Static Protective Relay

Static Protective Relay:

Electronic Relays : Electronic Relays – These were the first to be developed in the series of static relays. They date back to early 1928 when Fitzgerald presented a carrier current pilot relaying which constituted unit protection of the transmission line. Subsequently a series of electronic circuits for most of the common types of protective gear relays were developed. The components used were electronic valves for measuring unit. The two basic arrangements one as an amplitude comparator and another as a phase comparator are …


Hall Effect Relay Circuit : Hall Effect Relay Circuit is utilized to give a phase comparator. The effect is very predominant in certain semiconductors such as indium arsenide, indium antimonide, indium phosphate, etc. Figure (9.5) illustrates the basic Hall generator where the Hall crystal in the form of a slab carries current in the X-direction and is placed in a magnetic field in the Y-direction, a voltage known as Hall voltage is induced in the Z-direction across the edges of the crystal. Let then the …


Static Relays Basics : A Static Relays Basics refers to a relay in which the measurement or comparison of electrical quantities is done in a static network which is designed to give an output signal in the tripping direction when a threshold condition is passed. The output signal operates a tripping device which may be electronic, semiconductor or electromagnetic. Basis for Static Relay Development: As a result of the great expansion of electrical transmission and distribution systems during the last thirty years and with …


Transductor Relay (Magnetic Amplifier Relay): Transductor Relay – Since relays now have to perform much more complicated functions, many types tend to become very complex mechanically, and hence costly, to make and difficult to test and to maintain. The transductor controlling a simple slave relay, makes it possible to reduce a complex electromechanical device which operates in accordance with the interaction of fluxes and currents in a fully predictable way. A transductor comprises essentially a magnetic core on which there are two …


Transistor Relays : These are the most widely accepted type of static relays, so much so that when we say static relays, we can safely infer transistor relays only. The transistor which acts like an electronic valve can overcome most of the limitations posed by the electronic valves and thus has made possible to develop the electronic relays more commonly known as static relays. The characteristics of modern transistors are such that they can replace the functional elements which are used in electromechanical …