7.10.5 Torque Limit Setting
When the VFD output torque current exceeds the maximum torque limit setting for the motor,
the drive will limit output current. When this happens the drive displays TLIM on the keypad and
in the ToolSuite.
Regenerative Torque Limit Setting
For a 2 quadrant drive, an inverse speed function based on the regenerative torque limit setting
is used during drive deceleration. This forces the drive to absorb a minimal amount of power
from the load, enough only to overcome losses and maintain cell DC bus voltage.
For a 4 quadrant drive, i.e. a drive that is fully regenerative, there is no inverse speed function
and the full regenerative capability of the drive is allowed.
When power is owing from the motor back into the drive, the drive displays RGEN on the keypad
and in the ToolSuite.
Setting Parameters for Torque Limit Setting
Refer to Limits Menu (1120) in Section Options for Motor Menu (1) of Chapter Parameter
Assignment / Addressing for parameters to set the torque limit setting. The associated
parameters are:
• Motor torque limit 1 (1190)
• Motor torque limit 2 (1210)
• Motor torque limit 3 (1230)
• Regen torque limit 1 (1200)
• Regen torque limit 2 (1220)
• Regen torque limit 3 (1240)
7.10.6 Field-Weakening Limit
The eld-weakening limit is a torque limit that is based on the motor ux and motor leakage
inductance. Under this condition the motor has limited torque capability. This limit prevents the
motor slip from exceeding pullout torque slip. Therefore, it prevents unstable operation of the
motor. This limit normally occurs when motor ux is reduced signicantly during energy saver
operation, or when operating beyond the base speed of the motor. Under such conditions, a
large increase in load will force the output to be limited, resulting in a loss of speed rather than
motor pullout. A eld-weakening condition is indicated by the drive by displaying F WK on the
keypad and in the ToolSuite.
7.10.7 Cell Current Overload
The control provides a power cell current overload setting. A cell can operate at this overload
value for 1 minute out of every 10 minutes. When the current is between the cell rating and the
overload rating, the time spent at that level is inversely proportional to the overload current.
Operating the Control
7.10 Drive Output Torque Limiting
NXGPro+ Control Manual
216 Operating Manual, A5E50491925A
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