CP TD1 Reference Manual V 1.44
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Figure 5-19 CP TD1 measuring principle
The CP TD1 test system utilizes a method similar to that of the Schering bridge.
The main difference is that the CP TD1 measuring principle (Figure 5-19) does
not require tuning for measuring C and DF. C
n
is a gas insulated reference
capacitor with losses below 10E-5. For laboratory use, such capacitors are
regularly used to obtain precise measurements, as the ambient lab temperature
normally ranges between 20 - 25 °C (68 - 77 °F). When carrying out on-site
measurements, however, temperatures can vary significantly, which results in
changes of the electrodes geometry.
U
0
(t)
U
N
(t) U
X
(t)Z
1
Z
2
I
CN
I
CX
Z
N
C
X
Z
X
, L
X
C
N
Reference path Measurement path