User Manual
Table Of Contents
48
Appendix
User Manual V1.3
Category I
Applies to equipment connected to a circuit where measures have been
taken to reduce transient overvoltage to a low level.
Category II
Applies to equipment not permanently connected to the installation.
Examples are appliances, portables tools and other plug-connected
equipment.
Category III
Applies to a xed equipment downstream, including the main
distribution board. Examples are switchgear and other euiquipment in
an industrial installation.
Category IV
Applies to equipment permanently connected at the origin of an
installation (upstream of the main distribution board). Examples are
electricity meters, primary over-current protection equipment and other
equipment connected directly to outdoor open lines.
Pollution Degree I
No pollution or only dry, non-conductive polllution occurs. The
pollution has no inuence.
Pollution Degree II
Normally only non-conductive pollution occurs. Occasionally, however,
a temporary conductivity caused by condensation must be expected.
Pollution Degree III
Conductive pollution occurs, or dry. non-conductive pollution occurs,
which becomes conductive due to condensation, which is expected.
Pollution Degree IV
Persistent conductive pollution occurs, for example, the pollution
caused by conductive dust, rain or snow.
Overvoltage category denition
Pollution degree denition