Page 535 - Basic Electrical Engineering

called the primary winding. The other coil is called the secondary winding.
Supply is taken from the secondary winding by connecting any electrical load
like fan, tube light, electrical motors, etc.

The transformer core is made up of thin sheets called laminations. The
laminated silicon steel sheets are cut into proper size from a big sheet and are

placed one above the other to form the core of required width and cross
section. The laminated sheets are tightly fastened to form the core. If the

laminations are not tightly fastened, they will vibrate in the magnetic field
and give rise to humming noise. This magnetic vibration of laminations is

known as magnetostriction which is not desirable. The core is made up of a
magnetic material using thin laminated sheets instead of a solid one. This is
done to reduce power loss in the core due to circulating current flowing in the

core and producing undesirable heating of the core as well as of the windings
which are wound on the core. The reason for circulating current in the core is

explained below. When an alternating voltage is applied across the primary
winding, an alternating current I will flow through the winding. This current
0
will produce an alternating flux which will link (i.e., pass through) both the
primary and secondary windings. The flux will close their path through the

magnetic material, i.e., the core material. EMFs will be induced in the both
the windings due to change of flux linkage as induced EMF, e is expressed as