The IEC 62310 series applies to free standing operation a.c. static transfer systems (STS) intended to ensure the continuity of load supply through controlled transfer, with or without interruption of power, from two or more independent a.c. sources. The IEC 62310 series includes requirements for the switching elements, their control and protective elements, where applicable. The IEC 62310 series also includes information for the overall integration of the STS and its accessories into the a.c. power network. This standard applies to systems up to 1 000 V a.c. which are intended to be used in singlephase, phase-phase or three-phase applications This part of IEC 62310 takes precedence over all aspects of the generic standards, and no additional testing is necessary. The requirements have been selected so as to ensure an adequate level of Electromagnetic Compatibility (EMC) for STS at public and industrial locations. These levels cannot, however, cover extreme cases which may occur in any location, but with extremely low probability of occurrence. It takes into account the differing test conditions necessary to encompass the range of physical sizes and power ratings of STS. A STS, whether presented as a unit or an assembly of units shall meet the relevant requirements of this part of IEC 62310 as a stand-alone product. EMC phenomena produced by any supply or load connected to the input or output of the STS equipment shall not be taken into account. This standard does not apply to: – devices for d.c. source switching; – single source systems; – transfer systems using only electromechanical switching devices intended to be used in emergency power systems with interruption of the supply to the load during transfer; NOTE 1 Such equipment is covered by IEC 60947-6-1. – automatic switching devices integrated into Uninterruptible Power Systems (UPS) covered by the IEC 62040 series. NOTE 2 For STS intended to be used in vehicles, on board ships or aircraft, in tropical countries, for Emergency Power Systems (such as those used for health care facilities, fire fighting, emergency rescue, etc.), or at altitudes greater than 1 000 m, different requirements may be necessary.