desin of dry transformer

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Abstract:
This paper is a research based on the upcoming type if transformer which is a dry
type transformer or commonly
known as Cast resin transformer. The study focuses on the manufactu
ring process of producing transformer as well as the
design and temperature control relay. Moreover the advantages using dry type
transformer over the other types will be
analyzed.
The transformer is also widely used its load for maximum power transfer, is
olating one circuit from another, or
isolating direct current while maintaining ac continuity between two circuit. In this paper, the
design of 315 kVA, 11/0.4kV
dry
type distribution transformer is discussed. Rectangular wire is used in low voltage windin
g as well as round wire is used in high
voltage winding in this transformer design. Dry
type are normally cooled by natural circulation of air and also the type of epoxy
material that is used on the windings help minimize the heat dissipated by the copper
when the transformer is loaded.
Keywords
:
Transformer Design, Temperature Control Relay, Cooling System, Dry Type, Round And
Rectangular Wires.
I. INTRODUCTION
Transformers are electric equipment that changes the
voltage and the current of electrici
ty to facilitate its efficient
transmission and distribution. Transformers are commonly
use at power generation facilities to increase voltage and to
decrease current in order to transport electric energy across
transmission lines. When the electricity rea
ches the end user,
transformers are used to reduce voltage and to increase
current to make the electricity suitable for general use. The
process of transforming voltage results in energy loss that is
released in the form of heat and therefore transformers
must
contain effective cooling systems. Dry type transformers
dissipate heat directly into the ambient air. Liquid cooled
transformers dissipate heat into liquid mediums.
Dry type
transformers require little or no maintenance through their
service life oth
er than assuring that connections remain clean
and tight, that the loading on the transformer remains within
design limits, and that air flow through the transformer is not
impeded by extraneous materials or dust.
Dry
type transformers are therefore th
e primary choice for
indoor locations, and can be used anywhere a transformer is
required.
Dry
type transformers are replacing liquid
immersed transformers in many commercial and industrial
applications including power plants, hospitals, schools, multi
sto
ry buildings, paper and steel mills, mining, chemical
plants and subway systems.
There are many types of dry type
transformer. Some of dry
type transformers are

Cast resin dry type transformer

Gas
filled dry type transformer

Epoxy coated dry type transform
er

RESIBLOC epoxy cast type transformer

Vacuum pressu
re impregnated conventional dry
type transformer and so on.
II.
CAST
RESIN
DRY
TYPE
DISTRIBUTION
TRANSFORMERS
Cast resin dry type transformer is a transformer which one
of the dry type transformers
a
s shown in Fig.1
.
A cast resin
dry
type indoor 3phase, 315kVA, 11/0.4 KV, Dyn11,
distribution transformer has been developed. This
transformer is of IP00 protection degree
This transformer is
the most suitable transformer for distribution of electricity in
high degree of safety.
They do not propagate fire. They are
self
extinguishing and in the event of a break down, there is
no risk of leakage of inflammable or contaminating
substances such as oil.
The thickness insulation pouring with
transformer, with thi
ck insulation transformer is filter casting
resin encapsulation winding transformer, cast resin plus
quartz powder as casting, quartz powder 60%, only 40% of
resin and pigment of the product. Thickness of epoxy resin
before casting in general 6~12 mm, now
3~ 5 mm, thick
insulation pouring it said transformer. Flame
retardant, self
extinguishing, good, high mechanical strength.
In a two winding transformer two windings would be
present. The one which is connected to a voltage source and
creates the flu
x is called as a primary winding. The secondary
winding where the voltage is induced by induction is called a
secondary. If the secondary voltage is less than that of the
primary the transformer is called a step down transformer. If
A
YE
A
YE
P
YONE
,
M
YO
T
HET
T
UN
International
Journal of Scientific Engineering and Technology Research
Volume.0
3
,
IssueNo.
1
7
,
August
201
4
, Pages:
3500
350
4
the secondary voltage i
s more than it is a step up transformer.
A step down transformer can be made a step up transformer
by making the low voltage winding its primary. Hence it may
be more appropriate to designate the windings as High
Voltage (HV) and Low Voltage (LV) windings.
The high
voltage and low voltage coils are wound of either copper or
aluminium conductor which are suitable for class F and class
H insulation systems. The coils are completely impregnated
and cast under vacuum in fiberglass reinforced epoxy resin
into th
e moulds. The casting process produces an insulation
system of uniform fiberglass
epoxy laminate. The final
product is a composite of highest electrical and mechanical
quality. The windings are embedde
d into the first class
lamina
Fig.1.
Cast resin dry ty
pe transformer [3]
.
A.
Basic Parts of Cast Resin Dry
type Transformer
a)
Core
Fig.2 presents the c
ore is made of cold
rolled electro
technical sheet steel with a heat
proof coating. Stacking
technology and step
lap cutting provide low level of no
load
losses. Cutting of
lector
technical steel is carried out on the
automatic cutting line with the high cut accuracy.
Fig
.
2. Stacking core
.
b
)
High
And Low Voltage Windings
High voltage windings are made in layer or section
layer
form with the series conne
ction of sections forms.
Low
voltage winding are made in foil or layer form.
HV and LV winding is made of insulated wire on high
accuracy coil
processing machines. Vacuum resin filling of
windings is carried out during a completely automated
process. E
poxy compound includes a number of components
providing a good heat emission, and also a high
thermostability.
c
)
Transformer
Windings
Windings form another important part of transformers.
The windings of the transformer are normally arranged in the
f
ollowing two ways:

Concentrically in relation to one another (used for
core type) and called concentric winding.

In group of LV, HV coils stacked alternately one
over the other, along the height of the limb (used for
shell type) and known as interleaved w
inding or
sandwich winding.
Most commonly used types
of winding in transformers are
the following:

Cross over winding

Continuous disc coil type winding

Disc type section winding

Helical winding

Sandwich winding (for shell type transformer)

Dry type/
Cast resin [1]
d
)
Transformer
Housing
Transformer housing provides necessary protection degree
of the active part. It is made of steel construction with walls,
a bottom and a roof. The walls and the bottom havevent
holes, providing a normalized cooli
ng level of the
transformer. Wide walls have access panels for access to
adjusting taps. Al walls are deta
chabled that
assures visual
inspection and maintenance service on a schedule date.
Transformers can be manufactured of the following design
versions:

Lеft:
HV winding inputs are on the left regarding
the front;

Right:
HV winding inputs are on the right regarding
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