Lust CDA3000 - Page 173

Application Manual CDA3000
5-59
5 Software functions
1
2
3
4
5
6
A
DE
EN
FR
2. Calculation of max. overload time at operation point
f
ist
Actual frequency of operation point
i
ist
Actual current of operation point
MOPCA Motor current in [A] of interpolation point A
MOPCB Motor current in [A] of interpolation point B
MOPFB Motor frequency in [Hz] of interpolation point B
MOCNM Motor rated current in [A] of nominal point N
MOFN Motor rated frequency in [Hz] of nominal point N
i
lim
Limit current at operation point
i
start
Startup current for Ixt monitoring at operation point
i
off
Integration time to shut-off
Negative value
à Integrator not active
Positive value
à Integrator active
Condition Segment Calculation
Table 5.32 Overload calculation with adapted motor protection character-
istic
f
ist
MOPFB<
1
i
lim1
MOPCB MOPCA–
MOPFB
------------------------------------------ f
ist
MOPCA+⋅=
i
start1
11, i
lim1
⋅=
t
off
ixt
max
i
ist
i
start1
–
-------------------------=
MOPFB f
ist
MOFN<≤
2
i
lim2
MOCNM MOPCB–
MOFN MOPFB–
------------------------------------------- f
ist
( MOFN) MOCNM+–⋅=
i
start2
11, i
lim2
⋅=
i
start2
ixt
max
i
ist
i
start2
–
-------------------------=
MOFN f
ist
<
3
i
lim3
MOCNM=
i
start3
11, i
lim3
⋅=
t
off
ixt
max
i
ist
i
start3
–
-------------------------=