Core Type and Shell type Transformer Basic
You may ask, where shell type and core type transformer are used and why? Simply we can say actually there is no any hard and fast rule to choose your core type or shell type transformer for a particular ranges area.
Mostly you will find some tendency to choose the core
or shell type transformer used based on the practicalities; and it is a choice
made by the designer.
The core transformer has one magnetic circuits; in this type transformer
both the primary and the secondary windings are wound outside and surround the
core ring means both windings are placed on the side
limbs.
The shell transformer has one magnetic circuit; in this type transformer the
primary and secondary winding pass inside the steel magnetic core which forms a
shell around the winding.
In Practical core type transformer mainly uses in high
voltage applications like electrical energy transmission, primary distribution,
auto power transformer etc. The reasons are
simple-
High voltage system deals high flux and keeping this in
less iron loss the iron core need more
thickly;
1. Heavy insulation is required for high voltage system
and in core type transformer it is easier and cheaper to maintain heavy
insulation. In fact low voltage winding itself acts as an insulation between
high voltage winding and core;
2. The cylindrical coils used in core type transformers
that remarkable construction provides the advantage of getting better mechanical
strength;
3. The core type transformer is typically arranged to
create an overlapping joint with an extra pair of laminations that preventing
condensed flux leakage and iron loss.
4. The core type transformer is efficient for high
frequencies because the core type transformer uses several steel laminations,
which are protected by a non-conducting insulation material between
layers.
The Shell type transformers are popular in Low voltage applications like transformers used in electronic circuits and power electronic
converters etc. The reasons are simple-
1. In low voltage system normally require more volume for
the copper wires than that of iron core. So, shell type transformer is a better
choice in low voltage system;
2. In low voltage shell type transformer higher insulation
is not more considerable. So, it can put the winding anyway you want in the
shell;
3. High short-circuit withstand
capability;
4. High mechanical strength and high dielectric strength
as it’s special construction;
5. The
shell type transformer provides for excellent control of leakage magnetic flux
to prevent against local heating inside the
transformer;
6. The shell type transformer provides efficient cooling
capability;
7. The
shell type transformer also provides compact size
and
flexible design
facility.
Sponsored:
The difference between Core type and Shell type
Transformer, we may consider the key features as windings, limbs, copper requirement, lamination, flux
distribution, windings position, cooling system, repair, design, efficiency
& mechanical strength etc.
Types of Transformer by Construction
Constructionally the electrical transformers are of two general types, distinguished from each other merely by the manner in which the primary and secondary coils are placed around the laminated core.
The two types are known as
(i) core-type and
(ii) shelltype.
Another recent development is spiral-core or wound-core type, the trade name being spirakore transformer. In the so-called core type transformers, the windings surround a considerable part of the core whereas in shell-type transformers, the core surrounds a considerable portion of the windings as shown schematically in Fig.(a) and (b) respectively.
