Appendix 6 Effect of Eddy Currents
A8
The AC current generated in the instrument induces eddy currents in the sur-
rounding metallic plates, which generate induced voltage in the test lead. Since
the phase of this induced voltage is shifted from that of the AC current (reference
signal) by 180 degrees, it cannot be eliminated by the synchronous detection cir-
cuit, resulting in measurement errors. The influence of eddy currents is a phe-
nomenon unique to ohmmeters that measure resistance with AC power. To
protect the test lead from such effects, keep metallic parts, including metallic
plates, at a suitable distance from the test lead (branched section).
Appendix 6 Effect of Eddy Currents
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