Hioki CM4371 Mode D'emploi page 41

Symptom
• When readings from the
instrument are compared
with those of another
clamp-on current meter, the
measured values differ.
• The current value is larger
than expected.
• A current value is displayed
even though there is no
input.
• A sound is being emitted
by the instrument's clamp
sensor.
• The measured value does
not appear.
• No measured value is
displayed, even when the
test leads are shorted.
• Zero adjustment is
impossible.
Verification and/or Solution
• The instrument cannot accurately measure waveforms that contain a
component that falls outside the frequency characteristics range.
• Since the instrument performs true RMS measurement, it can accurately
measure distorted waveforms. When measuring a distorted waveform,
the measured value will differ from a clamp-on current meter that uses the
averaging method.
• The instrument cannot perform measurement accurately in the presence
of a strong magnetic field from a source such as a nearby transformer
or high-current circuit or in the presence of a strong electric field from a
source such as a wireless device.
• The clamp sensor may emit sound when measuring AC currents in excess
of approx. 500 A, however, there is no effect on the measurement.
• Check the continuity of the test leads. (p. 26)
If a wiring break is found, replace the test leads.
• Insert the test leads all the way.
• Use the proper measurement method.
If no problem can be found, the instrument may be damaged.
Send the instrument for repair.
• When performing current measurement, perform zero-adjustment while no
measurement target is being clamped.
Repairs, Inspections, and Cleaning
37