Fulfilling the vision of the His Majesty Jigme Dorji Wangchuck, the Third King of Bhutan, the Agreement for the implementation of the 336 MW Chukha Hydroelectric Project was signed between the Royal Government of Bhutan (RGOB) and Government of India (GOI) on March 23, 1974. Her Royal Highness Ashi Dechen Wangmo Wangchuck, who signed the Agreement on behalf of the RGOB, was the first Chairperson of the Chukha Project Authority (CPA), the implementing agency.
The 336 (4x84) MW project, estimated to generate 1,800 GWh of electric energy annually, was fully funded by the Government of India, with 60% of the project cost as grant and 40% as loan. The project was estimated to cost Nu. 831 million in 1974: the project was finally completed at cost of Nu. 2,465 million in 1988. The loan carried an interest of 5% and repayable in 15 years. The entire loan has been paid off as of December 2007.
RENOVATION & MODERNIZATION
Collectively, the four generating equipment of the plant have run 697,024 hours as of September 30, 2013. Over the years due to aging and obsolescence, besides regular routine maintenance, renovation and modernization programmes have been initiated and implemented. Major investments are due to be made over the next decade in renovating, upgrading, uprating, and generally modernizing; especially with the electro-mechanical equipment.
Following are some of the major R&M activities completed.
• 220 kV Air Blast Circuit Breakers (ABCB) have been replaced with new SF6 breakers in 2006;
• G-25 Governors have been replaced with G-40 Electro Hydraulic Governors in 2006 and 2007;
• Static Excitation Equipment have been replaced with Digital Automatic Voltage Regulator (DVAR) in 2006;
• Electro-mechanical distance protection relays have been replaced with numerical relays between 2007 and 2009;
• Forged-fabricated runners with higher efficiency have been put into service starting 2009 and 2010;
• Trash Rack Cleaning Machines were installed at Dam in 2009 and 2010;
• Fixed wheel type SFT gates have been replaced with bonnet type hydraulic gates in 2008-2009;
• 35 Ton Gantry Crane at Dam has been replaced in 2009; and
• Upper and lower bearing brackets of Unit-1 have been replaced with better designed brackets in 2011 and 2012.