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03.96
10.5 Frequency response measurement
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 Siemens AG 2000 All Rights Reserved
SINUMERIK 840D Installation and Start-Up Guide (IAD) – 04.00 Edition
Bandwidth
Analyzed frequency range
S 4.0 kHz on the 840D (sampling rate 8.0 kHz).
Averaging operations
The accuracy of the measurement, but also the measurement time, are in-
creased with this value. A value of 20 is normally suitable.
Settling time
This value represents the delay between recording of the measured data and
injection of the test setpoint and offset. A value of between 0.2 s and 1 s is re-
commended.
The transient response (response to setpoint changes or disturbances) of the
speed control in the time range can be assessed with the step stimulation func-
tion. The test signal is connected to the speed controller output for recording of
the response to disturbances.
Amplitude
This parameter determines the magnitude of the specified setpoint or distur-
bance step change.
Measuring time
This parameter determines the recorded time range (maximum 2048 x speed
controller cycles).
Offset (as from SW 4.1)
You can select a small offset of a few motor rpm to preclude the influence of
static friction.
SW 4.1 and higher:
S The Offset is run up via an acceleration ramp.
S The acceleration value is defined for an
Axis: check MD 32300: MAX_AX_ACCEL
Spindle: check MD 35200: GEAR_STEP_SPEEDCTRL_ACCEL
MD 35210: GEAR_STEP_POSCTRL_ACCEL
S The following applies:
Acceleration value = 0, no ramp
Acceleration value > 0, ramp active
S The actual measuring function is only activated when the offset value is
reached.
Settling time
This value represents the delay between measured data recording / test set-
point output and the injection of the offset.
Setpoint/
disturbance step
changes
Measurement
parameters for
setpoint/
disturbance step
changes
10 Drive Optimization with Start-Up Tool
05.97
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