INTRODUCTION-
Thyristor is unidirectional like a diode that allows flow of current only in one direction. In contrast to diode, thyristor can attenuate the forward current until its is set off by an appropriate gate signal among gate and cathode terminal.
 |
| Image source - Google | Image by - Pixabay |
Thyristor is also called "SCR" (Silicon Control Rectifier) because As silicon is used for construction and it is operated as a controlled rectifier i.e very low resistance in forward direction and very high resistance in reverse direction.
Construction of Thyristor-
Thyristor is a 4 layer , 3 Junction , with substitute layers of p-type and n-type materials. it has three terminals Anode(A) terminal , cathode(K) terminal , and Gate(G) terminal.
The terminal associated with external p-type material is called anode(A). The terminal connected to the outer n-type material is called cathode(K).Gate terminal is usually kept near the cathode terminal.
With four layers of interchange p-type and n-type materials it structures 3 intersections or junctions j1, j2 and j3.
Working-
A thyristor is a unidirectional part and takes after a diode yet with an additional terminal – gate. The purpose of the gate terminal is to enable the device to be switched from a non-conducting mode (forward blocking mode) into a low resistance, conducting state (forward conducting mode). When it has been turned on by the gate terminal, the gadget remains hooked in the on-state. Which means it doesn't require persistent gracefully of gate current to stay in conduction. However the anode remains emphatically one-sided, it can't be turned off until the anode current falls beneath the holding current.
If thyristor is connected to a DC source, there is no flow of current until the gate is triggered.
(OR)
I would associate the thyristor as a switch between a battery and a light, nothing occurs until the gate is set off.Then the lamp is switched on.However - there is no off-switch. The best way to turn it off, is to eliminate battery power.
Application-
Thyristors are utilized in engine speed controls, light dimmers, pressure-control frameworks, and fluid level controllers.
Advantages-
1) The SCR (silicon controlled rectifier) can deal with large voltage, current and power.
2) The Triggering circuit for silicon controlled rectifier (SCR) is straightforward. The SCR is not difficult to turn ON.
3) The SCR can be secured with the assistance of wire.
4) It can control AC power.
5) It is easy to control.
6) It cost is low.
Disadvantages-
1) The SCR (silicon controlled rectifier) is unidirectional gadgets, so it can control power just in DC power during positive half pattern of AC signal, in this manner just DC power is controlled with the assistance of SCR.
2) The gate current can't be negative.
3)In AC circuit, it ought to be turned on each cycle.
4)It can't be utilized at higher frequencies.
Comments
Post a Comment