Function
21
isoPV425_D00028_09_M_XXEN/05.2018
3.2.6 Measuring and response times
The measuring time is the period essential for the detection of the measuring
value. The measuring time is reflected in the operating time t
ae
.
The measuring time for the insulation resistance value is mainly determined
by the required measuring pulse duration, which depends on the insulation
resistance R
F
and system leakage capacitance C
e
of the system to be moni-
tored. The measuring pulse is produced by the measuring pulse generator in-
tegrated in the ISOMETER®. The measuring times for C
e
, U
L1e
, U
L2e
and R % are
synchronous. System disturbances may lead to extended measuring times. In
contrast, the time for the nominal system voltage measurement U
n
is inde-
pendent and considerably shorter.
Total response time t
an
The total response time t
an
is the sum of the operating time t
ae
and the re-
sponse delay time t
on
.
Operating time t
ae
The operating time t
ae
is the time required by the ISOMETER® to determine
the measuring value. The insulation resistance measuring value depends on
the insulation resistance R
F
and the system leakage capacitance C
e
. High sys-
tem leakage capacitances and system interferences lead to longer operating
times.
Response delay t
on
The response delay t
on
is set uniformly for all messages in the menu "t" using
the parameter "ton". This delay time can be used for interference suppression
in the case of short measuring times. An alarm will only be signalled when a
threshold value of the respective measuring value is exceeded for the period
of t
on
without interruption. Every time the threshold value is violated within
the time t
on
, the response delay "ton" restarts once again.
Every alarm message listed in the alarm assignment has its own timer for t
on
.
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