×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

How to add additional cooling to motor

How to add additional cooling to motor

How to add additional cooling to motor

(OP)
The hoist motor on a monorail crane occaisonally overheats during heavy use in hot weather.  We have no easy way to cool the building or upgrade the motor.

I'm hoping to find a simple way to provide additional cooling to the motor.  We will attempt to add fan to circulate more air around the motor, but I am not optimistic this will help.

We have some power available but not a lot of room.  We have no way to get compressed air or water to the motor since it is on a crane trolley.

RE: How to add additional cooling to motor

Is this an old motor?
90% of electric motor failure is due improper lubrication.  If dirt gets inside the windings it will cause hot spots and make the motor over heat.  This may be more of an issue if the ambient is high. Taking the motor apart and cleaning it may help.  

RE: How to add additional cooling to motor

(OP)
It is not very old and is TEFC and is probably not dirty based on no history of this.  The motor doesn't fail it just shuts down due when RTD (or thermistor?) hits its trip point.

It happens when there are a lot of start/stops and heavy usage in warm weather.  Hoping to knock temeprature down a little so we don't hit the trip point.

RE: How to add additional cooling to motor

Does it already have a VS drive or soft start?  Consider it.


Mike Halloran
Pembroke Pines, FL, USA

RE: How to add additional cooling to motor

Across the line starts generate lots of heat.  It this a replacement motor?  Most crane motors are built to deal with the frequent starts typical of cranes.  Are you a victim of "a motor is a motor"?

TEFC makes little sense for a crane because the fan is not on when the motor is not on.  

RE: How to add additional cooling to motor

Soft start and a fan that runs for 15 min after the motor is shut off would both help.  You might need to build a duct for the fan to make sure that the air does some good.
I am with MJ on this, it sound like your motor isn't rated properly.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
http://www.trent-tube.com/contact/Tech_Assist.cfm

RE: How to add additional cooling to motor

(OP)
You are correct it is not TEFC.

The duty cycle of the crane was not specified correctly and we are using it at or slightly beyond its rated duty cycle.

We are trying to figure out how to mount fan.  There is not much room.  I think that is the best solution though.

RE: How to add additional cooling to motor

Since the system is on a rail, have you consided putting the cooling system at the end of the rail and running dryer vent tubing to the motor?

TTFN



RE: How to add additional cooling to motor

The last company I worked for had three subsidiaries and between these four companies without exaggeration we had over 4 dozen cranes and hoists.  We went to all sorts of equipment auctions to buy such lifting equipment and then we would refurbish them, shorten and lengthen spans and install them in our facilities.  We never had an overheating condition.  So my question is, is it possible that you monorail crane may have been put together from miscellaneous parts and inadvertently the wrong size(under rated) motor was used?  Because in all fairness to crane manufacturers and suppliers, overheating should not be an issue.  

RE: How to add additional cooling to motor

To add a fan:

Buy fan and motor.

Figure out where and how to mount.

Fabricate mounting.

Run power.

Figure out how to control power.

Buy starter, control relays and enclosure.

Figure out where and how to install starter, control relays and enclosure.

Run wiring to fan.

To install a properly rated motor:

Buy proper motor.

Install.

RE: How to add additional cooling to motor

(OP)
This is P&H crane that was new in 1991 when it was installed.

Like I said above we are using it more than the rated duty cycle and the building is probably a lot warmer than it was designed for, just enough that we are tripping the motor on overheat.  This is not a new problem, just an annoying intermittent problem when using the crane a lot when weather is hot.

Sounds like the answer is a fan, which is normally an easy fix (as MintJulep indicated) but we don't have much space and environment is dirty.  Other fans in that area tend to quickly get caked with dust.  Of course a properly rated motor would also work but was hoping not to spend that kind of $.

Was hoping for some alternative easy fix.  I guess if there was one I would have known about it.

Thanks

RE: How to add additional cooling to motor

Does your crane have good soft start?  That might help reduce the heating a lot.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
http://www.trent-tube.com/contact/Tech_Assist.cfm

RE: How to add additional cooling to motor

These guys make soft starts and VS drives that are _intended_ for crane service:

http://www.peinfo.com/

Mike Halloran
Pembroke Pines, FL, USA

RE: How to add additional cooling to motor

We had a lot of P&H overhead cranes and tripping of the fuse from overheating were never an issue.  Research the crane model and serial numbers and ascertain that the trolley with its hoisting motor is the correct one.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources