Motor Derating
The continuously available torque decreases when the drive speed is re‐
duced (e.g. in case of self-ventilated motors). Thus, the continuous torque
has to be accordingly limited in the lower speed range. For this purpose, the
Sytronix-DRn function provides motor derating that automatically adjusts the
speed adaptation to the current load, if required. The derating function is par‐
ameterized via the following parameters:
Code
Name
Setting Range
Default
Attri.
C1.05
Motor rated power
See EFC documentation
C1.09
Motor rated speed
See EFC documentation
F4.55
Motor derating: Continuous torque at standstill
0.00...100.00 %
0.00
Stop
F4.56
Motor derating: Limit speed
0...10,000 rpm
0
Stop
Tab. 7-6:
Parameter list of motor derating
C1.05 Motor rated power / C1.09 Motor rated speed
The motor derating uses the nominal motor torque as a reference value. It is
internally calculated by means of C1.05 and C1.09:
F4.55 Motor derating: Continuous torque at standstill
The continuous torque at standstill of fan monitoring defines the torque that
can be permanently held at speed zero. The input is in percent of the motor
rated torque.
F4.56 Motor derating: Limit speed
The limit speed of the derating function defines the lower motor speed at
which the nominal torque can be permanently held.
The figure below visualizes the parameterization of the motor derating.
Fig. 7-26:
Parameterization of motor derating
As soon as the drive speed has fallen below the parameterized speed limit
value, the motor torque is monitored and it is made sure that the thermal limit
characteristic from the figure above is not exceeded. The thermal overload is
avoided by increasing the motor speed.
The fan monitoring is deactivated as soon as one of the two pa‐
rameters F4.55, F4.56 has the value "0".
Bosch Rexroth AG
DOK-SYTROX-DRN5020****-IT05-EN-P
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Frequency-Controlled Pump Drive System Sytronix DRn 5020
Commissioning of Sytronix DRn 5020 System
