Differences in IEC and NEMA/ANSI motor designs 2

[tinutom]

Hi,

Are there any specific differences in the designs of motors of IEC and ANSI standards which would make one preferable over the other in a large complesx that uses both types in different units?
Specifically relating to clearances and hazardous area classification certifications..

Thanks!

 

[jraef]

Certifications are all about where the equipment will end up. It does no good to have IEC certs if the equipment is going to be installed in the US, and vice versa.



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[jraef]

This website is a decent reference from a US manufacturer's standpoint. Unfortunately it doesn't go into a lot of details on NEMA.

http://www.iprocessmart.com/leeson/leeson_iec_article.htm

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[aolalde]

IEC attempts to be an international standard. ANSI is a local standard intended for USA.

 

[tinutom]

thanks guys!

the website was especially helpful.. my plant is in Asia-Pac and we do use both standards here, hence the original query.
although i see IEC tends to be more specific about some of the deaign details, is there any technical reason to say that IEC motors would be better designed than NEMA/ANSI motors when it comes to hazardous area applications? i.e. an IEC vs. NEMA motor certified for a certain area should both be identical in that regard, right?

 

[jraef]

Should be.
In general, IEC vs NEMA is not a quality assessment, especially in that the motor manufacturers are all over the world. These standards have mostly to do with form fit and function. IEC standards are a little more extensive only because they tend to be more application specific, whereas NEMA design specs are more broad so that there are fewer motor designs that can be used almost anywhere.

Once you get into hazardous area applications however, the requirements that you need to meet are more based upon what your environment is and what your local authorities require rather than standards. For instance, if you have an environment with a certain level of hydrogen in the atmosphere, your local authority may require a very specific EExA spec to be met, and a motor designed around NEMA standards may not list compliance to that spec, even if it meets or exceeds it technically. So your local authority may still reject it even if you prove it's capabilities based on NEMA specifications because it does not have a nameplate on it that says so. My advice is to find out what the local requirements are and select motors based on that.

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[UKpete]

I can't add anything to the posts above, but if you want data specifically on hazardous area applications of motors then the following document may be of use:

http://www.brookcrompton.com/pdf-files/2203e_hazcat_v1.pdf

It compares the detail on various national standards including NEMA.

 

[jraef]

Nice resource UKPete, I'll have to bookmark that one. An LPS for you.

 

[tinutom]

thanks guys... very useful responses! =)

 

[mc5w]

IEC terminology for explosionproof and dust-ignitionproof applications were added to chapter 5 of National Electrical Code a few Code cycles ago. As for IEC certifications, it is up to your local electrical inspector which cetifications and listings he will accept and the same foes for your insurance company.

I can tell that the Italian motors that I have seen have rather chintzy design and they are not as durable as NEMA motors. A lot of U.S. built motors, machine tools, and so forth have safety factors and ignorance factors built in them and European and Japanese machinery have smaller safety factors. This is because Europeans and Japanese do not abuse machinery like our factory people do. The United States volunteered to take in a whole lot of riff raff and quite few of these people do not know their own strength.