Extra-low voltage

Common card · No. 383012

Extra-low voltage (ELV) is an electricity supply voltage and is a part of the low-voltage band in a range which carries a low risk of dangerous electrical shock. There are various standards that define extra-low voltage. The International Electrotechnical Commission (IEC) in IEC 61140 define an ELV device or circuit as one in which the electrical potential between two conductors or between an electrical conductor and Earth (ground) does not exceed 120 volts (V) for ripple-free direct current (DC) or 50 VRMS (root mean square volts) for alternating current (AC). The IEC and IET go on to define actual types of extra-low voltage systems, for example separated extra-low voltage (SELV), protected extra-low voltage (PELV), functional extra-low voltage (FELV). These can be supplied using sources including motor / fossil fuel generator sets, transformers, switched PSU's or rechargeable battery. SELV, PELV, FELV, are distinguished by various safety properties, supply characteristics and design voltages...

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