GOR / Buchholz Relay
Buchholz Relay is a gas-actuated relay installed in oil immersed transformers for protection against all kinds of internal faults [Falling Oil Level, Short Circuited Core Laminations, Short Circuit b/w phases, Earth Fault, etc].
Relay is used to produce an alarm in case of incipient faults in the transformer and to disconnect the transformer from the supply in the event of severe internal faults. It is installed at the middle of the connection pipe between the conservator and transformer main tank. In-case of a transformer with OLTC, a surge relay is provided between the conservator and OLTC.
MS Tank
MS Tank provides mechanical protection for the Core Coil Assembly including Windings, holds the insulating oil & aesthetic look for the complete transformer. It is constructed & fabricated from low-carbon mild steel plates by qualified welders and designed to withstand vacuum & pressure according to CBIP norms. There are different types: Plain Sheet MS Tank, MS Tank with external cooling tubes, MS Tank with detachable radiators & MS Tank with corrugated wall panels.
MS Tank is grit blasted to have perfect finish on inner & surface to avoid corrosion. Inner surface is painted with hot oil. For MS Tanks of larger transformer rating additional stiffeners are provided to withstand higher/ internal pressure while in operation. The manufactured tanks are tested for leakages by including fittings & accessories before surface treatment and after final assembly.
Marshalling Box
The transformer is equipped with lot of fittings & accessories that are essential for the proper & safe functioning. Marshalling Box is mounted/fitted to the transformer main tank and leads from various measuring [OTI, WTI] instruments are connected to terminal connection blocks for the monitoring purpose. Thermostat, Space Heater, Terminal Connection Board, etc are components of Marshalling Box.
Radiators
Radiators (Pressed Mild Steel) are used to limit the temperature of the transformers to a safe limit. Fins type radiators are provided to radiate the heat of the oil to atmosphere more effectively. Hot oil circulates through the radiator tubes/fins and the heat is radiated to atmosphere by the principle of conduction and radiation.
In the radiator oil circulates downwards because the hot oil in the main tank goes to the top portion of main tank and to the radiator. After its heat is lost in atmosphere through the radiator, it becomes cool and goes downwards again entering the main tank through bottom valves of radiators. For distribution transformers with OCTC up-to 1000KVA is provided with weldable radiators to main tank whereas for above ratings with detachable radiators. For transformers with OLTC from 500KVA rating is provided with detachable radiators.
Design:
We use customised Pro-E software for designing of Electrical Transformers, 3D view is possible and by given parameters how the transformer will look once manufactured can be simulated. We design as per IS: 2026, IS: 1180, IEC: 60076 & CBIP norms which are followed in the industry. By the software we can predict how the transformer will behave under electromechanical stresses, short circuits and overloads. The designs are so chosen that the total cost including material, maintenance and the energy cost due to no load and load losses are minimum. The design and manufacturing operations are guided and controlled by experts in the field. All the above factors ensure that transformer is with optimum design, reliable and rugged in construction.
Copper Winding:
The most significant material in a transformer is the winding which comprises of rectangular and round conductors used for windings. The conductor is usually insulated with either high-grade multi-paper covering or with an insulating enamel coating.
The windings are designed so as to ensure reduced axial stresses during Short Circuit conditions and withstands impulse and over-voltages. Some standard forms of coil winding are Spiral,Helical, Cross-Over and Disc winding. For Power Transformers, both low voltage and high voltage windings are Disc type, which give highest resistance against short circuits. It is ensured proper tension is given on the winding for rigidness.
After receiving Copper conductor it will undergo Quality checking, Conductivity test (Resistance test) and during winding continuity of parallel conductors will also be checked.
Coil Tightening: Winding coils are compressed to the designed heights after the insulation is dried for specified duration to ensure their proper shrinkage to designed level. For higher rating transformers compressing is done by hydraulic press with suitably designed clamping fixtures.