Power Transformers

• Power Transformers - upto 500 MVA, 500 kV Class
• Traction Transformers - 25/31.5 MVA 132, 220 kV Class
• Distribution Transformers- upto 5 MVA, 33 kV Class
• Induction Furnace, Earthing and other Special Purpose Transformers (In accordance with IEC/ANSI/BS/IS).

Indigenously developed Computer Aided Engineering tools, having capability to check the integrity of design under various site conditions as well as under Short Circuit Condition are used to optimize the electrical design. Various mechanical /thermal programs are also used to ensure the performance of transformers under adverse site conditions.

These programs include calculation for two or three dimensional electromagnetic fields for verification of magnetic flux distribution and corresponding losses and mechanical forces, thermal distribution in windings, connection leads, core structure and tank walls, voltage distribution in windings and between windings and earth for electrical transients and AC tests.

2D/3D programs are used in drafting the mechanical layout which ensures no fouling of components apart from swift mechanical layouts and issuance of shop drawings. All drawings are made in Auto Cad Platform.

Our standard construction has vertical core design in 3 or 5 limb for three phase and 2 or 3 or 4 limb for single phase transformers. The use of high-quality cold rolled grain-oriented sheets in thickness down to 0.27 mm or 0.23 mm helps in achieving reduced no-load losses and noise. These cores are cut on modern machines and built without the use of core bolt which helps in favorable magnetic flux distribution and avoidance of flux concentration around holes and joints.

The windings are configured to ensure the highest mechanical and electrical performance. These are built on Horizontal or Vertical machines depending upon the need of the type of the winding. Disc winding is generally used for HV which has excellent electrical and mechanical stability under external over voltages and short circuit condition. The finished winding before coil assembly is stabilized under controlled temperature and pressure for pre-shrinking of insulation and proper dimensions. This process leads to high mechanical stability under short circuit and proper voltage distribution for longer insulation life.

The core coil assembly after connection with OLTC is dried in a Vapour Phase Drying/Vacuum Oven which ensures efficient drying of the insulating material. The process timing has been perfected to achieve the required moisture removal.

After drying process, the active part is rechecked for tightening, core coil assembly is then placed in the tank and the fitment is carried out swiftly allowing least exposure. The tank is first put on vacuum and then filled with high-quality insulating oil in a vacuum environment. Resting time is adjusted to the corresponding voltage level to ensure thorough impregnation of the insulating material of winding.

After assembling the bushings, conservator, radiators, accessories etc., the transformer is ready for final test and inspection.

Kanohar has in-house facilities for manufacturing of major transformer components like conductors, tanks, radiators, enabling us greater control over quality and delivery.

Tanks are produced in a state-of-the-art fabrication shop with modern machinery and skilled workmen. The stiffeners are provided at proper places to ensure rigidity and mechanical strength. The transformer tanks are suitable for sea/land or multi-modal transportation. The joints of the tank are welded on both sides to provide extra strength and minimize possibility of leakage under severe operating conditions. All tanks mounted with gaskets are individually subjected to pressure test. The tanks are shot blasted to Sa 2½ for removal of rust and cleaning from any oil and grease. Then immediately zinc rich primer coat is applied to provide adequate protective layer and prevent formation of rust. Epoxy/Polyurethane paint is then applied by spray guns in the paint booth to ensure proper thickness depending upon the atmospheric condition in which it has to operate.

In-house facility is there to produce the Cooling Radiators from 1 mm - 1.2 mm sheet having 305/520 mm width and flange center to center height up to 3 Meters. Latest machinery is used to ensure excellent quality of Radiators. Each Radiator is tested for leakage under pressure and then painted through Flood Painting method.

In order to ensure burr-free conductor and proper coverage of paper insulation of conductor, in-house facility is available to meet the need. The insulation paper is procured from the reputed manufacturers to achieve long life of insulation system.

Fully equipped insulation shop has machines with dust collector to cut the Insulation Board in various shapes and sizes. These insulation boards are from reputed manufacturer like ABB/Weidman. All sharp corners are chamfered to avoid concentration of electrical stress. Static Rings are also made as and when required.

A Quality Assurance System with quality norm at each stage of manufacturing and process is in place, which ensures the consistent quality for long life operation of the transformers. The system is regularly evaluated and upgraded to not only meet the stringent requirements of leading customers but exceed them.

Existing system is certified for ISO 9001, ISO 14001 and OHSAS 18000.

Apart from routine test facilities for transformers complying with IEC/ANSI/IS/BS, all major type and special test facilities (except Short Circuit Test) are also available in-house.

Till date, Kanohar has over 185 transformer ratings tested for Dynamic Short Circuit Withstand Test at STL laboratories like Central Power Research Institute (CPRI). We see this as a mark of a reliable manufacturer.