Motors and VFD's in hazardous areas

[humbled]

All,

This is my first post to one of these sites. I have been trying to solidify my opinion on VFD's in hazardous areas and how our company should proceed. If I am in the wrong area for this type of post please direct me to the correct forum.

The question is what motor design factors are most important when specifying a motor for use with a VFD when ATEX approvals are requested by the customer?

Please assume the following:
1. The motor is Exd rated.
2. The motor is being used in the 10-100% speed range.
3. The motor is inverter duty rated.
4. The VFD is provided by one of the largest and most reputable VFD manufacturers.

Also can inverter duty ratings be applied by derating the DOL ratings by a specified amount.

Are there any other pitfalls in regard to ambient temperature?

I use a spring applied electrically released brake with every motor. I have run into availability barriers with brakes for high ambient temperature environments.

 

[itsmoked]

This is the right place.

I believe some here will disagree that VFD motor should ever be Exd rated others will not agree with that sentiment.

There was a lengthy thread on the subject a while ago - dang'd if I can find it though.

Any Exd motor would likely be TEFC. The fan would be severely ineffective in those sub 50-70% ranges. If you were also demanding rated torque at those speeds you would need to pile on some sort of auxiliary blower/cooling.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[ietech]

itsmoked,
This may be the thread you are referring to.

thread237-95234

humbled,
Hope the thread above is of some help.

 

[DickDV]

humbled, what you can and cannot do is highly dependent upon where you are and what jurisdiction does the approvals.

Please tell us where you are and what rules you have to operate under

 

[itsmoked]

ietech; That be the one! I saw it in a search but discounted it because the title didn't ring any bells.. Thanks.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[ietech]

itsmoked,

Glad to help.