How Does A Transformer Work: 9 Answers You Should Know


The transformer is a device that contains magnetically coupled coils that are generally electrically isolated from each other—a transformer transfers electrical power from one circuit to another. How does a transformer work? this article s going to take you ride with transformer.

The fundamental principle a transformer work on is the electromagnetic induction (or mutual inductance), when two different electrically isolated coils are in close proximity such that one’s magnetic field can link to another when an alternating current is applied to the primary coil, a fluctuating magnetic field is generated which causes electromotive force in the secondary coil.

How does a step up transformer work?

Image Credit: Electrical Classroom, CC BY 4.0 , via Wikimedia Commons

The transformer which generates a higher voltage across the secondary than the applied voltage to the primary is the Step Up Transformer.

The transformer uses mutual induction (fundamental principle) between two circuits coupled by a common (fluctuating) magnetic flux. When alternating current (AC) is applied to the primary coil, a fluctuating magnetic field is generated, which causes electromotive force in the secondary coil.

How Does A Transformer Work
Fig. Step-up transformer circuit.

As the number of turns in the secondary coil (n2) of the (step up transformer) is greater than the primary coil (n1), the EMF(electromotive force) is corresponding to the number of turns. Hence, the secondary cal generates a higher voltage relative to the primary coil.

The voltage transformation ratio (K) of a step-up Transformer is greater than 1 (K>1).

K= E2/E1= N2/N1

Where K means voltage transformation ration, N1 means number of turns in primary coil,N2 means number of turn in secondary coil.

How does a step down transformer work?

A step-down(one type of substation transformer) transformer generates a lower voltage on the secondary side of the transformer.

A step-down transformer works on mutual induction between two circuits that are electrically isolated from each other while coupled through the magnetic flux. When an alternating current (AC) passes through the primary coil, a fluctuating magnetic field is generated, which causes electromotive force (emf) in the secondary coil.

 As the number of turns in the primary coil(n1) is greater than that of the secondary coil(n2) i.e.  n1>n2, is induced electromotive force(emf) is proportional to the number of turns resulting in the voltage generated across the secondary coil(of transformer) is lower than that of the primary voltage.

Fig. Step-Down Transformer circuit.

The voltage transformation ratio (K) of a step down transformer is less than 1 (K<1).

How does Auto transformer works?

The transformer whose (primary and secondary coil windings) are interconnected electrically is the autotransformer which means it has a single continuous winding common to both primary and secondary sides of the transformer.

Autotransformer works on the principle of Faraday’s law of electromagnetic induction (or mutual induction). When the primary coil is connected to an AC supply due to Faraday’s law of electromagnetic induction is an electromotive force (EMF) is generated in the primary coil. As in autotransformers, the primary and secondary coils are in the single continuous winding.

EMF will be developed as the voltage ratio per turn remains the same in both the winding. The secondary voltage generated will be proportional to the number of turns connected to the transformer’s secondary side.

Fig. Autotransformer circuit.

A direct electrical connection between windings (primary and secondary coils) ensures that a part of the energy is transferred through conduction between the primary and secondary winding of the transformer. The amount of winding that is shared by both the primary and secondary sides of the transformer(or of autotransformer) is referred to as the common sector. One end of the winding is linked between the supply and load, while the other end of supply (AC Supply) and load is linked to tabs along the winding.

An autotransformer can be a step down transformer when the AC supply is connected across the transformer winding. The load is connected by a tab across a relatively more minor portion of the winding.

How does a transformer work on the DC current?

The transformer is an electrical device that uses magnetic coupling (mutual induction) to pass an AC signal from one circuit to another.

DC current cannot pass through a transformer as for working of transformer AC supply is required, without AC supply there will be no fluctuating magnetic flux. Only a flyback transformer can be excited using a DC source.

How does a microwave transformer work?

Microwave transformers are robust, cheap, and generate high voltage arcs.

Microwave Transformer works on the principle of mutual induction, like other Transformers.

The microwave (oven) Transformer has three (1 primary and 2 secondary) windings. When electricity passes through the magnetron, electrons are influcenced to create microwave radiation. When the magnetron of the microwave (oven) transformer works, AC flow through the secondary winding (or coil) of the (microwave) transformer resulting in the iron core generates magnetic saturation; as the anode voltage of the magnetron shoot up. Anode current also increases along with an increase in current through the secondary winding, strengthening the magnetic separation and increasing the leakage magnetic flux resulting in the transformer generating High Secondary voltage.

How does an output transformer work?

Output Transformer blocks DC and its let AC signal to pass-through.

The output transformer is an electromagnetic device that works on the principle of Faraday’s law of electromagnetic induction, which isolates the input circuit from the output traffic while filtering AC signal to pass through magnetic coupling between input and output circuit.

The Output Transformer can be used to increase or decrease the applied voltage through the input circuit to the output circuit.

How does an optical current transformer work

An optical current transformer is a sensor that is used to measure electric current directly or indirectly.Optical current transformer working can be based on principles such as the Faraday effect, interferometric principle, the micromechanical sensor with optical readout, Bragg Grating. 

The magnetic optical current transformer (MOCT) uses Faraday’s effect (fundamental principal) to measure electric current; it measures the rotational angle of the polarized light under the influence of a magnetic field and converts it into a signal of voltage proportional (or corresponding) to the electric current.

According to Faraday effect the orientation (or inclination) of linearly polarized light under the impact of a magnetic field. When the light propagates (or travel) through a piece of glasses, the rotation angle is corresponding (or proportional) to the strength of the magnetic field component. Polarizer material is used to convert light into a linearly polarized light.

Polarized light passes through an optical rotator because of Faraday’s effect on the orientation of linearly polarized light rotates as it passes through the rotator material. Different polarization material is used as an analyzer that converts the amount of rotation of the polarized light into the corresponding amount of light intensity. This intensity-modulated light travels to the photodiode, which bring about the corresponding electrical signal.

How does flyback transformer

The flyback transformer (generates saw-tooth signal) is also recognized as a line output transformer. This transformer can be excited by using DC volt. It can transfer as well as store energy.

The basic working principle of the flyback transformer is mutual induction. In this Transformer, one diode is linked in series with the secondary coil of the (fundamental) transformer and one capacitor in parallel with the load.

Fig. Flyback transformer circuit.
  • The primary coil is connected to a DC supply along with the switch. When the switch is on, the (DC) current flows through the primary circuit of the transformer and excites the primary coil. The primary coil ramp(a steadily rise in voltage) is generated through primary inductance, which got stored in the form of magnetic energy between the inductive gap (between coils) of the transformer. A diode is connected in series with a secondary coil of the transformer, which is in Reverse bias that restricts the formation of current in the secondary circuit.
  • When the switch is off, the primary current falls down to zero, and stored energy in the gap is released and transferred to the secondary coil, resulting in a rapid rise of output voltage as the voltage shifts to forward bias.

How does a buck-boost transformer work?

Buck Boost Transformers is used to adjust voltage levels, and it can be used to make small changes to the applied voltage, which can be up to 30%.

A buck-boost transformer has four windings which can be connected in different ways as requirements. It was on the principle of mutual induction between magnetically coupled coils. The resulting (output) voltage of the buck-boost transformer is the function of input voltage. If input voltage varies, then the output voltage will change in the same percentage. This transformer can be step up or step down depending upon its connection between the coils.

Sneha Panda

I have graduated in Applied Electronics and Instrumentation Engineering. I'm a curious-minded person. I have an interest and expertise in subjects like Transducer, Industrial Instrumentation, Electronics, etc. I love to learn about scientific researches and inventions, and I believe that my knowledge in this field will contribute to my future endeavors. LinkedIn ID- https://www.linkedin.com/in/sneha-panda-aa2403209/

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