A 40 MVA, 11 KV, 2 pole ‘Rade Concar’ make Turbo Generator failed after 9 years in operation, due to an Earth Fault resulting in severe damage at the center of the Stator Core. As this was the first ever failure on a large generator in the country, the Power Generation Authorities were insistent that only the OEM’s should conduct the repair.
With the lack of response from the OEM and due to the severe power shortage in the country at the time, the Power Generation Authorities had no alternative but to have the Generator repaired locally.
Evans Electric was the only company who came forward and were prepared to undertake the repair at site, on an urgent basis. This was required to be done with the Stator in situ, due to the unavailability of a suitable crane to lift and move the 80 Ton stator.
The entire Core was re-stacked in the horizontal direction with jigs and fixtures designed entirely by Evans Electric. The full set of TOP and BOTTOM Roebel Bars were fully manufactured at our Andheri works with locally manufactured conductors and Insulating Materials, packed and transported to the site and the Generator fully rewound, tested and commissioned in record time.
The success of this project resulted in several horizontal in situ core re-stacks and rewinds the Company has successfully conducted over the years.
The generator worked successfully for 40 years from the date of completion. The power Station was shut down due to environmental requirements.
A 248 MW, 4 Pole, Turbo Generator, ‘GE’ make developed a Rotor Earth fault. The rotor weighed 105 Tons, just over a meter in diameter and due to its size, had to be repaired at site.
Evans Electric was the only Company willing to undertake the job of removing both Retaining rings, locating the fault and conducting the necessary repairs at site as was required.
The repaired rotor was brought back into service to the complete satisfaction of the Authorities.
The break down of a 50 MW, 33 KV rated, 2 pole Turbo Generator Stator required a very specialised repair and rewind, due to the unusual and extremely high operating Voltage and the complex winding configuration and construction.
The search for a suitable Repairer initially went Global with the OEM and several large overseas repair Companies refusing to undertake such a project.
Evans Electric were invited to investigate the possibility of repairing the damaged Generator Stator which would have to be done on site due to size and weight restrictions.
After a thorough site inspection of the Generator and its winding, we undertook the project of Completely rewinding the Stator with new Bars, and re-connecting the winding at site as it was not possible to move the 125 Ton Stator.
The entire winding was reverse Engineered and a new set of 120 round section Stator bars manufactured at the Andheri works in Mumbai. The uniquely designed Bars consisted of a three-tiered conductor layout, with continuously transposed conductors on all three layers which were each insulated from each other.
The new set of 120 Bars, 6.5 Meters in length, were manufactured with locally made Conductors and Insulating materials.
The specially fabricated Machines to process and cure the Round section Stator Bars, were fully designed and fabricated by Evans Electric.
The fully insulated and tested bars were specially packed and shipped to the site in individually fabricated tubular casings to protect against bending, deflection and physical damage in transit.
The entire winding was wound at site with all three phases progressively connected due to the stepped connections which would be inaccessible if done conventionally.
The Generator was commissioned in January 2005 and worked satisfactorily for 10 years before the Power Station was closed for economical reasons.
Having consistently proven itself in successfully conducting the most advanced and complex repairs and rewinds of Electrical equipment in the industry, the Company is poised to foray into several areas of untapped potential. The opportunities that lay ahead with the everchanging industrial scenario are boundless.
The range of specialised Services the Company offers are:-
1) Complete Repairs and Redesigns for improved performance
2) Component Redesign manufacture & replacement
3) Elimination of complex Electro -Mechanical operational problems
4) General and Special purpose Motor manufacture
5) Designing and building of special purpose manufacturing & test equipment
6) Special purpose machine design and manufacture
7) Analytical Tests for complex Electro – Mechanical issues