Spinning Load - Siemens 6SR41 series Product User Manual

LETHAL VOLTAGES!
Lethal voltages will appear on the drive outputs during both stages (1 and 2) of Auto
Tuning.
Auto Tune Stage 1
Stage 1 determines the Stator Resistance and Leakage Inductance. This stage of auto
tuning does not require the motor to be de-coupled from the load. The motor does not rotate
during this Stage. The data obtained from Stage 1 is used to tune the inner regulators that
control motor current. The current loop gains are automatically calculated and saved by the
control.
Auto Tune Stage 2
Stage 2 determines the no-load motor current and the motor inertia. The motor rotates at
30% of rated speed during this stage. Generally, this stage of auto tuning requires the motor
to be de-coupled from the load. Ensure that it is acceptable to spin the motor before this test
is enabled. Data obtained in Stage 2 is used to optimize the operation of the outer loops that
control motor speed and motor flux. The speed and flux loop gains are automatically
calculated and saved by the control.
The motor will spin during Stage 2 of Auto Tuning.
Note
Quadratic loads, such as pumps and fans, do not require the motor to be de-coupled for
Stage 2 auto tuning. The control is designed to minimize the errors introduced by such loads.
See also
Drive Tuning (Page 128)
6.8.2

Spinning Load

The Spinning Load feature allows the drive to determine the speed of a motor that is already
rotating. The drive is thus able to apply output voltages at the same frequency as the rotating
motor, and minimize any chance of a speed transient. The Spinning Load feature in NXG
Control is divided into two stages. During the first stage, Spinning Load operates
automatically when enabled, and requires no user adjustments. The drive control monitors
motor flux, and is able to provide an instantaneous restart. This stage is valid as long as
there is detectable flux in the motor. Typically, the drive is capable of restarting
instantaneously if the time duration between drive disable and re-start is within 3 to 4 motor
time constants.
Product User Manual
Operating Instructions, Version AE 12/2009, A5E01454341C
DANGER
DANGER
Application and Operation
6.8 Drive Tuning
129