Ingress Protection NEMA & IEC

[kimseunghee]

The air cooled braking resistor for VFD is built in U.S and its ingress protection is 3R as per NEMS standard but sepcification requires IP56 for outdoor installation. 3R is equivalent to IP14 which is not suitable for outdoor installation. However, 3R is also for outdoor installation. I believe that there is different test environment for each standards. In order to make the customer understood, I'd like to have the followings.
3R is for outdoor installation actually ?
what is different test conditions between both codes ?
If 3R is not suitable for outdoor(specifially marine installation), how should it be protected for it. I think it is not good way to install it any enclosed space because it dissipate a lot of heat during braking phase.

 

[dpc]

NEMA 3R is outdoor, raintight. It is suitable for outdoor use. It is not watertight.

You should have no problem finding a description of the various NEMA categories on the internet.

 

[burnt2x]

kimseunghee,
Here's a cut-and-paste text for your reference:

(1) IP degrees of protection and the NEMA types of enclosures do not directly compare, as additional environmental conditions such as coolants, oil, corrosion, icing, hail, etc., are specified in NEMA Pub No. 250.

(2) It is not possible to state that an IP rating is equivalent to a NEMA Type designation. An IP rating only considers protection against ingress of solid foreign objects and ingress of water. The NEMA Types consider these but also consider other items such as corrosions and construction details. For this reason it is possible to say that a NEMA Type is equivalent to an IP rating but it is not possible to state that an IP rating is equivalent to a NEMA Type. There is no direct conversion between NEMA Types and IP Codes. More detailed information can be obtained from NEMA 250 publication and the IEC Publication 60529.

NEMA 250 - "Enclosures for Electrical Equipment (1000 Volts Maximum)"
IEC 60529 - "Degrees of Protection Provided By Enclosures (IP Code)"

 

[ScottyUK]

Some cross-reference material in this thread. Be careful when determining equivalence as there is no direct correlation between the two systems.

http://www.eng-tips.com/viewthread.cfm?qid=163194

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