This part of IEC 61204 specifies the safety requirements for POWER SUPPLY units providing DC output(s) with or without auxiliary a.c. output(s) operating from a.c. or d.c. source voltages up to 600 V a.c. or 1 000 V d.c. (See exceptions in 1.1.3). NOTE – Ringing generators used in telecoms applications are covered by this standard. This product standard covers both STAND-ALONE and COMPONENT POWER SUPPLY units as defined in this document. POWER SUPPLY units, which comply with the main body of this standard, satisfy the requirements of POWER SUPPLY units for use in or with IT equipment normally covered by IEC 60950:1999 and/or IEC 60950-1:2001. POWER SUPPLY units will also comply with the appropriate standard or application requirements given below if they also meet the additional requirements of the appropriate annex. PS-A Measurement, control and laboratory equipment normally covered by IEC 61010-1: 2001. PS-B Medical equipment –covered by IEC 60601-1:2005. PS-C Reserved for future use. PS-D Audio, Video and similar electronic apparatus – normally covered by IEC 60065:2001. PS-E DC Power and distribution equipment. This standard also covers DC-DC converters. Where no standards exist, use of this standard for other applications is not precluded.