This article is all about transformers. A transformer is an electrical device used to transfer electrical energy from one winding to another. For this it uses the phenomenon of magnetic
induction. There are two windings; primary and secondary. The current flowing in the primary winding varies, which helps in
producing a varying magnetic flux. The varying magnetic flux flows into the secondary windings as well and causes
production of an EMF or voltage in the secondary winding.
Electromagnetic induction is the phenomenon in which an electrical current is
produced across a conductor with the help of a magnetic field.
It is stated that electromotive force which is produced around a closed path is
directly proportional to the rate of change of the magnetic flux through any
surface which is bound by that path. This is applicable when a conductor is
moved inside it or its strength is changed by any means. A transformer uses the
concept of Faraday's law. The core which we used inside the coil must be of iron
so that we can use its ferromagnetic properties and electromagnetic induction
phenomena can be used. The transformers are of two types: step up and step down
transformer. It all depends on the number of primary and secondary windings that
the transformer is stepped up or stepped down. If Ns, number of turns in secondary
coil is more than the turns in primary coil, Np then it is said to be as step-up
transformer.
![]()
Basic Principle on which it works: The transformer actually works on two principles.
First that an electric current can produce magnetic field and second principle
is that a varying magnetic flux can induce voltage in another coil. When the
secondary coil is open circuit the primary coil acts as a pure indicator.
What happens actuallyis that the current which passes through the primary coil creates
a magnetic field. Inside these primary and secondary coils, a core of high
permeability is used. Most commonly we use Iron as a core. Transformers are
bi-directional, and will work regardless of where the input is connected.
![]()
Now we know that when the secondary coil is open circuit then the primary coil acts as a
pure inductor. When a load is connected to its secondary coil then a current
will start flowing in its secondary windings. While using the transformer some rules
should always be kept in our mind: Voltage in very excess should not be applied
on the windings, a specific Direct current should not be allowed to flow through
any winding and the last but not the least and frequency should not be less than
the applied frequency.
However, you can always apply less than the rated voltage to any winding, and
use any winding as primary or secondary, so long as the current rating is not
exceeded. Any frequency higher than the rated frequency is also safe.
Ideal transformer is that transformer in which no losses has occurred and it
gives output at 100% efficiency but because it is not possible practically and
hence there are always some losses occurred during its working due to power
dissipation and hence we will now discuss about some of the important losses
which can occur during its operation. These losses are caused due to so many
reasons such as material used, number of windings and size also contributes in
causing losses. The transformer has windings and these windings have resistance,
the resistance causes losses in the form of heat. These losses are divided
into mainly two parts : Copper losses and Iron Losses.
![]()
Transformer losses are divided into losses in the windings, termed copper loss,
and those in the magnetic circuit, termed iron loss. Losses in the transformer
arise from: Winding resistance
Winding resistance: the resistance inside the wiring causes losses of power in
the form of heat some of its energy gets dissipated. Another type of
loss that can exist is that when the magnetic field is reversed, a small amount of
energy is lost in the cycle. This loss occurs inside the core. Here is another
type of loss as well which is caused due to eddy currents. Eddy currents
circulate within the core in a plane normal to the flux. Eddy current losses can
be reduced by making the core of a stack of plates electrically insulated from
each other. It occurs for transformers as all transformers operating at low
frequencies use laminated or similar cores. Except all these, leakage currents
are also a big reason for the losses.
Resources:
555 Timer IC in Robotics
Orchestration services in Robotics