Bender ISOMETER iso175 Manual page 19

holding Iso-Alarm = 0x01 users can reset all active alarm bits, provided that the corresponding alarm condition
is no longer met.
HV+ to chassis-ground error
The ISOMETER® offers the possibility of checking the electrical connection between HV+ and chassis ground.
For this purpose the offline self test must be carried out (see chapter "Offline self test", page 15). A faulty
connection is indicated with the signal Status: Warnings_and_Alarms, bit 1.
ADVICE
Prerequisite for proper functioning of this check is a system leakage capacitance ≥ 100 nF between
HV+ and chassis ground.
HV- to chassis-ground error
The ISOMETER® offers the possibility of checking the electrical connection between HV- and chassis ground.
For this purpose the offline self test must be carried out (see chapter "Offline self test", page 15). A faulty
connection is indicated with the signal Status: Warnings_and_Alarms, bit 2.
ADVICE
Prerequisite for proper functioning of this check is a system leakage capacitance ≥ 100 nF between
HV- and chassis ground.
Chassis-ground connection faults
The ISOMETER® continuously monitors the connection between LV pin 3 (earth connection) and chassis
ground (see chapter "Online self test", page 14). A faulty connection is indicated with the signal Status:
Warnings_and_Alarms, bit 3.
ADVICE
Prerequisite for proper functioning of this check is that the LV pin 3 connection is on the same
potential as terminal 31. Making this connection at chassis ground is recommended. This ensures
that LV pin 3 is connected not only to terminal 31 but actually to chassis ground, which is the
precondition for a functioning insulation measurement. For a correct connection, the ohmic
resistance between LV pin 3 and chassis ground must be ≤ 2 kΩ. With an ohmic resistance ≥ 4 kΩ a
connection fault is definitely recognised, and the corresponding alarm bit is set.
Insulation resistance fault (alarm)
The ISOMETER® signals a fault of the insulation resistance (Status: Warnings_and_Alarms, bit 4), when the
measured value falls short of the threshold value Isolation: Threshold _Error. The alarm bit is reset provided that
the currently measured insulation resistance is ≥ (Isolation: Threshold _Error + 25 % hysteresis).
ADVICE
The two parameters Isolation: Threshold_Error and Isolation: Threshold_Warning are cross-checked
for plausibility. When the parameter Isolation: Threshold_Error >Isolation: Threshold_Warning a
Device_Error_Alarm is triggered.
Insulation resistance warning (prewarning)
The ISOMETER® signals a fault of the insulation resistance (Status: Warnings_and_Alarms, bit 5), when the
measured value falls short of the threshold value Isolation: Threshold_Warning. The alarm bit is reset provided
that the currently measured insulation resistance is ≥ (Isolation: Threshold _Warning + 25 % hysteresis).
iso175_D00415_01_M_XXEN/11.2023
ISOMETER® iso175
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