The back-to-back capacitor bank switching test is an important type test item for assessing the re-strike probability of circuit breaker in switching the capacitor banks. In view of the difficulty in accurately adjusting the making inrush current peak

I

bi

and the inrush current frequency

f

bi

during the testing process

a three-phase switching test circuit using the impulse generator as power source is proposed on the basis of analysis of requirements of China National Standards. The general calculation formulas for inrush current peak

I

bi

and inrush current frequency

f

bi

are derived by using equivalent circuits

and the quantitative relationship among the line length

l

capacitance

C

S

and inrush frequency

f

bi

is obtained at the test voltage of 12 kV

the inrush current of 20 kA

and the breaking current of 400 A and 800 A

respectively. The results show that the line length

l

is positively correlated with with

C

S

and negatively correlated with

f

bi

. Finally

the back-to-back capacitor bank switching test of circuit breaker at rated voltage of 12 kV is performed by using a 3 200 MVA impulse generator test system

together with three-phase capacitor banks of power circuit and load circuit

both the making inrush current peak

I

bi

and inrush current frequency

f

bi

meet the standard requireme

nts

and the correctness and effectiveness of the calculation method as well as the test circuit in this paper are verified.