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Company Logo TE Connectivity

  • Surge Protection Circuit

  • Created: Aug 10, 2015

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This design a simple circuit protection that helps protect equipment from damage caused by transient surge voltages such as from lightning strikes and equipment switching operations. The device uses Gas Discharge Tube (GDT) of TE connectivity that effectively switches to a low impedance state and diverts the energy away from the equipment when an overvoltage is detected. This GDT has low capacitance and insertion loss with high accuracy spark-over voltages for high precision designs.

The protection circuit is connected between the live and mains lead that normally has no current flow. However, when the voltage between the terminals are higher than the sum of voltage ratings of GDT and varistor, the current starts to flow through the components. The current will never pass higher than the predetermined value. If the flowing current is more than the specified value of main self-resettable fuse, the fuse will break and the circuit will be protected. After the current is normal, the fuses resets and continue its function. The circuit is designed to protect sensitive electronic devices against overvoltage transients in normal mains voltage and overload/ short circuit. Two neon pilot lamps are placed to show the status of input and load supply. Varistor is used to protect circuits against excessive transient voltages by incorporating them into the circuit in such a way that, when triggered, they will shunt the current created by the high voltage away from the sensitive components.

This surge protection circuit essentially protects sensitive components from overvoltage transients without influencing the device’s normal operation. It has various applications such as protection for motor devices, telephone line and power lines.



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