Styristors

Styristors are not a standard term for a defined electrical component in widely used reference works. The word often appears as a misspelling or mispronunciation of thyristor, a four-layer PNPN semiconductor switch used to control high-power signals. Because no canonical device bears the name styristor, definitions and usage vary, and some sources treat it as equivalent to a thyristor.

If styristor is intended to refer to a thyristor, the device is a latching current-controlled switch. It consists of four semiconductor layers (PNPN) and includes a gate terminal that triggers conduction. Once triggered, the device conducts and remains on until the current falls below a holding value, at which point it naturally turns off. Gate trigger can be accomplished by a short current pulse; once on, the thyristor cannot be turned off by a gate signal and typically requires circuit conditions (such as a current zero-crossing in AC systems) to commutate off. Thyristors are sensitive to dv/dt and di/dt and require appropriate gating and protection to avoid unintended turn-on or damage.

Common applications include AC power control, motor speed regulation, and dimming in lighting systems, as well as high-voltage rectification and surge protection in power electronics. The thyristor family also includes related devices such as silicon-controlled rectifiers (SCRs), triacs for bidirectional AC control, gate-turn-off thyristors (GTOs), and other gated high-power switches.

In summary, styristor is not a distinct recognized component; the term most closely corresponds to thyristor concepts. For accurate design and terminology, references typically use thyristor, SCR, triac, or related power-switch devices. See also thyristor, SCR, triac, GTO, and IGBT.