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ZnO lighting arrester

zinc oxide varistor simulation, electric FEA finite element analysis of the varistor, lightning stroke protection with varistor

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.

Problem Type:
Axisymmetric problem of transient electric.

Geometry:
ZnO lighting arrester The arrester consists of ZnO tablet placed inside ceramic tube. Electrodes are connected to the end tablets Insulator ZnO Ground HV Ø 76 mm 200 mm

Given:
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.

Task:
Calculate the varistor current.

Results:
The arrester can be represented by the equivalent schema with resistor R and capacitance C connected in parallel.

HV arrester electric circuit

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.

Voltage Active current
35 kV 0.67 mA
197 kV 433 A

Surge impulse passing through the arrester

Surge impulse passing through the arrester

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