Calculation method for voltage distribution of the controlled metal oxide arrester

Equivalent capacitance of thyristor used in thyristor valve of the controlled metal oxide arrester (CMOA, shortly), C
T
, changes with thyristor terminal voltage, ϕ
T
. When voltage distribution of CMOA is calculated, such characteristic should be considered. Combining field-circuit combination method and variable rule of CT with ϕ
T
, a calculation program was put forward. Firstly, electric field numerical calculation models of MOA1, MOA2 and MOR were made and an equivalent capacitance network was calculated. Then function of C
T
and ϕ
T
was solved by test and curve fitting. Secondly, equivalent circuit of CMOA was founded. The function of C
T
and ϕ
T
was substituted to the circuit. Function between electrode voltage, ϕ
Fi
, and CMOA voltage, ϕ
s
could be calculated by iterations. Finally, the function between ϕ
Fi
and ϕ
s
was substituted to electric field numerical calculation model and variable rule of voltage distribution by ϕ
s
was solved. The calculation program was verified by tests. Results indicated that it was effective to calculate voltage distribution of CMOA.