Transients are pulsed electrical phenomena, which exist for just a short period of time.These are usually high frequency, steep signals in the form of transient oscillations.
The reliable detection of transient processes in the electrical supply network is very important in order to avoid damages. Through constant changes in the electrical supply network due to switching operations and faults, new network states arise constantly, which the entire system is required to tune itself to. In normal cases transient compensation currents and compensation voltages arise here. In order to assess whether the transient processes result from a desired or undesired change in the network, and whether these still lie in the tolerance range, one requires reliable decision criteria.
High transient overvoltage, and high dV/dt-ratios, can lead to insulation damage and the destruction of systems and machines, also depending on the energy input (e.g. lightening strike).
In order to detect and record transients it is necessary to use high quality, digital power quality analysers with a high sampling rate.
High transient currents often arise due to the switching – in of capacitors (without reactors or damping facility) – also with problem-free network configurations. Choking has a strongly damping effect and therefore protects against avoidable problems that are difficult to foresee. Alternatively, special capacitor contactors or switching devices should be used, e.g. with pre-charging resistors at LV side.