Overhauling duplex motors in our 1923 Panel Office

Museum volunteer Peter Amstein talks about his most recent project. These AC/DC motors were manufactured for the Bell system by General Electric. The idea was that if you lost AC or DC power, the motors could stay running on one until the other was restored.

[NipkowDisk]

At 2:38 is a NEMA 10-20 plug if I recall correctly. Not at all common but yes, replacements are still made.

[grillsandaxlegrease]

I heard Omaha, NE was the first city to get this system.

[billylowe]

In a power failure does the DC section of the motor take over until the back up power providing AC comes on line?

[roads]

AC section of this motors is a single-phase motor with no run capacitor?

[SuburbanDon]

isn't that a DC motor and a alternator (generator)?