This shows how a large motor is re-wound, serviced, and tested. The scale, complexity, teamwork, and know-how required by the people at the KOFFLER Electrical facilities in San Leandro, CA.
source/image: Michael Bukay
Everything, from making the wire coils to the Vacuum Pressure Impregnation (VIP) process, is done at this one location.
The motor in this video is used to power a pump that removes water from a submarine dry dock facility at Pearl Harbor.
If the choice is between rewinding a standard efficiency motor or purchasing a new high efficiency motor, the difference in efficiency will be 4 to 5% at full load in favour of the high efficiency motor, which will also have a much longer service life.