Operator´s Safety; General Information Concerning Earth Measurement - BEHA UNITEST TELARIS Bedienungsanleitung

Operator´s Safety / General Information concerning Earth Measurement:
3.0 Operator´s Safety
The respective accident prevention regulations
established by the professional associations for
electrical systems and equipment must be strictly
met at all times.
In order to avoid electrical shock, the relevant
safety and VDE regulations concerning excessive
contact voltages must be strictly observed, espe-
cially when working with voltages exceeding 120V
(60V) DC or 50V (25V)rms AC. The values in brack-
ets are valid for limited ranges (for example in med-
icine and agriculture).
Prior to usage, inspect electronic load for ex-
ternal damage.Prior to any operation, ensure that
the connecting leads used and the electronic load
are both in perfect condition.
If the operator's safety can no longer be guar-
anteed, the instrument is to be put out of service and
protected against use. The safety is no longer guar-
anteed, if theinstrument:
• shows obvious damage
• does not carry out the desired measurements
• has been stored for too long under unfavourable
conditions
• has been subjected to mechanical stress during
transport.
The instrument may only be used within the op-
erating ranges as specified in the technical data sec-
tion.
Avoid any heating up of the instrument by direct
sunlight to ensure perfect functioning
and long instrument life.
The opening of the instrument for fuse replace-
ment, for example, may only be carried out by pro-
fessionals. Prior to opening, the instrument has to
be switched off and disconnected from any current
circuit.
4.0 General Information concerning Earth Mea-
surement: (also refer to term descriptions
page 18)
The measurements are carried out independent
from the mains as power is supplied by the built in
batteries. Earth resistance is determined by means
of a current-voltage measurement procedure.
Grounding is an important part of a power supply
system. It is required to bring the individual system
parts and current circuits to a common reference
potential, in proximity to the reference ground.
Grounding is also used to protect systems from
overvoltages or short-circuit currents. Earth resis-
tance must be of sufficiently low resistance. Thresh-
olds are defined within the VDE regulations.
Grounding or grounding resistance is composed of
ground conductor (equipotential bonding conduc-
tor or PE), the ground (foundation ground, earthing
rod, band ground...), and the earth diffusion resis-
tance. This represents the resistance between
ground and reference ground. A voltage funnel is
formed around any ground. The shape depends on
the ground itself and the surrounding earth. As-
suming a regular earth composition of similar tem-
perature and
humidity, the voltage funnels around the ground are
of concentric shape. The lower the earth resistance,
the smaller the voltage funnels. For grounding mea-
surement, the voltage drop that is being measured
is generated by a known, constant current across
the ground resistance to be measured.
21