ABB Excount II - Metal-Oxide Arrester Leakage Current Components; Resistive Leakage Current Characteristics

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1HSA 801 080-15en EXCOUNT-II Users Manual
6. Surge arrester monitoring theory
Figure 6.3.1
Electrical representation of metal-oxide surge
arrester in the leakage current region
Resistive leakage current
The resistive leakage current is defined as the peak value of the resis-
tive component of the leakage current, i.e. the instantaneous value of
the leakage current when the voltage across the arrester is at its maxi-
mum (dU/dt = 0). In the leakage current region, the resistive current
depends on the voltage stress and temperature of the varistors. The
typical non-linear behavior of the resistive leakage current is shown in
figure 6.3.2 for two different varistor temperatures. The voltage stress
is expressed as the ratio of the operating voltage to the rated voltage
of the arrester (U/Ur).
Figure 6.3.2
Example of voltage-current characteristics
of a metal-oxide surge arrester