Main >>Applications >> Sample problems >> ZnO overvoltage arrester
This is an example of the ZnO arrester simulation, performed with QuickField software.
Axisymmetric problem of transient electric.
The arrester consists of ZnO tablet placed inside ceramic tube. Electrodes are connected to the end tablets.
Relative permittivity of the air ε = 1.
Relative permittivity of the ceramic ε = 2.
Relative permittivity of ZnO element ε = 60.
Conductivity of ZnO element - nonlinear.
Nominal voltage U0 = 35 kV.
Maximal current Imax = 520 A.
Surge peak voltage Umax = 200 kV.
Calculate the varistor current.
The arrester can be represented by the equivalent schema with resistor R and capacitance C connected in parallel.
At nominal voltage the arrester acts as a capacitance (IC>IR). At overvoltage (surge) IR prevails and arrester acts like a resistor. QuickField can calculate both active (IR) and reactive (IC) currents.
Surge impulse passing through the arrester