MV design guide - Schneider Electric
MV design guide - Schneider Electric
MV design guide - Schneider Electric
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Design rules<br />
Dielectric withstand<br />
U<br />
Lf<br />
O<br />
Insulating air interface between live parts<br />
c There are 4 severity levels of pollution, given in the table below,<br />
according to IEC 60 815*:<br />
Lf : tracking path<br />
Pollution<br />
level<br />
I-low<br />
II-medium<br />
III-high<br />
IIII-very high<br />
Example of characteristic<br />
environments<br />
v industry free zone with very low density of housing equipped with heating<br />
installations<br />
v zones with low density of industry or housing but frequently subjected to wind and/or rain<br />
v agricultural regions 1<br />
v mountain regions<br />
v all these zones can be located at distances of at least 10 km from the sea<br />
and must not be exposed to wind blowing in from the sea 2<br />
v zones with industries producing particularly polluting smoke<br />
and/or with an average density of housing equipped with heating installations<br />
v zones with a high density of housing and/or industries but subjected<br />
frequently to winds and/or to rainfall<br />
v zones exposed to a sea wind, but not too close to the coast<br />
(at a distance of at least several kilometres) 2<br />
v zones with a high density of industries and suburbs of major cities with a<br />
high density of polluting heating installations<br />
v zones situated near to the sea, or at least exposed to quite high winds coming<br />
in from the sea 2<br />
v generally fairly small areas, subjected to conductive dust and to<br />
industrial smoke producing conductive deposits that are particularly thick<br />
v generally fairly small areas, very close to the coast and exposed to mist<br />
or to very high winds and to pollutants coming from the sea 2<br />
v desert zones characterise by long periods without rain, exposed to high winds<br />
carrying sand and salt and subjected to regular condensation.<br />
*IEC 60 815 <strong>guide</strong>s you in choosing insulators for polluted environments<br />
1<br />
The use of sprayed fertilisers or the burning of harvested land can lead to a higher level of<br />
pollution due to dispersion by the winds<br />
2<br />
The distances to the waters edge depends on the topography of the coast region and the<br />
extreme conditions of wind.<br />
40 Merlin Gerin <strong>MV</strong> <strong>design</strong> <strong>guide</strong> <strong>Schneider</strong> <strong>Electric</strong>
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