Offline Self Test; Offline And Communication Self Test; Periodical / Automatic Self Test - Bender ISOMETER iso175 Manual

4.4.2

Offline self test

The offline self test checks the following device functions:
• Electrical connection from connector HV+ to connection cable HV_pos (L+)
• Electrical connection from connector HV- to connection cable HV_neg (L-)
ADVICE
During the test only the electrical connection is checked, the polarity of the connection, however, is
not checked.
This offline self test can be carried out at any time during the operating mode "normal insulation
measurement" (R_iso_status = 0xFE) by sending the control command Self test: Trigger_self_test with the
content (Data1) = 1. Here care must be taken that the offline self test is carried out only when the connection
switch to chassis ground (earth disconnector) is closed (Signal Earthlift: Status = 0x00). The self test takes ≤ 1 s.
In case the connection switch first needs to be closed, an additional delay time of maximal 1 s must be taken
into account.
Reading out the signal Status: Device_Activity permits verifying whether the offline self test is still ongoing
or whether it was fully completed. As long as the test is ongoing, this command is answered with
the value (Data1) = 2. The results of the offline self test are obtained by reading out the signal Status:
Warnings_and_Alarms, bits 1 and 2).
Bit 1: true = HV_pos connection failure
Bit 2: true = HV_neg connection failure
Please note that when there is a faulty earth connection, also the two connection tests to HV_pos and HV_neg
will signal an error, because for these tests a connection to chassis ground is indispensable.
4.4.3

Offline and communication self test

This test function can be started any time during the operating mode "normal insulation
measurement" (R_iso_status = 0xFE) by sending the control command Self test: Trigger_self_test with the
content (Data1) = 2. In addition to the described offline self test, this function also performs a test of the status
output OK (LV pin 8). For this, the status output is switched to low for approx. 5 s during the self test. During
HS
this time, the alarm 'Status: Warnings_and_Alarms, Bit 0' is also active (true).
4.4.4

Periodical / automatic self test

The ISOMETER® offers users the possibility of carrying out an automated offline self test at periodic intervals. By
programming the parameters Self test: Period, they can set the period duration as needed in 10 s increments.
Please note that the first test is only started when the device is in the operating mode "normal insulation
measurement" (R_iso_status = 0xFE) and the configured time interval has passed.
ADVICE
The first automated self test is performed 1 h after switching on the supply voltage. Should the
continuous operating time of the unit be < 1 h, it is recommended to adjust the period accordingly,
so that the connection check is carried out appropriate. In the event that the periodical self test is
deactivated (period duration = 0), the user is responsible for the appropriate connection to the HV
system.
iso175_D00415_01_M_XXEN/11.2023
ISOMETER® iso175
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