配电线路的电缆选型除考虑载流量、电压损失和热稳定外，还应对长距离配电线路的断路器进行灵敏度校验。结合工程实例，对隧道内远距离配电线路的断路器灵敏度进行探讨，阐述远距离配电线路安全性校验中断路器灵敏度校验的必要性和重要性，并提出当校验结果不满足要求时，可采用加大电缆截面、装设具有剩余电流保护功能的断路器、在满足配电和保护功能的前提下降低断路器动作电流的整定值等方法，从而提高断路器的灵敏度。

In addition to considering the cable load, voltage loss and thermal stability, the cable selection of the power distribution line should also be used for the sensitivity check of the circuit breaker of longdistance power distribution line. Therefore, the sensitivity of circuit breaker of longdistance power distribution line in tunnel is discussed based on the engineering practice. And then the necessity and importance of sensitivity check of circuit breaker in the safety check of longdistance power distribution line is introduced; and the technologies, i.e. enlarging the cable crosssection, adding the circuit breaker with residual current protection capacity and reducing the setting value of the action current of the circuit breaker based on keeping power distribution and protection function, should be adopted to improve the sensitivity of the circuit breaker when the sensitivity checking result does not meet the requirements.