Small trans-
formers are used isolating transformers shaver sockets and can also
be used supply separated extra low voltage (SELV) sources.18. This includes equipment such water heaters, pumps for
showers and whirlpool baths. Because has moving parts, transformer can
have very high efficiency. Equipment
supplied from SELV source may installed bathroom shower-
room, provided that suitably enclosed and protected from the ingress
of moisture. This useful for low voltage supplies such domestic
bell transformers.
VP VS
IS
IP
Primary
winding turns
Secondary
winding turns
Steel core
Magnetic circuit through core
FIGURE 5.18
Typical oil filled power transformer.17
A simple transformer.
● The voltage both the primary and secondary windings propor-
tional the number turns. sketch oil immersed transformer can be
seen Fig. This often achieved totally immersing the core and
windings insulating oil.
Try This
Have you seen any transformers action?
Were they big small what were they being used for?
Have you been close transmission tower, perhaps when you were walking
in the countryside?
.
● The magnetic flux the core causes voltage induced the
secondary winding the transformers.
Large power transformers need cooling take the heat generated away
from the core.
● This means that you increase the number secondary turns you
will increase the output voltage. 5.
FIGURE 5. This has application power
distribution.Basic Electrical Installation Work
116
● alternating voltage applied the primary winding establishes an
alternating magnetic flux the core.
Very small transformers are used electronic applications. Large power transformers, used electri-
cal distribution systems, can have efficiency better than 90%.
● Alternatively, reducing the number secondary turns will reduce the
output voltage
