Inspector V Venugopal said over 2000 workers, including their family members, were arrested when they tried to picket the mines.
NLC Public Relations Officer Sridhar said the strike has not affected power generation. The output was maintained at 1610 mw today against full capacity of 2490 mw, he said.
The three units of 210 mw capacity in second thermal station and 250 mw of three units in the first station was under major overhaul, mandated periodically, he said.
The workers are on indefinite strike to press their six point charter of demands, which include service regularisation, wage hike and bonus.
Six rounds of tripartite meetings held between trade unions and NLC management in the presence of the Central Labour Commissioner, have failed to break the deadlock.