Fig. 6a shows the simulation result of the
differential protective relay under three phase short circuit fault
condition using the proposed algorithm. The induced current ratio
of shield layer is 95% in steady state. However, if the fault occurs
inside of protection zone, the induced current ratio at shield layer
decreased from 95% to 39%. Consequently, the circuit breaker operates
according to the proposed algorithm. Fig. 6b shows the operational
characteristics of protective relay under outside of
protection zone fault condition. The induced current ratio at shield
layer decreased from 95% to 80%. From this result, the inside and
outside protection zones of HTS power cable could readily be
determined by the induced current ratio. Table 5.