Accidental overvoltages

Accidental overvoltages - Circuit elements for limiting voltage peaks

Reading time: <1 minut

Author: Ing. Turcu Gheorghe
Year of publication: 2014

What are electrical disturbances?

The largest part of the electromagnetic disturbances that occur in the industrial environment is caused by transient regimes of electrical drive equipment and installations as well as the variations of the amplitude and frequency of the supply voltage over the allowed limits, disturbances that propagate through the conduction (supply network).

The main causes of such disturbances are generally the following:

  • switching of power installations;
  • on-the-go reconfigurations of energy subsystems;
  • changing the operating sockets of the transformers;
  • operation with load shocks of electric motors for driving medium and high power;
  • current shocks specific to electric arcs (welding installations, electric arc furnaces, etc.);
  • ON / OFF switching of important inductive and capacitive loads (such as mixed filter-compensation installations);
  • accidental short circuits;
  • overvoltages due to atmospheric electric discharges;
  • rapid variations of the amplitude and frequency of the supply voltage over the limits allowed by the equipment manufacturers as a result of the network overload, switching of the energetic installations, short circuits, etc.

Course structure

  • Introduction
  • Types of network disturbances
  • Circuit elements for limiting voltage peaks
  • MOV Varistor (Metal Oxide Varistor)
  • Zener diode limiters
  • Gas discharge tube (spark plug)
  • Limiters with several floors
  • Commercial devices for eliminating surges



  1. You have surface traces that are burned up which by looks of the severity of the char you can also count on several of the inboard trace layers being fried.

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