Delta Electronics AC Motor Drive VFD-G, User Manual

Page: 103 / 183

Chapter 4 Parameters
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4-52 Revision July 2008, EG03, SW V1.06
Group 6: Protection Function Parameters
06 - 00 Over-voltage Stall Prevention
Factory Setting: 780.0
Settings 660.0V~820.0VDC
00: Disabled
This parameter selects the voltage level for the Over-Voltage Stall Prevention function.
During decelerations, the DC bus voltage may exceed its maximum allowable value due to
motor regeneration. When this function is enabled, the AC drive will stop decelerating and
maintain a constant output frequency. The AC drive will only resume deceleration when the
voltage drops below the preset value.
With moderate inertial loads, the over-voltage stall prevention will not occur and the
deceleration time should be equal to Pr.1-10. With high inertial loads, the AC drive will
automatically extend the deceleration time due to the step function shown below. If the
deceleration time is critical for the application, then dynamic braking resistors should be used.
Output frequency Deceleration characteristic
when Over-voltage stall
prevention enabled
Frequency held
Deceleration Time
Time
06 - 01 Over-current Stall Prevention during Acceleration Unit: 1
Settings 20~250% Factory Setting: 150%
This parameter selects the percentage of allowable over-current during acceleration before the
stall prevention is enabled.
During acceleration, the AC drive output current may increase abruptly and exceed the value
specified by Pr.06-01 due to rapid acceleration or excessive load on the motor. When this
function is enabled, the AC drive will stop accelerating and maintain a constant output
frequency. The AC drive will only resume acceleration when the current drops below the value
set in Pr.06-01 (please see the graph below).