Revisiting the core of power inducement


Home-Splash_ePowerCoil wound transformers are one of the most important components used in electronics manufacturing. The reason is simple–they meet tailored power demands of varied devices. Electronics Bazaar takes a peek into the world of these transformers and finds out the factors driving this market

Transformers, as we know them, are electrical devices that help in transferring electrical current between multiple circuits through electromagnetic induction. When it comes to electronics, everything requires a certain magnetic field. To create this magnetic field, what comes in use is a coil wound transformer. As the name suggests, coil wound transformers consist of metal pieces that act as the core of the transformer, on top of which a magnetic field is created by winding a copper wire around it. The size, shape, diameter and thickness of these coils depend on the requirements of a user. The determining factor is the intensity of a magnetic field that needs to be created for a particular product. In addition, the amount of induction that needs to be produced determines the dimension of the coil and the number of turns it needs to take when placed on a metal piece to complete the making of a coil wound transformer.

The power inducers
A coil wound transformer is an important part of any final product in electronics because it is one of the most primary factors that induces power according to the specific requirement of the device. Be it a laptop or an air conditioner, coil wound transformers are present in these devices. Surjit Singh, COO, Rosy Electronics Pvt Ltd, says, “One of the coil wound transformers that we manufacture is used in energy meters. This kind of magnetic transformer acts as the heart of any power meter because it measures exactly how much electricity is being consumed. So its basic function is to facilitate the reading on the meter.”

Ways the coils wind
Application areas of coil wound transformers in electronics include a wide range of products but broadly, they can be classified into two types based on the coil winding technique used—primary and secondary. Primary transformers have a single winding and are mostly used in electronic devices that do not require high amounts of power inducement. While, on the other hand, secondary transformers have multiple coil windings, depending upon the requirements of the customer. Usually, these transformers are sold only in customised forms on the basis of bulk orders placed by a company, which uses them in its manufacturing process. As Hari Shankar Tripathi, quality assurance – head, Rosy Electronics Pvt Ltd, puts it, “Some transformers have 1000 turns while some have 5000 or even more. The number completely depends on where the customer wants to use the transformer. Custom designs are usually provided by our clients depending upon their requirements.”

An emorphous based transformer

The heart of electronic devices
As mentioned earlier, the basic role of a coil wound transformer is to use its magnetic qualities to induce power between two or more electric circuits. To put this simply, its role is to draw power from the main source, and convert a high voltage current to a low voltage one as per the requirement of the connected electronic device. Tripathi says, “Take a plug point for instance; it releases about 220V of power but if it reaches a connected laptop to its full potential, the device will burn. This is where the role of a coil wound transformer comes in. The transformers present within the wire regulate the current and reduce the voltage from 220V to 6V or 12V, depending upon the laptop’s requirements.” This concept holds true for any device in electronics. In short, no electronics can survive without these transformers.

The common ones
The type of transformer used depends on the application. Since the number of application areas is large, it’s no surprise that the number of transformers available is reasonably high. But the most commonly used transformers in the electronics manufacturing sector are:

  • Ferrite core transformers: As the name suggests, these coil wound transformers come with different cores and are widely used in intermediate frequency (IF) stages in superheterodyne radio receivers. Even though there are several types of cores, the ones most commonly used are ring coil, drum coil (DR core), T core coil and E core coil.
  • Current transformers: What sets a current transformer apart from its counterparts is its ability to provide a current capacity to the secondary winding which is directly proportional to that of the primary winding. This type of transformer is most commonly used in the electrical metering industry apart from varied usages in the Indian electronics manufacturing sector. The most popular current transformers that are available in the market these days are:
  • Ferrite based transformers
  • Amorphous based transformers
  • Nanocrystalline based transformers
  • Hybrid core transformers
  • Cold rolled grain oriented (CRGO) based transformers

The new entrant

It is critical for all components to go through technological advancements. Coil wound transformers are also in the race. Nanocrystalline based current transformers are the latest in the market. These transformers come with iron based nanocrystalline ribbons and have moderate saturation magnetic induction, high permeability and low core loss. They are known to be efficient in reducing the amplitude error and phase displacement that are usually prevalent in current transformers. In addition, nanocrystalline cores also offer linear hysteresis loop and high permeability compared to other magnetic cores. But when it comes to usage, they are not a preferred option in India because the price is significantly higher compared to ferrite based current transformers. Hence, Indian companies prefer the latter. But the scenario is the opposite in other countries.

Current transformers being manufactured at Rosy Electronics’ manufacturing facility

Making an impact on the market
India is one of the fastest developing countries in the world. This fact is gaining wide acceptance globally, courtesy the Indian government which is trying to ensure a better manufacturing ecosystem in the country.
This phenomenon has also led to a rise in competition within the country. Hence, manufacturers prefer to source the cheapest options available. The reason is simple—low overhead costs lead to lower price and higher demand. This trend has pushed the demand for ferrite based transformers, as these are widely used in electronic energy meters and come at a low cost. Even though they have qualities like high resistance capacity, low current loss and a low weight, they have average accuracy levels.
The electronics manufacturing industry needs to pause and weigh its options, and decide whether to focus on quality or price. This will be reflected in the purchase decisions made by the buyers of transformers in the future.


By Samonway Duttagupta