The following is from IEC TC74's document 74/585/NP on Equipment
Installed Outdoors, a proposed supplement to IEC 60950.
It has not been adopted, but give an idea of the current thinking in TC74.
IPX6 is not addressed, but reference is made back to IEC 60950 for
Pollution degree 1.
It looks like this is a matter for negotiation with your certification
agency.
Bob
9 Protection of equipment within an outdoor enclosure
9.1 Protection from moisture
The OUTDOOR ENCLOSURE shall provide adequate protection from the effect
of moisture on the enclosed equipment. Examples of constructions
regarded as meeting the requirements are shown in table 2.
NOTE 1 - This does not preclude OUTDOOR EQUIPMENT being constructed with
segmented volumes, each providing a different Pollution Degree.
NOTE 2 - For consideration of the effects of the presence of conductive
pollution, as opposed to non-conductive pollution which may become
conductive only due to the presence of moisture, see the relevant
requirements in IEC 60529.
Table 2 - Examples of the application of enclosures to provide protection
1. The use of an ENCLOSURE meeting the IPX4 or the Annex B requirements
relating to the ingress of water is considered to provide a Pollution
Degree 3 environment within the ENCLOSURE.
2. Control of the Pollution Degree 3 environment to Pollution Degree 2
can be accomplished by either:
- providing continuous energization of the enclosed equipment; or
- providing separate heating within the OUTDOOR EQUIPMENT or OUTDOOR
ENCLOSURE; or
- the use of an ENCLOSURE meeting IP54.
3. Further control of the environment at the insulation surface to
Pollution Degree 1 can be accomplished by the methods in IEC 60950-1,
for example, encapsulation, potting or coating.
Where necessary, the ENCLOSURE of OUTDOOR EQUIPMENT shall be provided
with drain holes to control the accumulation of moisture due to:
- entrance of water through openings; and
- condensation, when this is likely to occur (for example, keeping the
equipment energized or separately heating the equipment is considered to
keep it free of condensation).
The provision of drain holes and their location shall be taken into
consideration when determining the IP rating.
Compliance is checked by inspection and, if necessary, by the relevant
tests of IEC 60529 or annex B.
Prior to testing, the equipment shall be mounted, so far as is
reasonably practicable, according to the manufacturer's installation
instructions. If fans or other means for ventilation are provided, which
could affect the ingress of water, the test shall be conducted with the
ventilation means both "ON" and "OFF" unless it is evident that one of
the modes of operation will produce the most onerous result.
At the conclusion of the test the following conditions shall exist:
-For OUTDOOR ENCLOSURES - no water shall have entered the ENCLOSURE.
-For OUTDOOR EQUIPMENT - water is permitted to enter the ENCLOSURE
provided it does not:
.. deposit on insulation where it could lead to tracking along the
creepage distance,
.. deposit on bare live parts or wiring, or on windings not designed to
operate when wet,
or
.. enter any supply wiring space, see IEC 60950-1, 3.2.9.
9.2 Protection from plants and vermin...
Massey, Doug C. wrote:
Hello group -
In the -950 series standards, three Pollution Degrees are defined for
detirming insulation coordination. For instance, in EN60950 3rd Ed., clause
2.10.1 defines Pollution Degree 1 " for components and subassemblies which
are sealed so as to exclude dust and moisture (see 2.10.7)." Clause 2.10.7
gives test requirements for temp cycling, humidity, and electric strength
tests, although compliance to the clause is given as "...inspection from the
outside, measurement, and, if necessary, by test."
I would like to use Pollution Degree 1 when evaluating a product that has a
dust and water ingress rating of IP66 per IEC - 60529, Degrees of protection
provided by enclosures (IP Code) . The product itself is intended for use in
a Pollution Degree 3 environment, but the creepages and clearances inside
the unit are subject to Pollution Degree 1, thanks to the protection
provided by the enclosure.
Is the IEC-60529 report, showing a IP rating of IP66, adequate to satisfy
the requirements of 2.10.1 & 2.10.7 for using Pollution Degree 1 when
assessing clearance and creepage ?
Thanks in advance.
Doug Massey
Safety Approvals Engineer
LXE, Inc.
Norcross, GA., USA
Ph. (770) 447-4224 x3607
FAX (770) 447-6928
e-mail: masse...@lxe.com
Cruise our website at: http:\\www.lxe.com
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