In Madurai, as is common throughout India, the power supply is 230 volts at 50 hertz. The types of plugs used are type C, D and M. Type C has two round pins, type D has three round pins in a triangular pattern, and type M has three round pins in a straight line. As a visitor, you may need to use an adapter or converter if your devices use a different type of plug or can't handle the power supply.