Tariff
Tariff means the schedule of rates framed for supply of electrical energy to the various categories of consumers. All types of tariffs must cover the recovery of costs of
Capital investment in generating, transmitting and distributing equipment
Operation, supplies and maintenance of equipment and
Metering equipment, billing, collection and miscall anions services
A satisfactory return on the total capital investment.
Types of tariff
Flat Demand Tariff
This is one of the earliest forms of tariffs used for charging the consumers for electrical energy consumption. This tariff is expressed as energy charges, y = Rs a kW where a is the rate per lamp or kW of connected load and x is the number of lamps or load connected in kW.
In these types of tariff the metering equipment, meter reading, billing, and accounting costs are eliminated. Now-a-days such a tariff is restricted to use such as in street lighting, signal systems, sign lightings etc.
Simple Tariff
This is the simplest type of tariff according to which the cost o energy is charged on the basis of units consumed and can be expressed in the form y = Rs ax
where a is charges in rupees per unit and x is the total electrical energy consumed in units or kWhr.
Flat Rate Tariff
This types of tariff differs from the former one in the sense that the different types of consumers are charged at different rates i.e. the flat rate for light and fan loads is slightly higher than that for power load. The rate for each category of consumers is arrived at by taking into accounts its load factor and diversity factor.
Step Rate Tariff
The step rate tariff is a group of flat rate tariffs of decreasing unit charges for higher range of consumption.
Hopkinson Demand Rate or Two Part Tariff
The total energy charge to be made to the consumer is split into two components namely fixed charge and running charge.
This type of tariff is expressed as Y = Rs a kW + b kWhr Where Rs a is the charge per kW of maximum demand assessed and Rs b is the charge per kWhr of energy consumed.
This tariff is mostly applicable to medium industrial consumers.
Maximum Demand Tariff
This tariff is similar to that of two part tariff except that in this case maximum demand is actual y measured by a maximum demand indicator instead of merely assessing it on the basis of rate able value.
KVA Maximum Demand Tariff
It is a modified form of two part tariff. In this case maximum demand is measured in kW instead of in kW.
This type of tariff encourages the consumers to operate their machines/equipment at improved power factor because low power factor will cause more demand charges.
Doherty Rate or Three Part Tariff
In this tariff total energy charge is split into three elements namely fixed charge, semifixed charge and variable charge.
Such a tariff is expressed as y = Rs a + b kW + c kWhr. Where a is a constant charge, B is unit charge in Rs per kW of maximum demand in kW during biling period (in some case it is also charged in Rs per kVA instead of Rs per kW) and C is the unit charge for energy in Rs per kWhr of energy consumed.
This type of tariff is usual y applicable to bulk supplies.
Off Peak Tariff
The load on the power station usual y has pronounced peak loads in the morning and early evening and a very low load during the night (from 10 P.M. to 6 A.M.).
During the night, therefore, and other off-peak period which may occur, a large proportion of the generating and distribution equipment will be lying idle.
In case the consumers are encouraged to use electricity during off peak hours by giving a special discount, the energy can be supplied without incurring an additional capital cost and should therefore prove very profitable.
This type of tariff is very advantageous for certain processes such as water heating by thermal storage, pumping, refrigeration.
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