HT F3000U, Руководство пользователя

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NEPTUNE
EN - 42
9.2.1. Polarization Index (PI)
The purpose of this diagnostic test is to evaluate the influence of the polarization effects.
Upon the application of a high voltage to insulation, the electric dipoles distributed in the
insulation align in the direction of the applied electric field. This phenomenon is called
polarization. Because of the polarized molecules, a polarization (absorption) current
generates, which lowers the total value of insulation resistance.
Parameter PI consists in the ratio between the value of insulation resistance measured
after 1 minute and after 10 minutes. The test voltage is maintained throughout the whole
duration of the test and, at the end, the instrument provides the value of ratio:
min) 1 (
min) 10 (
Riso
Riso
PI

Some reference values:
PI Value Insulation condition
from 1.0 to 1.25 Not acceptable
from 1.4 to 1.6 Good
>1.6 Excellent
9.2.2. Dielectric Absorption Ratio (DAR)
Parameter DAR consists in the ratio between the value of insulation resistance measured
after 30s and after 1 minute. The test voltage is maintained throughout the whole duration
of the test and, at the end, the instrument provides the value of ratio:
) 30 (
min) 1 (
s Riso
Riso
DAR

Some reference values:
DAR Value Insulation condition
< 1.0 Dangerous
from 1.0 to 2.0 Questionable
from 2.0 to 4.0
Good
> 4.0 Excellent