This part of IEC 61992 specifies requirements for d.c. disconnectors, switch-disconnectors and earthing switches for use in indoor fixed installations of traction systems. NOTE 1 Switchgear assemblies, electromagnetic compatibility (EMC) and dependability are not covered in this standard, but rather by other parts of the IEC 61992 series or other documents as indicated in IEC 61992-1. NOTE 2 In this standard, the word \"unit\" means \"disconnector and/or switch-disconnector and/or earthing switch\" as defined in 3.1.5, 3.1.6 and 3.1.7 of IEC 61992-1. NOTE 3 Disconnectors, switch-disconnectors and earthing switches may have electrically latched mechanisms and, in such cases, may be indicated with the current term of \"power contactors\".