Advanced Functions; Determining The Dielectric Absorption Ratio R Ab; Insulation Test - LEM ISO plus Manuel D'utilisation

Advanced functions

6 Advanced functions
6.1 Determining the Dielectric Absorption ratio R

Insulation test

The R value is only available if the insulation test is continued for
ab
more than 1 minute. The R
of the insulation. It is calculated using the following formula:
R
ab
Measuring procedure:
Connect instrument to the installation/equipment with the
supplied test leads.
Select the required Insulation test voltage with the rotary switch.
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.
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
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
screen.
The key toggles between R
and the actual measuring voltage UISO.
Measured value evaluation :
R >1.25 means: good insulation and R
ab
insulation.
in
ab
value gives an indication of the quality
ab
R
1 ( min)
= ISO
R s
( 30 )
ISO
ACTIVE
are displayed
key to select the R
, the latest measured value of RISO
ab
< 1.1 signifies poor
ab
- 19 -
ab