Difference between thyristor and TRIAC

The main difference between thyristor and TRIAC is that thyristor is unidirectional device while in TRIAC as bidirectional device. Now let us check it out the information about difference between thyristor and TRIAC to know more details about it.
  • Thyristor also called SCR stands for silicon controlled rectifier while TRIAC stands for triode for alternating current.
  • Thristor has four terminal semiconductor device while TRIAC has three terminal semiconductor device.
  • The main difference between SCR and TRIAC is that, SCR is unidirectional device, TRIAC is bidirectional device.
  • Thyristor is more reliable while TRIAC has less reliable.
  • Thyristor needs to two heat sink whereas TRIAC need only one heat sink.
  • Thyristor available in large rating while in TRIAC available in smaller rating.
  • Uni-junction transistor is used for triggering in SCR but in TRIAC the DIAC is sued for triggering.
  • Thyristor control DC power whereas TRIAC control DC as well as AC power.
  • Thyristor  is only  one mode of operation is possible while TRIAC has four different modes of operation is possible.
  • Thyristor can operate in only one quadrant V-I characteristics while TRIAC can operate only in two quadrant V-I characteristics.
  • Thyristor can be triggered by positive gate voltage only, the TRIAC can be triggered either by positive or negative gate voltage.
  • The main disadvantages of TRIAC over thyristor is that has lower current capabilities.