( = separated extra-low voltage,
"lahusväikepinge")

olemus
elektriliselt muudest ahelatest eraldatud ahela väikepinge
= extra-low voltage of a circuit electrically isolated from other circuits

IEC 60335-1:
(a) vahelduvpinge tippväärtusega mitte üle 42,4 V
(b) alalispinge mitte üle 60 V
(i) toitevõrgust kaitseväikepinge saamisel peab see toimuma läbi turvaeraldustrafo või eraldi mähistega muunduri, mille isolatsioon vastab topelt- või tugevdatud isolatsiooninõuetele.
(ii) spetsifitseeritud pingepiirid põhinevad eeldusel, et eraldustrafot toidetakse nimipingega
(iii) inglise keeles kasutatakse ka lühendit SELV
=
a) for a.c. the peak value of the voltage does not exceed 42,4 V;
b) for d.c. the voltage does not exceed 60 V
Note 1. When safety extra low voltage is obtained from the supply mains, it is to be through a safety isolating transformer or a converter with separate windings, the insulation of which complies with double insulation or reinforced insulation requirements.
Note 2. The voltage limits specified are based on the assumption that the safety isolating transformer is supplied at its rated voltage.
Note 3. Safety Extra Low Voltage is also known as SELV.

ülevaateid
https://en.wikipedia.org/wiki/Extra-low_voltage#:~:text=Types-,Separated%20or%20safety%20extra%2Dlow%20voltage%20(SELV),earth%20faults%20in%20other%20circuits%22.

http://www.sunpower-uk.com/glossary/what-is-separated-extra-low-voltage-selv/

https://www.edn.com/electronics-blogs/power-supply-notes/4414411/What-does-SELV-mean-for-power-supplies

https://www.saving-star.com/safety-extra-low-voltage/

https://www.scribd.com/document/506058745/EXTRA-LOW-VOLTAGE-AND-TERMINOLOGY-2