Rectangular and round conductors are used for the windings. The conductor is usually insulated with either high-grade multi-paper covering or with an insulating enamel coating. The windings are such designed so as to ensure reduced axial stresses in Short Circuit conditions and also to withstand impulse and over-voltages. Some standard forms of coil windings are spiral, helical, interleaved disc and plain disc. For Power Transformers, both low voltage and high voltage windings are disc type, which give highest resistance against short circuit forces. It is ensured that proper tension is given on the winding for rigidness.
The most significant material in a transformer is the core. Marson's uses high quality Cold Rolled Grain Oriented Magnetic Silicon Steel to ensure optimum losses and most efficient working of the Transformer. The type of magnetic steel is chosen according to the desired loss level. The laminations are cut geometrically to ensure optimum flow 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.
The "active" part of the Transformer consists of the magnetic core with windings and accessories. The windings are placed over the core limbs and necessary connections are made as per the tappings and vector group. Sufficient ducts are provided between the coils 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 including cooling, size compactness and tapping arrangement. All leads and conductors are rigidly supported by special wooden frames.
The Core-Coil Assembly is placed in the vacuum oven for removal of moisture. After the drying process, 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 oven, it is thoroughly cleaned by pressurised dry air and then placed into the tank and bolted up. All necessary accessories / fittings such as bushings, valves, oil level indicator, pressure relief device, temperature indicator, tap changer etc. are fitted on to the tank body. High quality filtered transformer oil is then filled in the tank to completely immerse the assembly. Finally, connections of primary and secondary to the terminal bushings are made.
Tanks are made of high quality mild steel sheets and plates. State-of-the-Art welding technology is applied to give immaculate finish and leakproof tanks. Cooling is provided by either Pressed Steel type Radiators, which are attached by flange or 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 tank is rigorously tested for any leakage or seepage. Air pressure test, fluid test and ultraviolet 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.
All the tanks are shot blasted to SA2 standard prior to application of paint. Suitable paints are applied according to recommended paint system for different environmental conditions. Internationally accepted paint system recommended by No.l paint manufacturer in the world is used. Facility of air and airless spray systems are used to achieve suitable thickness / protection layer. High precision measuring equipments are used to ensure proper DFT (Dry Film Thickness) levels. Suitable masks and necessary equipments are being provided to the painters ensuring their safety and health. Standard painting process involves, surface preparation by shot blasting the tanks followed by application of suitable coat of zinc primer, MIO and finally Finish