REXROTH IndraDyn A Series, Project Planning Manual

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Rexroth IndraDyn A Technical Data
4-3
Characteristic Curve
3
4
5
4
5
P [kW]
M [Nm]
2 1
n [1/min]
AsyncCurve.EPS
P [kW]: mechanical output in kilowatts
M [Nm]: torque available on the output shaft, in Newton meters
n [rpm]: motor speed, in revolutions per minute.
(1):
derating speed (n
1
in data sheet)
(2): rated speed (n
nenn
)
(3): max. torque (n
max
)
(4): characteristic curve without derating
(5): characteristic curve with derating
Fig. 4-4: IndraDyn A sample characteristic curves
Explanation:
Derating is present when there is a drop in torque and power before
reaching the
rated speed n
nenn
. This only occurs in some types of motor
windings.
The
continuous stand-still current, I
n1
, is applied to the motor until the
derating speed is reached.
If there is no derating, I
n1
= I
nenn
.
The
continuous stand-still torque, M
1
,
is available for S1 operation up
to the derating speed.
If there is no derating, M
n1
= M
nenn
.
Derating is in effect only while operating at speeds between (1) and (2)
(see Fig. 4-4). Both the power and the torque are reduced in this range.
With no derating in effect, induction motors provide a constant torque (the
rated torque) until the rated speed. Then, starting at the rated speed,
constant power (the rated power) is available.
The speed up to which a motor can safely be operated. This is normally
limited by the mechanical construction, e.g. by the type of bearings used
or by the use of a holding brake.
(1) Derating Speed
(2) Rated Speed
(3) Maximum Speed