Difference between scr and triac

The main difference between the two is that silicon control rectifier (SCR) switch direct current while in TRIAC is switch is alternating current. Here this post gives the main difference between them.
  • SCR stands for silicon controlled rectifier while TRIAC stands for triode for alternating current.
  • SCR is a unidirectional device but the TRIAC is a bidirectional device.
  • SCR is available in large rating but TRIAC is available for smaller ratings.
  • SCR is more reliable compared to TRIAC.
  • SCR is conducting current in one direction only while TRIAC is conducting current in both directions.
  • SCR need two heat sink, TRIAC needs only one heat sink.
  • SCR is only one mode of operation is possible whereas in TRIAC four different modes of operation are possible.
  • SCR can be triggered by positive gate voltage only but TRIAC can be triggered either by both positive or negative gate voltage.
  • SCR control a DC power, TRIAC control DC as well as AC power.