Press the ‘MODE’ button to cycle through and select the test mode.
Modes of test to be chosen from include an insulation resistance
‘IR’ test, a polarization index ‘PI’ test, a step voltage ‘SV’ test, and a
dielectric discharge ‘DD’ test. If timers T1 and T2 are set, the instrument
will automatically calculate the dielectric absorption ratio ‘DAR’ of
the insulation. PI, DAR, and IR values are automatically stored and
displayed if the data is available, irrespective of the selected test mode.
At the end of a test the instrument can be made to display either the
insulation resistances, insulation currents, the filter setting, or ratios plus
capacitance measurements by using the ‘
Ω
/I’ toggle button. See section
‘
Ω
/I button’ for cycling through results and toggling units.
Hardware filter
The hardware noise current filter may be switched on or off before, but
not during, testing. Turning the hardware filter off may be beneficial for
short test durations and higher load capacitances providing there is little
noise current.
This feature may be set in any mode, i.e. IR, PI, SV, or DD. Press and
hold the Fn button while repeatedly pressing the
Ω
/I button to scroll
through the filter options. Select FIL OFF for the fastest settling time, or
FIL ON for the default 4mA noise filter. Note that if FIL OFF is selected,
the firmware filtering option (refer to section “Insulation Resistance “IR”
test”) will be disabled. This setting may not be adjusted during a test.
Insulation Resistance ‘IR’ test
This is the default mode in which the instrument powers up. This
test mode measures insulation resistance continuously at the selected
voltage. The test voltage may be varied during an ‘IR’ test by pressing
the test voltage
s
or
t
buttons. The test duration can be set using the
‘main timer’. The test will finish automatically after this time has elapsed.
16
TEST MODE SUMMARY
On test completion, insulation capacitance and the time constant
associated with it is calculated and displayed.
Time Constant (TC) = R
ins
x C
ins
If timers T1 and T2 are set, the instrument will calculate and display
the DAR value under the segment ‘DAR’. On completion of the test,
the instrument will display the insulation resistances, measured at these
times under the segment symbols ‘T1’ and ‘T2’. If the test runs for longer
than 10 minutes, the instrument will calculate the ‘polarisation index’.
This value will be displayed under the display segment symbol ‘PI’.
On completion of the test, the instrument will display the insulation
resistance recorded at 1 minute and 10 minutes under the segment
symbols ‘1m’ and ‘10m’.
Pressing the ‘
Ω
/I’ button toggles the display to show the insulation
resistances, insulation currents, the filter setting, DAR and PI ratios, and
capacitance. The resistances and currents will be displayed under the
‘T1’, ‘T2’, ‘1m’ and ‘10m’ segment headings, the ratios under the ‘DAR’
and ‘PI’ segment headings. The capacitance reading is indicated by its
units of either ‘nF’ or ‘µF’. Refer to section ‘
Ω
/I button’.
Firmware filtering
There is an option (in Insulation Resistance mode only) to switch in
firmware filtering to average out slow variations. The firmware filter time
constants are 10, 30, and 100 seconds. The additional firmware filter
setting may be adjusted before or during a test, unless the filter was set
to FIL OFF before the test started, in which case the additional firmware
filtering option will be unavailable during testing. If the additional
firmware filter is switched in during a test, then any subsequent PI, DAR,
or TC calculated results are regarded as invalid, and are consequently
not displayed. The resistances and currents at these times are still
