ACST4-7CB

Thyristors - TRIACs

A TRIAC, also known as a bidirectional triode thyristor (BTDT) or thyristor, is a three-terminal electronic device that can be used as an electronic switch to control current through a circuit in both directions. It is composed of two opposite-facing thyristors that can be triggered by two separate signals. This makes it useful for switching AC current. There are many different types of TRIACs, but they all have the same basic properties. This article focuses on the application field and working principle of the ACST4-7CB.

Application Field of ACST4-7CB

The ACST4-7CB is a medium-power, low-cost TRIAC, used primarily in low-power household appliances. It is designed to work with AC current and is rated at 7 amp current carrying capacity. It has a breakdown voltage of 400V and its operating temperature is -40 to 125 degrees Celsius. The ACST4-7CB can be used for domestic or industrial applications such as lighting, speed control, load switching, temperature control, and motor control.

Working Principle of ACST4-7CB

The ACST4-7CB is a three-terminal SCR (Silicon Controlled Rectifier) that controls two-to-three output terminals. When a single gate voltage pulse is applied to it, the current flows through the two-to-three output terminals. The TRIAC gate is designed to provide an efficient switch for controlling the current flow in both directions. When the gate voltage is greater than the breakover voltage, the current will flow through the two-to-three output terminals, allowing the device to switch current in both directions. When the gate voltage is less than the breakover voltage, no current will flow.

The ACST4-7CB can be gated using either a single gate pulse or multiple gate pulses. In single-gate operation, the TRIAC acts like a switch and is triggered when the gate voltage is applied and the breakover voltage is reached. In multiple-gate operation, the TRIAC can be gated with multiple gate pulses, alternating between positive and negative gate pulses. This allows for more efficient current control in both directions.

In order to control the current flow while the TRIAC is in operation, different methods can be used. The most common method is through the use of a RC snubber circuit. The snubber circuit consists of a resistor and capacitor connected in series. When the TRIAC is triggered, the snubber circuit helps to reduce the power dissipation inside the TRIAC, allowing for more efficient switching.

Conclusion

The ACST4-7CB is a low-cost, medium-power TRIAC that can be used in a variety of applications. It is capable of controlling current in both directions, making it ideal for switching AC current. It can be gated using either single-gate or multiple-gate pulses, and its power dissipation can be reduced by using a RC snubber circuit. Overall, the ACST4-7CB is an effective and affordable TRIAC option suitable for many low-power AC circuits.