Electrical4U 
As explained in resistance variation with the temperature, the electrical resistance of a material can change when its temperature changes. The size and direction of that change depend on the material and the temperature range. What is the Temperature Coefficient of Resistance? The temperature coefficient of resistance measures changes in the electrical resistance of any … Read more
A 3 kV to 36 kV switchgear system is classed here as medium voltage switchgear or MV switchgear. IEC practice can run MV from 1 kV to 52 kV, so this band is a common indoor and outdoor range rather than the only definition. These switchgears come as metal enclosed indoor type switchgear, metal-enclosed outdoor … Read more
On this page, high voltage switchgear means gear that handles voltage above 36 kV. IEC lists other HV steps (often 52 kV and up), so 36 kV is a common site cut-off rather than the only one. Switching at these levels draws a long, hot arc, so the poles and tanks have to be designed … Read more
Arc interruption theory is how a breaker kills the plasma after the contacts part. The insulating material (gas, oil, vacuum or air) in a circuit breaker has to do two jobs: On a fault the relay trips the breaker. As the poles part, an arc is drawn in the ionized gap. The insulator and the … Read more
A magnetic circuit is a closed path that magnetic flux follows, the magnetic analogue of an electric circuit. An iron-cored solenoid carrying DC sets up flux that leaves the N pole, crosses air to the S pole, then returns in the iron. A path that uses both air and iron is a composite magnetic circuit. … Read more
Armature windings on a DC machine come in two families: lap windings and wave windings. This page is about lap windings, including simplex and duplex lap. Simplex lap has one set of paths (m = 1). Duplex lap has two (m = 2). What is a Lap Winding? Successive coils in a lap winding overlap. … Read more
What Are Flexible AC Transmission Systems (FACTS)? FACTS stands for Flexible AC Transmission Systems. IEEE defines the term as AC transmission systems that use power-electronic and other static controllers to improve controllability and power-transfer capability. Depending on the controller, FACTS can regulate voltage, supply or absorb reactive power, change effective line impedance or control power … Read more
The feed water and steam circuit is the water path through a boiler: economizer, drums, water tubes and superheater. Feed is heated, boiled and superheated before it leaves as steam. Economizer The next block of the Feed Water and Steam Circuit is the boiler drum. Boiler Drums Water-tube boilers usually have a steam drum at … Read more
A nickel-iron battery uses a rechargeable alkaline chemistry with nickel oxyhydroxide positive material and an iron negative electrode. The names Nickel Iron Battery and Edison Battery refer to this system. A Ni-Fe battery is mechanically rugged and can tolerate some electrical abuse, but it is not short-circuit proof and still requires correctly rated protection, charging … Read more
Losses in Transformer An electrical transformer is a static machine, so mechanical loss is not the usual concern. The losses in transformer that matter here are electrical. Loss is input power minus output power. When power is fed to the primary of a transformer, some of it covers core losses in transformer: Hysteresis loss in … Read more