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4.2 Measurement setup
Any measurement line (up to approx. 3,5
Ω)
can be
used between the reference earth (e. g. a potential
equalization conductor) and the EP 4, which can be
adjusted as described in section 4.3. Measurement
locations at distances over 100 m can be reached.
In environments with strong field influences the
circuit line should be reeled off completely, so
inductive influences can be avoided.
Fix the measuring line good electrical conducting
to the reference earth (remove any corrosion).
Stick the free end of measuring line into the
integrated bush of EP 4. By using the pay-off reel
the supplied short measuring line must be
sticked into the socket of reel.
Attention!
Before pressing the button
check external
voltage (see 4.7).
Attention!
In Ex-areas you may use only the EP 4Ex. In Ex-
areas you may use only unrolled lines. The use of
plastic decoilers in Ex-areas prohibited. Observe
maximum values of C
0
= 9 μF and L
0
= 0,4 mH.
4.3 Zero balancing
The EP 4 must be calibrated together with the
entire measurement line
before each measurement
test series
(see Measurement setup 4.2).
To consider temperature changes zero balancing is
necessary even if the same measurment line is used
again after a period of time.
Balancing occurs automatically for all measuring
ranges of 1μA ... 200 mA.
Attention!
For balancing the device has to be switched off.
Affix the measuring line to the reference earth
and ensure
safe contact
.
Ensure the EP 4 is switched off. Hold button
and press the button
, at the same time to
switch on the device. The display shows “CAL“
and the POL +/- LED lights up. A wait symbol
“-------“ occurs in the upper part of the display.
Maintain contact as long as “CAL“ is displayed
and the wait symbol runs. Balancing is
finished when “+1“ appears on the display and
the LED lights up.
Resistance of the measurement line remains in
storage until a new zero balance is performed.
This value also remains in storage if the measuring
instrument is switched off, or if the battery is
replaced.
If the message ”Err” appears zero balancing failed
and must be repeated. This error occurs if the test
probe slips during balancing or if the measurement
line is too high-resistive (>3,5
Ω
).
For test purposes we recommend that the first
measurement always be made directly at the
reference earth (see measuring with both
polarities 4.4). The result should always be
< 0.04
Ω
.
