Megger BM80/2 Série Guide De L'utilisateur page 14

Application Notes
longer e.g. long supply cables. The absorption
current decreases relatively slowly compared
with the charging current. In essence it
depends upon the nature of the insulation
material.
The conduction or leakage current builds up
quickly to a steady value and then remains
constant for a particular applied voltage under
stable conditions. It is this current that is
affected by moisture, dirt etc. and the degree
to which it flows bears a direct relation to the
quality of the insulation, and consequently to
the value of the insulation resistance
measured. An increase in the leakage current
is a pointer to possible future problems.
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