Process Data - Siemens LMV50 Series Manual

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18.1.8 Process data

In its operating position, the VSD module records data that show how well the system
components work together (LMV5, VSD module, VSD, motor, and LMV5).
These data can only be read.
The maximum static deviation indicates the greatest speed deviation that occurred
during a drive command in modulating operation. This means that the deviation
indicated is the maximum difference that has been measured during an individual run.
The maximum dynamic deviation indicates the greatest speed deviation between the ramp
predefined by the VSD module and the measured speed. This gives the existing
maximum deviation between the expected speed and the speed currently measured.
Hence, control of the fan motor by the VSD lags behind the presetting in terms of time or
amount; in other words, the VSD is not capable of exactly following the presetting. This
does not necessarily represent a problem if Num Dev >0.5% contains only a few entries,
or no entries at all.
In addition, the number of static deviations >0.3% or >0.5% respectively are counted.
This gives the number of speed deviations above 0.3% or 0.5% that occurred during a
drive command.
The number of deviations >0.5% also corresponds to the number of correcting cycles.
The process data are only stored in RAM, which means that they are reset via reset or
lockout reset.
Note!
Procedure in case the values are too high!
Great dynamic deviation:
∂
If no entries or only a few entries were made at Num Dev >0.5%, the value is of no
importance. It only shows that at the beginning of speed readjustment, the fan
motor will probably follow the readjustment with a certain delay
∂
For Num Dev >0.5%, refer to Max Stat Dev
Great static deviation and, usually, a large number of entries at Num Dev >0.5%:
∂
The VSD is not able to readjust the fan motor's speed in accordance with the VSD
module's presetting
This problem can be solved by increasing the ramp time on the LMV5, or by decreasing
the ramp time on the VSD (provided the VSD is powerful enough, also refer to chapter
Configuring the VSD).
If the display of the actual speed (AZL52, ACS450, or on the VSD itself) gives the
impression that the speed oscillates or lags behind, an internal control algorithm in the
VSD is probably active (slippage compensation or load compensation), counteracting
speed control in the VSD module. Deactivation of these functions can solve the
problem.
Parameter Max Stat Dev
Max Dyn Dev
Num Dev >0.3%
Num Dev >0.5%
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CC1P7550en
22.05.2018