Electricity Tariffs:
The amount of money framed by the supplier for supplying electrical energy to various types of consumers is known as an electricity tariff. In other words, the tariff is the method of charging a consumer to consume electric power.Various Types Of Electricity Tariffs with Characteristics:
1) Simple Tariff:
In this type of tariff, a fixed rate is applied for each unit of energy consumed. It is also known as a uniform tariff. The rate per unit of energy does not depend upon the quantity of energy a consumer uses. The price per unit (1 kWh) of energy is constant. This energy consumed by the consumer is recorded by the energy meters generally applied to tube wells used for irrigation purposes. Graphically, it can be represented as follows:
2) Flat Rate Tariff:
In this tariff, different types of consumers are charged at different rates of cost per unit (1kWh) of electrical energy consumed. Other consumers are grouped under different categories. Then, each category is charged money at a fixed rate similar to a Simple Tariff. The different rates are decided according to the consumers, their loads, and load factors. Generally applied to domestic consumers.
Graphically, it can be represented as follows:
3) Block Rate Tariff:
In this tariff, the first block of the energy consumed (consisting of a fixed number of units) is charged at a given rate and the succeeding blocks of energy (each with a predetermined number of units) are charged at progressively reduced rates. The rate per unit in each block is fixed. For example, the first 50 units (1st block) may be charged at 3 rupees per unit; the next 30 units (2nd block) at 2.50 rupees per unit, and the next 30 units (3rd block) at 2 rupees per unit. Generally applied to residential and small commercial consumers. Graphically, it can be represented as follows:
4) Two-Part Tariff:
In this tariff scheme, the total costs charged to the consumers consist of two components: fixed charges and running charges. It can be expressed as:Total Cost = [A (kW) + B (kWh)] Rs
Where, A = charge per kW of max demand (i.e. A is a constant which when multiplied with max demand (kW) gives the total fixed costs.)
B = charge per kWh of energy consumed (i.e. B is a constant which when multiplied with units consumed (kWh), gives total running charges.)
It can be further divided into the following types:
kVA Maximum Demand Tariff:
In this type of tariff, the fixed charges are made on the basis of maximum demand in kVA instead of kW.
Power factor = kW / kVA
Hence, the PF is inversely proportional to kVA demand.
Hence, a consumer having a low power factor load will have to pay more fixed charges.
This gives the incentive to the consumers to operate their load at a high power factor.
Generally, the suppliers ask the consumers to install power factor correction equipment.
kW And kVAR Tariff:
In this tariff scheme, the active power (kW) consumption and the reactive power (kVAR) consumption are measured separately.Also, a consumer having a low power factor load will have to pay more fixed charges.
Sliding Scale Tariff:
It can be expressed as:
Total Charges = [A + B (kW) + C (kWh)]
Where, A = fixed charges,
B = charge per kW of max demand (i.e. B is a constant which when multiplied with max demand (kW) gives the total fixed costs.)
C = charge per kWh of energy consumed (i.e. C is a constant which when multiplied with units consumed (kWh), gives total running charges.)
B = charge per kWh of energy consumed (i.e. B is a constant which when multiplied with units consumed (kWh), gives total running charges.)
The fixed charges will depend upon the maximum demand of the consumer and the running charge will depend upon the energy (units) consumed. The fixed charges are due to the interest and depreciation on the capital cost of building and equipment, taxes and a part of operating cost which is independent of energy generated. On the other hand, the running charges are due to the operating cost which varies with variations in generated (or supplied) energy. Generally applied to industrial consumers with appreciable max demand.
5) Maximum Demand Tariff:
In this tariff, the energy consumed is charged on the basis of maximum demand. The units (energy) consumed by him are called maximum demand. The max demand is calculated by a maximum demand meter. This removes any conflict between the supplier and the consumer as it were the two-part tariff. It is similar to the two-part tariff. Generally applied to large industrial consumers.
6) Power Factor Tariff:
In this tariff scheme, the power factor of the consumer’s load is also considered. The power factor is an important parameter in the power system. For optimal operation, the power factor(PF) must be high. Low PF will cause more losses and imbalance in the system. Hence the consumers which have low PF loads will be charged more.
It can be further divided into the following types:
kVA Maximum Demand Tariff:
In this type of tariff, the fixed charges are made on the basis of maximum demand in kVA instead of kW.
Power factor = kW / kVA
Hence, the PF is inversely proportional to kVA demand.
Hence, a consumer having a low power factor load will have to pay more fixed charges.
This gives the incentive to the consumers to operate their load at a high power factor.
Generally, the suppliers ask the consumers to install power factor correction equipment.
kW And kVAR Tariff:
In this tariff scheme, the active power (kW) consumption and the reactive power (kVAR) consumption are measured separately.Also, a consumer having a low power factor load will have to pay more fixed charges.
Sliding Scale Tariff:
In this type of tariff scheme, an average power factor (generally 0.8 lagging) is taken as a reference. Now, if the power factor of the consumer’s loads is lower than the reference, he is penalized accordingly. Hence, a consumer having a low power factor load will have to pay more fixed charges.
Also, if the PF of the consumer’s load is greater than the reference, then the customer is awarded with a discount. This gives incentives to the consumers. It is usually applied to large industrial consumers.
7) Three-Part Tariff:
In this scheme, the total costs are divided into 3 sections: Fixed costs, semi-fixed costs, and running costs.It can be expressed as:
Total Charges = [A + B (kW) + C (kWh)]
Where, A = fixed charges,
B = charge per kW of max demand (i.e. B is a constant which when multiplied with max demand (kW) gives the total fixed costs.)
C = charge per kWh of energy consumed (i.e. C is a constant which when multiplied with units consumed (kWh), gives total running charges.)
- 3-Ï• AC cable has a smaller wire than a DC cable.
- It sags less under emergency loads than a DC cable.
- It is less prone to damage due to wind and ice.
- It is generally used in overhead transmission and underground distribution.