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Real-World Control Device Interfacing
Published in A. Arockia Bazil Raj, FPGA-Based Embedded System Developer's Guide, 2018
A Triac is a three-terminal bidirectional semiconductor power electronic switching device which can control alternating current in both cycles. Triac is a word made from two words, Tri and AC, where Tri means three and AC means alternating current. It can conduct in both directions, that is, the positive half cycle and negative half cycle, for a specific time period. The symbol, picture and construction of a Triac are shown in Figure 9.29. As in that figure, a Triac is basically made by connecting two SCRs in inverse parallel combination with a common gate. A Triac is almost similar to an SCR, but the Triac is a bidirectional device, whereas the SCR is a unidirectional device like a diode. The internal layers and doping are done in such a way that the current can flow in both directions. The terminals are not called anode and cathode, as we know that a Triac can conduct with both terminals; the terminals are labeled Main Terminal 1 (MT1) or Anode 1 and Main Terminal 2 (MT2) or Anode 2, and the third terminal is the gate, which is common for both SCRs, but internally this gate is closer to MT1 [124].
Control Devices
Published in Stephen W. Fardo, Dale R. Patrick, Electrical Power Systems Technology, 2020
Stephen W. Fardo, Dale R. Patrick
The triac is widely used as a variable ac power control device. Control of this type is generally called full-wave control. Full wave refers to the fact that both alternations of a sine wave are being controlled. Variable control of this type is achieved by delaying the start of each alternation. This process is similar to that of the SCR. The primary difference is that triac conduction applies to the entire sine wave. For this to be accomplished, ac must be applied to both the gate and the conduction terminals.
Electronic Power Control
Published in Dale R. Patrick, Stephen W. Fardo, Electricity and Electronics Fundamentals, 2020
Dale R. Patrick, Stephen W. Fardo
The triac is widely used as a variable ac power control device. Control of this type is generally called full-wave control. Full wave refers to the fact that both alternations of a sine wave are being controlled. Variable control of this type is achieved by delaying the start of each alternation. This process is similar to that of the SCR. The primary difference is that triac conduction applies to the entire sine wave. For this to be accomplished, ac must be applied to both the gate and the conduction terminals.
A Consumer-Based Smart Home with Indoor Air Quality Monitoring System
Published in IETE Journal of Research, 2019
Kailas Patil, Meena Laad, Aakash Kamble, Shivani Laad
Fan speed controller was constructed by implementing PWM using firing angle mechanism. A circuit of zero cross detector, Optocoupler, and Snubber's circuit along with traic is used. The zero-cross detector circuit converts a sinusoidal wave into a square wave. An Optocoupler is used to prevent a device from back e.m.f. As ceiling fan has an inductive load, Snubber's circuit can withstand the high gain of ceiling fan. Triac is used as a power device which can handle a high power load of AC devices like a ceiling fan.