Introduction to Thyristors Family Devices
Q. What Is triggering ? With neat circuit, explain UJT SCR triggering method.
- Thyristors is a general term which includes devices such as SCR, Triac, GTO, LASCR, RCT, SCS, .. and many more.
- Thus thyristors is a family of devices. SCR i.e. silicon controlled rectifier is the most popular device of the thyristor family.
- The classification of thyristors is as follows :
Classification of thyristors
Classification of thyristors is shown bellow
1.
Thyristors
(A) Power
Control Thyristors
(i) Unidirectional
(a) SCR
(b) LASCR
(c) SCS
(d) LASCS
(e) SUS
(ii) Bidirectional
(a) Triac
(B) Triggering
Devices
(a) UJT
(b) DIAC
(c) SBS
(d) SUS
above charts shows that the thyristors can be classified basically into two categories :
- Power control thyristors
- Triggering devices.
1. Power control thyristors
- This category consists of those thyristors which are capable of controlling large power.
- The devices used popularly in this category are :
- Silicon Controlled Rectifiers (SCR)
- Gate Turn off SCR (GTO)
- TRIAC.
2. Triggering devices
- Triggering is defined as the process of turning on a power control devices such as SCR, TRIAC etc.
- Special device are required to be used to trigger the power control devices.
- The popularly used triggering devices are :
- Unijunction transistor (UJT)
- DIAC
- SBS and
- SUS