Tag Archives: Step Down Transformer Suppliers

What is Step Down Transformer?


A Transformer is a static apparatus which transforms electrical power from one circuit to another with no moving parts.

It performs its action with the changes in voltage and current and no change in frequency.

The main function of a transformer is to transfer AC electrical power from one circuit to another circuit while keeping the frequency level constant but with altered voltage, which means it increases or decreases the voltage based on the requirement of the machines.

Depending on the functionalities the transformers can be classified in 2 types:

1. Step Up Transformer

2. Step Down Transformer.

Table of Contents –


Step Down Transformer

A Step Down Transformer is the one which reduces the output voltage that means it functions for converting high voltage with low current into a low voltage with high current.

Let me elucidate it with an example, everyone knows that our power circuits carry a voltage between 230- 110 v right ? But electrical equipments like the bell require only 16v to operate properly. So, the Step Down Transformer acts upon the current and reduce the voltage from 230- 110 v to 16v.

Depending on the different areas sometimes, voltages are stepped down to 230v or 440v for the safety reasons.

But to make this reduction in voltages a reality, the number of turns on secondary winding or coils is kept less than the primary winding or coils that ultimately result in less voltage being induced at the secondary output of the transformer.

Applications of Step Down Transformer

The applications of Step Down Transformer is varied but the main applications of Step Down Transformers are as follows:

  • It is used in the main adapters and chargers for cell phones, CD players and stereos
  • It can be used to step down the voltage level in transmission line
  • In welding machines it is used in reducing voltage and increasing current.
  • And it is to be used in televisions, inverters, voltage stabilizers etc

Working Principle of Step Down Transformer


Transformers work on the “Faraday’s law of electromagnetic induction” principal which states that “when the magnetic flux linking a circuit changes, an electromotive force is induced in the circuit is being proportional to the rate of change in the flux linkage”.

Transmission action in a transformer is performed by mutual induction between the windings.

The number of turns in primary and secondary winding respectively determines the Electro Motive Force induced between the two windings and this ratio is called as Turns Ratio.

But do you know what decides the voltage reduction capability of Step Down Transformers?

It depends on the turn ratio of the primary and secondary coil.

The amount of flux linkage to the secondary coil of the transformer remains less compared to the primary coil as the number of windings in secondary coil is also less than the number of windings in primary coil.

As the consequence, the E.M.F which is induced will be less in the secondary coil, which ultimately reduces the voltage at the secondary winding compared to primary winding.

Please have a look on the formula used to design a Step Down Transformer

Relation between voltage & Turns

Ns / Np = Vs / Vp

  • Ns = No. of turns in Secondary Winding
  • Np = No. of turns in Primary Winding
  • Vs = Voltage in Secondary Winding
  • Vp = Voltage in Primary Winding

But remember to work a transformer as a “Step Down Transformer”, it is necessary that the number of turns in secondary winding should always be less as compared to the number of turns in the primary winding of the transformer that is, Np > Ns

Let’s understand it with an example:

There is a Step Down Transformer in which the secondary turns [Ns] are 400, primary turns [Np] are 8000 and the input voltage [Vp] is 240. Then the voltage at the secondary [Vs] can be calculated with the following formula:

Vs = Ns * Vp / Np

Putting values given in the formula:

Vs = 400 * 240 / 8000

Vs = 12 Volt

Hence, the voltage at the secondary winding of the transformer is 12v, and we can see that it is less than that at the voltage in the primary winding. Therefore, the transformer can be said the Step Down Transformer.

What are the Types of Step Down Transformer?

There are three categories of Step Down Transformer which are as follows:

  • Single Phase Step Down Transformer
  • Center Tapped Step Down Transformer
  • Multi Tapped Step Down Transformer

Advantages of Step Down Transformer

Please have a look on the advantages of Step Down Transformers:

  • These are useful in stepping down the voltage. It thereby makes the transmission power easier and cheaper
  • These provide more than 99% of efficiency
  • These provides varied voltage requirements
  • These are Low in Cost, Highly Reliable and Durable

Application of Step Down Transformer

The voltage is around 20kV from the Power Plant or Power Generation Station. For being able to transfer this voltage over to long distances, it is stepped up to 440kV with the use of Step up Transformer supplied by Servo Transformer Supplier in India. This voltage is then transmitted to a distribution station.

At the distribution station, the 440 kV is then reduced to 11kV with the help of a Step Down Transformer making the voltage ready for customer use.

The Power in a Step Down Transformer

The power in a transformer is measured by using the product of the voltage and the current. The power in a transformer is rated in Volt – Amps VA (or in kilo Volt – Amps KVA for larger transformer sets).

The power according to the design of the transformer is almost always constant which means the power available at the secondary end of the transformer is same as the power as the power at the primary end of the transformer.

This theory is even applicable in a Step Down Transformer. But, in this case the voltage is at the secondary coil of the Step Down Transformer is lesser than that at the primary coil, the current at the secondary coil increases to balance the total power of the transformer.

Uses of Step Down Transformers

The street transformers that we see near our homes are all Step Down Transformers. Before installing the switching power supplies all low voltage wall adapters use Step Down Transformers.

A premier Servo Transformer Supplier in Delhi- Servo Star offers a wide range of quality stabilizers and transformers that suit different types of domestic and industrial applications like for metal processing equipment, elevators, production lines, medical equipment, construction devices, air conditioners and many more.

Before the wide usage of switching power supplies, almost all low voltage wall adapters use Step Down Transformers.

7 Things you must know before Buying a Transformer from any Manufacturer

1. Voltage Ratios of Transformer (11 KV TO 33 KV):

You should first of all need to be aware about the Voltage Ratios of transformer because accurate voltage selection on H.V. Side (i.e. is it 11KV, 22KV or 33KV) and on L.V. Side (whether it is 400V, 415V or 433V) can vary the Price of transformer from 3% up to 17%.

2. Capacity of Transformer (25 KVA TO 10 MVA)

Choosing the right capacity of transformer like accurate KVA / MVA Rating of a Transformer based on Power Consumption can lead a Price variation from 8% to 13%.

3. Transformer Frequency (50HZ OR 60HZ)

If we talk about most parts of the World, then we will see that Frequency of Power Supply is 50 Hz, but in some Countries like USA the Standard Frequency is 60 Hz. This alteration in the design of the Transformer affects the cost up to 5%.Most of the transformer Suppliers choose Frequency on the basis of the inputs which customers are receiving in their power lines.

4. Installation/Environment

The transformer is placed based on the type of atmosphere i.e. Indoors, Outdoors, Salinity, Heat, Moisture, Fumes etc. Depending on the environment & installation place the mechanical designing and paint coating is taken into consideration which can contribute up to 5% less pricing.

5. Transformer Tappings (OLTC or OFF Circuit Type)

Taps on H.V. with Off Circuit Tap Changer or On Load Tap Changer, plays a significant role in the Cost Consideration of a transformer as well as its electric design which can vary the price up to 11% depending on the Transformer Rating.

6. Transformer Standards

There are many National and International Regulations which are set to abide before you buy a Transformer from any Transformer Manufacturer in India or abroad. These standards has been put up by Organizations like IEC, IS, BIS, IEEE, EEE, ANSI, NEMA, ASTM, UL and these are mandatory to follow by the manufacturers. These standards ate taken into the Electrical Design consideration of transformers and vary it up to 37% in performance & pricing.

7. Transformer Fitting / Accessories & Protection Level

There are several Electro-Mechanical devices which can be integrated with a Transformer for the safe functioning and appropriate monitoring of the transformer. Especially for the transformers of High Ratings, these Fittings and Protections are must for providing then the Enclosure Safety, Alarm & Trip functions for Temperature as well as the Pressure Control. Moreover, depending on the KVA / MVA Capacity of transformers, these features contribute up to 17% in performance & prices.

Where to buy Step Down Transformer?

If you are looking for prominent manufacturers & suppliers of Step Down Transformers then ServoStar is the right destination for you. We are engaged in manufacturing, supplying and exporting a wide range of Transformers & Servo Stabilizers.

Our complete range of transformers is tested at different levels to ensure the smooth performance, high productivity, low maintenance and longer life.

At Servo Star, we understand that a basic requirement for any transformer company is to efficiently deliver power to the consumer.

We use the best carriers in the business in order to make sure that the order gets delivered to our customers all over India on time.

Our quality, manufacturing and engineering groups work as a team to provide accurate, on time and damage free delivery of each Servo Star Transformer.

You can get your Step-Down Transformer or any other transformer or stabilizer with standard equipment and accessories by just looking at our website: www.servostar.org.in and by booking it online. We assure you to provide the most cost effective rates.

What should you check about a transformer company before making a purchase?

The manufacturer of the transformer is one of the most vital things to consider before you make a purchase.

  • You should check their manufacturing units
  • You can ask from their previous clients about the performance of their transformers
  • You must get assured about the reputation of that particular manufacturer in the market.
  • You can meet their engineers or other staff


1) What is the turn ratio of a step down transformer?

A Step Down Transformer is the device designed to reduce the voltage from primary to secondary. The transformation ratio of a transformer is equal to the square root of its primary to secondary inductance (L) ratio. Turn ratio is the test that done in order to test a transformer that whether it meets its design specifications or not. In a Step Down Transformer, the voltage turn ratio is 2:1 as the number of turns in the secondary coil are less than the number of turns in primary & secondary voltage is lower than its primary voltage.

2) What are the four practical uses of a Step Down Transformer?

A Step Down Transformer steps down the input voltage & its secondary voltage is less than the primary voltage. They used for various purposes given as below;

1. A Step Down Transformer is used in the induction furnace for melting the metals.

2. A Step Down Transformer is used for obtaining a large current for electric welding.

3. All the street transformers which are near to our homes are Step Down Transformer.

4. Step Down Transformer is used in main adapters & chargers for cell phones, stereos & CD players.

3) Which connection is used for a Step Down Transformer?

A Step Down Transformer used two types of connections, one is star delta & the other one is delta star. Basically, it is based on the application of the machine. In the star delta connection, the primary side connected in star fashion & the secondary side connected in delta fashion, hence the fewer number of turns are required. So this makes the connection economical for high voltage Step Down Transformers. Whereas In delta star connection, the primary side connected in delta fashion & the secondary side connected in a star fashion. It is commonly used in commercial, industrial & in high density residential locations.

4) Why do we use a Step Down Transformer ?

A Step Down Transformer is designed to reduce the voltage from the primary winding to secondary winding. We use a Step Down Transformer as it converts a high voltage & low current alternating source to a low voltage & high current alternating supply.