Delta Electronics VFD-F Series User Manual

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5-30

5.7 Group 6: Protection Function Parameters  

Over-voltage Stall Prevention 

Factory Setting: 390.0/780.0

 Settings 

230V series: 330.0 ~ 410.0VDC 
460V series: 660.0 ~820.0VDC 
00: Disable 

  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 brake resistors should be 
used.  

Output frequency

Deceleration characteristic
when Over-voltage stall 

prevention enabled 

Frequency held

Deceleration Time

Time

 

 

Over-current Stall Prevention during Acceleration 

Factory Setting:  120

 Settings 

20~150% 

Unit: 

1

  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). 

  When the over-current stall prevention is activated, the acceleration time of the AC drive will 

be longer than the time set in Pr. 01-09.