This part of IEC 61936 provides, in a convenient form, requirements for the design and the erection of DC installations in systems with nominal voltages above 1,5 kV DC, so as to provide safety and proper functioning for the use intended. For the purpose of interpreting this standard, a DC installation is considered to be one of the following: a) A converter station or DC switching station; b) one (or more) DC generating or storage unit(s), such as solar farms or battery storage units, located on a single site, the DC installation includes DC equipment and cables with all associated power electronics, controlgear, switchgear and all electrical auxiliary systems. Connections between DC generating or storage units located on different sites are excluded; c) DC installation erected on offshore facilities for the purpose of generation, transmission, distribution and/or storage of electricity; or d) DC transition station (between overhead lines and underground cable or between different sections of underground cables). This International Standard does not apply to the design and erection of any of the following: overhead and underground lines between separate installations; electric railways; mining equipment and installations; installations on ships according to IEC 60092 series and offshore units according to IEC 61892 series, which are used in the offshore petroleum industry for drilling, processing and storage purposes; 248 electrostatic equipment (e.g. electrostatic precipitators, spray-painting units); 249 test sites; 250 medical equipment, e.g. medical X-ray equipment; 251 valve hall or converter hall. 252 This International Standard does not apply to the requirements for carrying out live working on 253 electrical installations. 254 This International Standard does not apply to the design of factory-built, type-tested thyristor 255 valves, VSC valves and switchgear for which separate IEC standards exist.