Lenze L-force 8400 BaseLine D - Page 109

Firmware 03.00 - DMS EN 5.0 - 07/2009 L 109
8400 BaseLine D | Software Manual
Motor control (MCTRL)
Monitoring functions
Adjustment
Calculate the overload threshold I
2
xt:
 If you reduce C120
starting from the calculated value, the motor utilisation meter I
2
xt
(C066
) will already be counted up before the rated overload threshold has been
reached.
 If you increase C120
starting from the calculated value, the motor utilisation meter I
2
xt
(C066
) will be counted up after the rated overload threshold has been reached.
The motor utilisation meter starts to count up when the apparent motor current (C054
) is
higher than the rated motor current (C088
).
[5-7] Tripping characteristic of I
2
xt monitoring
 Example: C120 = I
r
/I
N
x 100 %
– C054
= 1.5 x rated motor current
– After approx. 60 seconds, C066
has reached the final value 100 % at output
frequencies f > 40 Hz. The controller switches off with the error "Thermal motor
overload, I
2
xt" (OC6) if C606 is set to "0" (trip).
•I
r
•I
N
Rated motor current (C088)
Rated current of the controller at a switching
frequency of f = 8 kHz
f: output frequency
t: release time
I
N
: Rated controller current at a switching frequency of f = 8 kHz
I
r
: rated motor current (C088)
C054
: Apparent motor current
C00120
I
r
I
N
---- -
100%⋅=
60
180
240
300
360
t [s]
0.5
0
0
1.0
1.5 2.0
C00054
I
r
120
f=0Hz
f=20Hz
f>40Hz
I x 100 %
I
r
N
C00120 <
I x 100 %
I
r
N
C00120 =
I x 100 %
I
r
N
C00120 >