Language:enStatus: Standard
Term: Safety Extra-Low Voltage
Synonym1: SELV
Definition: AC voltage the r.m.s. value of which does not exceed 50 V or ripple-free DC voltage the value of which does not exceed 120 V, between conductors, or between any conductor and reference earth, in an electric circuit which has galvanic separation from the supplying electric power system by such means as a separate-winding transformer

NOTE 1 – Maximum voltage lower than 50 V AC or 120 V ripple-free DC may be specified in particular requirements, especially when direct contact with live parts is allowed.

NOTE 2 – The voltage limit should not be exceeded at any load between full load and no-load when the source is a safety isolating transformer.

NOTE 3 – Ripple-free qualifies conventionally an r.m.s. ripple voltage not more than 10 % of the DC component; the maximum peak value does not exceed 140 V for a nominal 120 V ripple-free DC system and 70 V for a nominal 60 V ripple-free DC system.

Publication date:2008-06
SourceIEC 61558-1:2005, 3.7.16 MOD
Internal notes:2015-12-01: Editorial correction: hyphen added for consistency "Safety Extra-Low Voltage". JGO
2019-05-22: German terms updated as per request from DKE 2019-05-22."(abbreviation)" deleted from en synonym1 attribute. JGO
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