Meaning of thyristor :
The terms thyristor denotes a family of semiconductor devices used for power control in DC as well as AC system. One of the oldest methods of this thyristor family called silicon control rectifier.
SCR is a four-layer, three junctions, P-N-P-N semiconductor switching device and also have three terminal named: anode (A), a cathode (C) and gate (G).
At present, the use of SCR called thyristor is so vast that over the years, the word thyristor has become synonymous with SCR device. It appears that the terms thyristor is now becoming more common than the actual term of SCR.
The definition of thyristor was decided as under :
Thyristor has constituted three or more p-n junctions. It has two stable states as known as ON state, and OFF state, and it can change its state from one to another.
As per this definition, thyristor now includes a large variety of different semiconductor devices having similar basic characteristics.
Thyristors are used in many applications like light dimmers, motor speed controls, AC power switching, pressure-control systems, and liquid-level regulators.
The silicon controlled rectifier is one of the most popular members of the thyristor family. There are several other members of thyristor family-like PUT, SUS, SCS, Triac, diac etc.