Benning ST 720 Bedienungsanleitung Seite 29

on the display 8 . Press the key again to switch back to the preset testing voltage of 500 V
- Switch the test object on.
- Press the -key 2 to start the automatic testing procedure.
- The test starts with measuring the protective conductor resistance R
the admissible limiting value, the measured value of R
a will appear next to the R
measurement has been stopped.
- If R is lower than the admissible limiting value, the measured value of R
PE
a appears next to the R
reversed polarity and the highest measured value of both measurements will be displayed.
After the R test has been passed, the test of the insulating resistance is started.
PE
- If "Lo LOAD" is shown on the display, please check whether the test object is switched on.
- Press the key 2 to continue the testing procedure in case of the load being too low (R
> 6 kΩ).
- If "HIGH LOAD" is shown on the display, this indicates an excessive load (R
I (I ) > 16 A) of the test object. There might be danger of a short-circuit or of an earth
LAST LOAD
fault. Check whether there is a short-circuit between the external conductor (L) and neutral
conductor (N) of the test object.
- If there is no short-circuit, you can continue with the testing procedure by pressing the key 2 .
- If the insulating resistance R
next to the R
ISO
BENNING ST 720 in mains operating mode:
- The BENNING ST 720 interrupts the testing procedure after the R
measurement and requests the user to switch the mains voltage of 230 V to the test socket
1 by showing a flashing "I
press the key 4 to measure the protective conductor current by means of the differential
current measurement method.
- The protective conductor current measurement (differential current measurement method)
only starts as soon as the mains voltage is correct applied.
08/ 2010
symbol. "FAIL" appears on the display to confirm that the
PE
symbol. Now, the R
PE
is higher than the admissible limiting value, a
ISO
symbol.
" symbol. Make sure that the test sample is protected and
LEAK
BENNING ST 720
PE
will be shown on the display and
PE
measurement is carried out again with
PE
ISO

. If R is higher than
PE
is shown and
PE
<< 14 Ω,
L-N
appears
(insulating resistance)
.
DC
L-N
23