CHAPTER 4: SETPOINTS PROTECTION
869 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL 4–131
NOTE:
Variable frequency drives (VFD) generates significant distortion in voltage input, therefore,
Voltage Dependent Function is blocked when operand “VFD Not Bypassed” is asserted.
VFD Not Bypassed is asserted when VFD Function is enabled and operand Bypass Switch
is not asserted. More detail can be found in section System > Motor> VFD.
VD MIN MOTOR VOLTS
Range: 60 to 99% in steps of 1
Default: 80%
The setting defines the minimum allowable line voltage applied to the motor during the
acceleration if Voltage Dependent Function is enabled. This voltage is expressed as a
percentage of the Setpoints > System > Motor > Motor Nameplate Voltage setting. If
the measured line voltage drops below this setting during acceleration, the thermal
curve is switched to one based on the programmed minimum voltage thermal limit:
Eq. 23
VD VOLTAGE LOSS
Range: FlexLogic operand
Default: Off
The setting is used to address situations when the voltage input into thermal model has
been lost. In this case, the voltage dependent algorithm readjusts the voltage dependent
curve to avoid an inadequate thermal protection response. The VT fuse failure function is
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