15
PM5A2
7.1. Measurement of the Dielectric Absorption Index (DAI)
When pressing the
key during the test, the Dielectric Absorption Index (DAI) value will be exhibited on the
display. It is only possible to apply this function after a minimum of 1 minute of measurement; in case the key is
pressed before this minimum limit, the display will show the message of value exhibition of DAI value, but will not
show any value.
The DAI index is the quotient between the values of the insulation resistance measured at the 60 and 30 second,
and it is useful for preventive and predictive maintenance of windings (present in transformers, motors, generators,
etc.).
=
D
A
I
R
R
6
0
s
e
c
o
n
d
s
3
0
s
e
c
o
n
d
s
7.2. Measurement of the Polarization Index (PI)
When pressing the
key during the test, the Polarization Index (PI) value will be exhibited on the display. It is
only possible to apply this function after a minimum of 10 minutes of measurement. If the key is pressed before this
minimum limit, the display will show the message of PI value, but will not show any other values.
The polarization index is the quotient between the values of the insulation resistance measured both in 10 minutes
and 1 minute. This index is useful to detect the damage of the insulation resistance by the excessive presence of
dust, dirt and greases or through the action of chemical and physical agents.
=
P
I
R
R
1
0
m
in
u
te
s
1
m
in
u
te
