Section 1 Power Transformer Transformer is a vital link in a power system which has made possible the power generated at low voltages (6600 to 22000 volts) to be stepped up to extra high voltages for transmission over long distances and then transformed to low voltages for utilization at proper load centers. The power transformer adjusts the voltage to a suitable level of power transmission from generation to the end- user. This means stepping up the voltage at generation for long transmission with low losses and down to domestic voltage manageable in the power outlet for home and industry. Power transformers are used to convert from one voltage to another, at significant power levels. Types: (i) Closed - Core type The close-core transformer has heavily insulated coils wound around a square metal doughnut. The magnetic field is provided with a continuous path so that a relatively small amount of magnetic energy is lost. The transformer core is laminated (made up of thin strips of steel pressed together). Each strip or layer is insulated by paint or enamel. A laminated core offers a much higher resistance to the flow of eddy currents than a core of solid construction. The doughnut type of closed-core transformer is efficient 1
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Section 1
Power Transformer
Transformer is a vital link in a power system which has made possible the power
generated at low voltages (6600 to 22000 volts) to be stepped up to extra high
voltages for transmission over long distances and then transformed to low voltages for
utilization at proper load centers. The power transformer adjusts the voltage to a
suitable level of power transmission from generation to the end-user. This means
stepping up the voltage at generation for long transmission with low losses and down
to domestic voltage manageable in the power outlet for home and industry. Power
transformers are used to convert from one voltage to another, at significant power
levels.
Types:
(i) Closed - Core type
The close-core transformer ha s heavily insulated coils wound around a
square metal doughnut. The magnetic field is provided with a continuous
path so that a relatively small amount of magnetic energy is lost. The
transformer core is laminated (made up of thin strips of steel pressed
together). Each strip or layer is insulated by paint or enamel. A laminated
core offers a much higher resistance to t he flow of eddy currents t han a core
of solid construction. The doughnut type of closed-core transformer is
efficient and is commonly utilized in x-ray generating equipment. Usually,
t he high voltage transformer is submerged in a special type of oil to ensure
maximum insulation and cooling.
Core type transformer
(ii) Shell type
The shell-type transformer is considered t he most efficient. Such
transformers are used in transmitting commercial power. The core of t he
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shell-type transformer is made of laminated silicon steel sheets placed on top
of one another. The coils are wound around t he central section of t he core.
Since t he primary and secondary coils are wound close together around t he
core, t he windings must be highly insulated. A special insulating material is
coated on t he wires of both coils. For t he high voltage used in x-ray, t he
entire transformer is immersed in a container filled with a special insulating
oil or gas. The insulating oil also helps to cool t he transformer during
operation.
Shell type transformer
Power and water Corporation use Core type transformers.
Another classification is,
(i) Step Up or Step Down
A step up transformer works due to the secondary voltage being greater than the
primary voltage. When the secondary voltage is greater, it steps up the voltage input
at the power source. If the primary winding has fewer turns than the secondary
winding, the device becomes a step up transformer that will increase electrical
voltage.
Step up transformer
A step-down transformer is one whose secondary voltage is less than its primary
voltage. The step down transformer is designed to reduce the voltage from the
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primary winding to the secondary winding. This kind of transformer "steps down" the
voltage applied to it.
Step down pole mounted transformer
(ii) Oil-Filled or Dry
Oil filled transformers are transformers filled with a highly refined mineral oil that is
used to insulate internal live parts of the transformer. The oil prevents corona and
manages temperature control inside the transformer for the prevention of equipment
and machinery overheating during the operation of large job applications. Because of
the oil inside the transformer being of non-combustible properties, these transformers
are very safe and can operate machinery for long periods of time.
Oil Filled transformer
Dry-type transformers have high sound levels, but oil filled transformers are much
quieter due to the immersion of its mechanisms in liquid. This results in less vibration
as well. Oil filled transformers require low maintenance and are quite
environmentally friendly. Dry type means it is cooled by normal air ventilation. The
dry type transformer does not require a liquid such as oil or silicone or any other
liquid to cool the electrical core and coils. Dry type transformers are voltage changing