Glass Discharge TubeA glass discharge tube is a type of protective device that is used to prevent electrical fires and other hazards. It consists of a sealed glass tube that contains a small amount of a gas, such as argon or neon, at low pressure. The tube is connected in parallel with the circuit or device that it is protecting.
When a voltage or current surge occurs in the circuit, the gas inside the tube becomes ionized and conducts electricity, forming a plasma. This causes a current to flow through the tube, which diverts the surge away from the protected circuit and safely dissipates it to ground. Once the surge has dissipated, the plasma inside the tube dissipates and the tube returns to its non-conducting state. Glass discharge tubes are often used in conjunction with other protective devices, such as fuses and circuit breakers, to provide a high level of protection for sensitive electronic circuits.