Function
21
isoMIL425_D00203_03_M_XXEN/03.2019
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 the insulation resistance
R
F
and the system leakage capacitance
C
e
. For ex-
ample, a maximum permissible system leakage capacitance of
C
e
= 300 μF
and an insulation fault of
R
F
= 2.5 kΩ (
R
an
= 5 kΩ) in a 400 V DC system results
in an operating time of
t
ae
< 40 s.
High system 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 meas-
uring value is violated for the period of
t
on
without interruption. Every time
the threshold value is violated within the time
t
on
, the response time "ton" re-
starts once again. Every alarm message listed in the alarm assignment has its
own timer for
t
on
.
Delay-on release
t
off
The delay-on release
t
off
can be set uniformly for all messages in the menu "t"
using the parameter "toff".
An alarm will continuously be signalled until the threshold value of the re-
spective measuring value is not violated (including hysteresis) for the period
of
t
off
without interruption. Each time the threshold value is not violated for
the period of
t
off
, the delay-on release
t
off
restarts once again.
Every alarm message listed in the alarm assignment has its own timer for
t
off
.
