Zhao Wenxue, from the Northwest Electric Design Institute which designed the plant said in a statement that most of the accusations leveled against the plant, built by China Machinery Engineering Corporation (CMEC) are unfair.
The plant had been well designed but had been operated from March 2011 without annual maintenance he pointed out.
"According to normal practice in China, a thermal plant should undergo a one month maintenance period annually," Wenzue was quoted as saying in a statement.
"Only then can the unit be more reliable and efficient and expected to perform well.
"The lack of rain at the hydro catchment areas in Sri Lanka over the past several months posed a threat to the power generation around the island.
"The Norochcholai coal power plant was forced to work beyond its required limits and keep supplying electricity to the whole country.
"With the lack of rain and in an attempt to avoid burdening the public with power cuts the Ceylon Electricity Board had meanwhile decided to postpone the annual maintenance of the Norochcholai coal power plant."
Another source familiar with the matter said the plant is still within a 'defect notification period' which usually follow a large engineering project before being finally handed over to the client.
A coal plant cannot be compared to a hydro or diesel plant as it is more complex and problems also crop up when a plant is shut down and re-started. Some problems have to be repaired while the plant is still in operation Wenzue said.
Some of the technical aspects of such a plant also need to be maintained and repaired while the plant is in operation.
Wenzue said CEB and CMEC engineers were working around the clock to fix the problems.
"The Norochcholai coal power plant had past all the performance tests and it was in operation continuously from February 2012 till end of July 2012," he said.
"Questioning the quality of the equipment used in the project and pointing fingers at CMEC is without basis.
"The Norochcholai coal power plant is not as bad as one makes it look. It is just overused, tired and needs a break to rest like any other equipment does."
Analysts says that a coal plant would in any case be expected to about 80 percent of the time (plant factor) which would allow the 300MW plant to generate about 2,100 GigWatt hours of energy a year.
During the past year the plant had generated 1,875 GigaWatt hours (millions of units of electricity) at a cost of 6.67 rupees a unit at a total cost of 12.5 billion rupees.
To generate the same amount from a combined cycle plant at 15.79 rupees a unit would cost 29.6 billion rupees.
Assuming 80 percent of that energy came from a combined cycle and 20 percent from gas turbines (at 25.93 rupees a unit) it would have cost the CEB 33.4 billion rupees to generate the same amount of energy, Wenzue said.
Following the ground breaking ceremony in July 2007, on a request by Sri Lanka, the Chinese government had asked the builders to complete the project one year ahead of schedule.
"We agreed and mobilized our teams including a skilled workforce for early completion of the project ahead of the scheduled date," Wenzue said.
The design build transfer project was financed with a Chinese loan. The coal plant was long overdue.
However concerns have been raised about the way the deal was closed between the ruling classes of Sri Lanka and China through a so-called 'government to government deal' without open tendering.