Megger VLF SIN-45 - Page 33

Operating Modes
33
Once all the relevant parameters for the test as well as the phase(s) have been set, the
actual test can be started using the menu item
. After which 10 seconds remain to
enable high voltage with the “HV On” button .
At the start of a test with sine wave or rectangular voltage, load detection is performed.
If the load characteristics (capacitance and insulation resistance) do not permit a test
with the set parameters, this is indicated on the screen by a system message.
For tests with sine wave or rectangular voltage, testing using a lower frequency is
offered where required. The user can then either cancel the test or start it using a
different frequency. In the Auto frequency setting, the adjustment, if necessary, is
carried out without further inquiry.
Tests with DC voltage or cosine rectangular voltage must be stopped in any case and, if
possible, restarted using a lower test voltage.
During the test, the voltage curve (blue) and, if applicable, the leakage current (red) are
logged in the display area in real time. The display area of the diagram can be increased
or be reduced by means of the menu item .
In the operating mode, the tanδ measured values (green dots) are shown in addition
to the voltage curve (blue curve) and it is possible to switch to numerical representation
of the measured values via the menu item.
Depending on the operating mode, a few relevant parameters and measured values are
displayed next to the diagram:
Symbol Description
/
Remaining test time / current test duration (in continuous operation mode)
Leakage current (VLF-CR, DC and rectangular voltage)
Actual test frequency
The load capacitance determined at the start of the test
The insulation resistance determined at the start of the test
δ
Last measured tanδ value
If a test time was defined, the high voltage is automatically switched off at the end of this
time. In continuous operation mode, it must be switched off manually using the “HV Off”
button or the menu item .
If a voltage breakdown occurs in the test object during the test time, the test is also
interrupted. In which event, the test does not qualify as having been passed.
Irrespective of whether the high voltage is switched off automatically or manually, the
test object is discharged by means of an internal discharge-resistor.
The test data logged up to the switch-off are recorded in the history database (see page
29) and, if necessary, on the inserted USB flash drive as well.
Starting the test
Performing the test
Finishing the test