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We use Cortec VPCI foam emitters extensively in non vented enclosures & are very pleased with the results.

These particular motor markings designate suitability for gas atmospheres only (G). Being a surface coal conveyor I would assume the potential explosive hazard is coal dust. If that is the case then the motor should have a G/D or D marking.

To my knowledge there are no “IECEx” (ATEX) certification authorities in the US. However UL does have a subsidiary called UL International Demko A/S (Demko is an ATEX certification authority in Denmark). UL approved workshops are allowed to conduct testing, issue quality audits, or prepare...

I wonder...1750/2100 rpm. Could this perhaps be a motor that utilizes field weakening to obtain that speed range? But then again it should be stated on the nameplate if that was the case. Would it be possible to test the motor in-situ & supply the shunt field with an external variable voltage...

Max surface temp for T4 is 135 C. I don't think you have too much to worry about.

Great link electricpete! Furthermore, there are also a few good text books available on the subject of motor repair/rewinding. I can thoroughly recommend “Electric Motor Repair 3rd edition” by Robert Rosenberg (costs around $180 from Amazon). There are also some very good (but very old)...

Impossible to say, there are so many different types of polyester based varnish. You would have to check with your supplier or consult the product data sheet. Many polyester varnishes use Xylol (Xylene) as a thinning agent & it has a low flash-point.

Gaux, As I said VPI is the best method but if you don't have VPI then dip varnish is your only alternative. You are quite right that if an armature (or stator for that matter) has been dip varnished well enough, then a second dip is unlikely to achive any penetration. It will however contribute...

Sorry the link got mixed up. Here is the product sheet for class "H" G-11 laminate (also available is class "F).http://products.vonroll.com/web/download.cfm?prd_id=3140&are_id=2&lng_id=EN

Gaux, I guess your location is France...yes? The attachment ought to help you out with info on G-11 laminates (BTW, I think "Vonn Roll" still have an office in Delle). Polyester based varnish is fine for most dip & stove applications (stators), in the absence of a VPI system maybe you could...

Sorry...I forgot to ask. What type of varnish system are you using?

Slot wedge material should have at least the same thermal classification as the rest of the insulation system so that its mechanical strength is not degraded by operating temperature. Vulcanized fibre has a maximum service temperature of 120°C, and although it is pretty strong & tear resistant...

See attachment for B3 dimensions. "Z" denotes that all mounting dimensions are standard except the shaft extension (it could also used to designate motor with double shaft extension).http://www.siemens.com.pk/Pdf/motors/1LA7-DIM.pdf

An increase in HP requires an increase in conductor size and a decrease in turns. Coil pitch, coil grouping & internal connections remain the same. Assuming the core will take the increased flux density the new rewind data (turns & conductor cross sectional area) would be: T2 = T1 * HP1/HP2...

Have you tried asking Siemens? I have always found them pretty helpful. Alternatively EASA could probably plot a bare core design for you (providing your company is a member).

Edison123 Sadly they only released the bare-bones text, diagrams & figures are not shown. If you need the complete article perhaps you could try ordering a back-issue from Barks?http://barksbooks.com/backissues.html

This article might answer some of your questions.http://findarticles.com/p/articles/mi_qa3726/is_199804/ai_n8794829/pg_1?tag=artBody;col1

Are you using Arctic duty motors? Perhaps you should be if you are operating in severe winter conditions with prolonged sub-zero temperatures. There are several operational factors to consider. Arctic duty motors are designed for ambient temperatures as low as -70F. They have different bearing...

Were any of the rotor bars found to be loose, cracked or showing signs of local heating/arcing? Is the rotor a double cage type? it is difficult to ascertain from the photos.

Are you sure the original winding was delta connected?? 36 slots/2 coils per slot/8 poles is a winding with unequal coil groupings. You should have 4 groups of 2 coils & 4 groups of 1 coil per phase (24 groups in all). The grouping should be as you mention. Did you run a polarity test after...