Chris,
Whilst considering a 'standard office environment' it is worth considering
how mobile the equipment is and the variety of environments in which it could be
used. Although most P.C.'s sit on a desk in a heated office, condensation is not
really a problem, however, such equipment is not usually bolted to the wall, and
by the definition of EN60950 is regarded as 'moveable'. Consider, for example a
computer system unit that has just been brought in from a cold car into the warm
office, or one installed near a door in a warehouse and is subject to rapid
temperature and humidity changes. Most business and domestic products are going
to experience a degree of condensation in use, transport or storage.
The only real way to try and avoid condensation is with a potted or sealed
enclosure, or to keep the equipment within the non condensing temperature limit
for the given humidity. Unfortunately the latter cannot be controlled by us
manufacturers!
Most I.T. equipment would classed as polution degree 2 on the basis that in
storage transport or use you could not guarantee that the product would not
experience a degree of condensation.
Hope this helps,
Duncan
____________________Forward Header_____________________
Subject: pollution degree 1? 2?
Author: Chris Wells <[email protected]>
List-Post: [email protected]
Date: 1/16/00 7:59 AM
Kurt
In your feedback (thank you!) you state that pollution degree 1 is for
conditions with NO pollution at all like a potted epoxy environment. This is
the impression I got from UL and other sources.
Help me out here please.
>From my memory the definition in EN61010-1 (same as in IEC 664)
Pollution degree 1 is for non conductive dust environments - no condensation.
Pollution degree 2 is for non conductive dust environments - occasional
condensation
Pollution degree 3 is for conductive dust environments.
The definition for pollution degree 1 implies that this is a standard office
like environment.
Am I missing something here?
Do most PCB spacings get evaluated to pollution degree 2?
in ITE?
in Automation equipment like Programmable Logic Controllers ?
Thanks .
Chris Wells
Senior Design Eng
Cutler-Hammer
Pittsburgh Pa
[email protected]
Original Message-----
From: Andrews, Kurt [mailto:[email protected]]
Sent: Monday, January 10, 2000 12:14 PM
To: Price, Ed; '[email protected]'
Cc: 'Chris Wells'
Subject: RE: Pollution degree help
Ed, Chris,
Normally Pollution Degree 1 is used for items that receive no
pollution at
all. These are hermetically sealed or potted/encapsulated parts.
However you
can use pollution degree 1 for internal PCB layers. <snip>
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