ABB ACS880-104

Parameters 431
Quadratic Underload limit is calculated by using the formula:
I
lim
= I
set
* (F
act
/ F
max
)
2
Where,
I
lim
= 79.80 Underload actual limit
I
set
= 79.13 Underload limit
F
max
= 79.09 Load limit speed scale
F
act
= Actual speed
User curve Underload limit depends on the user input load curve, actual
speed/frequency and Underload supervision input.
79.12 Underload
supervision signal
Defines the source for the supervision signal used in the
underload protection.
Motor current
%
NULL Zero 0
AI1 scaled 12.12 AI1 scaled value (see page 197). 1
AI2 scaled 12.22 AI2 scaled value (see page 199). 2
FBA1 ref 03.05 FB A reference 1 (see page 156). 3
FBA2 ref 03.06 FB A reference 2 (see page 156). 4
EFB1 ref 03.09 EFB reference 1 (see page 156). 5
EFB2 ref 03.10 EFB reference 2 (see page 156). 6
Estimated motor
current
Parameter 09.13 Motor current estimated (see page 183). 7
Motor current % Estimated motor current in % of nominal motor current. 8
Other Source selection (see Terms and abbreviations on page 148). -
79.13 Underload limit Defines underload limit value.
Note: This parameter is not applicable in case User curve is
selected for the underload curve shape in parameter 79.11
Underload limit type.
0.00
0.00...30000.00 Underload fixed limit. 10 = 1
79.17 Underload delay
type
Selects the type of underload delay time setting.
The user has option to choose between fixed and floating
delay calculation methods.
Constant
Constant Fixed constant value of the delay.
Linear T
act
= T
set
* (I
act
/ I
lim
)
Where,
T
act
= 79.81 Underload trip count down
T
set
= 79.18 Underload delay time
I
lim
= 79.80 Underload actual limit
I
act
= 79.12 Underload supervision signal
Quadratic T
act
= T
set
* (I
act
/ I
lim
)
2
Where,
T
act
= 79.81 Underload trip count down
T
set
= 79.18 Underload delay time
I
lim
= 79.80 Underload actual limit
I
act
= 79.12 Underload supervision signal
79.18 Underload delay
time
Defines the time used as on-delay for the underload
protection function to react to the underload condition.
10.0
0.0...30000.00 s Underload delay time in seconds. 1 = 1s
No. Name/Value Description Def/FbEq16