On 12th Dec 2014, when everyone in Tamilnadu were fighting out to get a Ticket to Superstar movie Lingaa, TN government increased the Electricity tariff by 15%.
The new tariff is given below with comparison to old tariff. 
For customers using below 500 units(bi monthly) government will absorb the raise(effectively no increase). But others- mostly in the cities using AC, it is a steep increase in tariff.
The new TNEB tariff calculator is is alive with new rates.
If you need to check the old tariff( from April 2012 to 11th Dec 2014), it still available here.