overvoltage protection (OVP)
Overvoltage protection (OVP) includes all technical measures to prevent short-term voltage surges, voltage fluctuations or electrostatic discharges( ESD) in the mains voltage, on telephone lines or in the supply voltage of devices, as these can damage electronic components and assemblies, especially those of microelectronics.
There are various passive and active electronic components with which overvoltages can be effectively countered. Passive components include inductors and capacitors which, either individually or in combination as mains filters, attenuate voltage peaks with which the mains voltage or the supply voltage may be superimposed to a greater or lesser extent. Other passive components with voltage-stabilizing behavior are Zener diodes, varistors, suppressor diodes, Schottky diodes or thyristors and the surge arresters specially developed for these applications. These components and a battery buffer can keep the supply voltage at a constant level.
In another technique, known in English as crowbar, the supply voltage of the power supply is sampled and, in the event of an overvoltage, a thyristor short-circuits the supply voltage.
In addition to the components and circuits mentioned above, Polymeric Positive Temperature Coefficient( PPTC) components with positive temperature coefficients are also available, which have the function of overtemperature protection, but are resettable and do not need to be replaced.