ZnO lighting arrester - QuickField simulation example
This is an example of the ZnO arrester simulation, performed with QuickField software. The arrester consists of ZnO tablet placed inside ceramic tube. Electrodes are connected to the end tablets.
How to find surge current through ZnO lightning arrester?
Answer Typical applications Geometry
Given
Task
Solution
Results
*Reference: IEC 61000-4-5
Engineering question
Set up an axisymmetric QuickField Transient Electric problem for a ZnO lightning arrester and evaluate surge current from computed field results.
ZnO surge arresters, lightning protection devices, metal-oxide varistors
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Simulation problem
Problem Type
Axisymmetric problem of transient electric.
Nominal voltage U0 = 35 kV. Surge waveform is defined by IEC 61000-4-5*.
Relative permittivity of the ceramic insulator ε = 3.
Relative permittivity of ZnO element ε = 60, conductivity of ZnO element is a nonlinear function of electric field stress:
Calculate the varistor current.
We specify the voltage as a sum of two components: nominal voltage and the surge pulse. The surge pulse is defined by the double exponential equation*.
35000 + 165000 * (exp(-t/68.2e-6) - exp(-t/0.4e-6))
At nominal voltage the conductivity current is negligible. At overvoltage the resistance value diminishes and conductivity current increases.
Voltage
Current
35 kV
0.74 mA
194 kV
407 A
Video
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