Reference Manual

Table Of Contents
Diagnostics and Fault Handling
41.3.1 Fault Filtering
Purpose
The purpose of the subfunction is to determine whether a fault is
present or absent, see gure below, and the nature of the fault.
Fault filter
parameters
Fault filter
Disturbance/
Measurement
Fault present/
Fault absent
P002833A
Figure 103 Fault Filter
Preconditions and initiation
The selftest and supervision function has detected a disturbance.
Description
All disturbances are ltered before a fault is considered to be present or
absent. The ltering function is adapted to each fault situation for
optimum performance. Each fault has its own specied fault lter
parameters. For example, the following parameters (or combinations of
parameters) may be used for the lter function:
Frequency of disturbances
A frequency which is too high is considered to be a fault
The measurement value of a parameter
A parameter exceeding a threshold is considered to be a
fault.
Time
A condition which is valid for too long is considered to
be a fault
EN/LZT 720 0008 R1A
2001-06-26
317 (421)
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