Agilent Technologies 4349B - Precharge Time

4349B
Precharge
Time
and
W
ait
Time
When
setting
up
the
system
for
measuring
the
insulation
resistance
of capacitors
, consider
the
precharge
time
and
the
wait
time
.
Note
The precharge
time of
an ideal
capacitor is
described
in
this
section.
Generally
,
you should
consider characteristics
of a
dielectric
for
the
estimation
of
the
actual precharge
time.
Precharge
time
Figure 6-7.
Precharge Time
When the capacitor is charged through precharge register Rp
, the precharge time t
p
is
calculated as follows (where
,Rx
 Rp):
t
p
= 0 C
x
2 R
p
2 lnK
where, C
x
: Capacitance value [F]
K:(T
est voltage
0 Charge voltage) / T
est voltage
For example
, when Rp
is 1 k (=10
3
), Cx is 1
 F
(=10
0 6
F), and K is 0.1, the
precharge
time is,
t
p
= 0 10
0 6
2 10
3
2 ln 0 : 1
=2 : 3[ ms ]
In this example, one precharge stage is enough because t
p
is less than the measurement time.
6-12 Application Measurement