Benning IT 100, Operating Manual, Page: 21 / 42

Device description
4.3 Measuring ranges
5225 / 04/2022 en BENNING IT 100 21
4.2.4 “LOCK” key
By pressing the “LOCK” key, you can enable the “LOCK” function prior to a low-resistance or
insulating resistance measurement. If the “LOCK” function is enabled, a subsequent low-
resistance or insulating resistance measurement started with the “TEST” key will remain active
until it is stopped by pressing the “TEST” or “LOCK” key. During the measurements, a testing
current (low-resistance measurement) or a testing voltage (insulating resistance measurement)
is continuously applied at the measuring point.
If the “LOCK” function is disabled, the device can detect an inadmissible external voltage and
prevent a low-resistance or insulating resistance measurement if necessary. If the
“LOCK” function is enabled, the device can no longer detect an inadmissible external voltage.
NOTICE
Undetected inadmissible external voltage
The fuse of the device might blow because of an undetected inadmissible external voltage due
to the “LOCK” function being enabled.
• Make sure that the measuring point is free of voltage.
4.2.5 Blue key
Press the blue key to toggle between the standard function of the rotary switch position and the
secondary function in blue colour.
• Resistance measurement or continuity test: Toggling between the functions
• Low-resistance measurement or null balance (ZERO): Toggling between the functions
The “ZERO” function is intended for a null balance of the safety measuring lines. After
having performed the null balance, the device automatically switches back to low-resistance
measurement.
• Voltage measurement: Toggling between DC and AC voltage measurement
4.2.6 “PI DAR” key
Press the “PI DAR” key to toggle between insulating resistance measurement, polarisation
index (PI) measurement and dielectric absorption ratio (DAR) measurement in the
corresponding rotary switch position.
4.3 Measuring ranges
The device is provided with an automatic switch-over of the measuring range. For this reason, a
default setting is not required.
The symbol “>” indicates that a measuring range has been exceeded. In case of contact
voltages from 30 V‑DC or 2 V‑AC on, the red LED (high-voltage control indicator) lights
additionally.