Sunpower UK's Electronics Glossary - SELV
SELV: Separated Extra Low Voltage. This circuit must be safely separated from other circuits that carry higher voltages, isolated from earth and isolated from the protective earth conductors of other circuits.
The design of an SELV circuit typically involves an insulation transformer, guaranteed minimum distances between conductors and insulation barriers. The connectors of SELV circuits should also be designed to that they do not make with connectors commonly used for non-SELV circuits.
This Electronics Dictionary is a free service provided by Sunpower UK, and includes an ongoing list of current electronics vocabulary in use today. Sunpower UK sells a bespoke product range of electronics power supplies suitable for all your power supply needs, be it large or small.