Hioki RM3542-50, Инструкция по эксплуатации

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Appendix 3 Unstable Measurement Values
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Appendix
If the measurement value is unstable, verify the following.
(1) Effect of Noise from Power Supply Lines
Noise from power supply lines arises from commer-
cial power, and not only from power lines or outlets,
but also as radiated emissions from fluorescent lights
and home appliances. The frequency of the noise
from power supply lines depends on the commercial
supplied power frequency, and occurs at a frequency
of 50 Hz or 60 Hz.
One method typically used to reduce the effects of
noise caused by commercial power supplies is to set
the measurement time to a whole-number multiple of
the power supply cycle.
The instrument provides 3 measurement speed set-
tings: FAST, MEDIUM, and SLOW. With the FAST
setting, measurements are not synchronized with the
power line period, so high resistance or low-power
resistance measurements may become unstable. In such cases, use the SLOW setting or take noise suppres-
sion countermeasures.
For high-resistance measurements, connecting the
shield to the GUARD potential is helpful.
In low-resistance range and low-power resistance
measurement, it is effective not only to shield with the
GUARD potential, but also to twist the measurement
probe lines together where possible.
Even when the integration time is set by a PLC, mea-
surement values are unstable if the power supply line
frequency setting is 60 Hz and the instrument is used
in a 50 Hz region. Confirm the line frequency setting
of the instrument.
(2) Using Low-Power Resistance Measurement
Low-power resistance measurement employs a smaller measurement current than normal resistance mea-
surements. Therefore, measurements are more susceptible to the effects of external electrical noise and ther-
mal emf.
Appendix 3 Unstable Measurement Values
Noise from Power Supply Lines
Combined with the Measurement
Signal
Ideal Measurement Signal (DC)
Integration Period
Figure 1. Effect of Noise from Power Supply Lines
Figure 3. For Low-Power Resistance Measurements
Figure 2. For High-Resistance Measurements
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Twisted
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