Benning IT 105 - 8.4 Insulating resistance (Riso); 8.5 Loop impedance (Zs) and line impedance (ZI)

11/ 2018 BENNING IT 105
22

AUTO start (F4):
With the AUTO start function being enabled, the continuity test will be started automatically if the resis-
tance value applied to the measuring probes is < 20 kΩ. The function remains stored even after switching
off the tester.
- Connect the measuring leads to the BENNING IT 105 as shown in figure 2 and apply them to the test
object.
- The continuity test is started automatically if the AUTO start function has been enabled via the function
key F4
3
. Alternatively, press and hold the TEST key
4
to start the continuity test.
- In order to reverse the polarity of the testing current, repeat the measurement with inverted measuring
leads at the test object.
- The resistance value is shown on the main display K and the testing voltage is shown on the sec-
ondary display J.
8.4 Insulating resistance (RISO)

Measurements of the insulating resistance must be carried out at idle system parts only.

If a voltage of > 30 V AC/DC is applied to the test object, a flashing warning symbol  and
an acoustic signal will warn you of an external voltage being applied. The external voltage
is indicated on the digital display
2
and measurement will be blocked. Make sure that the
circuit is free of voltage and repeat the measurement.
- Select the desired function RISO (250 V D), 500 V C or 1000 V B) with the rotary switch
1
.
- The symbols of the function keys F1 A to F4 D are briefly shown on the digital display
2
. You can use
the function keys F1 to F4
3
to make the following settings which will be stored until they are changed
for the next time:
F1 F2 F3 F4
– –
Buzzer (F1):
With the buzzer being enabled, an acoustic signal will be emitted at a measured value of < 1 MΩ.
Lock (F2):
The lock function enables a continuous measurement of the insulating resistance without having to press
and hold the TEST key
4
again. For continuous measurement, first press the function key F2
3
and then
the TEST key
4
. The digital display
2
shows the LOCK symbol B and the testing voltage is continu-
ously applied to the measuring probes. The lock function can be stopped by pressing the function key F2
3
or the TEST key
4
.
- Connect the measuring leads to the BENNING IT 105 as shown in figure 2 and apply them to the test
object.
- Press and hold the TEST key
4
to start an insulating resistance measurement.
- The resistance value is shown on the main display K and the testing voltage is shown on the sec-
ondary display J.
8.5 Loop impedance (ZS) and line impedance (ZI)

Measurement requires correct connection of the mains voltage to the BENNING IT 105
as shown in figures 4, 5 or 6. The mains voltage indicator must light permanently:
If the mains voltage indicator flashes, turn the shock-proof plug of the test cable by 180° or check the
measuring leads for correct connection.

During measurement, the BENNING IT 105 monitors the contact voltage Uc applied to the
protective conductor (PE). If the contact voltage Uc > 25 V, “>25 V” is shown on the digital
display
2
and the user can continue the measurement at his/her sole discretion. If the con-
tact voltage Uc exceed the value of > 50 V, the measurement will be cancelled.