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Electrical Applications 2 by David W. Tyler

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Transformers
77
MEASUREMENT
OF
POWER
AND
POWER
FACTOR
Current
and
voltage transformers
are
used
to
isolate wattmeters
from the high voltage system in which the power is to be measured.
The connections
for
a
single-phase wattmeter are shown
in
Figure
5.21.
The
voltage
and
current coils
are
connected
on one
side
to
earth
for
safety reasons as already outlined.
V.T.
Figure
5.21
Earth
f
/.
.
C-T. Line
Λ
/I
rw> J\|
3.
Neutral
\Current coil
Wattmeter
Voltage coil
Example 5.
A
voltage transformer
of
ratio