Hioki RM3545, Instruction Manual, Page: 96 / 364

4.10 Checking for Poor or Improper Contact (Contact Check Function)
88
This function detects poor contact between the probes and measurement target, and bro-
ken measurement cables.
The instrument continually monitors the resistance between the SOURCE A
and SENSE A
probes and the SOURCE B and SENSE B probes from the start of integration (including
response time) and while measuring. When the resistance is outside of the threshold, a
contact error is determined to have occurred.a
When a contact error occurs, CONTACT TERM.A or CONTACT TERM.B error message
appears. No comparator judgment is applied to the measured value. When these error
messages appear, check the probe contacts, and check for broken measurement cables.
When the resistance value between the SENSE and SOURCE is high, for example when
the measurement target is conductive paint or conductive rubber, you will not be able to
perform measurement due to the continuous error state. In this case, turn off the contact
check function.
(If the error is not cleared by shorting the tips of a known-good measurement cable, the
instrument requires repair.)
See: "3.5 Checking Measured Values" (p.52)
See: "Appendix 14 Checking Measurement Faults" (p. A32)
•
The contact check threshold is about 50
Ω
. Because the threshold depends on the mea-
surement target, connection cables, measurement range, and other factors, it may not
reach 50
Ω
. Additionally, if the source resistance value alone is large, a current fault may
occur without a contact error. (p.55)
•
Turning the setting off with the 100 M
Ω
or greater range will cause the contact check
function to operate continuously.
•
When set to 2-wire with the multiplexer, the contact check function will be turned off.
•
During low-resistance measurement, poor contact of the SOURCE A or SOURCE B
probe may be detected as an over-range measurement.
•
When contact checking is disabled, measured values may be displayed even when a
probe is not contacting the measurement target.
•
When the contact check is disabled, the measured value error component may increase
when the contact resistance increases.
•
When using the INT trigger source, current will stop when a contact error occurs (when
not connected to the measurement target). By contrast, when using the INT trigger
source with the contact check function off, the measurement current is always applied,
even when the instrument is not connected to the measurement target. Consequently, a
rush current will flow at the moment the instrument is connected to the target (for exam-
ple, measuring a pure resistance in the 1 A measurement current range will result in a
maximum current of 5 A with a convergence time of 0.5 ms). When measuring easily
damaged elements, either turn on the contact check or use a range that results in a low
measurement current. However, if there is chatter even when the contact check is
enabled, it will not be possible to completely prevent a rush current.
•
Routing measurement cables together with power lines, signal lines, or measurement
cables for other devices may result in a contact error.
•
The contact check function default setting is disabled during low-power resistance mea-
surement. Turning on the contact check function will cause the open terminal voltage to
change to 300 mV.
4.10 Checking for Poor or Improper Contact
(Contact Check Function)