Electrical4U 
What is a Brushless Motor? A brushless DC motor (also known as a BLDC motor or BL motor) is an electronically commutated DC motor without brushes or a mechanical commutator. An electronic drive switches pulses of current through the stator windings. The switching sequence and pulse width help control the speed and torque of this … Read more
When Superconductors are cooled below their critical temperature, they expel magnetic field from the bulk. German physicists Walther Meissner and Robert Ochsenfeld reported that expulsion in 1933 and the response is now known as the Meissner effect. They cooled tin and lead in an applied field and measured a stronger field just outside the samples, … Read more
Zener breakdown is a sudden reverse current in a heavily doped diode once the thin depletion layer produces a high electric field. The layer is narrow because doping is high. A 3 V reverse voltage across about 100 Ao (10 nm) already gives a field of about 3e8 V/m. That field lets valence electrons tunnel … Read more
What is Squirrel Cage Induction Motor A 3 phase squirrel cage induction motor is a three phase induction motor that runs by electromagnetism. The rotor bars and end rings form a cylinder that looks like a squirrel cage, which is how the machine got its name. The rotor is a cylindrical stack of steel laminations … Read more
What is an Electrical Power Distribution System? An electrical power distribution system delivers power from substations to customer premises. It carries electric power at medium and low voltage levels, below those normally used to transfer bulk power over long transmission lines. A distribution network commonly includes the following parts: At a distribution substation, transformers reduce … Read more
What is a Thermal Power Plant? A thermal power generation plant or thermal power station makes electric power from heat. In the usual coal-fired plant, steam from a boiler drives a steam turbine coupled to a generator. The sections below follow that steam cycle, then efficiency and siting. Theory of Thermal Power Station Thermal power … Read more
History of SF6 SF6, or sulfur hexafluoride, is a synthetic compound with one sulfur atom and six fluorine atoms. Henri Moissan and Paul Lebeau reported its synthesis at the Faculté de Pharmacie in Paris in 1900. General Electric investigated SF6 as an electrical insulator in 1937. Research and industrial use increased in the mid-20th century, … Read more
What is a Diode? A diode is defined as a two-terminal electronic component that only conducts current in one direction (so long as it is operated within a specified voltage level). An ideal diode will have zero resistance in one direction, and infinite resistance in the reverse direction. Real diodes do not have zero or … Read more
What is a Capacitor? Capacitors are common passive electronic components. Together with resistors and inductors, they control voltage, current, timing, filtering and energy transfer in an electrical circuit. A capacitor separates equal and opposite electric charge on two conductors and stores energy in the electric field created by the applied voltage. A basic capacitor consists … Read more
An electrodynamometer type wattmeter measures average electrical power through the force between two current-produced magnetic fields. One coil carries a current proportional to load current, and the other carries a current proportional to load voltage. Their field interaction produces torque on the movable conductor. For sinusoidal AC and a nearly resistive voltage-coil circuit, average torque … Read more