The arrester consists of ZnO tablet placed inside ceramic tube. Electrodes are connected to the end tablets.

**Analysis Type:**

An axisymmetric problem of Transient electric field.

**Geometry:**

**Given:**

Relative permittivity of air ε = 1.

Relative permittivity of ceramic ε = 2.

Relative permittivity of ZnO element ε = 60.

Conductivity of ZnO element - *nonlinear*.

Nominal voltage *U _{0}* = 35 kV.

Maximal current

Surge voltage

**Problem:**

Calculate the varistor current.

**Solution:**

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 (*I*_{C}>*I*_{R}). At overvoltage (surge) *I*_{R} prevails and varistor acts like a resistor. QuickField can calculate both active (*I*_{R}) and reactive (*I*_{C}) currents.

**Results:**

Voltage |
Active Current |

35 kV |
0.67 mA |

197 kV |
433 A |

Surge impulse passing through the arrester

See the *Telec2.pbm* problem in the Examples folder.