Hioki RM3542-50, Инструкция по эксплуатации

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Appendix 3 Unstable Measurement Values
A
4
Measurement should be conducted as far as possible from devices emitting electric or magnetic fields such
as power cords, fluorescent lights, solenoid valves and PC displays. If electrical noise ingress is a problem,
prepare the measurement leads as shown in Fig. 2 and Fig. 3.
If thermal emf is a problem, use the RM3542A OVC function. If OVC cannot be used for reasons such as tact
time limitations, use a low-thermal emf material such as copper for wiring, and protect against airflow on con-
necting parts (test object or connectors).
(3) Multi-Point Contacts with Clip Type Probes
The ideal conditions for four-terminal measurements are
shown in Fig. 4: current flows from the far probe and voltage is
detected with uniform current distribution.
To facilitate measurement, the tips of the Model Hioki 9140-10
4-Terminal Probe are jagged. As shown in Fig.5 (enlarged view
of probe tip contact area), the measurement current flows from
multiple points, and the voltages are detected at multiple
points. In such cases, the measurement value varies according
to the total contact area.
Additionally, as shown in Fig. 6, when measuring the resis-
tance of approximately a 100 mm length of wire, the length
between the nearest edges of the clips is 100 mm, but the
length between the farthest edges of the clips is 110 mm, so
the actual measurement length (and value) has an uncertainty
of 10 mm (10%). If measurement values are unstable for any of
these reasons, maximize stability by measuring with point con-
tacts as far as possible.
Figure 4. Ideal Four-Terminal Method
HPOT, (LPOT)
(Voltage Detection)
HCUR, (LCUR) (Current generation)
Figure 5. Measurement with
Model 9140 4-Terminal Probe
HPOT, (LPOT)
(Voltage Detection)
HCUR, (LCUR) (Current generation)
Figure 6. Measuring the resistance of a 100
mm length of wire
Clips
110 mm
100 mm