The Ultimate Guide To Step-down Transformer

step-down transformer

Modern-day electronic devices is greatly based on the application of a Step-Down Transformer to satisfy the requirements of running electrical home appliances. A Step-Down Transformer decreases high voltage to reduced voltage and for this reason it plays a vital function in running electric appliances in our families and industries. Let us try to comprehend the concept of a step-down transformer, the functioning concept, advantages, and negative aspects in this blog post.

Table of Contents

What is a step-down transformer?

As the name suggests it is made use of to bring down the voltage from the primary winding to the second winding i. e. it transforms a high voltage to the reduced current rotating resource to a reduced voltage and high present rotating supply. It is a fixed tool that transmits electrical power from one circuit to another.


A Step Down Transformer is a tool which transforms high primary voltage to a low secondary voltage. In a Step Down Transformer, the Primary winding of a coil has more turns than the second winding. Figure 1 listed below shows the winding representation of a regular Step-Down Transformer.


A step-down transformer is an electric tool that lowers the voltage of an alternating existing (A/C) power supply. It consists of a Primary winding, a second winding, and an iron core.

When an a/c voltage is related to the primary winding, it develops a varying electromagnetic field in the iron core. This electromagnetic field then induces a voltage in the secondary winding yet at a reduced voltage level than the Primary winding.

How does the transformer step down the existing?

step down transformer

It functions based on the legislation of Faraday’s principle of electro-magnetic induction. Lowering the voltage in a step-down transformer is based on the turn proportion of the primary and secondary coils. As the number of turns in the secondary coil is much less, the induced EMF will certainly also be much less. So, the outcome voltage in the secondary coil will certainly be less than the primary input voltage.

Step-Down Transformer's Working Principle:

Transformers work on the concept of “Faraday’s regulation of electromagnetic induction”, where the transmission is caused by the common induction between the Primary and second windings.

According to Faraday’s legislation “when the magnetic linking circuit modifications, an electromotive force is caused in the circuit proportional to modification of the magnetic linking circuit”.

Turns Ratio is calculated by dividing the number of turns on the primary coil and the number of turns on the secondary coil.

The turn ratio of the primary and secondary coil figures out the voltage reduction capacity of Step-Down transformers. The quantity of change affiliation to the secondary coil of the transformer will certainly be less contrasted to the primary coil because the number of windings in the primary coil is fewer than those in the primary coil.

Therefore, the EMF produced in the secondary coil will certainly be low. Because of this, the voltage on the additional winding is lower than the voltage on the Primary winding. As a result, the voltage on the additional winding is lower than on the main winding.

Step-Down Transformer Equation

The formula made use of to make a Step-Down Transformer is


Ns = variety of turns in the additional winding of a transformer
Np = variety of kip down the Primary winding of a transformer
Vs = Voltage in the additional winding of a transformer
Vp = Voltage in the primary winding of a transformer
The number of turns in the secondary winding of a transformer ought to constantly be smaller than the variety of turns in the major winding. i.e. Np > Ns to function transformer as “Step-Down Transformer”.

The overall induced EMF will certainly be lower, and the second out voltage will be less than the primary input voltage because the secondary winding of the step-down transformer has less turns.

Take into consideration the complying with Step-Down Transformer circumstance: the second turns [Ns] are 250, the main turns [Np] are 5000, and the input voltage [Vp] is 240. The additional voltage [Vs] can then be calculated using the formula:

Acquire rearranging the equation we get:

Therefore, the second winding of the transformer has a voltage of 12V, which is lower than the primary winding. Consequently, the transformer is claimed to be a Step-Down Transformer.

Benefits of Step-Down Transformer

The advantages of Step-Down Transformers are as adheres to:

Effectively lowering voltage, making it easier and cheaper to transmit electricity
More than 99% of effectiveness
Gives varied voltage demands
High Reliability
High Durability
Drawbacks of Step-Down Transformer:
The disadvantages of Step-Down Transformers are as adheres to:

Regular maintenance is required, insufficient maintenance may damage the transformer
Volatility in feedstock costs
Fault rectification takes more time
Applications of Step-Down Transformer:
The different applications of Step-Down Transformers are as complies with:

In main adapters and chargers for cell phones, stereos, and CD players
To Step-Down the voltage level in the transmission line
In welding machines by minimizing voltage and raising present.
In tvs, voltage stabilizers, inverters, and so on.

In a power system, step-down transformers play an important function. They minimize the voltage and tailor it to the demands of power customers. It is accomplished in a collection of actions, which are outlined below:

A long-distance energy transmission system must have a voltage level as high as feasible. The transmission power loss will be considerably lowered with high voltage and reduced current. A power grid is developed that need to be connected to a transmission system with numerous voltage degrees. In the interconnection of transmission lines with various voltage degrees, step-down transformers are used. They bring voltage degrees from high to reduced. (e.g. 765/220 kV, 410/220 kV, 220/ 110 kV). These transformers are enormous and have a massive nominal power score (also 1000 MVA). In this instance, when the transformer turns ratio is not high the autotransformers are usually set up.

The following voltage level change action is adjusting the transmission voltage to the distribution degree. In this scenario, the characteristic voltage ratios are 220/20 kV and 110/20 kV (additionally the LV additional voltages 35 kV and 10 kV can be found). These transformers have a small result of as much as 60 MVA (typically 20 MVA). In these transformers, the on-load faucet changer is basically always installed. The faucet changer’s primary feature is to control voltage. In the USA, the tap changer is based upon the LV side, and in the remainder of the world mostly on the HV transformer side.

The final voltage improvement action is adapting the voltage to the home voltage degree. Small circulation transformers with nominal power approximately 5 MVA (generally less than 1 MVA) and nominal voltage values 35, 20, 10 kV on the HV side and 400/200 V on the LV side are known as step-down transformers. It is noticeable that those transformers have a high turns proportion. They typically have a de-energized faucet changer with 5 faucet positions (+/- 2 faucet positions) and do not have an on-load faucet changer.

Types of Step Down Transformer

step down distribution transformer

Step Down Transformers can be classified into three classifications based upon tappings in second coil. They are:
Solitary Phase Step Down Transformer
Facility Tapped Step Down Transformer
Multi Tapped Step Down Transformer
Single Phase Step Down Transformer
Utilized to step down the present ratings and input voltage, and it offers reduced voltage and existing output.
Facility Tapped Step Down Transformer
This sort of Step Down Transformers will be having one main winding and a facility split in the additional winding, by which it offers the outcome voltage with the facility pint.
Ex-spouse: 12v-0-12v.
Multi Tapped Step Down transformer
This sort of Step Down Transformers have numerous touching in Secondary coil. Several Tapping are used to obtain the desired diverse output with second coils.
Ex-spouse: 0-12v, 0-18v.

Final thought:

The demand to transform the high voltage to the low voltage in household and commercial applications has actually made Step-down transformer a substantial device in the transmission of electrical energy. We hope that you are now knowledgeable about what a step-down transformer is, its working concept, formula, advantages, and negative aspects.

If you want to recognize more regarding the step-down transformers, daelim transformer, the leading step-down transformer producer in china, is below to aid. daelim transformer produces step-down transformers exceptionally to accommodate your requirements to transform the high voltage (HV) and low existing from the primary side of the transformer to the low voltage (LV) and high current value on the secondary side of the transformer. We do provide various other different type of transformers such as distribution transformers, Small power transformers, Isolation/Ultra isolation transformers, converter/Inverter transformers, etc.

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About Bin Dong

Hello, I am Bin, General manager of Daelim which is a leading transformer manufacturer. If you have problems when you are looking for the equipment, what you need to do is tell us.