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 or ratios plus capacitance measurements
by using the ‘
Ω
/I’ toggle button. See section ‘
Ω
/I button’ for cycling
through results and toggling units.
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.
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 resistance 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’.
16
TEST MODE SUMMARY
Pressing the ‘
Ω
/I’ button toggles the display to show the insulation
resistances, insulation currents, 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’.
Breakdown mode / burn mode
The insulation resistance ‘IR’ test operates in either the ‘Burn’ or
‘Breakdown’ mode of operation. The default mode is breakdown. To
change mode press and hold the function button, then press and release
the mode button repeatedly until the desired mode is indicated by the
flashing symbol on the display. Release the function button to select it.
In the breakdown mode the ‘Breakdown Indicator’ will be illuminated –
refer to page 6. In this mode the test will automatically terminate should
the insulation break down to prevent damage to the insulation under
test.
In the burn mode the ‘Burn Indicator’ is illuminated – refer page 6.
The burn mode disables the normal breakdown detection and enables
the insulation test voltage to continue even after breakdown of the
insulation. This will enable the location of the failure to be seen and
heard. Due to the potential damage that could occur, the unit produces
two long beeps when starting a test with burn mode activated.
Alarm limit mode
The insulation resistance ‘IR’ test has an option of setting an alarm limit. If
this mode is selected, the instrument will beep should the resistance reading
exceed a user selectable threshold. To set the limit, hold down the function
button, then press and release the mode button repeatedly until
