SINGH, J. :- This order will dispose of twelve Miscellaneous Petitions Nos. 452 of 1966; 121, 124, 139, 140, 141, 142, 143, 144, 145, 146 and 465 all of 1967.

2. The petitioners in all these petitions are Public Limited Companies and consumers of electrical energy in bulk for industrial purposes which is supplied from Chambal Project by the Madhya Pradesh State Electricity Board, which is the sole respondent in all the petitions. The terms and conditions under which the electrical energy is supplied to the petitioners are same and are contained in agreements which each petitioner has entered into with the Board. At time when the agreements were made, the charges for electrical energy supplied were payable according to the Industrial (High Tension) Tariff applicable to the Chambal area, which was effective from 1st April, 1961 and was framed by the Board under Section 49 of the Electricity (Supply) Act, 1948. This tariff provides for payment of (a) demand charge which is a monthly minimum charge whether energy is consumed or not, and (b) energy charge, which is a charge for the units actually consumed. The tariff also provides that the rates for energy charge are subject to adjustment on account of variation in the cost of fuel according to a formula given in the tariff. The tariff in so far as it is relevant reads as follows :

"A. Two part tariff :

Demand charge per KW of M.D. Rs. per KW. per month

First 500 KW.

7.50

Next 1000 KW.

7.00

Above 1500 KW.

6.50

Plus

NP. per unit

First 50,000 Units per month 5.98

Next 1,50,000 units per month 5.95

Next 3,00,000 units per month 5.93

Over 5,00,000 units per month 5.75

Energy charge

Tariff Minimum

The maximum demand charge on the billing demand or on the contract demand, whichever is higher, is a monthly minimum charge whether energy is consumed or not.

Note : Supply of power under the industrial tariff A and B is intended for industrial motive power only. However, the consumer is permitted to use the electrical energy supplied upto 5% of the monthly consumption for purpose of providing lighting and ventilation etc. within the premises for which supply is given.

The foregoing tariff is subject to the conditions prescribed hereunder :

(1) Variation in energy charge :

(a) The rate per unit mentioned in the tariff shall be deemed to be based on the cost of 155 Np. (sic) per 10,00,000 B.Th.Us. of fuel delivered ex-coal yard at each of the Board's thermal generating stations serving the system in the area to which these tariffs apply. The unit rate under the tariffs shall be increased or decreased by the amount calculated as follows :

For each one per cent variation in the cost of fuel delivered ex-coal yard at each of the said generating stations per 10,00,000 B.Th.Us. there will be a variation in rates of Np. 0.055 per unit in respect of the units generated by the station for the system. The variation per unit for each thermal station shall be determined on the basis of the cost of fuel per 10,00,000 B.Th.Us. at the respective stations and the variation so determined shall be multiplied by the units generated at the respective stations. The sum of the products so obtained shall be divided by the total number of units generated at all the stations (thermal and hydle) in the area to arrive at the variation per unit.

For the purpose of this variation :

The cost of fuel shall be the average cost for the period of account from April to March each year as certified by the Chief Accounts Officer of the Board. The cost of fuel per 10,00,000 B.Th.Us. at each generating station shall be determined by multiplying the total cost of fuel delivered ex-coal yard and consumed in the period of account at the generating station by one million and dividing the product so obtained by the total gross thermal value expressed in B.Th.Us. of the fuel so consumed.

The thermal values of the fuel consumed at the different generating stations as determined by