SCR or Silicon Controlled Diode is one of the most important components in applications of power load control of high values from electrical grid. Working as a switch electronically triggered, it easily exceeds its mechanical equivalent, for its speed, sensibility and capacity of working in high voltage and current. There is no limit for the number of practical applications it can be used, which is important for all of us know a little about its operation principle, its limitations and main applications.
SCRs can work as trigger elements of electronics circuits, as solid-state relays, high power oscillators, power controls in AC circuits, inverters circuits and many applications which other semiconductors as bipolar transistors, field-effect transistors and common diodes cannot be used.
SCRs have a structure that manifests electrical properties that allows they be used in all of this applications. So, initially we can say that what differentiate a SCR of other common components as diodes and transistors is its structure which gives it well-defined properties.
Summing up, SCR can be understood as a diode that just conducts after the shot and just stop conducting after cutting the anode current.