SALIENT TECHNICAL FEATURES

Core :
The core is manufactured from good quality Cold Rolled Grain Oriented Silicon Steel Sheets and is of mitred construction to take advantage of grain orientation of the material. The clamping method is designed to reduce the noise level to the minimum.

Windings :
Both the Low and High voltage windings are made from high conductivity, electrolytic, copper or aluminium wires. Generally low voltage coils of Distribution transformers are made from rectangular paper covered strips and is of multi layer, spiral cosntruction. The high voltage coils of these ranges of transformer are manufactured using paper covered round-wire and is of disc cross over type.

Electrical, Thermal and Mechanical effects during operations are being considered while designing the coils. The interlayer and turn to turn insulation of the winding is designed to withstand Power Frequency and Lightning Impluse Test Voltages. The axial and radial brazing of the winding take care of the short circuit forces. Adequate cooling ducts are provided to limit temperature rise and to control hot spot temperature to the allowable level.

Main Insulation :
The main insulation is designed to meet all the electrical mechanical and thermal requirement, the material is sourced from reputed manufacturers only.

Tank :
The tank is made from lamination free quality steel. The tanks are tested for any leakages before surface treatment or final assembly. The inside of the tank is cleaned and coated with hot oil resistant paint or varnish. The outside is properly coated with stove enamelled good quality paints after 7 tank phosphating process.

Tapping :
Generally an off circuit Tap Changer is provided to adjust the HV winding to meet the local voltage condition. Normally +/- 2.5% and +/- 5% tapping are provided on HV side. Any special requirement from customers can also be considered. On Load Tap changers (OLTC) are also provided as per customer’s requirement.

Terminals :
The terminals of the low and high voltage windings are taken out through standard bushings to facilitate connection to the transformers. Either out door type or cable box type terminations can be provided as per the requirement from the customers.

Insulating Oil :
In case of oil filled transformers the filling is done with good quality transformer oil meeting the Indian Standard specification IS-335.