- Jun 23, 2010
Wow! That is GREAT information!Your motors are early Hansen Synchron clock motors; I have two, one in an American Clock Co. clock and branded as such, and the one pictured, which is still attached to its Synchron gearset. Yours appear to be missing the small glass and brass protection for the rotor and the nuts to secure the electrical connection, but otherwise look complete. Other than the American Clock Company, I don't know what other types of clocks these were used in, nor why one of yours is red instead of green (both of mine are green); the American Clock Company made neon clocks that are in demand by collectors, as they are scarce.
I find the motors to be robust and perfectly quiet, as opposed to the more common later models of similar age, where wear in the motor capsule can cause a lot of noise.
Some good links on this - and yes it seems like the lower frequency was used because of the lesser quality iron and issues with the speed of the generators.25Hz electrical power distribution is an old system in the US originally used for electric railroad service and rarely used heavily today except in some industrial areas.
Why was it used is something of a mystery to me and I can only guess that the massive iron transformer cores used at 25 Hz were less expensive as a "first cost" than those made for 50 Hz which would have smaller, lighter but with higher quality iron core material requirements.
Remember too, that the early Niagara River power was, I recall said to be 40 Hz with most of the US electrical power then at either DC or 50 Hz. Only when the TVA was built, most of the US electrical grid was standardized at 60 Hz.
Then too, beginning when aircraft needed electrical power for radio and electrical use, 400 was universally used owing to the smaller and lighter motors that were made with smaller copper and high quality iron having low magnetic retentivity. The large industrial computer systems made by IBM, used 400 Hz AC supplied from a 25 HP motor-alternator using 208 or 240 Volt three phase AC 60 Hz input.