Siemens CU240B-2 - Page 244

Advanced commissioning
6.5 Motor control
Converter with the CU240B-2 and CU240E-2 Control Units
244 Operating Instructions, 01/2016, FW V4.7 SP6, A5E34259001B AC
Starting current (boost) after selecting the application class Standard Drive Control
After selecting application class Standard Drive Control, in most applications, and no
additional settings have to be made.
At standstill, the inverter ensures that at least the rated motor magnetizing current flows.
Magnetizing current p0320 approximately corresponds to the no-load current at
50 % … 80 % of the rated motor speed.
In the following situations, after it has been switched on, the motor cannot accelerate up to
its speed setpoint:
● Excessively high load moment of inertia
● Excessively high load torque
● Ramp-up time p1120
The current can be increased at low
speeds to improve the starting behavior
of th
e motor.
The inverter boosts the voltage corr
e-
sponding to the starting currents
p1310
… p1312.
The adjacent diagram shows the vol
t-
age boost using a linear characteristic
as example.
Requirements
● Depending on the rated power of the motor, set the ramp-up time of the ramp-function
generator to a value of 1 s (< 1 kW) … 10 s (> 10 kW).
● Increase the starting current in steps of ≤ 5 %. Excessively high values in p1310 ... p1312
can cause the motor to overheat and switch off (trip) the inverter due to overcurrent.
When message A07409 is displayed, it is not permissible that you further increase the
value of any of the parameters.
Procedure
Proceed as follows to set the voltage boost:
1. Switch on the motor with a setpoint of a few revolutions per minute.
2. Check whether the motor rotates smoothly.
3. If the motor does not rotate smoothly, or even remains stationary, increase the voltage
boost p1310 until the motor runs smoothly.