Benning ST 720 Bedienungsanleitung Seite 33

Length
5 m
10 m
25 m
50 m
Table 1: Resistance values of the protective conductor depending on length and cross-section
- After the R test has been passed, the measurement of the insulating resistance is carried
PE
out automatically.
- Depending on whether the value is higher or lower than the limiting value, a
indicated next to the R
- After the R test has been passed, the external conductor (L) and the neutral conductor
ISO
(N) are checked for line breaks and short-circuits. A passed test regarding line breaks and
short-circuits is indicated by a
- The "PASS" symbol confirms successful testing of the entire testing procedure.
- If the test regarding line breaks and short-circuits has failed, one of the following symbols is
indicated instead of the "Good" symbol:
- "OPEN" symbol:
confirms a line break of the external conductor (L) or neutral conductor (N)
- "Shor" symbol:
confirms a short-circuit between the external conductor (L) and the neutral conductor
(N)
See figure 6a:
Note on measuring the protective conductor resistance:
- Alternatively, the measurement of the protective conductor resistance R
ried out as permanent measurement (max. 3 minutes). For this purpose press the key
2 for approx. > 5 seconds until the  symbol appears on the display. Check the con-
necting line of the test object by bending it over the entire length in order to detect
weak points or a break of the protective conductor. The BENNING ST 720 continuously
records the current measured value on the display and stores the maximum value in the
memory. By pressing the key 2 again, the measurement is carried out with reversed
polarity. Press the key 2 again to indicate the maximum value of R
to continue the testing procedure as described in section 8.2.3.1.
8.2.3.2 Testing of cable reels, multiple distributors and extension cables
- Disconnect the plug of the mains connection cable from the socket K of the BENNING ST 720.
- Connect the IEC power cord (IEC adapter cable) included in the scope of delivery to the IEC
connector J of the BENNING ST 720.
- Connect the line to be tested to the test socket 1 and to the shock-proof socket of the IEC
power cord.
- Press the key 2 to start the automatic testing procedure.
- The further testing procedure corresponds to the testing procedure described in section
8.2.3.1.
See figure 6b:
8.3 Testing RCDs with a nominal fault current of 30 mA
- Connect the mains connection cable to the mains connection socket K of the BENNING ST 720.
- Make sure to connect the shock-proof plug with a shock-proof socket which is protected by
the RCD to be tested. With the mains voltage being applied, the voltage measurement will
start automatically.
- Depending on the external conductor position (right or left) of the shock-proof socket, the
voltage potentials between the connecting terminals L, N and PE will be shown on the dis-
play for approx. 2 seconds.
08/ 2010
1.0 mm²
0.1 Ω
0.2 Ω
0.5 Ω
1.0 Ω
symbol.
ISO
next to the
Testing of device connecting cables with IEC connector
Testing of lines, multiple distributors and cable reels
BENNING ST 720
Cross-section
1.5 mm²
0.06 Ω
0.12 Ω
0.3 Ω
0.6 Ω
and the "GOOd" symbol.

2.5 mm²
0.04 Ω
0.08 Ω
0.2 Ω
0.4 Ω
or a
can be car-
PE
on the display and
PE
27
is