Delta VFD-BW Series, User Manual

Page: 143 / 251

Chapter 5 Parameters
|
VFD-BW Series
5-78 Revision May 2009, BWE0, SW V1.05
DC Brake during stopping is used to shorten the stopping time and also to hold a stopped load
in position. For high inertia loads, a dynamic brake resistor or brake unit may also be needed
for fast decelerations.
08 - 04 Momentary Power Loss Operation Selection
Factory Setting: 00
Settings 00 Operation stops after momentary power loss.
01 Operation continues after momentary power loss, speed search
starts with the Master Frequency reference value.
02 Operation continues after momentary power loss, speed search
starts with the minimum frequency.
This parameter determines the operation mode when the AC motor drive restarts from a
momentary power loss.
When using a PG card with PG (encoder), speed search will begin at the actual PG (encoder)
feedback speed and settings 01 and 02 will be invalid.
08 - 05 Maximum Allowable Power Loss Time Unit: 0.1
Settings 0.1 to 5.0 sec Factory Setting: 2.0
If the duration of a power loss is less than this parameter setting, the AC motor drive will
resume operation. If it exceeds the Maximum Allowable Power Loss Time, the AC motor drive
output is then turned off (coast stop).
The selected operation after power loss in Pr.08-04 is only executed when the maximum
allowable power loss time is
≤
5 seconds and the AC motor drive displays “Lu”.
But if the AC motor drive is powered off due to overload, even if the maximum allowable power
loss time is
≤
5 seconds, the operation mode as set in Pr.08-04 is not executed. In that case it
starts up normally.
08 - 06 Baseblock Time for Speed Search (BB) Unit: 0.1
Settings 0.1 to 5.0 sec Factory Setting: 0.5
When momentary power loss is detected, the AC drive will block its output and then wait for a
specified period of time (determined by Pr.08-06, called Base-Block Time) before resuming
operation. This parameter should be set at a value to ensure that any residual regeneration
voltage from the motors on the output has disappeared before the drive is activated again.
This parameter also determines the waiting time before resuming operation after External
Baseblock and after Auto Restart Times after Fault (Pr.08-14).