Introduction to Static Relays

Polarised Relay

Polarised Relay: This Polarised Relay is very frequently employed where operation is required in two directions. In a d.c. Polarised Relay contact A is closed when current in the operating winding flows in one direction contact B will be closed if the current direction reverses as shown in Fig. A.1.16(b). An exactly similar operation can …

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Time Delay Circuit

Time Delay Circuit: Several choices are available in the selection of suitable circuits for obtaining Time Delay Circuit depending on the magnitude of the time delay required. Delays of the order of microseconds can be obtained by what are known as delay lines or cables usually employed in communication systems. The delay line or cable …

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Level Detector

Level Detector: Schmitt trigger or level detector circuits are very often employed in static relay circuits as a final stage before the trip coil circuit of the circuit breaker. The name level detector is derived from the fact that the circuit operates abruptly when the input level exceeds a predetermined value. This is shown in …

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Switching Transistor

Switching Transistor: The characteristics of modern Switching Transistor are specially suited to the functional requirements mentioned already. These along with the other Semiconductor production of static relays. The properties particularly useful in the realisation of the functional requirements are amplification, switching characteristics, sensitivity, high speeds of response, flexibility of design and application, long life, compact …

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Generator Transformer Protection

Generator Transformer Protection: Generator Transformer Protection – Protective relays, being component parts of electrical switchgear, should be closely associated with the control section of such systems, e.g. indicating and signalling systems. Thus the signalling and indicating systems must also be designed on a static basis. The plug in type modular chassis has been widely adopted already in electronic regulating and control equipment. …

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3 Phase Relays

3 Phase Relays: In a 3 Phase Relays, it is economical to build it on a single phase basis. Thus there will be three converter elements, one for each phase, but thereafter the rest of the 3 Phase Relays circuits (e.g. measuring element, output element, etc.) will be common to all the three circuits. This …

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Types of Protective Relays

Types of Protective Relays: Basically, Types of Protective Relays are analogue-binary signal converters with measuring functions. The variables such as current, voltage, phase angle or frequency and derived values obtained by differentiation, integration or other arithmetical operations, appear always as analogue signals at the input of the measuring unit. The output will always have a …

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