Research transformer mam gina
1. TYPES OF TRANSFORMER According to Construction
(i)
Core type transformer
In core type transformer, windings are cylindrical former wound, mounted on the core
limbs. The cylindrical coils have different layers and each layer is insulated from each other.
Materials like paper, cloth or mica can be used for insulation. Low voltage windings are
placed nearer to the core, as they are easier to insulate.
(ii)
Shell type transformer
One of the main differences between a core-type transformer and a shell-type transformer is how the
winding surrounds the core. In shell-type transformers, the core surrounds the transformer's windings,
while on a core-type transformer, the windings wrap around the core.
a. A core type transformer has two cylinders and two horizontal bars forming the frame. The
magnetic core is a square form with a common magnetic circuit. The cylindrical coils (HV and LV)
are located on two cylinders.
b. b. Shell type transformer has a center cylinder and two outer cylinders.
Both the HV and LV coils of it are located on a center column. This
transformer has a dual magnetic circuit.
c. Berry type transformer: Magnetic circuit looks like a wheel. The metal
shell is tightly fixed and filled with oil inside. Sometimes, a berry type
transformer is also considered a shell type transformer. But due to
different core designs and shapes, it is named a berry type transformer.
TYPES OF TRANSFORMER According to Function/Application
2. Types of transformers based on voltage
conversion(function)
a. Step-up transformer
The step-up transformer helps the voltage increase on the output side because
the number of turns on the secondary is always more than the number of turns
on the primary. A high voltage is developed on the secondary side of the
transformer.
In countries like India, electricity is generated at 11kv. For economic reasons,
AC power is transmitted at very high voltage (220v-440v) over long distances.
Hence a step-up transformer is applied at the generating station.
b. Step-down transformer
A step-down voltage transformer reduces the output voltage. In other words, it
converts high voltage, low current power into low voltage, high current power.
For example, the power supply has a voltage of 230-110v, but the doorbell only
requires 16v. Therefore, it is recommended to use a step-down transformer to
reduce the voltage from 110v or 220v to 16v.
For many regions, the voltage is reduced to 440v / 230v for safety reasons, so
the number of turns on the secondary is less than the primary ones; Less
voltage is generated at the transformer's output (secondary) end.
3. Types of transformers based on their purpose (usage)
a. Power Transformer
Power transformers are mainly used in the transmission networks of higher
voltages. Its ratings are as follows 400kv, 200kv, 110kv, 66kv, 33kv. Most of
the power transformer is rated above 200MVA. They are installed at the
generating stations, transmission substations, which need a high-capacity
transformer. The power transformer is designed for maximum efficiency of
100% and is larger than the distribution transformer.
At a very high voltage, the power cannot be distributed to the consumer directly
because they need smaller voltage, so the power is stepped down to the
desired level with the help of a step-down power transformer. The transformer
is not loaded fully; hence the core loss occurs for the whole day, but the copper
loss is based on the load cycle of the distribution network.
Suppose the power transformer is connected to the transmission network. In
that case, the load fluctuation will be significantly less as it is not connected to
the consumer end directly. Still, if connected to the distribution network, there
will be fluctuations in the load.
The transformer is loaded for 24 hours at the transmission station; thus, the
core and copper loss will occur for the whole day. The power transformer is
cost-effective when the power is generated at low voltage levels. If the voltage
level is raised, then the current of the power transformer is reduced, resulting
in I2R losses and the voltage regulation is also increased.
b. Distribution Transformer
A distribution transformer, also known as a consumption transformer, is
responsible for switching from a low medium voltage source to the voltage used
for home appliances and industrial equipment.
Distribution transformers are intended to reduce the voltage for distribution for
users or commercial use. This machine has good voltage regulation and can
operate 24 hours a day with maximum efficiency at 50% load.
c. Isolation Transformer
Isolation transformers are transformers with the primary and secondary winding
independently of each other, and there is only a magnetic flux relationship
between them. Unlike autotransformers, isolating transformers are composed
of the primary and secondary windings linked only through a magnetic field. The
windings are separated so that they are electrically independent and form the
distinct points of the isolation transformer:

Any point on the secondary coil has a voltage of zero relatives to the
ground. So when we touch any point on the secondary winding, there will
be no shock. The voltage is different in the 2 points of the secondary
winding, which is the most significant advantage of the isolation
transformer. It helps to reduce the risk of electrical leakage in the device
housing and provides safety during use.

Each primary or secondary winding has a different volt-ampere
characteristic according to the ratio of turns on the primary and secondary
districts.
d. Instrument Transformers
The instrument Transformer is generally called an isolation transformer. It is an
electrical device used to transform current as well as a voltage levels. The most
common use of instrument transformers is to safely isolate the secondary
winding when the primary has high voltage and high current supply. The
measuring instrument, energy meters, or relays connected to the transformer's
secondary side will not get damaged. The instrument transformer is further
divided into two types:

Current Transformer (CT)

Potential Transformer (PT)
e. Current Transformer
The current transformer is used for measuring electricity and also for protection.
When the current is high to apply directly to the measuring instrument, the
current transformer is used to transform the high current into the current
required value in the circuit.
The transformer's primary winding is connected in series to the main supply and
the various measuring instruments like an ammeter, voltmeter, wattmeter, or
protective relay coil to measure and control electricity. They have an accurate
current ratio and phase relation to enable the meter accurately on the
secondary side. The term ratio is significant in CT.
f. Potential Transformer
The potential transformer is an instrument transformer used to transform
voltage from a higher value in the primary windings to a lower value in the
secondary windings. This transformer steps down the voltage to a safe limit
value that the ordinary low voltage instrument like wattmeter, voltmeter, and
watt-hour meters can easily measure.
It has distributed magnetic circuit with more than two magnetic flux paths.
Due to a more significant number of paths, it creates more leakage flux. And
hence, the efficiency of this transformer is less compared to the core type and
shell-type transformer.
Generally, the berry type transformer is kept in tightly fitted metal tanks.
These tanks are manufactured from specific high-quality steel plates and
make a rigid structure.
Why is a Berry Type Transformer Used?
In berry type transformer, the flux has many paths available, and it has a
separate core to complete the magnetic circuit. In most cases, this type of
transformer is only used to build high-capacity transformers.
Due to the unique construction of the core, the heat produced in the winding
is distributed. So, in this type of transformer, the coils remain cooler than a
core and shell-type transformer.
Hence, this type of transformer is used to build a large capacity of a
transformer. For a small rating of transformer, this type of construction is not
used.
The core of a berry type transformer looks like spokes of wheels. The core of
this transformer is constructed in such a way that the magnetic circuit finds a
number of paths to pass flux.
TYPES OF TRANSFORMER According to Lamination
thin sheet steel plates known as laminations (this reduces 'eddy current' losses)
types of lamination are known by the shape of alphabetic letter that they
form. The most common type is the 'E' & 'I' form, the 'T' & 'U' is still used, but was
more common in days past. The laminations are often oxidized to form a surface
film of oxide that has a higher resistance than plain steel, thus isolating each layer
to a certain extent and reducing eddy currents that may occur perpendicular to the
plane of lamination. Sometimes one or both sides of a lamination are sprayed with
lacquer for insulation purposes.
These lamination stampings when connected together form the required core
shape. For example, two “E” stampings plus two end closing “I” stampings to
give an E-I core forming one element of a standard shell-type transformer
core. These individual laminations are tightly butted together during it’s
construction to reduce the reluctance of the air gap at the joints producing a
highly saturated magnetic flux density.
Transformer core laminations are usually stacked alternately to each other to
produce an overlapping joint with more lamination pairs being added to make
up the correct core thickness. This alternate stacking of the laminations also
gives the transformer the advantage of reduced flux leakage and iron
losses. E-I core laminated transformer construction is mostly used in isolation
transformer’s, step-up and step-down transformer’s as well as the auto
transformer.
Berry transformer is also called toroidal transformer, which is a large type of electronic transformer
and has been widely used in home appliances and other electronic equipment with high technical
requirements. Its main use is as a power transformer and an isolation
transformer. Berry transformers have a complete series abroad and are widely used in computers,
medical equipment, telecommunications, instruments and lighting.
Berry Transformer Product Classification
Berry transformers can be divided into three types: standard type, economic type and isolation type.
Other forms are possible and one of these is the 'F' & 'F' type .
Laminations are mostly used at power distribution frequencies of 50 Hz or 60
Hz and audio frequencies, if higher frequencies (up to a hundred or so kHz) are
envisaged then ferrite or other sintered iron oxide compounds are used to make
solid split cores.
The laminations when assembled form an interleaved 'stack' or 'core'. The
interleaving is usually to avoid any gaps in the magnetic circuit as air is much less
permeable to magnetic flux than iron and steel.
2. PARTS OF POWER TRANSFORMER -Uses or Function of each part
basic parts of a Power Transformer
1. Transformer Tank – this holds the transformer windings and its insulating
medium (oil-filled). Transformer tanks must be air-tightly sealed for it to
isolate its content from any atmospheric contaminants.
2. High Voltage Bushing – this is the terminals where the primary windings
of the transformer terminates and serves as an insulator from the transformer
tank. Its creapage distance is dependent on the voltage rating of the
transformer.
3. Low Voltage Bushing – like the high voltage bushing, this is the terminals
where the secondary windings of the transformer terminates and serves as an
insulator from the transformer tank. Low voltage bushing can be easily
distinguished from its high voltage counterpart since low voltage bushings are
usually smaller in size compared to the high voltage bushing.
4. Cooling Fins/Radiator – in order for the transformer to dissipate the heat it
generated in its oil-insulation, cooling fins and radiators are usually attached
to the transformer tanks. The capacity of the transformer is dependent to its
temperature that is why it is imperative for it to have a cooling mechanism for
better performance and higher efficiency.
5. Cooling Fans – can be usually found attached to the cooling fins. Cooling
fans can be either be a timer controlled or a winding/oil temperature controlled.
Cooling fans helps raises the transformer capacity during times when the
temperature of the transformer rises due to its loading. Cooling fans used on
the transformer are actuated by the help of a relaying device which when senses
a relatively high temperature enables the fan to automatically run.
6. Conservator Tank – An oil preservation system in which the oil in the main
tank is isolated from the atmosphere, over the temperature range specified, by
means of an auxiliary tank partly filled with oil and connected to the
completely filled main tank.
7. System Ground Terminal – system ground terminals in a power
transformer are usually present whenever the connection type of the
transformer windings has wye in it. This terminal can be found in-line with the
main terminals of the transformer.
8. Drain Valve – can be usually found in the bottom part of the transformer
tank. Drain valves are used whenever oil replacement is necessary. Through
this valve, the replacement of oil in an oil-filled transformer can be easily done
simply by opening this valve like that of a faucet.
9. Dehydrating Breather – Dehydrating breathers are used to prevent the
normal moisture in the air from coming in contact with the oil in electrical
equipment as the load or temperature changes. This reduces the degeneration
of the oil and helps maintain its insulation capability. When used with
conservator system with a rubber air cell it reduces moisture accumulation in
the cell. Some breathers are designed for sealed tank transformers and breathe
only at pre-set pressure levels.
10. Oil Temperature/Pressure gauges – these are used for monitoring the
internal characteristics of the transformer especially its windings. These
gauges help the operator in knowing the level of temperature and pressure
inside the transformer (oil & winding). This will also serve as an alarm
whenever a certain level is reached that could be harmful to the transformer
windings.
11. Bushing Current Transformers – modern transformer construction
today now includes current transformers. These are usually found around the
transformer terminals which will be later be used for metering and relaying
purposes. Its terminals are found in the control panels attached to the
transformer.
12. Control Panel – this houses all of the transformer’s monitoring devices
terminals and auxiliary devices including the terminals of the bushing current
transformers and cooling fans. Control panels are very useful especially when
a remote control house is needed to be constructed, this will serve as their
connection point.
13. Surge Arresters – this type of arresters are placed right directly before and
after the transformer terminals in order to minimize the exposure of the
transformer. Like any other surge arresters, its purpose is to clip sudden voltage
surge that can be damaging to the winding of the transformer.
https://www.rgpv.ac.in/campus/BTech_I/transformer.pdf
https://vietnamtransformer.com/our-news/types-of-transformer#1a
https://www.electrical4u.com/berry-typetransformer/#:~:text=Sometimes%2C%20a%20berry%20type%20transformer,it%20creates%20more%2
0leakage%20flux.
https://www.electronics-tutorials.ws/transformer/transformer-construction.html
https://www.kritester.com/new/core-shell-berry-typetransformer.html#:~:text=The%20iron%20core%20of%20the,than%20the%20traditional%20laminated%
20core.
http://www.dave-cushman.net/elect/transformers.html
https://powersystemsloss.blogspot.com/2011/06/parts-of-powertransformer.html?m=1&fbclid=IwAR1X0oyZNKmj7B8mCTnP3EXrl8b2ODjjLQxKhSDpdEnDFA7BLpi8pywGrM