Transformer design. Transformer engineering.

Virginia Transformer is a transformer engineering and transformer design company manufacturing power transformers for utility, industrial and specialty applications. In the early days of the company (the 1970’s), it was a humble beginning and VTC catered mostly to the mining industry in the Appalachian mountains, with a limited range and scope of products. Designs in those days were carried out using cardex and slide-rules. In the early 1980’s the product range was expanded. From simple distribution transformers, VTC moved into transformers for industrial applications like drives and motor-duty, rectifier applications including transit duty and for sub-station applications. During the 1980's, the KVA and the voltage classes went up, reaching 69 kV in 1989 in our Roanoke facility.

For the last 30 years, VTC has steadily built its engineering strength in all aspects of transformer engineering. Though transformer is viewed primarily as electrical equipment, in fact it encompasses many other disciplines of engineering. Apart from the design of the tank to withstand pressures during operation, the internal clamping structures have to be designed to withstand the short-circuit forces and there comes the mechanical engineering. The heat generated inside the transformer due to core loss and load losses need to be carried away from inside of the transformer and dissipated to atmosphere and that requires thermal design. The knowledge of the properties of the different materials used, such as their dielectric (Insulation), magnetic, thermal, chemical, metallographic, etc are very vital for proper engineering of a large transformer. In VTC, we have that multi-disciplinary knowledge base and we apply them to the transformers we build.

The facility in Chihuahua (VTCW) was set up in 1995, entirely with internal technical resources. In the beginning, the engineering of VTCW was supported from the Roanoke facility. Soon a local engineering department was set up. Today, VTCW handles most of their routine design work, under the Corporate Design manual system. In 2003 we acquired an existing transformer repair facility and within a short time started designing and building new transformers there. The technical Integration of this plant promoted cross fertilization of knowledge and enriched us technically.

Each of our three manufacturing plants, which specialize in specific size ranges, has a local engineering group, supported by the corporate engineering group. By locating the corresponding engineering group within the manufacturing location, we build expertise and ensure quick resolution of problems, maximum efficiency and short lead times. Corporate engineering controls and harmonizes the engineering practices and technical continuity throughout the corporation, and also directs the development work. All our plants are very well connected with each other through modern audio/ video/ data links.

VTC prides itself on the large number of very experienced engineers and senior engineers with a cumulative transformer related experience of several hundreds of years up to 400 KV / 100 MVA range. These senior engineers are supported by a team of well-trained junior engineers.

Electrical Engineering

Many of VTC’s senior electrical engineers are experienced in transformers up to 400 kV class, and as large as 100 MVA. Many of them have been in the transformer industry for more than 30 to 40 years. This vast wealth of experience gives VTC the edge. They are also the trainers, who coach the junior electrical engineers to learn from their knowledge and experience.

Mechanical Engineering

Here again, many of our senior mechanical engineers are experienced in transformers up to 400 kV class and as large as 100 MVA, having 15 to 20 years of experience in the transformer industry. These experienced engineers are also the trainers for our junior engineers. We have active training program to further the skills of all engineering levels.

All engineers are equipped with a variety of special purpose software such as:


  • Core & Coil automatic optimization for the best performance at optimal cost.
  • No-load and Load Loss Optimization
  • Impulse Voltage calculation
  • Short circuit calculation and magnetic field calculation using Andersen’s FLD 12
  • Thermal calculations including overloads
  • Hot-spot temperature calculation for windings and core
  • Pressure Ring and clamping structure strength calculation, etc.
  • Computer program for preparing drawings for the customers and the manufacturing shop.
  • Inventor (3D), Solidworks (3D) and AutoCad (2D) for mechanical designs
  • Finite Element analysis.


The automation in engineering is linked with the rest of the system within the company, beginning with quotes, through order intake into various design processes all the way up to test results. This high degree of automation allows VTC to be efficient in those areas where routine calculations and procedures are handed over to the computer, while retaining control over critical functions where inputs from experienced engineers can enrich the designs. VTC uses the principle of Interactive automation, whereby VTC makes use of huge man-years of engineering experience.

Today, because of the extensive maturing process, VTC’s engineering offers many advantages. A library of more than 10,000 designs and test data archive is maintained, which is an excellent source of reference when preparing designs. The design manual is a repository of knowledge and a major vehicle for technical continuity. This is updated in line with VTC’s technological progress. Over a period of the last 20 years our design manual has grown from an one-volume book to six volumes, spanning a vast array of subjects related to all aspects of transformer engineering. Our engineers participate in professional/ industry meetings and seminars to keep themselves abreast of the latest developments. Our engineers have contributed and published several technical papers in industry journals and magazines.

Design Reviews

Under VTC’s ISO 9001-2008 certification process, every design undergoes a quality assurance process which involves thorough checking and review process. Design Reviews are carried out at various stages and levels during the design process. The first of such reviews take place fairly early when the basic design of the core & coil is ready. This is conducted by the VP/ Engineering manager and with the local/ online with participation of the designers, through the audio/ video links. Checking of all designs and packages are always done by experienced engineers/ senior engineers. The next round of design review is done by manufacturing technicians, before releasing drawings to shop. Mistakes found, If any, are followed up by suitable NCRs. The final round of design review is done when the test results are verified against the design and the results are archived for future references.

Engineering at VTC maintains its customer focus with timely submission of drawings, prepared in 3-D, which offers the customers a better visualization of the product. We supply transformers complying with a large number of national and international standards such as ANSI/IEEE, IEC, CSA, UL, CUL, CE, ABS, etc. VTC continues its on-going initiative to build reliable, more efficient, environmentally friendly transformers, including offering FR3, a bio-degradable fluid, as an alternative to mineral oil.


VTC has its disposal several tools for making developments. Model testing has been a powerful tool for development, as this technique allows verification of results through alteration of parameters and actual application of voltages, currents, heat, force etc.

We have the complete equipment for carrying out transient voltage analysis using recurrent surge generator. This is a scaled down version of an Impulse generator which can produce the same response as of a full magnitude impulse, but at a reduced magnitude. The results can be very useful when developing any new coil/ winding/ insulation arrangements and assessing its ability to withstand surge voltages.

In our effort to produce cost-competitive designs, we have developed sophisticated computer programs which run the design programs through optimization routines. Such programs take into account the material quantities, grades of materials, their rates, the required no-load and load losses, their evaluation rates, etc and take a composite view while arriving at the optimum designs.

Continuous development is the culture at VTC. Each year several development projects are identified in all areas of design, manufacturing and testing. This makes VTC more efficient, allows lower costs, and improved product quality and greater customer satisfaction. The input for the development process comes from different sources, such as in-house issues (like NCRs and CARs), field issues, interaction with customers, consultants, brain storming, etc. VTC has a dedicated development engineering group comprised of experienced engineers, supported by their counterparts in other functions.

Looking to the future, VTC anticipates a higher level of automation, higher productivity, shorter cycle time and bigger unit rating.

ISO 9001

Virginia Transformer strives to meet and exceed the highest standards of quality in our industry. Using our mature, well established ISO9001 Quality Management System as a framework for improvement, we are positioned to provide to our customers new technologies and innovations designed for now and the future. From state of the art coating systems to the latest in electronic controls testing, VT processes are continually monitored for compliance to the rigorous standards demanded by ISO.

Our goal is to maintain a stable, but continuously evolving, customer oriented manufacturing environment which produces the finest, most cost effective products available.

This ambitious goal can only be achieved through the synergy of our system of processes and our people. We consider our people to be a vital, necessary part of the company who raise ISO9001 above a static technology, to a living, growing system of ideas and interaction driven by skills and imagination.

In addition to ISO operational procedures, VT has approval from both UL and CUL. We can comply with ABS standards, and provide CE Certification if required. All phases of our manufacturing operation are designed to meet or exceed the industry standards established by ANSI/IEEE, CSA, IEC, NEMA, and virtually all recognized national and international organizations.