Hioki 3504-40 C HiTester, Instruction Manual

Page: 274 / 292

Appendix 1 Countermeasures Against Incorporation of External Noise
A2
Attaching an EMI Suppression Ferrite Core to the Power Cord
Pass the power cord through a commercially available EMI suppression fer-
rite core and secure the core as close as possible to the AC power inlet of the
unit in order to suppress the incorporation of noise from the power line.
Suppression is even more effective if you also attach an EMI suppression fer-
rite core close to the power plug of the power source.
If a toroidal ferrite core or split ferrite core with a large enough internal diam-
eter is used, the amount of noise suppression can be increased by passing
the power cord through the core several times.
EMI ferrite cores and ferrite beads are commercially available from various
specialist manufacturers.
You can use the following countermeasures to reduce the effect of noise
being incorporated from, for example, a probe or fixture.
Attaching an EMI Suppression Ferrite Core to Commercial Cables
Noise from things like probes can be suppressed if you pass them through
commercially available EMI suppression ferrite cores and secure the cores as
close as possible to the measurement terminals. Furthermore, if large
enough ferrite cores are used, the amount of noise suppression can be
increased by passing things like probes through the cores several times in
the same manner as with the power cord.
Appendix 1.2 Countermeasures Against Incorpora-
tion of Noise from the Input Line
(Types of Probe)
EMI Suppression Ferrite Core