Gas Discharge Tubes (GDTs) or Gas Plasma Arrestors protect circuits from transient voltages caused by lightning, switching, and other sources. They allow the passage of AC currents but act as a short circuit for high-energy transients. Essentially, they provide a conductive path for the discharge of high voltage transients, while preserving the normal DC voltage. GDTs are low-cost and provide a simple and effective solution for protecting sensitive electronic equipment. They are an essential component of any system which is subject to high voltage surges or transients, such as in lightning storms or when high power is switched on or off. GDTs are typically constructed using a glass or ceramic tube, containing two electrodes. The gas inside is usually a mixture of noble gases such as argon, neon, and xenon. When a high voltage transient occurs, the gap between the electrodes breaks down and a low impedance path is formed which allows the transient to be discharged to ground. GDTs provide a range of advantages such as high dielectric strength, low operating voltage, and low leakage current.