Voltech ATi User Manual page 355

7.1.14 C2 – C
APACITANCE
Measurement
Range
1:1000 to 1000:1
Capacitance occurs in transformers due to the physical proximity of, and
electrostatic coupling between, different turns of wire.
In general, the capacitance is distributed between different layers within
a winding, and between the outside layer of one winding and the inside
layer of the next. Although the capacitance is distributed, it is usually
represented by a simple equivalent circuit showing a single capacitance
from one winding to the next.
Where Used
The capacitance match test – as opposed to an ordinary capacitance
measurement (C) - is used on power conversion, audio and
telecommunications transformers where it is important that the capacitance
between different pairs of windings is controlled and matched. Mismatched
capacitances may couple unwanted noise signals from one winding to another
or ground. The test will determine if one winding has been placed incorrectly or
if the wrong thickness of insulation has been used.
V AT U
OLTECH I SER
M
ATCH
Test
Voltage
1mV to 5V
M
ANUAL
Test
Frequency
20Hz to 3MHz
Basic
Accuracy
0.2%
P 7-57
AGE