Hioki ST4030, Instruction Manual, Page: 30 / 256

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Inspecting before Measurement and Verifying Operations
(2) Waveform reproducibility is poor.
Periods of magnetic saturation reduces the workpiece inductance, so the vibration frequency of the
response waveform increases (i.e., inclination is more sudden).
The waveform may experience major variation when multiple impulse tests are performed on the
same workpiece because of the magnetic characteristics of the core.
If the core is magnetically saturated, the
waveform will tilt rapidly.
(3) Being affected by the magnetic anisotropy of the workpiece core.
The characteristics of the magnetic materials may depend on its orientation. Implement the tests
using the same layout as during the voltage calibration.
(4) The master workpiece has been changed.
Recalibrate the voltages.
Even if the coil and motor have the same model number, if they have different magnetic core
characteristics (varied by lot), there is a risk that the waveform will change due to differences in the
stray capacitance of the workpiece.
(5) The equipment cable or device connected in parallel to the instrument has changed.
The cable capacitance and the parasitic capacitance of the equipment connected in parallel affects
the vibration frequency. Recalibrate the voltages.
Example: Waveform difference due to cable length when implementing impulse tests on coils with
the same inductance values (1 mH).
If 1.5 m
If 3.0 m