3. Incidence of duty

(1) Subject to the provisions of sub-section (2), there shall be levied and paid to the State Government, either on the units or on the value of energy consumed or sold, excluding losses of energy in transmission and transformation, a duty at the rate or rates to be specified by the State Government in a notification. Provided that, the State Government may, by notification, specify different rates of duty in respect of different categories of consumption or sale of energy. Provided further that, the rate of duty shall not exceed twenty paise per unit in case the duty is levied on the basis of units consumed or sold and ten percentum of the value of the energy consumed or sold in case the duty is levied on the basis of the value of energy (2) No duty shall be leviable on units of energy- (a) consumed by the Government of India, or sold to the Government of India, for consumption by that Government. (b) consumed in the construction, maintenance, or operation of any railway company operating that railway, or sold to that Government or any such railway company for consumption in the construction, maintenance or operation of any railway. (c) consumed by the licensee in the construction, maintenance and operation of his electrical undertaking.. (d) consumed by or sold by any class of persons exempted from payment of duty under section 9. (e) consumed by the Damodar Valley Corporation for the generation, transmission or distribution of electricity by that Corporation. (f) consumed for any purpose which the state Government may, by notification, in this behalf declare to be a public purpose and such exemptions may be subject to such conditions and exemptions if any, as may be mentioned in the said notification,.