME
Designed for all Motor Control Modes, except PMAC control mode.
The purpose of the inverse time is to automatically reduce the drive current limit in response to prolonged overload conditions. As the motor current
exceeds the AIMING POINT level, the excess current is integrated. Motor current is allowed to flow at the CURRENT LIMIT (refer to the
CURRENT LIMIT function block) for a period defined by the DELAY parameter. At this point the inverse time current limit is ramped down from
the CURRENT LIMIT. The rate at which the inverse time current limit is ramped to the AIMING POINT is defined by DOWN TIME.
Once the overload condition is removed, the inverse time current limit level is ramped back toward the CURRENT LIMIT at a rate determined by
the UP TIME.
In Quadratic Torque mode, the allowed overload is reduced to 110.0 % for 60.0 s before inverse time current limit action occurs.
Parameter Descriptions
AIMING POINT PREF: 84.01 Default: 105.00 % Range: 50.00 to 150.00%
Determines the final level of the inverse time current limit after a period of prolonged motor overload
DELAY PREF: 84.02 Default: 60.0 s Range: 5.0 to 60.0s
Determines the maximum allowed overload duration for 150.0 % motor current (110.0% in QUADRATIC TORQUE mode) before inverse time
current limit action is taken.
DOWN TIME PREF: 84.03 Default: 10.0 s Range: 1.0 to 10.0s
Determines the rate at which the inverse time current limit is ramped to the AIMING POINT after a period of prolonged overload.
UP TIME PREF: 84.04 Default: 120.0 s Range: 1.0 to 600.0s
Determines the rated at which the inverse time current limit is ramped back to the CURRENT LIMIT (refer to the CURRENT LIMIT function
block) once the overload is removed.
IT LIMITING PREF: 84.05 Default: FALSE Range: FALSE / TRUE
This diagnostic indicates if the inverse time current limit is active.
INVERSE TIME OP PREF: 84.06 Default: —.00 % Range: —.00 %
This diagnostic indicates the present level of the inverse time current limit.