Hioki ST4030, Instruction Manual, Page: 245 / 256

237
Precautions when Processing Test Leads
15.10 Precautions when Processing Test Leads
WARNING
To prevent electric shock and instrument malfunction, separate the core of the
processed lead and the shield (=case pole) by at least 16 mm, and do not connect
them.
OK NO
16 mm or
longer
Shield
core wire
OK NO
Precautions when creating a switching device
• To boost test reproducibility, use coaxial measurement cables. When single-wire cables are
used, differences in cable routing will result in significant fluctuations in the coupling capacitance
between cables. Use coaxial cables whose rated voltage is higher than the test voltage.
The instrument uses special-order coaxial connectors that are not available commercially. It is
recommended to use Model L2250 Clip Type Leads or Model L2252 Unprocessed Lead Cable to
connect probes to the instrument. Model L2250 Clip Type Lead with a cable length of 3.0 m and
5.0 m are available on a special-order basis. Please contact your your authorized Hioki distributor
or reseller.
• Test lead shielding, the coaxial connector outer conductor, and the instrument’s enclosure are at
ground potential. When fabricating cables yourself, connect the coaxial cables’ shielding to the
ground potential. Failure to do so will make the setup more susceptible to external noise.
• The parasitic inductance of the test leads connected to the HIGH and LOW terminals will fluctuate
on the order of several microhenries depending on the shape of the 2 cables.
• For example, the inductance difference when winding a 1.5-m cable (Model L2250) in the 2 ways
shown below is approx. 1 µH.
15
Appendix