It would appear to be either higher or lower than the impedance during the other half cycle.. far too many variables to predict the answer.
earth impedance
- Thread starter SparkyTris
- Start date
Assuming that you are talking about the impedance as measured with sine wave AC, the only mechanisms I can think of which would result in such a figure being appreciably different from resistance (measured with DC) are ones which would result in the 'DC resistance' being higher. In that sense, I don't think the DC measurements are likely to ever be "unsafely misleading" - it is much more likely that they would be 'unnecessarily pessimistic' (i.e. producing an over-estimate of earth impedance).
However, another factor to consider is that of the voltage used for testing, whether AC or DC, since the apparent impedance/resistance will probably vary, to at least some extent, according to the test voltage.
Kind Regards, John
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