The elec-
tricity generated power station stepped for distribution the
National Grid Network.
A Current Transformer (or CT) has the large load currents connected to
the primary winding the transformer and the ammeter connected the
secondary winding.
Definition
Step down Transformers are used to
reduce the output voltage, often for
safety reasons.
Types transformer
Step down Transformers are used reduce the output voltage, often for
safety reasons. The ammeter calibrated take account the turns
ratio the transformer, that the ammeter displays the actual current
being taken the load when the ammeter actually only taking small
proportion the load current.
From the general equation:
V
V
N
N
p
s
p
s
the equation for the secondary turn is:
N
N V
V
N
V
V
s
p s
p
s
∴
800 12
230
42 turns
42 turns are required the secondary winding this transformer give secondary
voltage 12V. Figure 10.
Step Transformers are used to
increase the output voltage.
. The turns ratio 1:2 and, therefore, the secondary voltage doubled. Figure 10.23 shows step transformer where the
primary winding has only half the number turns the secondary wind-
ing. The elec-
tricity generated power station
is stepped for distribution the
National Grid Network.
Instrument Transformers are used industry and commerce that large
currents and voltage can measured small electrical instruments.
Step Transformers are used increase the output voltage.
Key Fact
Transformers
● Transformers are very efficient
(more than 80%) because they do
not have any moving parts.Baisc Electrical Installation Work
214
Secondary coil
500 turns
Ns 500
Vp 230V supply 115V output
Primary coil
1000 turns
Np 1000
L
o
a
d
Magnetic flux
2:1 turns ratio
FIGURE 10.22 shows step down transformer where the pri-
mary winding has twice many turns the secondary winding. The turns
ratio 2:1 and, therefore, the secondary voltage halved.22
A step down transformer
