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Tirathai Public Co., Ltd., is a manufacturer of made-toorder transformers for domestic and overseas distribution and service provider of transformer installation, maintenance, and testing. During 2011-2015, the Company and its subsidiaries have generated over 70% of the total incomes from domestic markets. The Company has 2 manufacturing plants; one for manufacturing power transformer and the second one for distribution transformer. At present, the Company is the sole local manufacturer of transformers in Thailand, which has manufactured both power transformers and distribution transformers and has received the transfer of manufacturing technology from Siemens Transformers Austria GmbH & Co KG (VA TECH EBG Transformatoren GmbH & Co) of Austria; and Fuji Electric Systems Co., Ltd. of Japan, the world’s leading manufacturers of transformers. Currently, the Company is holding shares in 3 subsidiary companies that supply the transformer’s components to the Company as follows;

Thai Fin Co., Ltd., located in Bangpu Industrial Estate, is operating a business of manufacturing, distribution, repairs, and maintenance of transformer tank body and accessories including cover, fins, clamps, etc., and has manufactured and distributed the products solely to the Company. The Company has increased its investments in Thai Fin Co., Ltd., totally 5 million Baht in September 2006 for purchase and improvements of tools, machineries, and factory buildings in order to meet the expansion of production capacity; as a result, Thai Fin Co., Ltd., has its paid-up registered capital of totally 15 million Baht which TRT holds 99.99% of Thai Fin’s common shares.

Tirathai E&S Co., Ltd., is providing distribution, installation and maintenance services of electrical power equipment and being established under the business plan as a separated business unit in order to increase the flexibility of management and competitions in the markets. Tirathai E&S Co., Ltd., had now started its operation since 3rd quarter 2010. TRT E&S currently has its paid-up registered capital of 5 million Baht which TRT holds 99.99% of TRT E&S common shares. Currently, the company assemble and distribute Aerial / Digger Derrick Crane for Electrical maintenance for Metropolitan Electricity Authority and Provincial Electricity Authority.

L.D.S. Metal Work Co., Ltd. Located in Bangpu Industrial Estate. Its nature of business provides general custom metal work service, specialized in large size casing transformer. The largest casing transformer L.D.S currently produced is 300 MVA. TRT had been approved to enter into the transaction to purchase 85% of common share in L.D.S. Metal Work Co., Ltd by EGM No.1/2012 held on 5 October 2012 in order to secure the procurement of main raw material and to cope up with the business expansion as specified in 5 year business plan. LDS has increased its capital from 20 million baht. to 120 million baht as per the TRT Board’s resolution No.3/2015 dated 9 August 2015, as a consequent the shareholding of the company has increased from 85% to 92.50%.

During the fourth quarter of 2013, LDS had won the auction and signed contract for Engineering Procurement and Commissioning (EPC) over The Conveyor Belt System to transport Ashes and Gypsum for Hongsa Power plant at The Laos People’s Democratic Republic worth 448 million baht. The project had been completed in the third quarter of 2015. In compensation for on-going quality of the delivered work, on December 2014 LDS had awarded and signed the second contract, called the contract for Operation and Maintenance of the Conveyor Belt System to unloading soil (Waste Line 2) under the name of JV – N.D.P. (JV) This was worth 1,315 million baht. over the 4.5 years contract. These projects have enlarged the capability of the Company in business expansion into EPC of The Conveyor Belt System including services over the Operating and Maintenance for Power Plants, Mine, and every industry who uses Conveyor Belt System to support the growth potential to achieve the target of the Company.

JV L.D.S..N.D.P. (JV) (LDS hold shares 80% and TRT E&S 20%) established in 2014 according to new business expansion policy of the Company and its subsidiaries regarding the Operation and Maintenance Service, located at the same address as LDS. It’s core business is an Operation and Maintenance of Conveyor Belt System which JV had entered in to an agreement with Hongsa Power Co., Ltd in 2016 for Operation and Maintenance of Waste Line 2 with total project value of 1,315 million baht (or 300 million baht per year) and Operation and Maintenance of Ash and Gypsum Conveyor Belt System with value of 29 million per year with the project term of 4.5 years under the condition to renew the contract every 5 years through the project life. In September 2016, The JV had signed contract for Coal Conveyor System Service Agreement in relation to Hongsa Mine- Mount Power Project worth 24 million baht per year under the condition to renew the contract on a yearly basis through the project life.

Products and Services of TRT Group

Products, businesses, and services of Tirathai Group of Companies consist of two groups:

Transformer Group, manufacture and distribute by the Company

The Company’s products and services are divided into 2 types as follows:


The Company’s transformer products are classified into 3 types, according to the electrical power and voltage, as follows:

Power Transformers

Transformers which have the electrical power of over 10 MVA or having the voltage of over 36 kV (maximum electrical power is 300 MVA; and maximum voltage is 230 kV) or massive MVA shall be able to supply more electricity. This type of transformer uses oils as an insulator to prevent short circuits in transformers. The Company has manufactured the power transformers under the technology of Siemens Transformers Austria GmbH & Co KG (VA TECH EBG Transformatoren GmbH & Co) of Austria and Fuji Electric Systems Co., Ltd. of Japan.

Since power transformers are of large sizes; therefore, before delivering the products to customers, the Company shall disassemble components of transformers as deemed necessary, to facilitate the ease of transportation. Regarding the assembling and installation of power transformers, the Company shall calculate the service fees separately from the prices of transformers; and such services must be provided by experts. The majority of users of power transformers are manufacturers and suppliers of electrical energy such as the Electricity Generating Authority of Thailand (EGAT), the Provincial Electricity Authority (PEA), the Metropolitan Electricity Authority (MEA), industrial estates and large-size industrial factories, which use the electricity from the transmission line, etc. At present, the Company is regarded as one of the three manufacturers in Thailand that can manufacture power transformers of 200 MVA 230 kV; and one of the three manufacturers in Thailand that can manufacture power transformers of 300 MVA 230 kV.

Distribution Transformers

Distribution transformers are the transformers that receive the electricity from the distribution line of the Electricity Generating Authority. Normally, power transformers will have the electric power of not more than 10 MVA; and the voltage of not more than 36 kV.

Special Transformers

The Company has its own strengths in manufacturing special transformers, which are particularly designed and manufactured according to the objectives of use and specifications prescribed by the customers. Parts of the design and the manufacturing technology are different from the production process of normal transformers, which require a lot of expertise of the manufacturers. Special transformers include rectifier transformers, which are used in chemical industrial factories, induction furnace transformers, which are used in metals smelting industry; or transformers using other insulators such as silicone oil, etc. The Company has manufactured this type of transformers under the technology of Fuji Electric Systems Co., Ltd. from Japan.


The Company’s services are diversified and provided, in connection with transformers, for 24 hours a day in order to meet the customers’ demands and to provide convenience to customers. The Company has emphasized its service provision to customers by using specialized personnel and modern tools and equipment. Our service includes erection and installation of transformers, oil filling services, maintenance services, modification and repairs services, testing services, and transformer rental services.