Agilent Technologies 16451B, Operation Manual

Page: 109 / 149

between electrodes and their theoretical value . Use the following
procedure:
1. Measure the capacitance at three dierent electrode distances ,
such as 40 m, 50 m, and 60 m.
2. Calculate the theoretical capacitance value of each distance . The
theoretical capacitance value C
t
can be obtained as follows .
C
t
=
a
2
0
2
2 (d= 2)
2
t
set
2
a
Where ,
C
t
Theoretical capacitance value [F]
a
Dielectric constant of air (=1.00059)
0
= 8.854 2 10
-12
[F/m]
a
Eective area coecient of electrode when the electrode
distance is t
set
.
(Refer to \Eective Area of Electrode " in \Error F actor
using Contacting Electrode Method".)
t
set
Reading value of the electrode distance on the micrometer
[m]
3. Calculate the equivalent distance error at each electrode distance .
The equivalent distance error of each electrode distance 1t
e
can be
obtained as follows:
1t
e
=
C
t
C
m
0 1 2 t
set
[m]
Where ,
C
m
Measured capacitance value [F]
4. A verage equivalent distance error The average of equivalent
electrode distance error 1t
a
is derived as follows .
1t
a
=
1t
40
+ 1t
50
+ 1t
60
3
[m]
Where ,
1t
40
Equivalent distance error 1t
e
at 40 m
1t
50
Equivalent distance error 1t
e
at 50 m
1t
60
Equivalent distance error 1t
e
at 60 m
The equivalent electrode distance t
eq
can be derived from a set
value of micrometer t
set
and equivalent distance error 1t
a
shown as
follows:
t
eq
= t
set
+ 1t
a
The compensated dielectric constant is obtained as follows:
r
=
1
1 0 1 0
C
s 1
C
s 2
2
b
a
2
t
eq
t
a
Where ,
a
and
b
are Eective area constants . F or more
information, refer to \Eective Area of Electrode ".
Operation 3-63