tariff

 The rate at which electrical energy is supplied to a consumer  Therefore tariff naturally becomes attention inviting for electric supply company  The supply company has to ensure that the tariff is such that it not only recovers the total production cost of electricity but also earns profit on the capital investment.

 The tariff cannot be the same for all consumers as the cost of producing e’ power depends considerably on the e’ energy consumed by the user & his load conditions.

 Therefore due consideration has to be given to different types of consumers  (i.e. .)industrial, domestic and commercial)  While fixing tariff.

Objectives of tariff

 Recovery of cost of production  Recovery on the capital investment on pp  Recovery on the capital investment on TXN & DXN s/m  Recovery of cost of operation and maintenance of equipments like enery meter ,billing equipments etc.

 Earn a suitable profit on capital investment

Desirable characteristics of a tariff

 Proper return – this will ensure continuous & reliable service to the consumers  fairness – tariff must be fair so that different types of consumers are satisfied with the rate  Simplicity – must be simple so that an ordinary consumer can easily understand it.

 Reasonable profit – profit element should be reasonable  Attractive – it should be attractive so that large number of consumers are encouraged to use e’ energy

Types of tariff

 Simple tariff  Flat rate tariff  Block rate tariff  Two part tariff  Max. demand tariff  Power factor - 1)kVA max. demand tariff 2)sliding scale tariff 3)kW and kVAR tariff

Simple tariff

 Here there is a fixed rate per unit of energy consumed.i.e. price charged per unit is constant.

 The rate will not vary with decrease or increase of no of units consumed  The consumption is recorded by Energy meter  This is the simplest of all tariffs and is readily understood by the consumers

disadvantages

 There is no discrimination between different types of consumers  The cost per unit delivered ius high  It does not encourage the use of electricity

2. Flat rate tariff

 Here different types of consumers are charged at different uniform per unit rates.

 The consumers are grouped into different classes and each class is charged at different uniform rates.

 For example the flat rate /kWhr for lighting load may be 60paise, whereas it may be 55paise/kWhr for power loads

Advantages

 Simple in calculations  More fair to different types of consumers

disadvantages

 Separate meters are required for lighting loads, power loads etc. this makes the tariff expensive and complicated.

 A particular class of consumers are always charged at the same rate irrespective of the magnitude of energy used.

Block rate tariff

 When a given block of energy is charged at a specified rate and the succeeding blocks of energy are charged at progressively reduced rates , it is called block rate tariff  Here the energy consumption is divided into blocks and the price per unit is fixed in each block.

 The price p.u. of the 1 st block is the highest and it is progressively reduced for the succeeding blocks of energy.

 (e.g.)for 1 P.U.

st 30units may be charged @60paise p.u. and next 25 units @55 paise p.u. remaining additional block @30

Advantages

 THE CONSUMER GETS INCENTIVE TO CONSUME MORE E’ ENERGY

disadvantages

 IT LACKS A MEASURE OF CONSUMERS ACTUAL DEMAND

Two part tariff

 When the rate of electricity is charged on the basis of max. demand of the consumer &the unit consumed ,it is called 2 part tariff.

 Here the total charge is split into 2 components 1)fixed charges 2) running charges

Total charges

Fixed charge

   Depends on max. demand It is assessed from the total connected load It is in kW

Running charge

  Depends on the no of units consumed It is in kWhr

Total charge

Rs (b * kW + c * kWhr)

Where b - charge/kW of max. demand C – charge/ kWhr of energy consumed

Advantages

 Easily understood  It recovers fixed charge which depends on max. demand, but are independent of units consumed

disadvantages

 The consumer has to pay fixed charges irrespective of the fact whether he has consumed energy or not.  There is always error in assessing the max. demand of the consumer .

Max. demand tariff

 It is similar to 2 part tariff with the only difference that max. demand is actually measured by installing max. demand meter in the premises of the consumer .

 This removes the objection of 2 part tariff where max. demand is assessed on the basis of total connected load.

 This tariff is mostly applied to big consumers. However it is not suitable fo small consumers as a separate max. demand meter is required

Power factor tariff

 Here the power factor of the consumer is taken into account.

 P. f. plays an important role in ac systems  A low p f results in so many disadvantages like v drop, loss etc  Therefore a consumer having low p f should be penalized.

Types of power factor tariffs

 kVA max. demand tariff It is a modified form of 2 part Tariff Here fixed charge is in kVA not kW as kVA is inversly proportional to pf(pf = kW/kVA).

Therefore a consumer having lpf has to contribute more towards fixed charges This tariff encourages the consumer to operate their equipments at improved pf.

 Sliding scale p.f. tariff Also called average pf tariff.

Here average pf , say 0.8 lagging is taken as reference If pf of the consumer falls below this pf suitabe charges are made.

If pf is above this reference a discount is allowed

 kW and kVAR Tariff Here both active and reactive power supplied are charged separately.

A consumer having lpf will draw more reactive power and hence shall have to pay more.