Electric Energy is the source of energy for electrical appliances. Your computer, the cooling, and the lighting at your home are all powered by electric energy. Can you imagine life without electric energy? Do you even know how much it costs? Electric Energy is measured in kWh (kilowatt-hour) or MWh (megawatt-hour). Power is equal to work done in respect to time, so work equals power multiplied by time. Since work equals energy, electric energy would be measured by a kilowatt-hour.
The cost of each kWh depends on your location and the company you use. In New York, the average kWh costs 14.31 cents, but it can cost as high as 16.73 cents in Hawaii or as low as 5.81 cents in Kentucky. You’re probably thinking that’s not so expensive, but when it all adds up, the number can become significant. Just look at your electric bill. An electric bill in New York can come out to be $81.68, depending on which appliances are being used. But imagine you’re electric bill when you’re blasting your air conditioner. It can cost you a few hundred dollars. But you candecrease that cost by using more of your fan in place of your air conditioner because a typical fan would cost you in the teens rather than in the hundreds. This is mainly due to the amount of watts used to power your electric appliances. An air conditioner can use up to a few thousand watts, while a fan would only use a few hundred watts. If you want to keep your electric bill low, substitute high watt appliances for low watt appliances .
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
(i) Capital investment in generating, transmitting and distributing equipment
(ii) Operation, supplies and maintenance of equipment and
(ii) Metering equipment, billing, collection and miscall aneous services
(iv) A satisfactory return on the total capital investment.
(i) 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. Ax 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.
(ii) 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 kwh.
(ii ) 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 account its load factor and diversity factor.
(iv)Step Rate Tariff: The step rate tariff is a group of flat rate tariffs of decreasing unit charges for higher range of consumption.
(vi) 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 runign charge. This type of tariff is expressed as
Where Rs a is the charge per kw of maximum demand assessed and Rs b is the charge per kwh of energy consumed.
This tariff is mostly applicable to medium industrial consumers.
(vi ) 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.
(vii) KVA Maximum Demand Tariff: It is a modified form of two part tariff. In tis case maximum demand is measured in Kva instead of in kw. This type of tariff encourages the consumers to operate their machines/equipment at improved power factor because low power factor wil cause more demand charges.
(ix) Doherty Rate or Three Part Tariff: In this tariff total energy charge is split into three elements namely fixed charge, semi-fixed charge and variable charge. Such a tariff is expressed as
y = Rs a + bkw + c kwh.
Where a is a constant charge, b is unit charge in Rs per kw of maximum demand in kw during bil ing 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 kwh of energy consumed. This type of tariff is usual y applicable to bulk supplies.
(x) 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 wil 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.
