Duncan watthour meters (1892-1898) Previous
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The first model shown represented a landmark in watthour meter development. This model was developed by Thomas Duncan in 1892, two years before O.B. Shallenberger introduced his watthour meter. This also predated Tesla's patent on the induction motor principle - this was one of his many patents bought by Westinghouse, and the one that was invoked in 1903 against all the other manufacturers (except for GE due to a licensing arrangement). It was also the first meter to use a single disk for both the driving and braking element. For reasons unknown, Duncan never patented or adapted this model for production. If he had done so, Duncan would have had a significant advantage over GE and Westinghouse!

The second model shown is of the watthour meter Duncan later developed for the Fort Wayne Electric Corporation. The overall appearance of this meter is very similar in design to the Thomson Recording Wattmeter introduced by Thomson-Houston around that time. The main difference between this model and the T.R.W. is in the arrangement of the coils and the can-type rotor (which carried over into the K series of meters). Duncan may have been inspired to base his new meter design on the TRW as he did work for a short time in the 1888-1889 timeframe at Thomson-Houston alongside Elihu Thomson while the Ft. Wayne Electric Co. rebuilt its facility after the disastrous fire of 1888.

 
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