ABB ACS280, Firmware Manual, Page: 38 / 430

38 Program features
Settings and diagnostics
• Speed reference ramping - Parameters 23.11 … 23.15 , 23.32 Shape time 1 ,
23.33 Shape time 2
and
46.01 Speed scaling
.
• Torque reference ramping - Parameters
01.30 Nominal torque scale
,
26.18
Torque ramp up time and 26.19 Torque ramp down time .
• Frequency reference ramping - Parameters 28.71 … 28.75 and 46.02
Frequency scaling
.
• Jogging - Parameters
23.20 Acc time jogging
and
23.21 Dec time jogging
.
• Motor potentiometer - Parameter
22.75 Motor potentiometer ramp time
.
• Emergency stop (“Off3” mode) - Parameter
23.23 Emergency stop time
.
Events: -
 Constant speeds/frequencies
Constant speeds and frequencies are predefined references that can be quickly
activated, for example, through digital inputs. It is possible to define up to 7
speeds for speed control and 7 constant frequencies for frequency control.
WARNING! Speeds and frequencies override the normal reference
irrespective of where the reference is coming from.
Settings and diagnostics
Parameter groups 22 Speed reference selection and 28 Frequency reference
chain
.
Events: -

Critical speeds/frequencies
Critical speeds (sometimes called “skip speeds”) can be predefined for
applications where it is necessary to avoid certain motor speeds or speed
ranges because of, for example, mechanical resonance problems.
The critical speeds function prevents the reference from dwelling within a
critical band for extended times. When a changing reference enters a critical
range, the output of the function freezes until the reference exits the range. Any
instant change in the output is smoothed out by the ramping function further in
the reference chain.
When the drive is limiting the allowed output speeds/frequencies, it limits to
the absolutely lowest critical speed (critical speed low or critical frequency low)
when accelerating from standstill, unless the speed reference is over the upper
critical speed/ frequency limit.