Since the total electric circuit length of upstream circuit breaker side is longer than that of downstream circuit breaker, constant earth leakage current by ground capacity is greater. Earth leakage protective coordination is a method that only branch circuit occurring ground fault (earth leakage) trips and a main earth leakage circuit breaker does not trip and therefore continues to provide power supply to other fault-free branch circuits. Generally high-sensitivity product is used for downstream (branch) earth leakage circuit breaker, however for achieving earth leakage discrimination, time-delay type is selected for upstream and the rated residual operating current should be 2 times or more as slow as that of downstream circuit breaker. Also for the rated residual operating current and operating time of Earth Leakage Relay, you can use the same way as above.