One
has generally only the tension of the sector, of which the most current
values lie between 110 and 240 V, but for the electronic instruments,
the tensions necessary often have a different value. The mains
transformer precisely ensures the transformation of the tension of the
sector, while increasing or by decreasing its value in order to obtain
the supply voltages of the various circuits
CONSTITUTION OF THE TRANSFORMER
On
the figure 1-a, the essential elements of a transformer are
represented, i.e. the closed ferromagnetic core and the rollings up laid
out around the central part of the core
On
this figure only two rollings up are represented ; it is the minimal
number which a transformer can present: indeed, one of rollings up is
connected to the sector while the other, at the ends of which one
obtains a tension of value different from that of the sector, is
connected to the circuits to feed
When one needs several tensions of different values, one uses an additional rolling up for each tension ; the transformers can thus comprise three rollings up or more one of them is always connected to the sector and it is called primary winding or more simply primary, while the other rollings up connected to the circuits to feed are called secondary windings or more simply secondary
Since all the secondaries behave in the same way, it is enough, to analyze the operation of a transformer, to examine only one secondary, as one did on the figure 1-a
On this figure, the primary education was drawn a little above it secondary to clearly distinguish two rollings up which, actually, are superimposed: the primary education is rolled up initially, then, the secondary
On the figure 1-b, one drew the graphic symbol representing the transformer on the electric diagrams: the same graphic symbol as that used in the preceding lessons to represent rollings up of windings is used here for rollings up, while the core is represented by a segment of right-hand side traced between the primary education and the secondary. When there are several secondaries, one generally draws them all on the same side of the segment, so that other side, it has only the primary education there
We will see now how a transformer functions, i.e. how its secondary can provide a power of a value different from that which is applied to its primary education
When one needs several tensions of different values, one uses an additional rolling up for each tension ; the transformers can thus comprise three rollings up or more one of them is always connected to the sector and it is called primary winding or more simply primary, while the other rollings up connected to the circuits to feed are called secondary windings or more simply secondary
Since all the secondaries behave in the same way, it is enough, to analyze the operation of a transformer, to examine only one secondary, as one did on the figure 1-a
On this figure, the primary education was drawn a little above it secondary to clearly distinguish two rollings up which, actually, are superimposed: the primary education is rolled up initially, then, the secondary
On the figure 1-b, one drew the graphic symbol representing the transformer on the electric diagrams: the same graphic symbol as that used in the preceding lessons to represent rollings up of windings is used here for rollings up, while the core is represented by a segment of right-hand side traced between the primary education and the secondary. When there are several secondaries, one generally draws them all on the same side of the segment, so that other side, it has only the primary education there
We will see now how a transformer functions, i.e. how its secondary can provide a power of a value different from that which is applied to its primary education
