Haryana BSEH Senior Secondary NSQF Power flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Kilowatt-hour

The commercial unit of electrical energy, equal to 1000 watts used for one hour or 3.6 megajoules. Electricity bills charge consumers per kWh consumed.

Load factor

Ratio of average load to maximum demand over a given period. A high value shows the plant capacity is used evenly and lowers the cost per unit generated.

Diversity factor

Ratio of the sum of individual maximum demands to the maximum demand of the whole system. It is always at least one because consumers peak at different times.

Primary energy source

A source available in nature before conversion, such as coal, natural gas, wind or sunlight. Secondary energy is the converted form, for example electricity or refined fuel.

Rankine cycle

The thermodynamic cycle of a steam power plant, with boiler heating, turbine expansion, condenser rejection and pump compression. Reheating and feed heating improve its efficiency.

Betz limit

The maximum fraction of wind power a turbine can extract from an air stream, equal to 16/27 or about 59.3 percent. No practical turbine exceeds this theoretical value.

Plant capacity factor

Actual energy generated divided by the energy the plant would produce running at rated capacity for the whole period. It measures how fully the plant is used.

Solar cell

A p-n junction semiconductor device that converts light into electricity. Its performance is described by open-circuit voltage, short-circuit current and fill factor.

Hydro power equation

Power equals density times gravity times discharge times net head times overall efficiency. Doubling the head or the flow doubles the output of the plant.

Skin effect

The tendency of alternating current to concentrate near the conductor surface, raising effective resistance. It grows with frequency and conductor diameter and is ignored at DC.

Surge impedance loading

The power a lossless line delivers when terminated in its surge impedance, equal to voltage squared divided by surge impedance. It indicates the natural loading of the line.

Ferranti effect

The rise of receiving-end voltage above sending-end voltage on a long, lightly loaded line, caused by the line charging current flowing through line inductance.

Radial feeder

A distribution feeder connected from a single source with no back-feed path. A fault near the source interrupts all consumers downstream of the fault point.

Corona loss

Power lost as ionisation of air around high-voltage conductors, producing hiss, glow and ozone. Bundled conductors and larger diameters reduce it.

Transformer EMF equation

Induced EMF equals 4.44 times frequency times turns times peak flux. It shows that the voltage per turn is the same in both windings.

Synchronous speed

The speed of the rotating magnetic field, equal to 120 times frequency divided by the number of poles. A four-pole machine on 50 Hz supply runs at 1500 rpm.

Slip

The difference between synchronous speed and rotor speed, expressed as a fraction of synchronous speed. Rotor frequency equals slip times the supply frequency.

Star-delta starter

A starter that runs the motor windings in star during starting and delta during run. Starting current falls to one-third of the direct-on-line value.

Transformer maximum efficiency

A transformer reaches maximum efficiency when its variable copper loss equals its constant core loss. This occurs at a specific load fraction, not necessarily full load.

Distance relay

A relay that measures the impedance from voltage and current to locate a fault. Zones are set by reach, with zone one covering about 80 percent of the protected line.

Differential protection

A scheme comparing currents entering and leaving a protected transformer or generator. It trips on internal faults but stays stable for faults and load outside the zone.

Current transformer

A measuring transformer that reduces line current to a standard secondary value for relays and meters. Its secondary must never be open-circuited while primary current flows.

Isolator

A switch that provides a visible isolation gap in a circuit but has no arc-quenching capability. It must be operated only after the circuit breaker has cleared the load.

Protective earthing

Connecting exposed metal parts to earth so that fault current flows and the protective device trips quickly. It also limits touch voltage to a safe level.

Energy audit

A systematic study of energy use in a facility to identify waste and cost-saving measures. It may be preliminary, detailed or targeted, and uses metered data.

Payback period

The time needed for annual savings from an efficiency measure to recover its initial investment. It ignores savings after payback, so life-cycle costing is often preferred.

Specific energy consumption

Energy input divided by production output, for example kWh per tonne of product. Tracking it over time shows whether plant efficiency is improving or drifting.

Power factor correction

Adding capacitors to supply reactive power locally, reducing line current and kVA demand. Required kVAR equals active power times the difference of the two tangent values.

BEE star label

A rating from one to five stars awarded by the Bureau of Energy Efficiency to appliances, based on energy performance. More stars mean lower running energy consumption.

Electricity Act 2003

The Indian law that unbundled generation, transmission and distribution, created open access and electricity trading, and set up regulatory commissions for tariffs.

ESCO performance contract

An arrangement where an energy service company funds efficiency improvements and is paid from the measured savings, sharing the benefit with the client.

AT&C loss

Aggregate technical and commercial loss, the gap between energy input and energy billed and collected. It combines technical losses with billing and collection shortfalls.