Arrangement for gas circuit breaker with reactor and capacitor connected in series and method for setting its circuit parameter

An arrangement for a gas circuit breaker with a reactor and a capacitor connected in series to interrupt a DC current, said arrangement comprising:

• a plurality of series-connected DC circuit breakers of substantially the same ability for controlling a flow of DC current in a power system;
• a parallel impedance means connected in parallel with the DC circuit breakers and having a parallel capacitor and a parallel reactor;
• an energy-absorbing element for said parallel capacitor;
• said parallel reactor having an inductance L (measured in .mu.H) determined to satisfy ##EQU38## where i.sub.o is the an interruption current value of the DC current (measured in amperes), I.sub.c is the critical normalized interruption current of the DC circuit breaker;
• said parallel capacitor capacitance C (.mu.F) having a value determined to satisfy ##EQU39## and the normalized interruption current I.sub.o is defined as ##EQU40## where k is a number of said DC circuit breakers, n.sub.s is the energy loss of arc generated when the DC current is interrupted in one of said circuit breakers, and .theta. is a time constant of arc.

A reactance setting method for use in an arrangement for a gas circuit breaker comprising a DC circuit breaker for controlling the flow of DC current in a power system, a parallel impedance means connected in parallel with the DC circuit breaker and having a parallel capacitor and a parallel reactor, and an energy-absorbing element for said parallel capacitor, said method comprising the steps of:

• providing a normalized interruption current I.sub.o being defined as ##EQU45## where i.sub.o is an interruption current value of the DC current (measured in amperes);
• n is an energy loss of arc generated when the DC current is interrupted;
• C is a capacitance of the parallel capacitor, and e is the time constant of arc;
• a parameter k.sub.1 is substantially equal to ##EQU46## a parameter k.sub.2 is substantially equal to ##EQU47## determining a parallel capacitor capacitance C (.mu.F) and a parallel reactor inductance L (.mu.H) to satisfy ##EQU48##