Siemens Sinamics G120P Operating Instructions Manual page 13

7 Functions ............................................................................................................................................ 335
7.1 Section content ..................................................................................................................... 335
7.2 Inverter control ...................................................................................................................... 335
7.2.1 Switching the motor on and off ............................................................................................. 335
7.2.2 Two-wire control, method 1 .................................................................................................. 338
7.2.3 Two-wire control, method 2 .................................................................................................. 339
7.2.4 Two-wire control, method 3 .................................................................................................. 340
7.2.5 Three-wire control, method 1 ................................................................................................ 341
7.2.6 Three-wire control, method 2 ................................................................................................ 342
7.3 Setpoints ............................................................................................................................... 343
7.3.1 Analog input as setpoint source ............................................................................................ 344
7.3.2 Specifying the setpoint via the fieldbus................................................................................. 344
7.3.3 Motorized potentiometer as setpoint source ......................................................................... 345
7.3.4 Fixed speed as setpoint source ............................................................................................ 347
7.4 Setpoint calculation ............................................................................................................... 349
7.4.1 Overview of setpoint processing ........................................................................................... 349
7.4.2 Invert setpoint ....................................................................................................................... 349
7.4.3 Enable direction of rotation ................................................................................................... 350
7.4.4 Minimum speed ..................................................................................................................... 350
7.4.5 Skip frequency bands ........................................................................................................... 351
7.4.6 Speed limitation .................................................................................................................... 352
7.4.7 Ramp-function generator ...................................................................................................... 352
7.5 Motor control ......................................................................................................................... 356
7.5.1 Vector control or V/f control .................................................................................................. 356
7.5.2 Closed-loop speed control .................................................................................................... 357
7.5.2.1 Properties of the sensorless vector control........................................................................... 357
7.5.2.2 Select motor control .............................................................................................................. 358
7.5.2.3 Optimizing the closed-loop speed controller ......................................................................... 358
7.5.3 V/f control .............................................................................................................................. 360
7.5.3.1 Characteristics of V/f control ................................................................................................. 361
7.5.3.2 Selecting the V/f characteristic ............................................................................................. 362
7.5.3.3 Optimizing with a high break loose torque and brief overload .............................................. 363
7.6 Protection functions .............................................................................................................. 364
7.6.1 Inverter temperature monitoring ........................................................................................... 364
7.6.2 Motor temperature monitoring using a temperature sensor ................................................. 365
7.6.3 Protecting the motor by calculating the motor temperature .................................................. 368
7.6.4 Overcurrent protection .......................................................................................................... 368
Limiting the maximum DC link voltage .................................................................................. 369
7.6.5
7.6.6 Minimum DC-link voltage limit .............................................................................................. 370
7.7 Application-specific functions ................................................................................................ 374
7.7.1 Unit changeover .................................................................................................................... 374
7.7.1.1 Changing over the motor standard ....................................................................................... 375
7.7.1.2 Changing over the unit system ............................................................................................. 376
7.7.1.3 Changing over process variables for the technology controller ............................................ 377
7.7.2 Energy-saving display ........................................................................................................... 378
7.7.3 Braking functions of the converter ........................................................................................ 380
7.7.3.1 Electrical braking methods .................................................................................................... 380
7.7.3.2 DC braking ............................................................................................................................ 380
7.7.3.3 Dynamic braking ................................................................................................................... 383
Inverter cabinet units
Operating Instructions, 12/2014, A5E32923362A
Table of contents
13