Hioki RM3545, Instruction Manual, Page: 343 / 364

Appendix 13 Making Your Own Measurement Leads, Making Connections to the Multiplexer
A31
A
ppend
ix
•
Since the voltage detection circuit’s input resistance is sufficiently large, the SENSE line
wiring resistance can be as high as 1 k
Ω
without affecting measured values. However,
the wiring resistance should be minimized due to susceptibility to noise. If an excessively
high wiring resistance causes the contact check to generate an error, decrease the wiring
resistance or disable the contact check function.
•
Long wires are susceptible to noise, and measured values may be unstable.
•
Extensions should maintain the four-terminal structure. If converted to a two-terminal cir-
cuit in the wiring, correct measurement may not be possible due to the effects of wiring
and contact resistance.
Example that would result in error:
Four-terminal wiring from the instrument to the relay, but two-terminal wiring from the
relay.
•
After extending measurement leads, confirm operation and accuracy ("Measurement
Specifications" (p.250)).
•
If cutting the ends off of Hioki measurement leads,
make sure that the shield does not touch the center
conductor of the SOURCE A, SENSE A, SENSE B
and SOURCE B leads. Correct measurement is not
possible with a shorted lead.
•
Do not connect the end of the shielding wire to a
ground or other terminal. Doing so will create a
ground loop, making the instrument more suscepti-
ble to noise. Keeping the shielding wire away from
the center conductor, process the ends of the leads
so that they do not come into contact with nearby
metal objects.
•
Do not apply a current of 1 mA or more to the
GUARD terminal. This terminal is not for guard-
ing network resistance measurements.
Center
conductor
Shielded
wiring
Example of defeated guard measurement