Hi Peter:
There are two issues in your question:
1. The equipment use environment.
Test and Measurement Equipment is likely to be used in
outdoor or sheltered environments, including arctic regions.
Hence, a lower temperature limit of 5 C.
Information Technology Equipment is likely to be used in
indoor environments, usually heated. Hence, a lower
temperature limit of 25 C.
2. The protection mechanisms that are affected by temperature.
Protection against electric shock is principally provided
by insulation. We know that insulation deteriorates as a
function of elevated temperatures, not as a function of low
temperatures (although some may become brittle). So, as a
general rule, we can ignore low temperatures insofar as solid
insulation is concerned. We can say the same for the
supplemental protection schemes such as grounding and
double/reinforced insulation.
Protection against fire is principally achieved by using flame-
retardant materials and a fire enclosure. These are not
affected by low temperatures.
Protection against mechanical hazards is achieved by using
interlock schemes and mechanical enclosures. These, too are
not affected by low temperatures.
Protection against hot parts is provided by an enclosure. This,
too, is not affected by low temperatures.
Etc.
As far as I can tell, there are no protective mechanisms that
are adversely affected by low temperatures (excluding extremely
low temperatures). So, it seems to me that IEC 61010 may be
overly conservative in considering temperatures down to 5 C.
(The requirements ignore the problem of condensation resulting
from moving a cold unit into a warmer environment.)
Best regards,
Rich
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> To: <[email protected]>
> From: [email protected] (Peter Merguerian)
> Subject: Extremes of Operating Ambient Temperature for ITE
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> Hello There!
>
> For IEC1010 Type products (measurement and test equipment), the standard
> specifies it is written for units operating from 5 - 45 deg C. For any
> other ambient operating temperature, additional tests should be made to
> ensure an equivalent level of asfety is achieved.
>
> What about IEC 950/ UL1950? The standard is based on a 25 deg C ambient. It
> also has formula to use for limits of temperature rises above for equipment
> rated for a higher ambient operating temperature. However, nothing is
> mentioned regarding lower than 25 deg C ambient temperatures.
>
> I have seen many units Listed/CE Approved with an ambient operating
> temperature say of -20 deg C to 60 deg C without additional tests in the
> Listing/CE Reports.
>
> Any comments would be appreciated.
> Peter Merguerian
> Managing Director
> Product Testing Division
> I.T.L. (Product Testing) Ltd.
> Hacharoshet 26, POB 211
> Or Yehuda 60251, Israel
>
> Tel: 972-3-5339022 Fax: 972-3-5339019
> e-mail: [email protected]
> website: http://www.itl.co.il
>
>
>
>
>
>
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