Common Terms Used in the Electricity Sector and Their Definitions

Kathmandu; This week's column in our weekly feature "Urja Gyan" presented by Urja Khabar every Friday presents some common technical terms used in the electricity sector and their definitions. We discussed wind energy, its advantages and disadvantages last week.

Some common terms used in the electricity sector with their definitions are presented below:

The following are some of the most important technical and specific terminology employed in the electricity industry. Without knowing them, it may be hard to understand many of the aspects of electricity. These indicators assist in comprehending many aspects of power producers/distributors, power plants, and industries. Besides, these terminologies are also required for the design of associated systems. Every field has its own terminology and indicators based on research.

1. Depreciation

Following 12 years of operation of the power plant, regular maintenance needs to be carried out. Periodically, it becomes more economically feasible to sell and replace the equipment rather than maintain it. The period before it ceases to be economically worthwhile to keep the asset and it needs to be sold is known as its useful life. Even then, if the machine is being sold, it retains some value, known in English as salvage value or in Nepali as depreciated value.

Since machines have to be replaced once their life, some portion of income is set aside every year for the same. This portion is known as depreciation amount. It is the annual deduction for the machine's wear and tear so that money is kept available to purchase new ones. Various methods can be employed to determine depreciation.

2. Peak Demand

When supplying electricity to a new area, a new hydroelectric facility is constructed. In the initial years, the plant is not operating at full capacity because demand is low. In countries like ours, peak demand is generally for about three hours in the evening. Demand reduces considerably after that, and demand is extremely low at midnight. Maximum demand is the term applied to describe the peak demand. A relatively constant load for a long period of time is referred to as base load.

3. Load Factor

Load factor is a value of the utilization efficiency of electricity. It can be defined as the ratio between the average load over any duration and the peak or maximum load, usually a percentage. An almost 100% high load factor indicates persistent and efficient usage of electricity. A low load factor is a characteristic of unpredictable usage, where maximum peak loads but minimum average loads occur, leading to inefficiencies and cost in the system.

4. Average Power

Average power is the total energy produced or consumed in a specific time interval divided by the duration of time. It gives the average rate at which power is produced or consumed during that time. It is used in load analysis and is used in billing, energy efficiency analysis, and power system planning.

5. Diversity Factor

The factor of diversity is an electrical system engineering factor that determines how well a group of loads is utilizing the capacity of the system. It is equal to the sum of individual maximum demands divided by the system's total maximum demand. The factor of diversity is always greater than or equal to 1. A high diversity factor implies that not all the loads rise to their maximum at the same time, and this makes it easier to design systems with lower capacity requirements. It is most important in generation, transmission, and distribution system design.

6. Demand Factor

Demand factor is an electrical engineering parameter that defines the ratio of connected load actually used at maximum demand. It helps to determine how much of the connected capacity is used practically. Demand factor always equals or is less than 1 (or 100%). It shows the utilization percentage of connected electrical appliances. When demand factor is low, the majority of the connected loads are never used simultaneously. It is utilized while planning substations, feeders, and energy-efficient networks.

7. Plant Factor or Capacity Factor

Capacity or plant factor refers to one of the most vital measures of electric generation performance. It tells the degree to which a plant of power was being used in an interval of time by computing actual energy generated on the amount that could be created if the facility was producing to its peak all the time. Percentage wise, it will always be below or equal to 100% since no power plant runs at full capacity over the entire year. It measures reliability, utilization, and efficiency of performance. This can be used for hydro, thermal, solar, wind, and any type of power plants.

8. Load Curve

A load curve is a plot describing how electrical load (demand) varies with time. It is a valuable aid to power system operation and planning. It helps utilities comprehend and regulate usage patterns.

• Peak Load: The apex of the curve – helps to determine the system's maximum capacity needs.
• Base Load: The minimum constant load – helps to design base load power plants.

Demand factor and load factor may also be determined from the load curve. It is used for load forecasting, scheduling of production, and designing tariff regimes. For example, since demand rises between 6 PM and 9 PM, the load curve helps schedule extra generation or utilizing load control during this period.