Integrated in-house production & testing facilities supplemented by state-of-the-art technologies guarantee reliability and efficiency for all the Indian Markets.

The Winding

Rectangular and round conductors are used for the windings. The conductors is usually insulated with high grade multi paper covering of with an insulating enamel casting. The windings are such has designed so as to
ensure reduced axial stress in short circuit conditions and also to withstand impulse and over voltages. Some standard forms of coil windings are spiral, helica, interleaved disc and plain disc. For Distribution Transformers, both low voltage and high voltage windings are disc type, which give highest resistance against short circuits. It is ensured that proper tension is give on the winding for rigidness.

Core-coil Assembly

The “active” part of the Transformer consists of the magnetic core with windings and accessories. The windings are place over the core limbs and necessary connections are made as per the tappings and vector groups. Sufficient ducts are provided between the coil to ensure heat dissipation through circulation of oil. Best quality insulation is provided at all joints and gaps. The optimum design of Core Coil Assembly is achieved by considering the required technical particulars, cooling, size compactness and tapping arrangement. All leads and conductor are rigidly supported by special wooden frames.


The Core-Catt Assembly is placed in the vaccum oven for removal of moisture. After the drying presses, the assembly is retightened to take up all shrinkage and then the unit is ready for tanking.


After removing the Core-Coil Assembly from the heating over, it is thoroughly cleaned by pressurised air and then placed into the tank and bolted up with all necessary accessories. High quality filtered transformer oil is filled in the tank to completely immerse the assembly. Finally, connections of primary and secondary to the terminal. Tanks made of high quality mild steel sheets and plates. State-of-Art welding technology is applied to give immaculated finish and task proof tanks. Cooling is provided by either Pressed Steel type Radiators, which are attached by flange of welded directly onto the body, or by corrugated fin walls. Either types of tanks can be supplied as per customer’s requirement, however, corrugated type tank has merits over conventional radiator type tank because of its compact size and aesthetics. Every tanks is rigorously tested for any leakage or seepage, air pressure test, fluid test and ultra voilet lamp test are conducted on each tank to ensure that no leakage takes place. Continuous efforts in Research and Development result in excellent finish, leakproof and rigid tanks.

The Core

The Prime core of a transformer is the core. PTT uses high quality cold rolled grain oriented magnetic silicon steel to ensure optimum losses and most efficient working of the transformers. The type of magnetic steel is chosen according to the desired loss level. The laminations are out geometrically to ensure optimum now of magnetic flux and minimum air gap between the joint of two consecutive sheets. The supporting structures and clamping devices of the core contribute to the compactness of the design and also ensure low sound levels.