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Distance relays, also known as impedance relay, differ in principle from other forms of protection in that their performance is not governed by the magnitude of the current or voltage in the protected circuit but rather on the ratio of these two quantities. Distance relays are actually double actuating quantity relays with one coil energized by ...
In 1971 M. Ramamoorty was the first to describe [8] calculation of impedance for distance protection using discrete Fourier analysis. The first practical commercially available microprocessor based digital/numeric relay was made by Edmund O. Schweitzer, III in the early 1980s.
Power system protection is a branch of electrical power engineering that deals with the protection of electrical power systems from faults [citation needed] through the disconnection of faulted parts from the rest of the electrical network. The objective of a protection scheme is to keep the power system stable by isolating only the components ...
21 - Distance Relay; 21G - Ground Distance; 21P - Phase Distance; 22 – Equalizer Circuit Breaker; 23 – Temperature control device, Heater; 24 – Volts per Hertz Relay (in some old analog applications, a 59 and an 81 device would be chained together as a 59/81 to implement the equivalent of V/Hz protection) 25 – Synchronizing or ...
Fundamental to radiation protection is the avoidance or reduction of dose using the simple protective measures of time, distance and shielding. The duration of exposure should be limited to that necessary, the distance from the source of radiation should be maximised, and the source or the target shielded wherever possible.
[citation needed] The distance from an arc flash source within which an unprotected person has a 50% chance of receiving a second degree burn is referred to as the "flash protection boundary". The incident energy of 1.2 cal/cm 2 on a bare skin was selected in solving the equation for the arc flash boundary in IEEE 1584 . [ 15 ]
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The basis of a STATCOM is a voltage source converter (VSC) connected in series with some type of reactance, either a fixed Inductor or a Power Transformer.This allows a STATCOM to control power flow much like a Transmission Line, albeit without any active (real) power flow. [12]