Hioki BT3564, Инструкция по эксплуатации, Страница: 189 / 210

Appendix 5 Configuration and Extension of the Test Leads
A
7
Appendi
x
The test lead extension is normally performed by Hioki. If you want extension
performed, contact your authorized Hioki distributor or reseller.
Observe the following points when extending test leads:
• Use the thickest lead available. Extend the lead only by the necessary
amount.
• Maintain the AC four-terminal configuration while extending the lead. Chang-
ing the four-terminal configuration to a two-terminal configuration can result in
measurement data being affected by lead resistance and/or contact resis-
tance, resulting in inaccurate measurement.
• Make the branch section as short as possible. Try to extend the thick lead
instead.
• While measuring, avoid as much as possible pulling or repositioning the test
leads after executing zero adjustment.
• Extending test leads may result in excessive voltage drop. The total resis-
tance of the test leads and contacts must remain below 20  .
• To prevent eddy currents from affecting measurement, keep test leads away
from metallic parts.
• After extending the test leads, confirm proper measurement operation and
accuracy.
Reducing Induced Voltage
Since the instrument measures a minute resistance with AC power, it is affected
by induced voltage. Induced voltage refers to voltage that allows the current gen-
erated in the instrument to build an inductive coupling in a lead and affect signal
lines. Since the phase of the induced voltage is shifted from that of the AC cur-
rent (reference signal) by 90 degrees, it can be eliminated with the synchronous
detection circuit if the voltage is low. But for high levels, the induced voltage dis-
torts the signals, causing incorrect synchronous detection. The instrument moni-
tors induced voltage internally and generates an abnormal measurement signal
if the level rises above a certain level. Reducing the length of the lead will lower
induced voltage. Reducing the length of the branched section is particularly
effective.
Appendix 5 Configuration and Extension of the
Test Leads
HIOKI BT3564A961-02