Protective insulation
The insulation causes the protection against contact with electrical, under voltage standing parts by the operatively necessary basic insulation still applies an additional insulation. A metal housing can also be completely isolated inside or outside. The additional insulation must not be interrupted at any point, not even at a switch connection. The disadvantage is that the first error is difficult or impossible to detect.
Double-insulated devices may have a two-pole connection cable and are identified by a symbol with two squares inside one another, which indicate the double insulation. The protective insulation corresponds to protection class II.
Devices with protection class III have low-voltage circuits that are separated from mains circuits by protective insulation. This protective insulation is also used for isolating transformers . It is also known as safe electrical separation .
See also
literature
- Gerhard Kiefer: VDE 0100 and practice. 1st edition, VDE-Verlag GmbH, Berlin and Offenbach, 1984, ISBN 3-8007-1359-4