Winding

Winding are made and designed to meet fundamentals requirements i.e. (Mechanical, Thermal and Electrical) Paper covered insulated conductor is made from best quality of paper available and high conductivity Al/Cu conductor) which comply with IS-6160,6162 ( Part I and Part II) and IS (7404 Part I and part II) requirements, is used to make winding which are cylindrical in shape and are assembled concentrically. HV and LV winding are reinforced to achieve a strong and self supporting structure. Interlayer cooling ducts are provided to ensure minimum gradient between oil and winding and also to reduce hotspot temperature rise. This minimises the rate of distortion of insulation and ensures high life for transformers. LV windings are made from strips and HV windings which are of relatively low current are made (cross over type) from round conductor. Insulation provided between layers and turns is based upon the insulation level and voltage class of winding. The coil connections are crimped brazed and insulated to withstand test and service conditions. Connections leads to HV terminal.

Construction
The core is made from Cold rolled grain Oriented Steel sheet, such as ZDKH and HIB etc., having a low loss component. Its best characteristics such as free from scale, brittleness, inherent losses due to hysteresis and eddy current are ensured to compile with the international standards. The laminations are imported from well known and reputed world class manufacturers. Core with mitered joints are made to reduce iron losses and magnetising current and is designed to have uniform flux distribution through the magnetic circuit. The core is clamped securely to minimise vibration and inherent noises. Top and bottom channels are clamped with the tie rods to transfer load at the time of lifting core and winding assembly and this also avoids any tensile stress being setup in the core which can affect the iron losses. Insulation is provided between the core and the clamping structure and is tested at 2500V to ensure proper insulation level. Stepped core are made to get proper circle for winding and to provide longitudinal Radial duct for cooling of core, elimination of hotspot without effecting the flux distribution.