Insulation Measurement; Checking The Connection Of The Device; Profile Selection - Bender ISOMETER iso175 Manual

8.3

Insulation measurement

When monitoring the insulation resistance of an HV system the following must be taken into consideration:
Selection of the correct response value (Isolation: Threshold_Error, Isolation: Threshold_warning)
In accordance with standard LV 123, an insulation resistance > 500
An insulation fault is correspondingly present starting with an insulation resistance < 100
values in the standard configuration (Error, Warning) are designed for a 1000 V HV system and, if necessary, can
be reconfigured and adapted correspondingly to the respective HV system.
The device with article no. B91068200 can already be set to specific customised default parameters at the
factory. For further information, see customer configuration under "Ordering information", page 33.
Evaluation of Status: Warnings and Alarms
Specific alarm messages signal that the insulation measured value is no longer reliable even though the
measured value may be higher than the set alarm threshold values (Error, Warning). One example for this is a
faulty connection to chassis ground (Status: Warnings_and_Alarms, bit 4). Monitoring the status of the alarm
bits continuously and reacting to imminent alarms accordingly is recommended (see chapter "Maintenance
and trouble-shooting", page 27).
Quality of the insulation resistance measured value
For every insulation resistance measured value there is also a quality information (Isolation: Quality), which
reflects the reliability of the measured resistance value. In a fault-free HV system (e. g. no voltage fluctuations)
the quality should always be between 90 % and 100 %. In a faulty HV system it may occur that internal
individual measured values have lower reliability. When such measured values ar incorporated into the
internal statistical evaluation, also the quality of the calculated measured value is reduced correspondingly.
Therefore also the quality value should be monitored continuously, and if it falls below an individual limit value
designed for the respective HV system, users shall react accordingly (see chapter "Maintenance and trouble-
shooting", page 27).
8.4

Checking the connection of the device

That the ISOMETER® is connected correctly to the HV system is a prerequisite for the measurement of the
insulation resistance value. In the standard configation the device automatically performs an "offline self test"
every hour which checks for proper functioning of this connection.
ADVICE
The first automatic check does not take place after a cold start / power cycle, but when the duration
of the configured period has expired (default: 1 h). However, users can also perform the test manually
(Self test: Trigger_self_test). Here it must be taken into account that the self test can only be carried out
when the device is in R_iso_status = 0xFE.
The selection of the connection cable used is decisive for a properly functioning connection. For information
on validated cable types and cable lengths recommended by Bender, see chapter "Tabular data", page 29,
HV connection.
8.5

Profile selection

The active measurement profile can be changed at any time during the insulation measurement. Every
measurement profile has specific properties with the concomitant advantages and disadvantages for
the insulation measurement (see chapter "Measurement profiles", page 16). Low quality of the insulation
resistance measured value is an indicator that the measurement is disturbed / adversely affected. In such a
/ V is considered to be not dangerous.
iso175_D00415_01_M_XXEN/11.2023
ISOMETER® iso175
/ V. The response
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