It specifies requirements for adjustable speed power drive systems, or their elements, with respect to electrical, thermal and energy safety considerations. It does not cover the driven equipment except for interface requirements. It applies to adjustable speed electric drive systems which include the power conversion, drive control, and motor or motors. Excluded are traction and electric vehicle drives. It applies to d.c. drive systems connected to line voltages up to 1 kV a.c., 50 Hz or 60 Hz and a.c. drive systems with converter input voltages up to 35 kV, 50 Hz or 60 Hz and output voltages up to 35 kV. The major areas of change in this edition are the following: addition of alphabetical Table 1 in Clause 3; addition of Table 2 in 4.1 for relevance to PDS/CDM/BDM; addition of Table 4 summary of decisive voltage class requirements; expansion of subclause on protective bonding (4.3.5.3); clarification of distinction between touch current and protective conductor current; revision of section on insulation (now 4.3.6) to include solid insulation; addition of overvoltage categories I and II to HV insulation voltage; revision of section on Solid insulation (now 4.3.6.8); addition of high-frequency insulation requirements (4.3.6.9, Annex E); addition of requirements for liquid-cooled PDS (4.4.5); addition of climatic and vibration tests (5.2.6); clarification of voltage test procedure to avoid over-stress of basic insulation (5.2.3.2.3); revision of short-circuit test requirement for large, high-voltage and one-off PDS (now 5.2.3.6); addition of informative Annex B for overvoltage category reduction