Parameters 267
24.41 Speed error window
control enable
Enables/disables (or selects a source that 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 19.12 and
19.14), or when the drive is a speed-controlled follower (see
page 69).
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) which the
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 word.
The window boundaries are defined by 24.43 Speed error
window high and 24.44 Speed error window low as follows:
Note that it is parameter 24.44 (rather than 24.43) that
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).
0 = Speed error window control disabled
1 = Speed error window control enabled
Disable
Disable 0. 0
Enable 1. 1
Other [bit] Source selection (see Terms and abbreviations on page 148). -
No. Name/Value Description Def/FbEq16
Speed (rpm)
0 rpm
Reference + [24.43] rpm
Reference
Reference - [24.44] rpm
Reference + [24.44] rpm
Reference
Reference - [24.43] rpm
Speed error
window
Speed error
window
Forward
Reverse
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