Nim Dorji | Trongsa

One of the four turbines (Unit-III) of the 720 MW of Mangdechhu Hydroelectric plant has been down since September 21 and about three months to fix it.

Joint Managing director of MHPA, Chencho Tshering said that a flashover has occurred and it had to be shut down.

“Flashover is a kind of spark that may be caused due to the vibrations or insulation failure which has created carbonization in the machines and we had to shut down,” he said.

Carbonisation is the phenomenon of dirtying of stator windings and other components, with dark dust, inside the turbine when there are sparks or flash thereby causing an electric short-circuit.

Chencho Tshering said that the whole system needs to be cleaned up and also replace the jumper and rotor poles.

“These happenings are not fundamentally and electrically very catastrophic as it was safe for us to not have a fire but just a flashover,” he added.

A similar flashover followed by carbonisation occurred in one of the turbines but it was restored within a month.

“Such a problem arises during the operation and maintenance period of any new hydropower plant,” according to the JMD.

With the monsoon over, there is no haste in restoring the unit. The work is carried on a rotational basis to update each problem.

It also because the annual maintenance for all the machines needs to be done and at the moment the restoration work of unit III is in full swing.

The same unit was shut down three weeks in June due to a fault developed in the stator of the turbine

It was learnt that a committee from DGPC visited the site, and assessed the damages.

According to MHPA official, although the unit is non-functional there is no loss in power generation as the water volume is only enough for three turbines.

The water volume is declining and the water in the dam is enough to generate full for the three units, according to the official.

As of yesterday, the three units generated around 593.16 MW. Over a year of its commissioning, MHPA generated around 16B.