ABB ACS880 Firmware Manual page 170

170 Parameters
No. Name/Value
24.41 Speed error window
control enable
Disable
Enable
24.43 Speed error window
high
0.00 ... 3000.00
rpm
Description
Enables/disables speed error window control, sometimes
also referred to as deadband control or strip break protection.
It forms a speed supervision function for a torque-controlled
drive, preventing the motor from running away if the material
that is being held under tension breaks.
Note: Speed error window control is only effective when the
Add operating mode is active (see parameters
19.14).
In normal operation, window control keeps the speed
controller input at zero so the drive stays in torque control.
If the motor load is lost, then the motor speed will rise as the
torque controller tries to maintain torque. The speed error
(speed reference - actual speed) will increase until it exits the
speed error window. When this is detected, the exceeding
part of the error value is connected to the speed controller.
The speed controller produces a reference term relative to
the input and gain (25.02 Speed proportional gain)
torque selector adds to the torque reference. The result is
used as the internal torque reference for the drive.
The activation of speed error window control is indicated by
bit 3 of 06.19 Speed control status
The window boundaries are defined by
window high and 24.44 Speed error window low
Speed error
window
Forward
Reverse
Speed error
window
Note that it is parameter
defines the overspeed limit in both directions of rotation. This
is because the function monitors speed error (which is
negative in case of overspeed, positive in case of
underspeed).
Speed error window control inactive.
Speed error window control active.
Defines the upper boundary of the speed error window. See
parameter 24.41 Speed error window control
Upper boundary of speed error window.
19.12
word.
24.43 Speed error
Speed (rpm)
Reference + [24.44] rpm
Reference
Reference - [24.43] rpm
0 rpm
Reference + [24.43] rpm
Reference
Reference - [24.44] rpm
24.44 (rather than 24.43) that
enable.
Def/FbEq16
Disable
and
which the
as follows:
0
1
0.00 rpm
See par.
46.01