Note
：
Overvoltage Category Definition
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. For example, appliances,
portable tools and other plug-connected equipment;
Category III:
applies to fixed downstream equipment, including the main distribution board. For example, switch-
gear and other equipment in an industrial installation;
Category IV:
applies to equipment permanently connected at the origin of an installation (upstream of the main
distribution board).For example, electricity meters, primary overcurrent protection equipment and
other equipment connected directly to outdoor open wires.
Moisture Location Category Definition
Environment Category Definition
Outdoor : the ambient air temperature is -20~50
℃
. Relative humidity range is from 4% to 100%,
applied to PD3.
Indoor unconditioned:
the ambient air temperature is -20~50
℃
. Relative humidity range is from 5% to 95%, applied to
PD3.
Indoor conditioned:
the ambient air temperature is 0~40
℃
. Relative humidity range is from 5% to 85%, applied to PD2.
Pollution Degree Definition
.
Pollution degree 1:
No pollution or only dry, non-conductive pollution occurs. The pollution has no influence.
Pollution degree 2:
Normally only non-conductive pollution occurs. However, a temporary conductivity occasionally
caused by condensation should be expected.
Pollution degree 3:
Conductive pollution occurs. Or dry, non-conductive pollution becomes conductive due to
condensation, which is expected.
Pollution degree 4:
Persistent conductive pollution occurs. For example, pollution caused by conductive dust, rain or
snow.
31
