Power Electronics

SCR Selection Criteria

There are two categories of SCR, the fast turn-off inverter grade SCR and relatively slow turn-off converter grade SCR. Some of the properties of these are interdependent and designers have aimed to combine them in most suitable manner. The application therefore decides what category is to be chosen. Once the category is chosen in each

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Triac Working

Triac Working The triac is a three-terminal device essentially equivalent to two SCRs joined in reverse parallel (paralleled but with the polarity reversed) and with their gates connected together. The result is a bidirectional electronic switch that can be used to provide load current during both halves of the AC supply voltage. Triac connections, shown

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Operation of Triac & GTO

TRIAC (Triode thyristor for alternating current) or triac is a bi-directional thyristor switch mainly used for AC control applications. It conducts in both directions, unlike the thyristors (SRCs) which conduct in one direction only. It can be considered to be equivalent to two thyristors connected in anti-parallel but having only three terminals. It has a

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Operation of Thyristors

Thyristors are a family of semiconductor switches having four or more layers, that is, p-n-p-n type of structure. Nowadays, thyrsitors with blocking voltage in excess of 6 kV and continuous current rating in excess of 4 kA are available. In a thyristor, if the ohmic connection is made to the first p-region and the last

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