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3 Degree pollution (based VDE 0110-1 and IEC 60664-1)
The micro-environment determines how contamination affects the
insulation.
Overvoltage category II
Equipment intended for operation plants, parts thereof, where transient
overvoltages not have taken into consideration; but where
overvoltages caused operation equipment may occur.
Here, transient overvoltages not have taken into consideration,but
because special demands placed this equipment with regard the
safety and availability and the networks that depend it, overvoltage
remains factor for consideration.g.1.g. Domestic
electrical appliances are included this category, for example. This includes equipment for permanent
installations, e. However, the macro-environment should also considered.
Overvoltage category IV
Equipment intended for operation plants, parts thereof, where transient
overvoltage has taken into consideration. control devices, meters.1.
. protective devices, contactors, switches and outlets.
Overvoltage category III
Includes equipment intended for the operation plants parts thereof. rule, contamination becomes conductive when
mixed with water.
4. This circumstance has led the specification minimum
clearance distances. Contamination caused water, soot, metal coal dust is
always conductive. Equipment this overvoltage
category primarily operated low voltage.6.Insert 161
4.
Small clearance distances can bridged completely solid particles, dust
or water.6.
Micro-environment: Immediate surrounding the insulation, which
especially influences the creepage distance rating. This includes equipment
connected overhead lines, e. with surge arrestors).
Macro-environment:Environment room other location which the
equipment installed operated.g.2 Overvoltage categories
Equipment divided into one the following excess voltage categories:
Overvoltage category I
Equipment intended for use devices parts plants where overvoltages
cannot occur, which are protected with suitable measures against such
overvoltages (e
