MI 3321 MultiservicerXA
Switchgear testing operating mode
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*Notes:
Before first use and after “Original Settings”, Password HV-test must be set in
General settings >> Password menu.
If a 5 s start timer runs out, HV-test will not start for safety. Initiate start
measurement procedure with STOP key and start test within a 5 s delay.
In case of 3-phase switchboard, the temporary test connection shall cover all
applicable L1, L2, L3 and N.
Examples of high voltage withstanding test results
Notes:
Tested switchboard should be de-energized before the measurement!
Components and devices that are not rated to withstand the test voltage shall be
disconnected during the testing
– refer to related product standard for tested
switchboard.
Components and devices that have been voltage tested in accordance with their
product standards may be disconnected during testing.
Consider any warning on the display before starting the measurement!
Do not forget to remove the temporary L-N connection after withstanding
tests are finished.
10.2.5 Discharging Time (Residual voltage test)
If large capacitors in switchboards are disconnected from supply there is often a
remaining (residual) charge on internal switchboard components. Live parts having a
residual voltage greater than 120 V shall be discharged to 120 V or less within a time
period of 5 s after disconnection of the supply.
Measuring principle
The test leads are connected to terminals where residual voltage is to be measured.
The switchboard is switched ON, the voltage on terminals can be of a.c. or d.c. type.
Phase 1:
The instrument monitors the voltage and internally stores the peak voltage
value.
Phase 2:
The switchboard is disconnected from the power supply and the voltage at the
test terminals starts to fall. Once the voltage falls for 10V the instrument starts the timer.
Phase 3:
After the voltage drops below an internally calculated voltage value the timer
is stopped. The instrument recalculates the measured time to a value as it would be if
the disconnection occurred at the maximum voltage value.
