Appendix 7 Unstable Measured Values
A18
(6) Measurement target Becomes Warm
The maximum applied power to a measurement target by this instrument is determined as
follows. The resistance of samples with small thermal capacity can change due to heating.
In such cases, switch to a range with a lower measurement current.
(7) Measuring Transformers and Motors
If noise enters an unconnected terminal of a transformer or if motor rotor moves, measure-
ments may be unstable due to induced voltage on the measured winding.
The effects of noise can be reduced by shorting transformers’ empty terminals. Exercise
care not to induce motor oscillation.
(8) Measuring Large Transformers or Motors
When measuring measurement targets with a large inductance component and a high Q
value, such as large transformers or motors, measured values may be unstable.
The RM3544 depends on constant current flow through the measurement target. To obtain
stability in a constant-current source with a large inductance, response time is sacrificed. If
you find that resistance values are scattered when measuring large transformers or motors,
please consider the above or contact your local HIOKI distributor for further assistance.
Range
Measurement
Current
Maximum Applied Power
= (Measured Resistance) × (Measurement Current)
2
30 m 300 mA 3.2 mW
300 m 300 mA 32 mW
3 30 mA 3.2 mW
30 10 mA 3.5 mW
300 1 mA 350 W
3 k 1 mA 3.5 mW
30 k 100 A 350 W
300 k 5 A 8.8 W
3 M 500 nA 0.88 W
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