3 phase Electric Motor greasing Schedule?

[electricaleng30]

We are in the process of improving our electrical preventive maintenance schedule at work and with all the equipment that we have it makes it difficult to find the recommended maintenance for all the different types of motors. What I was wondering is if there was a chart or a web site that someone could recommend me to figure out the frequency and amount of grease (type as well) that a motor should take depending on its size and frame. I know that its probably dependent on many variable, but there has to be some kind of general procedure out there to get started other than contacting every OEM for their recommendations? Thanks guys!

 

[fflinders]

Generally the greasing regime will be motor specific. The greasing frequncy, amount and type will have be selected by the manufacturer on the basis of the motor and bearing design. Relavent factors are grease cavity size, is there a grease relief drain, normal running/ambient temperature, running environment, how much intial grease has be put in the machine ect. I still think you need to look at every machine on an individual basis. For example some grease types (because of the carrier bases are not compatiable with each other)cannot be mixed. So you need to know what has been used previously in a machine. The temperature ratings of the grease needs to be chosen in relation to the bearing normal running temp. which is related to the motor running temperature.

Be careful of overgreasing a machine. This has the potential to make the bearing run hot and cause uneccessary contamination of the motor windings with grease/oil. Once combined with dust this restricts the cooling of the machine. In HV machines the accumulation of oil and dust can cause winding surface discharge issues.

Having said this, it is good to standardise, however this needs to be done with caution and after adequate research. You will need to seek info from the motor manufactures.

 

[powerjunx]

electricaleng30,
To establish a greasing procedure to different motors is quite tricky since each machine has a definite duty unless you never know the general procedure.

There is a general procedure on greasing the machine's bearing and varies on the following;
1.) On-line greasing
2.) Overhauled greasing
3.) Duty (continuous, intermittent, Short duty, etc)
4.) General purpose
5.) special purpose
7.) Enclosure type

 

[waross]

Here are some old Rules of thumb.
Some of them may not agree with others but all have been used.
When in doubt, don't grease.
Normal motors, Once a year maybe, every two years better, if you miss the 2 year greasing, try harder the third year.
Quantity of grease. One pump of the grease gun for 25 Hp motors and below, 2 pumps for motors up to around 150 Hp., 3 pumps for 250 Hp. and over.
3600 RPM motors, twice as often.
There is not much loading difference between similar motors of different manufacturers. You can use the same plant schedule for all good quality motors.
Many motors now have sealed bearings. Trying to grease them can lead to failure.
As stated earlier, more bearings fail from over greasing than under greasing. When in doubt, don't grease.
For larger motors, you may want to look up a procedure for changing grease. It involves draining the grease and flushing the old grease out with new grease while the motor is running and the bearings are hot. The motor is then run with the drain plug out for about 15 minutes to drain excess grease before the drain plug is replaced. I would only consider this procedure on larger motors.
respectfully

 

[powerjunx]

electricaleng30, this would help you.



Motor Bearing Lubrication Guide:
Type of Service*
Rpm Motor Frame 8hr/day 24hr/day
Range (in Months)

143T-256T ** **
3600 284TS-286TS 6 2
324TS-587US 6 2 _______________________________________________________
143T-256T ** **
284TS-326T 4 18 1800 364T-365T 12 4
404T-449T 9 3
505U-587U 6 2
_______________________________________________________

143T-256T ** **
1200 & 284TS-326T 4 18
below 364T-365T 12 4
505U-587U 9 3
_______________________________________________________

* for roller bearing, divide above times by 3.
** These motors normally do not have bearing that can be re-lubricated. their bearings should be replaces @ least every 5 years for 8 hr/day service, or every 2 years for 24hr/day service.

More info please refer to EASA Mech'l Ref. Handbook, 1993 or latest version. Grease Application Table is also specified. Very often, you can acquire this to any motor repair and service provider who is an EASA member.

In your case, since there were plenty of machine in your premise, It is impractical to use different grease that is specified by the motor's manufacturer. It is better to evaluate or do an inventory to all machine's grease type and secure a Grease Compatibility Chart (from NLGI) to obtain a common grease type that is widely used in your plant. So you'll have a few grease type to purchase.

In our workshop, we do have one type of grease applied to all machines unless specified by our customer. This beast is
Calcium 12-hydroxy Grease where evidently have almost comptible to all grease type except Polyurea. More info for grease on NLGI(National Lubricating Grease Institute).

I hope this might clear you.




"No act of kindness, no matter how small, is wasted"

 

[aolalde]

This is what a Motor Manufacturer recommends:

http://www.usmotors.com/default_service.htm