Difference between thyristor and TRIAC

The main difference between thyristor and TRIAC is that thyristor is a unidirectional device while in TRIAC as a bidirectional device. Now let us check it out the information about the 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.
  • Thyristor has four terminal semiconductor device while TRIAC has three terminal semiconductor device.
  • The main difference between SCR and TRIAC is that SCR is a unidirectional device, TRIAC is a bidirectional device.
  • A thyristor is more reliable while TRIAC has less reliable.
  • Thyristor needs to two heat sink whereas TRIAC need only one heat sink.
  • A thyristor is 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 used for triggering.
  • Thyristor control DC power whereas TRIAC control DC as well as AC power.
  • A thyristor is only one mode of operation is possible while TRIAC has four different modes of operation is possible.
  • A thyristor can operate in only one quadrant V-I characteristics while TRIAC can operate only in two quadrant V-I characteristics.
  • A thyristor can be triggered by positive gate voltage only, the TRIAC can be triggered either by the positive or negative gate voltage.
  • The main disadvantages of TRIAC over thyristor is that has lower current capabilities.