Power supply in Kerala was affected on Thursday after a blast in the Moolamattom power house of the Idukki hydroelectric project.
Soon after the blast in what engineers said was the feeder potential of the switch yard of the fourth generator, the five functioning generators of the power house were switched off, but by night, four of them were put back into operation, reports said.
A senior official said engineers would examine the extent of damage on Friday, and a decision on restoring full power generation would be taken after inspecting all the generators.
The shutdown has come as a severe blow, coming as it did when normality is yet to be restored after a blast in the circuit breaker of the fifth generator on Sunday evening. This generator has been shut down since then.
The latest incident took place after a potential transformer used for measuring the voltage on a 220-kV electric line burnt, Ouseph Joseph, Chief Engineer (Generations), said. The transformer was used for measuring the voltage on the line supplying power to Thrissur. The reason for the blast is not immediately known, he said.
Officials of the Kerala State Electricity Board were looking into the problem, but a deadline has not been set to solve the issue, he said.
Idukki accounts for about 40 per cent of the power supplied in the State. The burning of the three-decade-old circuit breaker on Sunday led to the shutting down of three generators. Later, two of the three were switched on.
The safety and security measures in the power house were in question when a blast in the underground power station in 2011 resulted in the death of two engineers.