HV Motor Storage

[marks1080]

Hello all. I've browsed these forums for a long time, but am now just making an account. I'm a new electrical engineer, and am always looking for new reference tools to use on the job. Any support would be appreciated.

I have been asked by my boss to draw up some spec's on HV Motor Storage. We have purchased to 13.8kV spare motors and are having them put into storage. I have a spec for storage written up that I believe is fairly complete. I am wondering if anyone out there may have some advice or suggestions on information to add to the spec which may not be commonly known.

My spec so far includes issues such as: temp/humidity, clearance, insulation tests, cleanliness, heaters, shaft rotation, checking for rodents in and around motor, vibrations/shock-free storage area, bearing care...

There are more aspects to my spec, but they do not need to be lised here. Again, any help would be greatly appreciated.

Regards,
marks

 

[itsmoked]

You could drop your write-up in here, we'd love to give it a quick review. Your question comes up fairly regularly. There are some real experts on the subject that can help you fine tune it. You could then move it to a FAQ.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[oldfieldguy]

Interesting that you should come up with this question. My company is in the process of acquiring and storing a large spare motor.

You've already hit on the main considerations. If you have space in a climate-controlled storage facility, that's the prime real estate for this. Otherwise, shoot for an enclosed, ventilated shelter. Humidity control is important, as is avoiding large, rapid temperature swings. Provide power for the space heaters within the motor and make sure they're monitored regularly. You might want to discuss additional heat with the manufacturer. If the storage area is prone to dust, covers might be indicated. Backing these with rodent-proof screens is prudent if rodents are a problem in your area.

The shaft should be rotated several turns periodically. Again, consult the manufacturer. Absent his suggestion, do several turns bi-monthly. This will also take care of bearing care. If there is a vibration issue in the storage area, then brinnelling of roller or ball bearings can be an issue. Provide rubber isolation pads on which to set the motor if you cna't find a better storage area without the vibration.

Periodic (annually maybe) do a polarization index test on the windings and compare data with previous tests.

Realize, of course, that when this motor is called out for service, you will still have to do comprehensive tests ind inspections suitable for large motors, but proper storage will give you a very good chance that the motor will remain serviceable for years in storage.

old field guy

 

[electricpete]

For oil bearing equipment, to prevent rust and facilitate rotation, of course you'll have to keep oil in the bearing. This can easily be forgotten since oil is usually drained for motor movement.

Also grease bearing motors are shipped from the repair/manufacturing site with grease and stored that way. Now an interesting question when you withdraw it from storage after X years - do you "change" the grease, which would usually entail replacing the bearing and repacking the cavity? Our grease supplier (Mobil) says "yes" if the motor was stored more than 5 years.

Another question particularly for critical motors or motors that have a very short window for installation - do you do an uncoupled run on a shop platform before you install the motor into the plant. It's a lot of extra work, but if finding a problem after installation after sitting in stores for 10 years will be a showstopper, you might be second-guessed if you don't.

I posted on this same topic a few years ago. Try searching for posts by me with storage in the title.

=====================================
Eng-tips forums: The best place on the web for engineering discussions.

 

[electricpete]

I found this one...
thread237-167437

I thought there was another one somewhere

=====================================
Eng-tips forums: The best place on the web for engineering discussions.

 

[marks1080]

Thanks people. Appreciate all the feedback. My spec is almost 100% complete. My boss made some revisions (which makes it more general than not) which I am going to mark up tomorrow (as it is 4:55pm here and I waiting to get off work )... I will post my final mark-up hopefully tomorrow.

Thanks again for the help!

marks

 

[marks1080]

Here's the technical section of my spec as it stands so far. Minor changes may be required before it is released... again, any comments/suggestions would be appreciated. Also, some information (such as appendix references) have been purposley left out here...

Motor Storage:

Upon receipt, inspect the packing case for damage. If any is found, ensure that the motor has not been damaged as well. The motor and packing case should not be lifted by via the packing case. Steel wire ropes connected from the motor lifting lugs or trunnions are to by employed.

The motor is to be stored in its packing case. Environmental conditions are to consist of a clean, dry, enclosed building where temperature and humidity variations are small. The average temperature should be approximately 20° (C), and should not vary by more than 15° in either direction.

In order to facilitate essential preservation upkeep and monitoring, a clear space of at least 1.5 meters must be left around the packing case. No other materials/equipment should be stored in the area above the motor.

The storage area should be free from shock or vibration.

As soon as possible, activate the motor heaters. The position of the terminals is labelled on the side of the packing case. Connect the two terminals to a suitable 120V supply. Ensure current is being drawn, indicating the heaters are operating.

Motor current analysis and resistance readings should be taken when a motor is put into and taken out of storage as per the Operating and Maintenance manual.

External parts should be coated with a rust inhibitor as per Manufacturers’ recommendations.

Ventilation openings should be protected from rodent entry.
Monthly:

Visual inspection of equipment for accumulation of dirt, and rodents or other nesting small animals. Clean as needed.

Verify all heaters are functioning properly.

Motor shaft should be hand rotated for a minimum of 15 turns. Shaft movement should be fluid and smooth with no noticeable ‘grinding’ which would indicate bearing failure

Semi-annual:

Measure the winding insulation resistance in accordance with the details given in the Operating and Maintenance manual.

Annually:
Strip-down the D.E. and N.D.E. bearings and inspect the journals, shells and shaft seal diameters for signs of corrosion.
• Reapply the Castrol Rustilo DWX 32 rust protector.
• Refer to Operating and Maintenance manual.

 

[itsmoked]

Seems like the annual might be a little onerous.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[marks1080]

itsmoked: You're probably right. However, in the name of "covering my own ass under all circumstances" I've left it in

On that note... I've also added a 5yr action. It deals with cleaning the bearnings and rebuilding the shaft. Don't even know if this storage contract is gonna last for 5 years but its going in there anyway.

marks