Nothing but praise here. And from a designers point very slick. Just put some DIN rail down and away you go. The dial in overloads and phase loss detectors, all fit together so neat. And if your installing them the enclosures can be alot smaller and lighter. The one problem I've had is at the supply house. The ole boys that sell pipe and THHN, tubs and all, don't have a clue what Telemechanique is at all. When I come through the door with the Square D digest they scatter. I have to fill out my own order forms for Square D.
Lighting the way
Re: IEC Contactors#11102 06/29/0209:09 AM06/29/0209:09 AM
echoing Don's comment, be VERY careful about their ratings, if you are even approaching their max, go up, or go with NEMA. I know of at least one case where a manufacturer used them within their ratings, but at the top quadrant, after we put the fires out (literally) we changed to NEMA.
They are space savers, agreed, but again, be very cautious.
BTW, I won't discuss the incident on the forum, the manufacturer.....voluntarily.....changed the contactors. By measurement, and calculation, the IEC's fit (again, but just) but would not take a ...normal... abuse. obviously the wrong application.
Re: IEC Contactors#11103 06/29/0210:25 AM06/29/0210:25 AM
A polite way of describing IEC motor control is: ∙ “…very materials conservative” or ∙ “…makes good use of your smaller hand tools” or ∙ “…For when you just don’t need any of that silly, overpriced reliability.”
[It takes a whole different mindset. Electrical gear is now being whored out more.]
On the ‘crank-it-up’ OL-trip settings, there’s the assistant-junior-production-manager-trainee mentality: “I don’t care what you have to do—just get me through to the end of my shift!”
[This message has been edited by Bjarney (edited 06-29-2002).]
I don't get involved with commercial switchgear much, but I would echo some of the other comments about the IEC/DIN-mount stuff being a little liberally rated and not always as rugged as it could be. At least, that's my opinion of the versions sold here.
It's certainly not as rugged as our old switchgear used to be.
"Nothing but praise here. And from a designers point very slick." Not flaming you, Joeh20, but this is where a lot of the problems arise. The fact that they fit nicely in small areas and enclosures increases the likelihood that they will be crammed into small enclosures with restricted heat dissipation properties. The dial overload settings abets the “I don’t care what you have to do—just get me through to the end of my shift!” scenario. The cost of initial installation encourages use in facilities that are trying to cut costs and may over-look quality and the results of abuse or system abnormalities, such as power sags. We have all heard stories of every part of an installation being built to the 100% minimum standards and any weakness or overuse of one component brings everything down.
IEC contacts pass the exact same NRTL life testing (nominal 10 million no-load and 1 million full load operations) as any NEMA device. They are smaller because their terminals operate at 75C versus the NEMA 55C, and they are not designed to be repaired.
They are often misapplied because they are available in so many different ampacities. But there is nothing inherently wrong with them. For example: an Allen-Bradley NEMA size 1 contactor is rated as 27A continuous, 32A service limit, and 10HP@480V. Now you can chose an AB IEC contactor based on 10HP@480 and get a 16A device or chose a 27A device and get a 20HP contactor. The selection choice is yours, but remember a 10HP 480V motor has a NEC current of 14A, and a typical running current less than that, which means when pushed to the typical service factor of 1.15 the motor will still only draw 16.1A max.
The adjustable overload is the same concept as any NEMA bi-metallic or even the new solid-state designs. People will misadjust them, but they will also put in incorrect heaters or even jumper across them.