Siemens SINAMICS G120C User Manual

8.22 Overcurrent protection
Overview
The U/f control prevents too high a motor current by in󹪞uencing the output frequency and
the motor voltage (I-max controller).
Requirement
You have selected U/f control.
The application must allow the motor torque to decrease at a lower speed.
Function description
The I-max controller in󹪞uences the output frequency and the motor voltage.
If the motor current reaches the current limit during acceleration, the I-max controller
extends the acceleration operation.
If the motor load is so high during steady-state operation that the motor current reaches the
current limit, then the I-max controller reduces the speed and the motor voltage until the
motor current returns to the permissible range again.
If the motor current reaches the current limit during deceleration, the I-max controller
extends the deceleration operation.
Changing the settings
The factory setting for proportional gain and the integral time of the I-max controller ensures
faultless operation in the vast majority of cases.
The factory setting of the I-max controller must only be changed in the following exceptional
cases:
• Speed or torque of the motor tend to cause vibrations upon reaching the current limit.
• The converter goes into the fault state with an overcurrent message.
Parameter
Number Name Factory setting
r0056.0…13 CO/BO: Status word, closed-loop control -
p0305[M] Rated motor current 0Arms
p0640[D] Current limit 0Arms
p1340[D] I_max frequency controller proportional gain 0
p1341[D] I_max frequency controller integral time 0.300s
r1343 CO: I_max controller frequency output - rpm
Advanced commissioning
8.22Overcurrent protection
SINAMICS G120C Converters
336 Operating Instructions, 02/2023, FW V4.7 SP14, A5E34263257B AK

Siemens SINAMICS G120C Specifications

General

Brand	Siemens
Model	SINAMICS G120C
Category	Inverter
Language	English