Power Transformers Used In Electronic Products

By Research Team, ComConnect Consulting


This project report is focussed on setting up a production unit for step-down power transformers that are generally used in consumer electronics.

Transformer, an electromechanical component, transfers electrical energy from one circuit to another by means of changing the magnetic field, without changing frequency. Various types of transformers are used for different electronic applications. Depending on applications, transformers can be classified into the following broad categories:

1. Power transformer
2. Current transformer
3. Constant-voltage transformer
4. Impedance-matching transformer
5. Driver transformer
6. Audio-output transformer
7. Ignition transformer
8. Pulse transformer
9. Fly-back transformer
10. Ferrite-core transformer
11. Intermediate-frequency (IF) transformer

The main difference between the various types of transformers is the type of core used and the number of turns in primary and secondary coils. Advancements in the field of electronics have influenced change in design and use of new type of core materials. For example, ferrite-core transformers are used in switch-mode power supplies and electronic chokes, dynamo-type core to silicon-grade cold-rolled steels for general-type nickel iron alloys, ferrite-core for high quality and high reliability, and so on. This project report is focussed on step-down power transformers that are generally used in consumer electronics.

Market potential

Transformers and coils are used in almost all electronic products, including consumer electronics, process control instruments, power electronics, medical electronics, industrial electronics, defence electronics and telecommunications, to perform various functions.

Performance of an electronic equipment depends on the quality of transformer. Therefore growth of the electronics manufacturing industry also drives the demand for transformers.

There is huge scope for the transformer and coil industry if high quality and competitive costs are maintained. Moreover, it is relatively easy to start a transformer manufacturing business, as manufacturing equipment and raw materials are indigenously available.

However, as a new entrepreneur you must manufacture different types of transformers, and have marketing tie-ups with electronics manufacturing companies to ensure economic viability.

Manufacturing process

The manufacturing process starts with quality checks. Incoming raw materials must be tested for required quality before being released for production. Then, super-enamelled copper wires are wound on bobbins or former, as per specifications, using a CNC winding machine. Coils are then stalked with core material, terminated and clamped. The completed transformer and coils are vacuum-impregnated using varnish and baked in an oven at a particular temperature.

Important manufacturing steps are explained below.

Core forming

High-quality cold-rolled grain oriented (CRGO) laminations are used in transformers. These come in the form of thin sheets and are cut as per the design, varying for different capacity transformers. Highly skilled people assemble the laminations on a core channel to form the core. These should be perfectly assembled without any gaps to avoid energy loss.


Both high and low voltage windings are done using coil winding machines. Copper or aluminium strips/wires used in winding are meticulously selected for their quality to give the best output. These strips/wires are paper-covered and act as insulators. This helps increase short-circuit strength, thermal strength and maintain higher efficiency.


Wound coils are placed carefully in the assembled core. Insulations are given wherever required using materials like press board. The core bolt and tie rods are fixed in position. Primary and secondary windings are connected as per requirement. Complete assembly is kept in the hot air chamber, and a high temperature is maintained to prevent any moisture in the core coil assembly.


Transformers are individually-tested. Following routine tests are conducted in the lab:

1. No load loss
2. Full load loss
3. Double frequency
4. Double voltage
5. High voltage
6. Insulation
7. Measurement of resistance
8. Heat run
9. Break down voltage (BDV)

Good manufacturing practices

Pollution control

The government places utmost importance on controlling environmental pollution. Therefore small-scale entrepreneurs need to follow environment-friendly practices and adopt pollution control measures by process modification and technology substitution.

India acceded to Montreal Protocol in September 1992. Hence, production and use of ozone-depleting substances like chlorofluoro carbon (CFC), carbon tetrachloride, halons and methyl chloroform must be phased out immediately with alternative chemicals/solvents. A notification for detailed rules to regulate ozone-depleting substances phase-out under Environment Protection Act, 1986 was put in place with effect from July 19, 2000.

Energy conservation

With growing energy needs and shortage coupled with rising energy costs, a greater thrust in energy efficiency in the industrial sector has been given by the government of India since 1980s. The Energy Conservation Act, 2001 was enacted on August 18, 2001. It provides for efficient use of energy, its conservation and capacity building.

Following steps may help in the conservation of electrical energy:

1. Adoption of energy-conserving technologies, production aids and testing facilities
2. Efficient management of processes/manufacturing machineries and systems, quality control and testing equipment for yielding maximum energy conservation
3. Using efficient temperature-controlled soldering and de-soldering stations for optimum use of electrical energy for heating during soldering
4. Periodical maintenance of motors, compressors and the like
5. Use of power factor correction capacitors, proper selection and layout of lighting system, timely switching on/off of lights, use of compact fluorescent lamps wherever possible and so on

Raw materials and equipment

Basic raw materials for making a transformer include laminated core, windings and insulating materials.

As a manufacturer, you must procure some basic machinery and equipment for this business, including the following: CNC winding machine, semi-automatic winding machine, oven (3.5kW), vacuum impregnation plant, digital LCR-Q meter, oscilloscope, insulation tester, high-voltage break-down tester, megger, 4.5-digit digital multimeter, analogue multimeter, and tools, jigs, fixtures and soldering iron station.

In addition, arrange utilities like water and electricity.

Further, a medium- and large-scale unit demands 300sqm area for the operation.

Business economics

An indicative analysis has been given on the following basis and presumptions:

1. Basis for calculation of production capacity is taken on a single shift of eight hours per day basis on 75 per cent efficiency.
2. Maximum capacity utilisation on single-shift basis for 300 days a year is considered. During the first and second years of operations, capacity utilisation is 60 and 80 per cent, respectively. The unit is expected to achieve full capacity utilisation from third year onwards.
3. Salaries and wages, cost of raw materials, utilities, civil construction, etc are based on prevailing rates in and around north India. These cost factors are likely to vary with time and location.
4. Interest on term and working capital loans is taken at the rate of 16 per cent on average. This rate may vary depending on the policy of the financial institution/agency from time to time.
5. Cost of machinery and equipment refer to a particular make/model. Prices are approximate.
6. Break-even point percentage indicated is of full capacity utilisation.
7. Project preparation cost, whenever required, can be considered under pre-operative expenses.
8. Essential production machinery and test equipment required for the project are indicated. The unit may also utilise common test facilities available at Electronics Test and Development Centres (ETDCs) and Electronic Regional Test Laboratories (ERTLs) set up by state governments and STQC, Directorate of Department of Information Technology, Ministry of Communication and Information Technology, to manufacture products conforming to Bureau of Indian Standards (BIS).

Financial analysis

Table I shows fixed capital, that is, land and building, and machinery and equipment. Table II shows the cost of working capital per month.

Total capital investment is given in Table III. Cost of production per annum is shown in Table IV. Turn over per annum is shown in Table V.

Profit before taxes = Turnover per annum – Cost of production per annum = ₹ 1,831,842

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