DRL
1 mW
In another work life I was involved with Heavy Component Rebuild of very large mining and locomotive traction motors. One aspect of electric motor service life after rewinding and so forth was a process known as VPI or Vacuum Pressure Impregnation of varnish to the devices, this was applied both at original manufacture and subsequent rebuild.
The advantage of VPI is....
For every 10 degrees a motor runs over its rated temperature. the life of the insulation in that motor will be cut in half. A motor's ability to dissipate generated heat into the atmosphere is a part of its calculated efficiency, as well as its effective life span. When a motor is dipped in varnish and baked air can get trapped in the windings. Air is a very poor conductor of heat as opposed to a solid mass. Vacuum Pressure Impregnation provides maximum protection of the winding with minimum coverage. Too often many coats or multi-dipping of varnish creates a heat jacket around the winding which restricts heat dissipation.
In essence VPI is a vacuum chamber into which the device is suspended, once all air is removed the varnish is introduced yielding maximum penetration, then the vacuum chamber is pressurized ensuring even further saturation of windings with no air voids.
The VPI Process
In the VPI chamber the vacuum process removes all air and moisture from the windings
The regulated vacuum draws the solvent less resin through out the windings from an adjoining vessel
A calculated and timed pressure is applied and forces this resin into the copper windings, tape and any empty air pockets or voids
The final process is achieved by curing the stator or armature in the temperature controlled oven creating a solid mass which is an excellent conductor of heat
Use Vacuum Pressure Impregnation in All:
Medium and High voltage equipment
Direct current field coils and armatures
Motors with inverters as power source
Problem motor applications
Since adopting ebike transportation 5 or 6 years ago as my "retirement" mobility means, and since getting interested in the (mostly sketchy) tech of EV it crossed my mind that VPI could be a great process in achieving a more efficient, reliable motive and controller component for the EV world, making a sows ear into an ev silk purse
Although there are commercial treatment places they are more geared to very large applications and are probably cost prohibitive (maybe).
It may even be feasible to cobble up a miniature VPI type "machine" useful for treating components before they are used thereby extending service life, reliability, efficiency and rated output, anyway, probably just an idle thought from an old codger but!!!
I am thinking EV VPI cottage industry type thoughts
Anyway, just thought this may be interesting for some who like pushing the envelope
The advantage of VPI is....
For every 10 degrees a motor runs over its rated temperature. the life of the insulation in that motor will be cut in half. A motor's ability to dissipate generated heat into the atmosphere is a part of its calculated efficiency, as well as its effective life span. When a motor is dipped in varnish and baked air can get trapped in the windings. Air is a very poor conductor of heat as opposed to a solid mass. Vacuum Pressure Impregnation provides maximum protection of the winding with minimum coverage. Too often many coats or multi-dipping of varnish creates a heat jacket around the winding which restricts heat dissipation.
In essence VPI is a vacuum chamber into which the device is suspended, once all air is removed the varnish is introduced yielding maximum penetration, then the vacuum chamber is pressurized ensuring even further saturation of windings with no air voids.
The VPI Process
In the VPI chamber the vacuum process removes all air and moisture from the windings
The regulated vacuum draws the solvent less resin through out the windings from an adjoining vessel
A calculated and timed pressure is applied and forces this resin into the copper windings, tape and any empty air pockets or voids
The final process is achieved by curing the stator or armature in the temperature controlled oven creating a solid mass which is an excellent conductor of heat
Use Vacuum Pressure Impregnation in All:
Medium and High voltage equipment
Direct current field coils and armatures
Motors with inverters as power source
Problem motor applications
Since adopting ebike transportation 5 or 6 years ago as my "retirement" mobility means, and since getting interested in the (mostly sketchy) tech of EV it crossed my mind that VPI could be a great process in achieving a more efficient, reliable motive and controller component for the EV world, making a sows ear into an ev silk purse
Although there are commercial treatment places they are more geared to very large applications and are probably cost prohibitive (maybe).
It may even be feasible to cobble up a miniature VPI type "machine" useful for treating components before they are used thereby extending service life, reliability, efficiency and rated output, anyway, probably just an idle thought from an old codger but!!!
I am thinking EV VPI cottage industry type thoughts
Anyway, just thought this may be interesting for some who like pushing the envelope
