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What are SCR thyristors?

What are SCR thyristors?

In many ways the Silicon Controlled Rectifier, SCR or just Thyristor as it is more commonly known, is similar in construction to the transistor. It is a multi-layer semiconductor device, hence the “silicon” part of its name.

What does SCR mean?

A silicon controlled rectifier or semiconductor-controlled rectifier is a four-layer solidstate current-controlling device. SCRs are mainly used in electronic devices that require control of high voltage and power. This makes them applicable in medium and high AC power operations such as motor control function.

Why is an SCR a thyristor?

The term thyristor is mostly applied to silicon controlled rectifiers (SCR). The term is derived from Thyratron and transistor because such a device combines the rectification of thyratron and control action of transistors.

What is SCR principle?

The basic working principle in the SCR is that as the triggering or the biasing is applied at the terminal gate then the conduction begins. As it is a unidirectional device the current will be in a single direction.

What is thyristor and how it works?

Thyristor blocks voltage in both forward and reverse direction and thus a symmetric blocking is formed. A Thyristor turns ON by the application of positive gate current and turns OFF when the anode voltage drops to zero. A small current from gate to cathode can trigger the Thyristor by changing it from open circuit to short circuit.

What is the function of thyristor?

The primary function of a thyristor is to control electric power and current by acting as a switch. For such a small and lightweight component, it offers adequate protection to circuits with large voltages and currents (up to 6000 V, 4500 A).

What is the thyristor firing circuit?

DC Thyristor Switching Circuit. This simple “on-off” thyristor firing circuit uses the thyristor as a switch to control a lamp, but it could also be used as an on-off control circuit for a motor, heater or some other such DC load.

What is the use of a thyristor?


  • AC power electronic switching.
  • Overvoltage protection crowbar for power supplies.
  • Control elements in phase angle triggered controllers.
  • and then cut it off at the required time.