What is the difference between triac and scr

The SCR has a third lead called the gate. Normally, the device does not conduct until it receives a voltage at the gate; then it remains on until the voltage across the cathode and anode drops past a critical point. It typically switches large currents many thousands of times per second. Like an SCR, the triac has three leads and acts as a current switch but it is more complex than an SCR, because it conducts electricity in two directions. This makes the triac more useful in alternating current circuits than an SCR, because the current direction for AC changes times per second.

Though a triac conducts in both directions, the diode conducts somewhat unequally in each direction. The SCR, when turned on, conducts in only one direction. In addition, applying a trigger at a controlled phase angle of the AC in the main circuit allows control of the average current flowing into a load phase control. Low-power TRIACs are used in many applications such as light dimmers, speed controls for electric fans and other electric motors and in the modern computerized control circuits of many household small and major appliances.

Viva Differences. Comments are closed. To operate on AC mains, the solution is therefore to use 2 SCR connected back to back: The triggering of the thyristor is done by applying a current pulse positively circulating from Gate to Cathode The latching of the Thyristor to switch Thyristor to on-state condition after a gate current pulse can only occur since : — Anode-to-Cathode voltage is positive — Anode-to-Cathode current after trigger exceed the Latching Current.

Thyistor and Triac are semiconductor devices Because they are semiconductor devices they cannot ensure a galvanic insulation when they are not controlled. In which case using Triac or back-to-back Thyristors : typical application Triacs are based on a single silicon chip whereas back-to-back SCR are 2 separated silicon chips. Contact us. Contact our sales teams. Contact our technical experts. Find a distributor.