lack of any seal at shaft on TENV motor 3

[electricpete]

We have a small (5hp?) TENV crane motor in outdoor application, approx 2 years old. We recently heard lots of vibration. Investigated and found that the drive end had apparent moisture intrusion. Shaft and external bearing surfaces inside motor showed early signs of rust. Bearings are double-shielded (require no lubrication).

Inspection shows that shaft penetrates the end bell and there is no lip seal or slinger ring or anything (other than close clearance between housing and shaft) to prevent moisture entry. There was however grease in the end bell bearing cavity, which is strange since it's a double-shielded bearing. Called manufacturer who told us that the grease is intended to stop the entrance of moisture around the shaft, and we should replenish it to solve the problem.

That sounds pretty hokey to me. What do you guys think?

 

[SteveKW]

In my pump & motor repair shop I often do that when I know there will be a moisture problem. It's a cheap trick that I had read elsewhere and it works to some degree.

 

[teco]

electicpete:- you dont state the ip (ingress protection) rating of the motor. what you have is quite adequate for ip44.
however for outdoor service ip55 vee rings should be fitted to the outboard side of the shaft and run up against the end cover(bs 4999art 20 iec publication 34-5).
the only time grease should be used is when a double cavity is present in the end cap and grease relief is fitted. a slinger should also be fitted.
should you require drawings pls advise email address
kind regds.

 

[electricpete]

The motor nameplate says: "Encl: TENV". (totally enclosed non-ventilated).

I assumed that this defines the degree of protection and I would have assumed that is good enough for outdoor service. (but I might be wrong... is there something else on the nameplate that tells the degree of protection.

NEMA MG-1-1998Rev1 SECTION 1.26.1 seems to equate TENV with "IC410", but I can't decode what those letters stand for.

 

[teco]

electricpete:-the tenv as stated only tells you the cooling form of the machine not the ingress protection.
most i.e.c machines state the ip rating on the name plate.
if you are going to change the bearings, we reccomend you fit a vee ring or some type of slinger to prevent this re occuring.
kind regds.

 

[electricpete]

TECO - You are exactly right that I mistakenly believed that cooling classification would provide some info on ingress-prevention classification. But I see now they are treated separately by NEMA MG1 .... Enclosure ingress protection (IP) in Section 1 Part 5 and Cooling (IC) is Section 1 Part 6.

Although the logic escapes me. The only reason I can see for building a TENV motor would be for ingress protection. (it's a 25hp motor by the way, not 5hp). Why would a manufacturer (not teco) offer a TENV that has no attempt to seal the shaft?

 

[teco]

electricpete:- as a manufacturer most motors are produced to be "cost efective"as well as complying to bs nema iec specs. we regually make mods to machines to meet customer demands and specs (normally at no extra charge).
in you case we think an over sight was made on initial application engineering .
kind regds.

 

[electricpete]

I agree that by specifying TENV and not specifying IP rating, we failed to specify what we needed.

But still... doesn't a TENV cost more than a comparable open motor? Why would anyone build or specify on except to exclude moisture/contaminants or possibly for hazardous environment?

By the way: what does IC stand for?

 

[electricpete]

One more question regarding NEMA terminology (I know you didn't invent it... but it does seem misleading to me).

If the IC and IP ratings are truly separate, does that also mean that an IC rating corresponding to Open, Weather Protected Type II is not necessarily suitable for outdoor operation (may not have any shaft seal)?

Comment: The terminology ("weather protected","totally enclosed&quot sounds a little misleading since it sounds like those types should be suitable for outdoor use. (I realize the proper answer would be to specify an IP rating IPX3, 4, 5,6,7,8).

 

[teco]

electricpete:- we not familiar with the correct nema terminology. however you are correct in assuming "weather protected" "tefc&quotipw44 should be ok for out door sevice, as the "w" stands for weather protection (bs 4999).
we would suggest in future if you spec new or repaired machines ip55 you can use them for inside or outdoor service.
kind regds.