Each unit is tuned for optimum efficiency while operating between 45% and 65% of full load (which is the average loading) by delicate proportioning of core and winding losses.
By using CRGO silicon steel mitred cores and paper enamel covered conductors the units are made compact, resulting in lower losses, better regulation and longer life.
Careful design of the core and tank reduces noise level to the minimum. The clamping method adopted helps to keep the optimum properties of the grain-oriented silicon steet, without reducing their mechanical stability.
Winding on HT side are provided with sufficient end-turn reinforcement for extra strength. Windings are pre shrunk and impregnated under, vacuum with hot dry Transformer oil before assembly to ensure their proper functioning.
Radial as well as axial clearances and cooling ducts provided for the coils add to the safety and uniform cooling of the windings and limbs.
Windings are designed to withstand sufficient thermal, dynamic and electrical stresses induced during operation as well as under short circuit conditions.
Each tank is pressure tested and the exterior surface coated with primer and 2 coats of weather-proof paint, the shade being dark grey 1110. 6 of IS-5/1980. The interior is given anti-corrosive protection with oil Hesistant varnish.
Transformers are supplied with first filling of insulating oil conforming to IS-335/1980.
Voltage regulation is provided with winding tappings as per customer's specifications generally at +/- 2.5% and +/- 5% of input voltage. As a standard, Tap changing is effected by means of externally hand-operated 'OFF CIRCUIT' tap-changing switch.
On-Load tap changers (OLTC) with variety of steps to offer optimum control can be offered. All tap-changing switches have indicators and locking device. Special Multi tapping transformers are also in the product range, besides the special duty transformers.
Every transformer undergoes a series of tests throughout the manufacturing process, right from raw material stage to final stage. All routine tests are carried out at our works as per IS 11171, IEC 726 and other International Specifications.
Type tests for impulse withstand short Circuit strength etc have been conducted on representative ratings and voltage classes, at approved national test houses. The ISO certificate has also been revalidated recently.