LEM ISO plus, Руководство по эксплуатации

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Advanced functions
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6 Advanced functions
6.1 Determining the Dielectric Absorption ratio R
ab
in
Insulation test
The R
ab
value is only available if the insulation test is continued for
more than 1 minute. The R
ab
value gives an indication of the quality
of the insulation. It is calculated using the following formula:
) 30 (
min) 1 (
s R
R
R
ISO
ISO
ab
=
Measuring procedure:
Connect instrument to the installation/equipment with the
supplied test leads.
Select the required Insulation test voltage with the rotary switch.
Initiate the test by pressing the
START key, hold this key down for 10
seconds to activate continuous measurement.
The test can be terminated anytime by pressing „
START“ again.
(ATTENTION: The measuring voltage is applied all the time!).
While the test is in progress the annunciators
ACTIVE
are displayed
as a warning of the high tension at the measuring terminals.
After a minimum period of 1 minute indicated by frequence change of
the buzzer signal warning every 5 s the presence of high voltages.
The Rab value can be displayed using the
key to select the R
ab
screen.
The key toggles between R
ab
, the latest measured value of RISO
and the actual measuring voltage UISO.
Measured value evaluation :
R
ab
>1.25 means: good insulation and R
ab
< 1.1 signifies poor
insulation.
CAUTION: The installation / test specimen must be set potential-free
prior to measurement!
In case of external voltages above 10% of the selected test voltage
(10V, 25V, 50V and 100V) the measurement is blocked.