Optimizing With A High Break Loose Torque And Brief Overload - Siemens SINAMICS G120 CU230P-2 HVAC Operating Instructions Manual

Functions
7.6 Motor control
V/f control for drives requiring a precise frequency (textile industry) (p1300 = 5),
V/f control for drives requiring a precise frequency and FCC (p1300 = 6)
These characteristics require the motor speed to remain constant under all circumstances.
This setting has the following effects:
● When the maximum current limit is reached, the stator voltage is reduced but not the
● Slip compensation is locked.
For more information about this function, see function diagram 6300 in the List Manual.
V/f control with independent voltage setpoint
The interrelationship between the frequency and voltage is not calculated in the inverter, but
is specified by the user. With BICO technology, P1330 defines the interface via which the
voltage setpoint is entered (e.g. analog input → P1330 = 755).
7.6.1.3

Optimizing with a high break loose torque and brief overload

The ohmic losses in the motor stator resistance and the motor cable play a more significant
role the smaller the motor and the lower the motor speed. You can compensate for these
losses by raising the V/f characteristic.
There are also applications where the motor temporarily needs more than its rated current in
the lower speed range or during acceleration in order to adhere to the speed setpoint.
Examples of such applications are:
● Driven machines with a high break loose torque
● Utilizing the brief overload capability of the motor when accelerating
Voltage increase in V/f control (boost)
Voltage losses resulting from long motor cables
and the ohmic losses in the motor are
compensated for using parameter p1310. An
increased break loose torque when starting and
accelerating is compensated using parameter
p1312 and/or p1311.
The voltage boost is active for every
characteristic type of the V/f control. The figure
opposite shows the voltage boost using the
example of a linear V/f characteristic.
208
speed.
Frequency inverters with Control Units CU230P-2 HVAC, CU230P-2 DP, CU230P-2 CAN
Operating Instructions, 01/2011, FW 4.4, A5E02430659B AD