ABB ACS880 Firmware Manual page 47

drive normal operation until passive motor speed reduces down to speed region
defined as safe to restart.
Note: When restart delay is active, the Backspin speed observer function cannot
show motor speed estimate unless requested by the user Drive start command.
The figure below shows the control scenarios of Restart delay and Backspin speed
observer functions.
User Drive start comman
Speed measurement delay
The table below describes the control scenarios of Restart delay and Backspin
speed observer functions.
Control Description
scenario
1 Parameter
set to OFF.
1-2 New normal start command cannot accept for the period of time set in parameter
74.21.
2-5 You can safely enable drive start command when restart delay is active.
Backspin speed observer function detects the actual motor speed without inter-
fering the motor mechanically.
3-4 If the restart delay function is still active, it prevents drive from starting normal
operation even if observer measured speed is in the speed region defined as
safe to restart.
5 Drive stops measuring the actual pump-motor speed if Start command is OFF
when parameter
74.30
74.20
74.21
09.41
06.16, bit 6
Start interlock
74.39
74.99, bit 6
74.33
74.99, bit 8
Actual speed
Measured speed
74.32
0
74.31
74.20 function activates as soon as the user drive start command is
0
9.41 timer is still counting.
1
2 3 4 5
ESP program features 47
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