Delta CFP2000 Series User Manual page 339

Chapter 12 Description of Parameter SettingsCFP2000
Traditional over-voltage stall prevention
 Used for uncertain load inertia. When it stops under normal load, the over-voltage does not
occur during deceleration and fulfills the deceleration time setting. However, load regenerative
inertia may occasionally increase and does not trip due to over-voltage when decelerating to
stop. In this case, the drive automatically increases the deceleration time until it stops.
 Because of the motor load inertia, the motor may exceed the synchronous speed when the drive
decelerates; in this case, the motor becomes generator. If the motor load inertia is larger, or the
setting for drive's decelerating time is too small, the motor regenerates energy to the drive, and
makes the DC bus voltage increase to the maximum allowable value. Thus, when traditional
over-voltage stall prevention is enabled, the drive does not decelerate further and maintains the
output frequency until the voltage drops below the setting value again.
 When the over-voltage stall prevention is enabled, the drive deceleration time is larger than the
setting time.
 When there is a problem with the deceleration time, this function is disabled. See below for
solution:
1. Increase the deceleration time properly.
2. Install a brake resistor (refer to Section 7-1 Brake Resistors and Brake Units Selection
Chart for details) to dissipate the heat, that is, the electrical energy regenerating from the
motor.
12.1-06-3