Manual

34 Gossen Metrawatt GmbH
8.4 Absorption Index Measurement – DAR
(METRAHIT IM XTRA BT and METRAHIT IM E-DRIVE BT only)
The absorption index test is part of the polarization index test (PI).
Insulation resistance measurements are placed in relationship to
one another after 30 and 60 seconds.
Application: faster version of the polarization index test.
➭ Set the rotary switch to “
RISO ”.
➭ Repeatedly press the Func softkey until the measurement view
for DAR appears at the display.
➭ Contact the device under test with alligator clips which have
been plugged onto the test probes.
➭ Interference voltage measurement (V AC+DC TRMS) is con-
ducted in this switch position.
➭ Measurement may only be started when the device under test
is voltage-free (U
ext
= 0000 V).
➭ Activate the measurement by pressing the Start softkey. The
high-voltage symbol next to the battery level display blinks
during measurement.
➭ You can interrupt the measurement at any time by pressing the
Stop softkey.
The measurement is recorded and you can observe its progress
which is displayed as a curve over the time axis.
Results for R
30
are displayed after reaching the 30 s mark. Mea-
surement is stopped automatically and results for R
60
and DAR are
displayed after reaching the 60 s mark.
The following measured values are displayed digitally next to the
graphic representation:
DAR Absorption index after 60 s
Riso Momentary measured value in M/G
U
ext
Momentary measuring voltage (actual
value)
U
set
Test voltage (target value)
t
act
Measured time since beginning of mea-
surement
R
30
Measured value after 30 s in M/G
R
60
Measured value after 60 s in M/G
After measurement has been completed, any
remaining residual voltage U
ext
is displayed which
may result from cable capacitance and a capaci-
tive device under test. The instrument’s internal
1M resistor causes rapid discharging.
Contact to the insulation resistance must be retained to
this end.
+
–
0V!
Discharge
Func
Func
Func
Zero:
RISO
COIL
RISO
Coil
DAR
PI
The above symbol
blinks when test volt-
age is active.
Func