ABB DriveIT ACH550-01 User Manual page 236

Group 25: Critical Speeds
This group defines up to three critical speeds or ranges of speeds that
are to be avoided due, for example, to mechanical resonance problems
at certain speeds.
Code Description
2501 CRIT SPEED SEL
Sets the critical speeds function on or off. The critical speed function
avoids specific speed ranges.
0 = OFF – Disables the critical speeds function.
1 = ON – Enables the critical speeds function.
Example: To avoid speeds at which a fan system vibrates badly:
• Determine problem speed ranges. Assume they are found to be:
18...23 Hz and 46...52 Hz.
• Set 2501
• Set 2502
• Set 2503
• Set 2504
• Set 2505
f
output
52
46
23
18
2502 CRIT SPEED 1 LO
Sets the minimum limit for critical
speed range 1.
• The value must be less than or equal to 2503
• Units are rpm, unless 9904
then units are Hz.
232
= 1.
CRIT SPEED SEL
1
CRIT SPEED LO
1 = 23 Hz.
CRIT SPEED HI
2
CRIT SPEED LO
2 = 52 Hz.
CRIT SPEED HI
f1L f1H f2L f2H
18 23 46 52
ACH550 User's Manual
Range
0=OFF, 1=ON
= 18 Hz.
= 46 Hz.
f (Hz)
REF
0...30000 rpm/
0...500 Hz
MOTOR CTRL MODE
Parameter listing and descriptions
1 .
CRIT SPEED HI
= 3 (
SCALAR SPEED
),