Power generation was stopped after a blast at the Moolamattam power house of the Idukki hydroelectric project around 6.30 p.m. on Friday. The blast was in Generator 4.
The blast occurred at the auxiliary system of the transformer when power generation was on, Kerala State Electricity Board (KSEB) sources said.
When lighting was noticed close to the generator, personnel at the spot ran away. No one was injured in the incident.
All the six generators of the power plant had been functioning after recent repairs. The KSEB had increased generation to meet the increasing demand in the summer season. The power generation on Thursday was 12.38 million units.
After stopping power generation, the KSEB imposed load shedding in various parts of the State. The KSEB in a statement said efforts were on to resume power generation at Moolamattam.
The blasts in the power house have raised concerns over the safety of those manning power generation there. Lack of timely upgrade of generators had been cited as reasons for the blasts.
A major explosion occurred at the underground power plant on April 28, 2015 after the circuit-breaker of Generator 3 broke down. In another explosion on June 20, 2011 two engineers lost their lives. Last year also blasts were reported in generators.