Siemens 6MD85 Manual page 404

Control Functions
6.4 Synchronization Function
The rule of three may be used to estimate the minimum dead time as follows:
360° = 10 s
120° = t
min
[fo_frequenzband, 1, en_US]
Set the parameter T close without balancing to a higher value, as in a practical case, the current
differential frequency is less than 0.1 Hz (for example, set point value 0.04 s).
At a differential frequency of 0.04 Hz, a 360° rotation takes 25 s and this leads to a minimum dead time of
approximately 8 s.
The example shows that the default setting of 5.00 s is a practicable value.
Parameter: Release for the kick pulse
•
Default setting (_:149) Release for the kick pulse = off
With the parameter Release for the kick pulse, you can activate the kick pulse.
If you need a kick pulse for your application, change the default setting.
Parameter: Δf for the kick pulse
•
Default setting (_:150) Δf for the kick pulse = 0.04 Hz
With the parameter Δf for the kick pulse, you define the set point value for the kick pulse. The pulse
duration is derived from this.
Set the parameter Δf for the kick pulse to the same value as the parameter Δf set point for
balancing.
The setting value of 0.04 Hz leads to the following duration for the kick pulse:
[fo_frequency-adujsting-command_02, 1, en_US]
If the controller does not respond to this brief pulse (tfact < t pulse min), the minimum pulse T f pulse
min applies.
Parameter: Stabilization
•
Default setting (_:151) Stabilization = no
If the dead time is too short, the parameter Stabilization results in a faster compensation of the speed
controller.
Parameter Value
no
yes
404
Description
The default setting no is a practicable value for typical synchronization
applications.
If the dead time is short, the transition process has not yet been completed
after a control pulse for the frequency. The frequency can fluctuate around
its set point value.
If you set the parameter Stabilization = yes, the transient status is
attenuated by canceling the control pulse or by issuing a control pulse in
the reverse direction in time.
Siemens only recommends this setting value if you wish to achieve fast
synchronization by means of short dead times or for special applications.
SIPROTEC 5, High-Voltage Bay Controller, Manual
C53000-G5040-C015-9, Edition 11.2017