PERMANENT (TOV)
Protection against permanent overvoltages: voltage peaks of some hundreds of volts lasting for an indeterminate time lapse and resulting from an unbalanced electrical network, usually due to a neutral fault (loose neutral terminal or cut-off neutral cable)
Protectors against Temporary Overvoltages
Protection against temporary overvoltages requires a different protection system from that used for transient overvoltages.
Instead of shuting the excess voltage to ground, we need to disconnect the equipments of the installation from the electrical network to prevent the overvoltage reach the equipments avoiding a massive damage.
In certain zones, the use of this kind of overvoltage protectors is obligatory, according to utilities regulations.
Neutral fault generate an unbalance among the phases, meaning that some users receive a voltage value that is much higher than the nominal voltage and that its equipment can withstand, damaging all the equipments connected to electrical network.
The use of these protectors is vital in areas where there are constant power cuts and where there are fluctuations in the value of the voltage supplied by utilities.
Supplying equipment with a voltage above that for which it has been designed can lead to:
- Overheating
- Early ageing
- Fire destruction