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The main source of heat generation in transformer is its Copper Loss Or I2r Loss. Although there are other factors contribute heat in transformer such as hysteresis & eddy current losses but contribution of I2R loss dominate them. If this heat is not dissipated properly, the temperature of the transformer will rise continually which may cause damages in paper insulation and liquid insulation medium of transformer to avoid this THERMO Group offers following range of cooling solutions based on the customer requirements.

OFWF - Oil Forced Water Forced:

This system uses water as cooling medium. In this system both the fluids namely Cold And Hot are pumped into the heat exchanger hence the name. This is the most efficient cooling system for transformers. Thermo Group offers wide range of OFWF heat exchangers with best in class performance and quality which are completely designed as per customer requirements or as per standards.


Power Rating Up to 3000 kW/Each
Cooler Orientation: Vertical and Horizontal mounted
Cooler Construction: Fixed tube plate, Floating tube plate
Tube Execution: Single and Double
Tubes: Copper, Copper-Nickel (70:30), Copper-Nickel (90:10), Admiralty Brass, Stainless steel 304/316, Titanium
Tube sheet: C-Steel, Naval brass, Stainless steel 304/316, Copper Nickel (70:30), Copper-Nickel (90:10), Titanium.
Tube to tube-sheet joint: Expanded or welded.

OFWF - Oil Forced Water Forced
Transformer Without Cooler
OFWF - Oil Forced Water Forced

Our Double wall type coolers are designed and manufactured with special care where transformer oil cooling is a critical application. Because we understand that failure in transformer due to cooler leakage may lead to heavy financial losses. Unlike single tube coolers, this execution of the tube bundle requires double tubes. This advanced safety design prevents the chances of water and oil mixing in heat exchanger and also the cooling water pressure is not limited by oil pressure Also the processes need not to be terminated immediately after the failure. Thus keeping the transformer in service. In case of leakage, water or oil is led into the chamber between tubes and the tube plates, therefore the double tube system always prevents water and oil from mixing. The double tube design is the most valid solution to protect the transformer, especially when, using sea or industrial water, and where the site maintenance is not easy. In case of leakage an alarm is provided to a leakage detector provided at the collecting box fitted to the cooler.


OFWF - Oil Forced Water Forced

OFAF- Oil Forced Air Forced

TIn this system the heat dissipation is accelerated by using Forced Air on the dissipating surface &oil is forced to circulate within the closed loop of transformer tank by means of oil pumps. The main advantage of this system is that it is compact system and for same cooling capacity OFAF occupies much less space compared to ONAN system. THERMO group offers wide range of OFAF systems which are specifically designed as per the customer needs with the aid of latest technology and techniques.

Power Rating Up to 1000 kW/Each
Cooler Orientation: Vertical, Horizontal & Inclined.
Tube Execution: Single and Double
Tubes: Copper, Copper-Nickel (70:30), Copper-Nickel (90:10), Admiralty Brass, Stainless steel 304/316, Titanium
Tube Sheets: C-Steel, Naval brass, Stainless steel 304/316, Copper Nickel (70:30), Copper-Nickel (90:10), Titanium.
Tube to tube sheet joint: Expanded or welded.

(OFAF) - OIL forced air forced
(OFAF) - OIL forced air forced
ONAN/F - Oil Natural Air Natural/Forced
In this system natural convectional flow of hot oil is utilized for cooling. In convectional circulation of oil, the hot oil flows to the upper portion of the transformer tank and the vacant place is occupied by cold oil. This hot oil which comes to upper side, will dissipate heat in the atmosphere by natural conduction, convection & radiation in air and will become cold. For improved heat dissipation forced air is used, such system is called ONAF.
Pressed Steel Radiators (ONAN & ONAF)
Thermo Group has a special wing involved in manufacturing Pressed Steel Radiators for Distribution & Power Transformer Cooling. Pressed Steel Radiators/ Fin Type Radiators are the thermal exchangers for the oil cooling with natural ambient air circulation. These Radiators are made with several elements with cooling channels connected in parallel. Radiators are manufacture as per the guidelines of IEEMA (Indian Electrical Equipment Manufacturing Association) standards. CRCA steel radiators suitable for Oil Natural Air Natural (ONAN) and Oil Natural Air Forced (ONAF) cooling. We have highly automatic and customized CNC machines to cater all the needs of our esteem customers. We have specially designed shot blasting room and painting booth to give world class finishing. Our product differentiates us from others with outer surface blast cleaned and painted in our painting booth. We have technologically sound and skilled workforce to deliver a quality product. Our designed and manufactured radiators have distinct advantages over other types and styles in terms of Performance & Quality.

Pressed Steel Radiators
Pressed Steel Radiators
Salient Features:

• Customized Designed as per requirement
• High Quality
• World Class finishing
• Durable
• Low on Cost
• After sale service
• Technical Support

Our standard pressed steel radiators meet "IEEMA" specifications. All radiators after assembly undergo a full dimensional check. We also design and manufacture customized pressed steel radiators to meet client's special requirements. Thermo Group guarantee of our products to customer. After sale service and technical support is our key to keep our customer happy and satisfied.
Transformer Corrugated tanks:

Thermo Group is also involved in manufacturing of corrugated tanks. In this system the walls of the tank itself act as heat transfer medium thus eliminating the need of any other external or special system for cooling of transformer oil.
Corrugated Tanks
Corrugated Tanks
Corrugated Tanks






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