Hioki RM3545, Instruction Manual, Page: 72 / 364

4.1 Switching to Low-power Resistance Measurement
64
In low-power resistance measurement, the open terminal voltage is limited to 20 mV to
allow measurement with an extremely low current.
When measuring signal contacts (wire harnesses, connectors, relay contacts, or switches),
the low-power resistance measurement function can be used to minimize the effect on the
contact state.
When you measure signal contacts with the low-power function off, the oxide film on the
contacts is more readily damaged.
If the contact’s oxide film is damaged, it will tend to produce lower resistance values.
By contrast, the oxide film on power contacts (high-current contacts) is eliminated during
use. When such contacts are measured with the low-power function on, it is not possible to
break down the oxide film, resulting in higher measured values.
See: "3.1 Checking the Measurement Target" (p.48)
See: "Appendix 11 Measuring Contact Resistance" (p. A26)
•
Because the detection voltage decreases when the low-power function is on, measure-
ment is more susceptible to external noise. If measured values fail to stabilize, take steps
to address the noise, referring to "Appendix 7 Unstable Measured Values" (p. A12). The
following four steps are particularly effective in this situation:
• Shield the measurement cable (connect the shielding to the instrument’s GUARD termi-
nal).
• Twist the measurement cables together.
• Shield the measurement target (connect the shielding to the instrument’s GUARD termi-
nal).
• Decrease the measurement speed or use the averaging function.
•
Since the effects of thermal EMF are eliminated when the low-power function is on, the
instrument will be automatically set to OVC ON. If the measurement target has a large
reactance component, it will be necessary to increase the delay.
See: "4.8 Compensating for Thermal EMF Offset (Offset Voltage Compensation - OVC)" (p.82)
See: "4.9 Setting Pre-Measurement Delay" (p.84)
•
When using the SLOW2 measurement speed with low-power resistance measurement
on, the instrument will average measured values twice and display the result, even if the
averaging function is set to off. If the averaging function is on, the instrument will perform
averaging using the set number of iterations.
•
When low power is set to on, the contact improvement function will be set to off.
•
When low power is set to on, the contact check default setting is off.
4.1 Switching to Low-power Resistance
Measurement
Ranges, measurement currents, and open voltages that can be used with the low-
power function on
Range Max. measurement
range
Measurement
current
Open voltage
1000 m
Ω
1200.00 m
Ω
1 mA
20 mV
MAX
10
Ω
12.0000
Ω
500
μ
A
100
Ω
120.000
Ω
50
μ
A
1000
Ω
1200.00
Ω
5
μ
A