Functional Description .
ECW500 | 49
Figure 6.19 - Example of configuration for the limiter LEUC
Considering the capability curve of Figure 6.19, an apparent nominal power (S) of 10 MVA and the points
chosen according to the figure, initially the parameters of minimum and maximum power are set. In this case,
the following values were determined:
The selected points can then be configured with the following values:
NOTE!
The excitation undercurrent limiter operates in all operation modes, except in the MECC mode.
LEUC can be disabled using the 30148 parameter and a relay can be configured to indicate its
operation.
6.6.4 Terminal Overcurrent Limiter (LTOC)
The aim of the terminal overcurrent limiter (stator overcurrent limiter) is to prevent an excessive and destructive
current through the terminals of the synchronous machine. When the LTOC acts, the ECW500 controls the
excitation current in order to keep the stator current below the specified levels. The gains of the LTOC PI loop
must be set to ensure a dynamic operation suitable for each application.
Likewise the LEOC, the LTOC limiter has two configurable levels with different forms of action:
■ high level (parameter 30126), with immediate action and
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