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DC power distribution sub-systems are essential components of electrical power facilities since they allow the carrying out of vital facility functions in normal operation even in the event of a collapse in grid voltage. Therefore, such systems should be a reliable and safe source of electrical power. When taking into consideration that the manner of terminating DC current is significantly different from terminating AC current, it is important that, when designing DC power distribution sub-systems in electrical power facilities, care be taken concerning their characteristics. A proper selection of protection devices (low-voltage fuses and circuit breakers) and their proper allocation according to distribution protection levels achieves protection selectivity. This paper presents the basic types of protection devices and their possible uses in DC power distribution sub-systems and the manner of achieving protection selectivity.