Step-Up Transformer: Principle, Application, Advantages, Disadvantages

Wonder!! which transformer is used to supply energy to your home? It is a power transformer. Would it be a step up transformer or step-down transformer? It could be any of them.

But the objective of this post is to give you brief information on the step-up transformer. This post is not only for getting the basic knowledge. But also for students of science background.

But the aim of this post is to give you a brief idea of a step-up transformer. And also, this article is not just for getting the basic knowledge. But also for science students.

So buckle up, we are going to cover the principle of the step-up transformers, how they are made, their practical application along with its advantages and disadvantages.

What is a Step Up Transformer?


Simply, “It converts low voltages into high voltages electricity”. But here is a catch, as you know, the current is inversely proportional to voltages when defining power. Therefore, another function of this type of transformer is to convert the high current value into low current values.

So, the proper step up transformer definition would be, a type of transformer that converts low voltages (LV) and high current into the high voltage (HV) and low current values.

In countries like India, a step-up transformer is being used with a typical power supply at 11kv. This makes the process more economical— A.C. power can be transmitted at longer distances (with voltages ranges from 220v-440v).

However, for safety reasons and also to provide widely applicable voltages for appliances, voltages are stepped down to 230v.

Key Features of Step Up Transformer

Key Features of Step Up Transformer
  • Input Voltage < Output Voltage.
  • Input Current > Output Current.
  • Widely used transformer in electrical systems and transmission lines.
  • They nearly have the same operating frequency and nominal power— because they are very efficient.
  • A higher number of winding is seen at the secondary output coil.
  • The primary winding is made up of thick insulated copper wire.
  • The output voltage ranges from 220v to 11000 volts or above.
  • Commonly seen in power plants, X-rays machines, microwaves, etc.

Principle of Step Up Transformer


A. General Approach

Whether it is a step-up transformer or step-down transfer, it consists of at least two coils of insulated wire that are stretched around an iron core. But the key difference relies on which part the winding is done.

Therefore, when the source voltage is applied to the primary coil, it invaded the iron core to get magnetized. This finally induces the voltages in the secondary coil.

As stated earlier, the turns ratio at both coil winding determines the type of transformer and also the amount of voltages transformation.

For example, if the primary coil has 50 turns, and the secondary coil has 100 turns then the ratio would be 1:2. Then it is a step-up transformer.

B. Academic Approach 

The principle of the step-up transformer (all transformers have the same principle) is based on the theory of mutual inductance between the two coils that has a common magnetic flux.

In this, the induced voltage from the first coils generates inductance voltage in the second coil. Hence, the conversion takes place.

So, all transformers are appliances whose working is based on the ratio of turns at their primary and secondary end. 

Mathematically, the relation of voltage and number of turns in any transformer is given by

V2/ V1 = N2/N1

Here, V1 and N1 represent the voltages and number of turns in the primary winding. While V2 and N2 are the respective voltages and turns for the secondary coil.

Consider the following figure as an example of step-up voltages.

Academic Approach 

Clearly, the number of turns at the secondary coil (N2) is greater than the primary (N1). That means when the voltage is induced at the primary part— due to magnetic iron flux— it stepped up because of mutual inductance that took place at the N2 end. Hence, a stepped-up voltage is generated. 

In addition, the primary coil in the step-up transformer has thick insulated copper wires.

Transmission and Power Loss

As stated earlier, step-up transformers are used in transmission lines for transforming high voltage. Therefore, in transmission, a certain amount of power loss is seen which is governed by the following equation.

Power Loss = I2R

I= Current; R= Resistance

As you know, the output current of the step-up transformer is less. Therefore, less power loss is seen. And this is what makes it economical.

How to Make a Step up Transformer?

How to construct a Step-up Transformer?

To construct your working model of a step-up transformer, you have to follow the following procedure.

Materials Required

  • Electrical Insulated tape
  • Coated copper wire (magnetic wire)
  • Large steel bolt as core material flux
  • AC Power supply (e.g., wall socket)
  • Any Resistors (light bulb)
  • A voltage regulator


  1. Choose a steel bolt that has magnetization property. In order to check it, you can stick the magnet to steel bolt, if it sticks then you’re good to go.
  2. Now, you have to warp the steel bolt with insulating electrical tape.
  3. With one part of coated copper wire, start winding the coil at one end of the steel bolt with two free ends. And try to make at least 12 turns.
  4. Now, repeat the same process with the other piece of coated copper wire, and this time place it on the other part of the steel bolt. However, make sure you make more turns than the previous primary winding.
  5. Now connect the bare ends of the secondary coil in contact with the resistor (bulb).
  6. At the final step, connect the bare ends of the primary coil to the AC power supply with a voltage regulator. And starts with the lowest AC power level to a high level.


Even at low AC power levels, the bulbs glow but they differ from the brightness level in a step-up configuration.


  1. In case of a burning smell, you should remove the power cord immediately.
  2. Keep all the metallic objects away from the experiment area. It is because, in step-up configuration, it acts like a magnet.
  3. Electricity is dangerous. Therefore, this experiment must be performed under the supervision of an adult.

Applications of Step Up Transformer

These are the following step up transformer applications

  • A small step-up transformer is used for voltage boosting for small appliances.
  • They are in electrical devices such as electric motors, in the microwave oven, X-rays machines, inverters, and even stabilizers.
  • The most important and widespread use of a step-up transformer is in the electrical transmission and distribution of power.

Advantages and Disadvantages

Advantages of Step-Up Transformer

Advantages of Step-Up Transformer

These are the following key advantages of a step-up transformer.

1. Very Economical: As they increase the value of the voltage and decrease the current value, which finally decreases the resistance of transmission. Hence for longer electric transmission, they are an economical choice.

2. Higher Lifecycle: They are capable to work nonstop. This makes it the backbone of an efficient and merely uninterrupted power distribution system.

3. Low Maintenance Cost: Step-up transformers require minimal maintenance which additional cover-ups by regular oil check and replacement of physically damaged pieces.

4. Quick Starts up: Just with the inducing electricity it starts functioning in no time. And doesn’t need any prior booting time.

5. Higher Efficiency: With the recent development in technologies, the step-up transformer has become more efficient. And nearly serves an efficiency rate of 95%.

Disadvantages of Step-Up Transformer

Disadvantages of Step-Up Transformer

The following are the demerits of a step-up transformer;

1. Cooling System: Because the step-up transformer works non-stop, it needs a reliable cooling system which again needs to be regulated regularly.

2. Need a huge area of installation: Higher the voltage capacity bigger the size. So, for urban cities, the normal size of the step-up transformer takes around 6’x6’ of land. That’s again is a huge deal.

3. No DC Workable Model: They use only AC current to stepping up the voltages. And hence, they are nonfunctional for direct current (DC).

Step Up Transformer Uses

Inverters, batteries, and stabilisers all need step-up transformers to convert the lower voltage to the higher voltage required by the Transformers. They are also employed in the transmission of electrical power.

Short Summary

Step-up transformer is an appliance that is used to convert a low voltage (and high current) into corresponding high voltages (and low current) values.

This can be done by the principle of mutual inductance, where the primary coil has fewer winding than the secondary coil. Therefore, a step-up transformer has more winding in the output coil than the primary one.

These transformers are mostly used in transmission lines and electric distribution systems for longer distances. In addition, many electrical appliances such as inverters, stabilizers, x-ray machines too have a step-up transformer.


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General FAQ 

What is the difference between a step up and a step-down transformer?

In step-up transformer primary winding is less in number than secondary winding. While the opposite is true for a step-down transformer. Apart from this, the step-down transformer has lower output voltages and higher current voltage, which is again the opposite of the step-up.

How does a Step up Transformer Work?

To boost the voltage in the secondary coil, a step-up transformer has more twists of wire in its secondary coil…. Hence, a step up transformer raises the secondary coil’s electrical voltage from a lower to a greater level depending on the application’s needs.

Why does the step-up transformer not work for DC current?

The reason is based on its principle. When you induce DC current to the primary coil, it produces a constant and uniform magnetic field. This will fails to produce inductance to the second coil. Hence, the system fails to produce any output voltage (or current).

Which connection is used for the step-up transformer power distribution system?

Most commonly AC 3-phase, 4-wire system is used in the electricity distribution system.