Antique Ten Horsepower electric motor....

 

Thanks Steve.  I also acquired another early A-C motor, which is more enclosed. It's got Timken tapered roller bearings instead of the journal bearings on this one.

 

Does this look like what you saw at the plant? https://youtu.be/0Rz51yqEnrw 

 

Must have been a very neat facility to work at; although back in the day I know things may have been somewhat harder on a day to day basis.

 

I love the glass oiler cups, as well. That design sounds like my 1925 B.F. Sturtevant 42" exhaust fan motor. It's a Western Electric with glass oiler cups.

 

Westinghouse Electric decided to standardize on a lower frequency to permit operation of both electric lighting and induction motors on the same generating system. Although 50 Hz was suitable for both, in 1890 Westinghouse considered that existing arc-lighting equipment operated slightly better on 60 Hz, and so that frequency was chosen.[5] Frequencies much below 50 Hz gave noticeable flicker of arc or incandescent lighting. The operation of Tesla's induction motor required a lower frequency than the 133 Hz common for lighting systems in 1890. In 1893 General Electric Corporation, which was affiliated with AEG in Germany, built a generating project at Mill Creek, California using 50 Hz, but changed to 60 Hz a year later to maintain market share with the Westinghouse standard.

DonBC wrote: A few decades ago I worked for a school system and occasionally a school's basement might flood because of a burst pipe or major rain storm. Our electrical maintenance dep't had and old electric range in their shop where they would  place the drowned electric motors in the oven and 'bake' them dry.

 

That's a great idea. I could use an old oven for that, and for baking paint / powder coatings. But yeah, moisture needs to be combined with electricity (at significant voltage) to do damage to motor windings. If the motor isn't in operation, at the time it gets wet, you can just dry it out and it will be fine. The bearings, however, may need more in-depth service if they got filled with water as well.

 

 

Understood. There's a lot of debate about the expected life span on most industrial motors. The average reported life from across the industry seem to be in the 10 to 20 year range before a major failure.

 

It seems that it's so dependent on the application that one has a hard time predicting motor life in any new application; however once a trend is established it's usually repeatable unless something changes in the application.

 

Were the powerstation motor rewinds done based on measured parameters with the motor, before a failure - or were they done when the motor finally did suffer a major failure?

 

Sincerely,

David

 

Sounds like they had the maintenance / rewind schedule pretty well figured out.

I bet those were high speed motors as well, probably driving multistage pumps for the condensed water. I bet there was a lot of bearing heat involved to need that sort of oil cooler. Some of our generators run at 1800 RPM and use journal bearings which have water cooled oil coolers. I bet the condensate pump motors were running about twice as fast.

steve(ill) wrote: apparently WESTINGHOUSE set the standard at 60 Hz for the USA..

Although higher frequency operation allows smaller transformers and motors at the same power level, there's a pile of tradeoffs that come on as frequency increases.

The 60hz standard was not so much chosen for electrical properties, as it was for OTHER purpose:  Timekeeping standards.

George Westinghouse was a railroad man... by using a 60hz base frequency, it was very simple to make an electric clock that would keep accurate and synchronized TIME at ANY point in a power system.  They set up governance, so that, at the end of each 24 hours, they had averaged exactly 5184000 cycles in a given 24 hour period.

Realize that an AC power 'grid' has a generator at one end of a line, that's connected to loads along a line, and that's conected to another line, going in another direction, to more loads, and more generators... all the generators are spinning TOGETHER, and pushing power on the same line.  The LOAD limits frequency- a generator must be strong enough to push the WHOLE LOAD, if it is going to increase the line frequency, but to do so, the generator must be strong enough to take the load, which is effectively infinite (at least, in the perspective of a generating plant), so it cannot go 'faster' than the line frequency.  it's very clever...

And this is why your old fashioned synchronous motor-type electric clock was always correct, as long as the power didn't go out.  Westinghouse's building clocks, railway clocks, signalling timers... all used that line voltage not only as power, but as a frequency standard for time-division.