User manual SEFELEC 5x Series 73 v1.06
PRECAUTIONS TO BE OBSERVED DURING MEASUREMENT:
To perform a measurement of resistance above 100 Gohm, use effective shielding connected to
the guard terminal (grey terminal on the front panel). This avoids erroneous measurements due
to the presence of leakage currents or the introduction of alternating residues.
The proximity of an operator approaching his/her hand to a sample under test can distort the
measurement. It is important to beware of nylon laboratory coats or objects made from insulating
materials likely to generate, by static electricity, significant fields that can disrupt the operation of
the device at very low currents. A measurement of 100 GOhm at 100 volts devolves to measure
a current of 1 nA.
During measurements on capacitive circuits (use the capacitor mode, see paragraph 7-4) never
perform measurements by reducing the measurement voltage at each test but always increasing
it; the hysteresis and polarisation phenomena of the dielectric would distort the results. In this
case the device has a tendency to indicate the maximum and takes a very long time to return
down to the real value to be measured.
Never disconnect a capacitive sample without passing through the discharge mode with the
Stop push button and waiting the time required for the capacity of the sample to be dis-
charged into the resistance of 2.2 kΩ of the discharge circuit.
It is recommended to check the proper functioning of the device regularly by
connecting an element of known value to the measurement output and perform-
ing a measurement. In the absence of an element of known value, it is possible
to make a measurement on an open circuit and on a short-circuit to confirm the
consistency of the indications of the device.
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