Gas Discharge Tubes (GDT)

Gas Discharge Tubes (GDTs) are a type of overvoltage protection device that operates by using the ionization of gas to conduct electricity. They are designed to protect sensitive electronic equipment from voltage surges, which can be caused by lightning, power line switching, or other electrical disturbances.

Definition:
A Gas Discharge Tube is a passive electronic component that contains two or more electrodes within a gas-filled envelope. When the voltage across the GDT exceeds a certain threshold, the gas ionizes, creating a conductive path that allows the excess voltage to be safely discharged.

Function:
The primary function of a GDT is to clamp the voltage to a safe level by diverting the surge current away from the protected equipment. When the voltage across the GDT is below the ionization threshold, it acts as an open circuit, allowing normal operation of the equipment. Once the voltage exceeds the threshold, the GDT ionizes the gas, becoming a low-impedance path for the surge current to flow, thus protecting the equipment from damage.

Applications:
GDTs are widely used in various applications where overvoltage protection is necessary:
1. Telecommunications equipment, such as telephone exchanges and network infrastructure.
2. Power distribution systems to protect against lightning-induced surges.
3. Industrial control systems to safeguard against voltage spikes.
4. Consumer electronics, like televisions and computers, to protect against power surges.
5. Automotive electronics to protect against transient voltages.

Selection Criteria:
When selecting a GDT, several factors should be considered:
1. Voltage Rating: The GDT should have a continuous voltage rating that is compatible with the system's operating voltage.
2. Surge Current Capability: The GDT must be able to handle the expected surge current without failing.
3. Response Time: The GDT should have a fast response time to effectively protect against fast-rising surges.
4. Recovery Time: After discharging, the GDT should return to its non-conductive state quickly to minimize the impact on normal operation.
5. Physical Size and Mounting: The GDT should be compatible with the available space and mounting requirements of the equipment.
6. Environmental Considerations: The GDT should be suitable for the environmental conditions it will be exposed to, such as temperature and humidity.

In summary, Gas Discharge Tubes are crucial components in the protection of electronic systems from overvoltage events. They are selected based on their ability to handle the specific voltage and current requirements of the application, as well as their physical and environmental compatibility.
Please refer to the product rule book for details.