Break-over devices are components designed to switch between an off-state and an on-state, typically used for overvoltage protection and switching applications in industrial electronics. Here are some common types:
1. Bilateral Break-Over Devices (BID):
- Silicon Controlled Rectifiers (SCRs):
- Most common type of BID.
- Uni-directional current flow (only allows current in one direction).
- Requires a "gate" signal to trigger conduction.
- Used in AC and DC power control, motor speed control, and welding applications.
- Triacs:
- Bidirectional current flow (allows current in both directions).
- Used in AC power control, dimming circuits, and motor control applications.
- Diacs:
- Two-terminal devices.
- Act as voltage-controlled switches.
- Used in AC power control, triggering SCRs, and overvoltage protection.
2. Unilateral Break-Over Devices (UID):
- Unijunction Transistors (UJTs):
- Three-terminal device with unique characteristics.
- Used in timing circuits, oscillators, and pulse generation.
- Programmable Unilateral Break-Over Devices (PUB):
- Similar to UJTs but with adjustable break-over voltage.
- Used in voltage sensing, overvoltage protection, and triggering SCRs.
3. Other Devices with Break-Over Characteristics:
- Thyristors:
- A family of devices including SCRs, Triacs, and GTOs (Gate Turn-Off Thyristors).
- Exhibit break-over characteristics.
- Used in power control, motor drives, and other high-power applications.
- MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors):
- Can be configured to have break-over characteristics.
- Used in switching applications, power control, and high-frequency circuits.
Note: The specific characteristics and applications of each break-over device vary depending on the type and manufacturer.
Key Considerations:
- Break-over voltage: The voltage required to trigger conduction.
- Hold-on current: The minimum current required to maintain conduction.
- Switching speed: The time it takes for the device to switch between states.
- Power dissipation: The amount of heat generated during operation.
- Operating temperature range: The temperature range over which the device can function properly.
Choosing the right break-over device for your application depends on factors like:
- Desired voltage and current handling capabilities.
- Switching frequency and speed requirements.
- Cost and availability.
For more information, refer to datasheets and application notes provided by manufacturers.