Chapter 6: SERVICE-INFORMATION
Operating Manual FU3AM-03
Page 25 of 30
6.2.2 Characteristic curve
The frequency inverter’s characteristic curve must be adapted to the connected motor:
U
in
U
out
U-0
U-50
0 Hz
50 Hz
f
knick
f
out
f
nenn
The diagram shows the relationship between output frequency (f
out
) and output voltage
(U
out
). The position and steepness of the characteristic curve is determined by the two pa-
rameters U-0 (voltage when f
out
=0Hz, also termed Boost) and U-50 (voltage when f
out
=50Hz,
can as a rule be taken from the motor rating plate).
Setting U-0 high results in improved start-up behaviour, but also causes the motor to heat up
more.
This characteristic curve is continued in linear fashion until it is limited by the available input
voltage (U
in
). At this point, the kink frequency occurs (f
kink
).
Above the kink, the motor’s nominal moment is no longer available (because of physical limi-
tations).
6.2.3 Set point adaptation, fixed set points and ramps
Adaptation of analogue set-point is possible by means of the parameters ‘Offset’ and ‘Mult.
N-Nom.’. The ‘Offset’ parameter offsets the set point (e.g. for zero balancing); the ‘Mult N-
Act.’ represents the evaluation factor for the set point.
Set-point
Offset
multiplier
Analogue set point voltage
It must be noted that the physical range of the set point voltage remains restricted to 0...10V.
Fixed set points are programmed by parameters ‘#1’, ‘#2’ and ‘#3’. See also section 4.6.
