Mediaspace scheduled maintenance: Aug 25, 2026 07:00 - 12:00 AM. During this time, videos will be temporarily unavailable. Check status updates.

Lecture

Three-Phase Power: Active Power

Description

This lecture covers the concept of three-phase power, focusing on active power in electrical engineering. The instructor explains the four types of power, including reactive power, and discusses the symmetrical nature of three-phase systems. Through examples and formulas, the lecture demonstrates how to calculate power in a symmetrical system and emphasizes the importance of considering active power in three-phase problems.

In MOOC

Electrical engineering II

Official source

Quiz

Ontological neighbourhood

Electrical engineering

Power engineering: Electric power transmission

Related concepts (24)

Three-phase electric power

Three-phase electric power (abbreviated 3φ) is a common type of alternating current (AC) used in electricity generation, transmission, and distribution. It is a type of polyphase system employing three wires (or four including an optional neutral return wire) and is the most common method used by electrical grids worldwide to transfer power. Three-phase electrical power was developed in the 1880s by several people. In three-phase power, the voltage on each wire is 120 degrees phase shifted relative to each of the other wires.

Power factor

In electrical engineering, the power factor of an AC power system is defined as the ratio of the real power absorbed by the load to the apparent power flowing in the circuit. Real power is the average of the instantaneous product of voltage and current and represents the capacity of the electricity for performing work. Apparent power is the product of RMS current and voltage.

Two-phase electric power

Two-phase electrical power was an early 20th-century polyphase alternating current electric power distribution system. Two circuits were used, with voltage phases differing by one-quarter of a cycle, 90°. Usually circuits used four wires, two for each phase. Less frequently, three wires were used, with a common wire with a larger-diameter conductor. Some early two-phase generators had two complete rotor and field assemblies, with windings physically offset to provide two-phase power.

Single-phase electric power

In electrical engineering, single-phase electric power (abbreviated 1φ) is the distribution of alternating current electric power using a system in which all the voltages of the supply vary in unison. Single-phase distribution is used when loads are mostly lighting and heating, with few large electric motors. A single-phase supply connected to an alternating current electric motor does not produce a rotating magnetic field; single-phase motors need additional circuits for starting (capacitor start motor), and such motors are uncommon above 10 kW in rating.

Polyphase system

A polyphase system is a means of distributing alternating-current (AC) electrical power where the power transfer is constant during each electrical cycle. AC phase refers to the phase offset value (in degrees) between AC in multiple conducting wires; phases may also refer to the corresponding terminals and conductors, as in color codes. Polyphase systems have three or more energized electrical conductors carrying alternating currents with a defined phase between the voltage waves in each conductor; for three-phase voltage, the phase angle is 120° or 2π/3 radians (although early systems used 4 wire two-phase).

Related lectures (35)

Power in Single-Phase AC, Different Power Types MOOC: Electrical engineering I

Explores instantaneous power, active power, reactive power, and apparent power in single-phase AC systems.

Star or Triangle Connection MOOC: Electrical engineering II

Explains star and triangle connections in electrical engineering for balanced three-phase loads and the merging of phase tensions.

Triangle-Star Transformation MOOC: Electrical engineering II

Explores the transformation of a triangle assembly into a star assembly.

Symmetrical Three-Phase Systems MOOC: Electrical engineering II

Explains symmetrical three-phase systems, line voltages, line currents, and neutral current.

Asynchronous Machine: Characteristics and Performance Analysis