kamikazeCHIP
Industrial
- Apr 9, 2009
- 10
Hello,
I am trying figure out the root cause of ATF fluid leaking into the stator rotor gap leading to horsepower loss and eventually motor failure. The ATF is used to cool the motors by flowing through the windings and pulling heat out. ATF is pumped through the gearbox and into the motor housing under pressure forcing it through the windings and out the other side of the motor.
The motor is made up of stator stack of laminations. Attached to both ends are two powdercoated stainless steel plenums. These plenums are bonded to the stator stack. An encapsulate material is used on both sides of the stator to fill in gaps between the windings and around the plenum to keep ATF from leaking to the plenum/stator bond line and to keep ATF from reaching the stator laminations.
Over time ATF gets through/around this encapsulate material and under pressure leaks into the stator through the laminations and also through the plenum/stator bond line.
Upon physical inspection of the motors the plenum on the gearbox side is almost always detached from the stator. It shows signs redish black tint material attached to the powdercoat. Also often the powdercoat closest to the windings is gone and just the stainless is left. Further up the plenum away from the stator powder coat is cracking and pulling away from the stainless.
With the evidence seen heat seems to be the main root cause of the leaks. Sources of heat include electrical current through the windings and the rotor spinning in the stator. I have also been told that eddy current/magnetic flux could be a source of heat. (Don't understand eddy current or flux portion well as I do not have an electrical background) Once the powdercoat fails on the plenum ATF can be pushed between the powdercoat and steel and behind the encapsulate material which is bonded to the powdercoat.
I was wondering if anyone has seen anything similar to what I have descibed or has any other ideas as to what could be causing increased heat. As designed flow through windings should be suffencient. Could eddy currents be a source of heat on the stainless steel plenums causing thermal expansion and cracking the powdercoat? Any help or additional avenues I could go down would be greatly appreciated.
Additional info: 250 HP 3 phase electric motor.
Note: Motor in photo missing plenum
I am trying figure out the root cause of ATF fluid leaking into the stator rotor gap leading to horsepower loss and eventually motor failure. The ATF is used to cool the motors by flowing through the windings and pulling heat out. ATF is pumped through the gearbox and into the motor housing under pressure forcing it through the windings and out the other side of the motor.
The motor is made up of stator stack of laminations. Attached to both ends are two powdercoated stainless steel plenums. These plenums are bonded to the stator stack. An encapsulate material is used on both sides of the stator to fill in gaps between the windings and around the plenum to keep ATF from leaking to the plenum/stator bond line and to keep ATF from reaching the stator laminations.
Over time ATF gets through/around this encapsulate material and under pressure leaks into the stator through the laminations and also through the plenum/stator bond line.
Upon physical inspection of the motors the plenum on the gearbox side is almost always detached from the stator. It shows signs redish black tint material attached to the powdercoat. Also often the powdercoat closest to the windings is gone and just the stainless is left. Further up the plenum away from the stator powder coat is cracking and pulling away from the stainless.
With the evidence seen heat seems to be the main root cause of the leaks. Sources of heat include electrical current through the windings and the rotor spinning in the stator. I have also been told that eddy current/magnetic flux could be a source of heat. (Don't understand eddy current or flux portion well as I do not have an electrical background) Once the powdercoat fails on the plenum ATF can be pushed between the powdercoat and steel and behind the encapsulate material which is bonded to the powdercoat.
I was wondering if anyone has seen anything similar to what I have descibed or has any other ideas as to what could be causing increased heat. As designed flow through windings should be suffencient. Could eddy currents be a source of heat on the stainless steel plenums causing thermal expansion and cracking the powdercoat? Any help or additional avenues I could go down would be greatly appreciated.
Additional info: 250 HP 3 phase electric motor.
Note: Motor in photo missing plenum
