Chapter 4 Parameters
4-125
DC Brake during Start-up is used for loads that may move before the AC drive starts, such as
fans and pumps. Under such circumstances, DC Brake can be used to hold the load in
position before setting it in motion.
DC Brake during stopping is used to shorten the stopping time and also to hold a stopped load
in position, such as cranes and cutting machines. For high inertia loads, a brake resistor for
dynamic brake may also be needed for fast decelerations. Refer to appendix B for the
information of brake resistors.
08.04
Momentary Power Loss Operation Selection
Factory Setting: 0
Settings
0
Operation
stops
(coast
to stop) after momentary power loss.
1
Operation continues after momentary power loss, speed search
starts with the Last Frequency.
2
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.
The power connected to the AC motor drive may be off temporarily with unknown factors. This
parameter can restart the drive after momentary power loss.
Setting 1: the drive will operate by the last frequency before momentary power loss. It will
accelerate to the master frequency after the drive output frequency and the motor rotor’s
speed are synchronous. It is recommended to use this setting for those motor loads which
have a large inertia and small resistance to save time by restarting without waiting the flywheel
stops completely, such as machinery equipment with a large-inertia flywheel.
Setting 2: the drive will operate by the min. frequency. It will accelerate to the master
frequency after the drive output frequency and motor rotor speed are synchronous. It is
recommended to use this setting for those motor loads which have a small inertia and large
resistance.
When using with PG card, the speed search will start with the actual motor speed detected by
the drive and accelerate to the setting frequency (setting 1 and 2 are invalid at this moment).
Related parameters: Pr.08.05(Maximum Allowable Power Loss Time), Pr.08.07(Baseblock
Time for Speed Search (BB)) and Pr.08.08(Current Limit for Speed Search)
08.05
Maximum Allowable Power Loss Time
Unit: second
Settings
0.1 to 20.0 sec
Factory Setting: 2.0
If the duration of a power loss is less than this parameter setting, the AC motor drive will act by
Pr.08.04 setting. 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
20 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
20 seconds, the operation mode as set in Pr.08.04 is not executed. In that case it
starts up normally.
