Category: Basic Components of Static Relays

Zero Crossing Detector Circuit

Zero Crossing Detector Circuit: Zero Crossing Detector Circuit basically involves the sine to square wave conversion by a level detector circuit followed by a pulse circuit, which consists of one shot monostable circuit or a differentiator. The zero crossing detection is associated with the production of a pulse at the particular zero crossing. Figure (10.37) […]

Sampling Circuits

Sampling Circuits: Sampling Circuits is one which allows a comparison of instantaneous values derived at different instants of time, thereby dispensing with the need to phase shift and mix signals derived from the primary line quantities. Figure (10.36) shows a sampling circuits in conjunction with an amplitude pulse width convertor (A/W convertor), this complete circuit […]

Summation Device

Summation Device: Summation transformers and sequence networks as already discussed can combine a number of electrical quantities into a single quantity. The operational amplifier is commonly used as a mixer or summer and the Summation Device is shown in Fig. (10.35). The arrangement is used to obtain an output which is a linear combination of […]

Square Wave Generators

Square Wave Generators: Diode clippers can be used to remove the curved portion of the sinusoidal wave to give square waves. The operational amplifier together with an integrator, can be used to generate a square wave. The simplest form of the Square Wave Generators is the astable multivibrator shown in Fig. (10.30). where two junction […]

Smoothing Circuits

Smoothing Circuits: The rectified a.c. consists of a series of undirectional half waves of current or voltage. It is generally desirable to smooth this output. The various filters used for Smoothing Circuits are the conventional RC filter, RC chain filter, transistorized filter, bucking transformer filter, phase splitting circuits, etc., some basic Smoothing Circuits are shown […]

Logic Circuit in Static Relay

Logic Circuit in Static Relay: The concept of Logic Circuit in Static Relay can be better understood by considering the logic operations performed by the devices rather than the actual happenings that occur during their operation. This makes complex static relay operation also simple, because the interest then is only on what happens rather than […]

Thyristor in Static Relay

Thyristor in Static Relay: The structure of Thyristor in Static Relay consists of four alternate p-and n-type layers. In the thyristor (also called a silicon controlled rectifier—SCR) connections are made available to the inner layers. It acts like two transistors in tandem, one pnp and another npn. Figure (10.16) shows the circuit symbol for the […]

Unijunction Transistor in Static Relay

Unijunction Transistor in Static Relay: Unijunction Transistor in Static Relay is a three terminal device with only one pn-junction. It is made up of n-type silicon wafer having two base controls and a p-type alloy junction which acts as emitter electrode. In normal operation the lower ohmic contact (base B1) is grounded. If the emitter […]

Field Effect Transistor in Static Relay

Field Effect Transistor in Static Relay: Field Effect Transistor in Static Relay is a unipolar device as compared to bipolar transistor already discussed. It consists of a bar of semiconductor material whose resistance is modulated by varying either the cross-sectional area of the bar or the density of current carriers in it, or both, by […]

Transistor Use in Static Relay

Transistor Use in Static Relay: Transistor Use in Static Relay – In its simplest form, it consists of two pn junction diodes coupled together by a very thin common base, either of p-type or n-type semiconductor material. It is possible to separate input and output circuits, which may be controlling circuit and controlled circuit respectively. […]