Delta Electronics VFD-M manual Pr.27, Pr.28, over-current Stall Prevention, during Acceleration

Chapter 4 Parameters

Under certain conditions, the AC drive output current may increase abruptly, and exceed the value specified by Pr.26. This is commonly caused by 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. Drive will resume accelerating only after the current drops below the setting for Pr.26.

Pr.27	Over-Current Stall Prevention during Operation	Unit: 1%
		Factory Setting: 150%

Settings 20 to 200% 00: disable

During a steady-state operation with the motor load rapidly increasing, the AC drive output current may exceed the limit specified in Pr.27. When this occurs, the output frequency will decrease to maintain a constant motor speed. The drive will accelerate to the steady-state output frequency only when the output current drops below the setting for Pr.27.

Output current output current

over-current	over-current
detection	detection
level	level
	Pr.27
	time
output
frequency
	output
	freq.
	time
	over-current Stall Prevention
	during Acceleration

time

time

Over-current Stall Prevention during Operation

Pr.28	DC Braking Current Level	Unit: 1%
	Settings 00 to 100%	Factory Setting: 00

This parameter determines the amount of DC Braking Current applied to the motor during starting and stopping. When setting the DC Braking Current, please note that 100% corresponds to the rated current of the AC drive. It is recommended to start with a low DC Braking Current level and then increase it until proper holding torque has been attained.

4-28 Revision May 2008, ME14, SW V3.04