HCSR auxiliary breaking shunt arc-extinguishing chamber is one kind of effective method for disposingthe failure of large current interruptions. As the negative voltage current characteristic of the SF

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arc affects the cur-rents of the parallel branches passing zero simultaneously

the difficulty for breaking shunt SF

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arc branch is in-creased

and its applications to the high voltage field is limited. Combining the design idea of shunt branches

auxilia-ry breaking with high coupled reactor

experimental studies of the SF

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arc shunt branches breaking under lower cur-rents are carried out firstly

using two same arc-extinguishing chambers of a 40.5 kV circuit breaker. The relation-ships of the short current

arcing times

current dividing and current limiting are analyzed in emphasis. Then

aim-ing at the breaking characteristics of larger current 80 kA shunt branches

preliminary study and verification are car-ried out by the opening operations. The results show that in the case of lower current and constant HCSR parameters

current sharing breaking in the two shunt chambers are easier to achieve with the decrease of the short current. Withthe increasing of the short current

the current sharing interval deviates to the direction of the longer arcing time. Inthe case of larger current with matched HCSR parameters

current sharing breaking of the shunt branches can alsobe acquired

but the current limiting breaking cannot be avoided absolutely. Two sets of the experiments both indi-cate that after the arc of the first breaking circuit extinguishes

the abrupt change of the breaking voltage and its oscil-lation can be observed due to the potential fall adding from the branch inductance of the reactor

but the total currentcan be limited to some extent by the branch inductance of the coupled reactor.