Appx.
11
Self-calibration
An effective approach for dealing with conductive noise is to implement countermeasures while
monitoring the results with the Hioki 3145 Noise HiLogger. Once the offending circuit has been
identified, the countermeasures depicted in Figure 2 provide an effective way to address the issue.
L
N
PE
L
N
PE
Instrument
Power lines
Separate circuit’s power lines
Isolation
Isolation
Common-mode filter
on ingress circuit
Physical separation of power lines
External device
(computer,
programmable
controller)
Figure 2. Conductive Noise Countermeasures
Physically separating power lines
It is desirable that powered devices, welders, and similar equipment be connected to a power
supply on a separate circuit than the instrument.
Inserting a common-mode filter (EMI choke) into the ingress circuit
For maximum effectiveness, choose a common-mode filter with high impedance. The more filters
are added, the more effective this measure will be.
Isolation
Photoisolation of control lines is an effective noise countermeasure. It is also effective to isolate
power lines with a noise-suppressing transformer. Please note that use of a common ground line
across the isolation will reduce the effectiveness of this approach.
Appx. 5
Self-calibration
The instrument’s self-calibration function serves to maintain measurement precision by correcting
for fluctuations in the internal measurement circuitry. The instrument is designed for automatic self-
calibration.
Specific operation depends on the measurement state (p. 37)
RUN
state
Self-calibration is performed between measurements.
STOP
state and
when using
the
EXTERNAL
trigger source
Self-calibration is performed continuously while waiting for a trigger. When a trigger
is input, self-calibration stops, and measurement starts. Once measurement is
complete, self-calibration resumes.
If the trigger function’s “number of measurements” parameter is set to a value other
than 1, self-calibration will resume after the set number of measurements has been
performed.
10
9
8
7
6
5
4
3
2
1
Appx.
索
索
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