Encoders For Speed And Position Control; Defining Additional Requirements For The Application - Siemens SINAMICS G120 Operating Instructions Manual

Commissioning
5.2 Preparing for commissioning
5.2.6

Encoders for speed and position control

Vector control without encoder or speed control with encoder?
The inverter can control the motor speed both with as well as without encoder.
Figure 5-6
Speed control with encoder has the advantage of higher speed accuracy when compared to
vector control without encoder, especially for speeds < 5 % of the rated speed.
Encoders for position control
The inverter can evaluate a second encoder for the position control. You can find information
on the position control in the "Basic positioner" Function Manual, also see Section Manuals
for your converter (Page 461).
5.2.7

Defining additional requirements for the application

What speed limits should be set? (Minimum and maximum speed)
● Minimum speed - factory setting 0 [rpm]
The minimum speed is the lowest speed of the motor independent of the speed setpoint.
A minimum speed is, for example, useful for fans or pumps.
● Maximum speed - factory setting 1500 [rpm]
The converter limits the motor speed to this value.
What motor ramp-up time and ramp-down time are needed for the application?
The ramp-up and ramp-down time define the maximum motor acceleration when the speed
setpoint changes. The ramp-up and ramp-down time is the time between motor standstill and
the maximum speed, or between the maximum speed and motor standstill.
● Ramp-up time - factory setting 10 s
● Ramp-down time - factory setting 10 s
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Speed control with and without encoder
Converter with the CU250S-2 Control Unit (vector)
Operating Instructions, 06/2013, FW V4.6, A5E31759476B AB