The are-circuit interaction plays an important role in the current int
errupting process of High-Voltage Circuit Breakers. For the developmen
t of circuit breakers, testing in the High Power Laboratory is necessa
ry. For UW circuit breakers nem test circuits have to be developed. Th
e design and development of nem synthetic circuits relies on computer
simulations only. A correct representation of the current zero behavio
r of the circuit breaker by means of an are model is absolutely necess
ary. In this paper are modelling, and the development of new test circ
uits are discussed and measurements of are voltage and are current are
presented for two 72 kV SF6 power circuit breakers.