2053-07-SM-RPLF Circuit Protection

Gas Discharge Tube (GDT) arresters are surge protection devices (SPDs) primarily used to both protect personnel and electrical equipment from the damaging effects of both lightning strikes and man-made electrical transients. They are a form of electronic component used to protect electronic circuits from undesired and potentially damaging high voltage surges that may originate from lightning, electrostatic discharge (ESD), or faults in an electric power grid. Commonly used GDT arresters are axially-leaded bi-directional surge arresters. The GDT arrester contains two electrodes (known as the "cathode" and "anode") separated by a gas-filled space. Tiny gas-filled tubes (known as "escapes"), filled with inert metal vapor, are distributed throughout the gas filled space. A highly resistive material, usually graphite, is wrapped around the gas filled tube and sealed in place.

The GDT arrester is usually mounted onto a mounting base that is connected directly to the load circuit. The current to be protected is directed to the cathode or anode of the arrester. During normal operations, the GDT arrester functions as an insulator between the cathode and the anode. In the event of a surge or transient, the gas-filled space of the arrester will become ionized. The ionized gas will transfer electrons from the cathode to the anode and an electric arc will be created in the gas filled space. The arc will be extinguished quickly due to the reduced electric field. The electrons transferred may cause damage to sensitive electronic components in the circuit.

The operation of GDT arrester can take many forms, including single-ended and dual-ended operation. In single-ended operation, the currents flows through the arrester only in one direction. It is typically used to protect circuits from single, transient surges originating from lightning strikes or inductive switching. In dual-ended operation, the current flows through the arrester in both directions. This type of arrester is more effective in protecting against multiple transients or surges that may originate from fault currents or voltage spikes.

The GDT arrester is also capable of performing both instantaneous and continuous over-voltage protection. Instantaneous over-voltage protection helps protect against the highest surge voltages, which are greater than the voltage rating of the GDT arrester. Continuous over-voltage protection helps protect against potentially damaging long-term voltage disturbances. The application field of the GDT arrester can vary depending on the specific connection, circuit, and specific application.

In addition to the application field, the working principle of the GDT arrester needs to be understood. The GDT arrester works by providing a safe path for energy to discharge into the ground. During normal operation, the arrester operates as an insulator between the cathode and the anode. In the event of a surge or transient, the gas-filled space of the arrester will become ionized. The ionized gas will transfer electrons from the cathode to the anode and an electric arc will be created in the gas filled space. The arc will be extinguished quickly due to the reduced electric field. The electrons transferred may cause damage to sensitive electronic components in the circuit.

The GDT arrester is a critical component in protecting personnel and electrical equipment from the damaging effects of lightning and other surge-related transients. Its effective application fields and working principle should be clearly understood in order to ensure that the desired protection is achieved. With proper design and implementation, GDT arresters can provide years of reliable over-voltage protection for sensitive equipment.