A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors or the transformer's coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformer's core, and thus a varying magnetic field through the secondary winding. This varying magnetic field induces a varying electromotive force (EMF) or "voltage" in the secondary winding. If a load is connected to the secondary, an electric current will flow in the secondary winding and electrical energy will be transferred from the primary circuit through the transformer to the load. In an ideal transformer, the induced voltage in the secondary winding is in proportion to the primary voltage, and is given by the ratio of the number of turns in the secondary to the number of turns in the primary. Usually the transformers those installed in the substation shall be called power transformer having minimum rated voltage 69 kV and the ransformers those installed at the poles, pad-mounted, in the high rise buildings and small factories are called distribution transformer having maximum rated voltage 33 kV.

Transformer losses are divided into losses in the windings, termed copper loss, and those in the magnetic circuit, termed iron loss. Most of our electrical power construction project contracts, we will consider the cost effective for our clients by helping them to reduce losses caused by the ineffective use of transformers, and minimizing the need for new investment through the clients’ loss reduction programs and minimizing negative environmental impact on the future.

Our expectation is to:

  • Encourage greater energy efficiency in low loss energy consuming transformers
  • Start cost effective savings programs
  • Reduce losses from clients owned transformers, and
  • Minimize life cycle costs

In addition, this will not only reduce energy use, but also decrease the investment cost of transformers, while meeting the demand of future expansion business. The tradeoff between the transformer’s price and the losses of the transformer is simplified to reflect the clients’ true investment cost in the energy efficient transformers.


The equipment shall have successfully passed all the type tests or design tests in accordance with the Thai Industry Standards and the following international standards:

  • ANSI Publication C57.12.00 - 1993: General Requirements for Liquid-immersed Distribution, Power, and Regulating Transformer.
  • ANSI Publication C57.12.40 - 1988: Requirements for Secondary Network Transformers, Subway and Vault Types(Liquid Immersed)
  • ANSI Publication C59.2-1966: Method of Testing Electrical Insulating Oils
  • ANSI Publication C57.13-1993: Requirements for Instrument Transformers
  • ANSI Publication C57.12.01.1979 : General requirements for dry-type distribution and power transformers
  • IEC Publications 60044-1(1996) Instrument Transformers Part 1: Current transformers.
  • IEC Publications 60076-1(1993) Power Transformers Part 1 : General.
  • IEC Publications 60076-2(1993) Power Transformers Part 2 : Temperature rise.
  • IEC Publications 60076-3(1980) Power Transformers Part 3 : Insulation level and dielectric tests.
  • IEC Publications 60076-3-1(1987) Power Transformers Part 3 : Insulation level and dielectric tests, external clearances in air.
  • IEC Publications 60076-5(1976) Power Transformers Part 5 : Ability to withstand short circuit.
  • IEC Publications 60076-10(2001) Power Transformers Part 10 : Determination of sound levels
  • IEC Publications 60099-4(1991) Metal oxide surge arresters without gaps for a.c. systems
  • IEC Publications 60214(1989) On load tap changers
  • IEC Publications 60354(1991) Loading guide for oil-immersed power transformers
  • IEC Publication 60044-1 (1996): Current Transformers
  • IEC Publication 60044-2 (1997): Voltage Transformers
  • TIS 384 (1992) Standard for Power Transformer

All the products shall be completely passed the routine test before delivery to the local and oversea customers.


  • 69-230 kV On-Load Tap Changing Power Transformer
  • 12-33 kV Conventional Type Single Phase Distribution Transformer
  • 12-33 kV Secondary Network Transformer
  • 12-33 kV Completely Self-Protected (CSP) Distribution Transformer
  • 12-33 kV Cast Resin Transformer
  • 12-33 kV Substation Pad-Mounted Transformer
  • 12-33 kV Indoor Type Instrument Transformers
  • 12-33 kV Outdoor Type Instrument Transformers


The equipment shall have successfully passed all the type tests or design tests in accordance with the Thai Industry Standards and the following international standards:

Distribution Transformer
Distribution Transformer
Power Transformer
Power Transformer