article for the pa center for the book--electric meter invention

8/9/2019 Article for the PA Center for the Book--Electric Meter Invention

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Im paying how much for a kilowatt-hour?!

Most of us have paid the electric bill at one point or another (some less frequently and/or punctually

than others), but its likely few of us have ever stopped and wondered who it was that designed the

electric meter mounted to the side of our house. We just go about our daily lives without ever

considering such a thing, despite the annoyance of getting a monthly electric bill in the mail. The truth

is, however, that without such a design and device, power companies would have no way to regulate

and monitor the amount of electricity consumed by each household.

As such, before the invention of the electric meter, power companies had no way to monitor or price

the power they supplied to individual households and businesses. And before there were power

companies, individual households were responsible for producing their own power. Imagine today if

every house was connected to a water wheel, giant windmill, or noisy generator rather than most

having a convenient little box counting off every kilowatt-hour consumed. Most people, unless they live

by a stream that can wistfully turn a water wheel, would opt for the little box and monthly bill.

So, who do we owe credit to for the modern day design of the electric meter that so unassumingly adds

up our periodic power usage? His name is Oliver B. Shallenberger, and his invention enabled so many of

us to be connected to the grid and charged accordingly. But to understand Mr. Shallenbergers great

contribution and how we have come to be so dependent on electricity, it is helpful to first understand

the evolution of this power source.

Most people are familiar with the story of Benjamin Franklin tying a key to a kite and discovering

electricity when it was struck by lightning. This colorful interpretation of certain events has been

skewed from real facts by Americans through its telling and retelling, generation to generation. The

truth is people have known about electricity, or at least had some understanding of it, since the AncientEgyptians in 2750 B.C. It remained no more than an intellectual curiosity, however, until the late

nineteenth century.

It was around this time that a great debate was going on between two famous physicists. Known as the

War of the Currents, this battle was between Thomas Edison and George Westinghouse over the idea

of DC versus AC power for commercial American use. (AC or alternating currentis current that flows

with a constantly changing magnitude, or goes from positive to negative repeatedly. DC ordirect

currentdescribes current that is at a constant value with no phase. SPOILER ALERT: Modern American

homes and businesses have outlets that supply 120V 60Hz AC power.)

The main reason for this debate was that Edison was the first to design numerous DC-orientedtechnological advancements, and DC power was the standard in the U.S. In the late 1880s, however,

Nikola Tesla came up with the ideas for transformers and other electronic circuits, and AC became much

more practical for residential consumption. George Westinghouse bought the rights to Teslas

polyphase system patents along with other transformer designs and formed Westinghouse Electric &

Manufacturing Co. in 1886. Once Westinghouse had the rights and support from Tesla himself, he was

able to commercialize the production of AC power in the U.S.


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It was around this time that Westinghouse hired an ex-naval officer eager to pursue his interest in

electricity. This man was O.B. Shallenberger. And by 1888, Shallenberger had become Westinghouses

chief electrician.

Though its less popular than Ben Franklins key and kite legend, the invention of Shallenbergers meter

is a story equally apocryphal. It goes that while Shallenberger and an assistant were working on an ACarc lamp, a spring fell and came to rest on the inside ledge of the lamp. As the assistant went to reach

for it, Shallenberger stopped him when he realized the spring had rotated. Shallenberger eventually

discovered that the changing electric fields induced a magnetic field which caused the metal spring to

rotate. With this at the heart of his idea, Shallenberger designed an AC ampere-hour meter three weeks

later. His design implemented the use of an induction-based motor which comes from coiling a number

of current carrying wires together that inherently possess a magnetic field through the beautiful

relationship know as electromagnetism.

Using the original figure from the patent

Shallenberger received for his design, (B) is

the coil of wires that carry the current the

resident is using. This current produces a

magnetic field which points in the direction

through the wires (e and e). This force acts

upon the metal disc or armature (A), causing

it to rotate. This rotation spins the metal rod

(a) the disc is connected to causing a

registering worm (h), which is like a screw,

to rotate as well. The rotation of this worm

turns a worm-gear or wheel, which isconnected to a registering train that is

calibrated to display the amount of electricity

used. The registering train is like a bunch of

dials that point to numbers that represent the

amount of current used. Also connected to

the rod are four fan blades (N), which are

used to slow down and eventually stop the

disc from spinning once the force is removed

(i.e. once the current stops flowing). The

systems were calibrated by using a knownamount of power and then using a little

algebra and testing to determine coefficients,

which took the fans retarding force into

effect along with friction in the bearings between the disc and mounting rod, and in the gears.

Overall the design was simple yet ingenious and very effective in doing what it needed to do, so much in

fact that the same design is still used in most meters today albeit with some modern day improvements.


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Shallenberger himself was responsible for many improvements and reinventions of his first AC electric

meter and received a number of patents because of it. The reason the design was and still is so effective

is because it consumes very little power assuring that customers only pay for the power they are using,

while still being very accurate in recording power consumption. Modern day electric meters now use

better materials for the armature and rod, along with better casings and registering components to

minimize external defects.

According to the 1903 textbook ElectricalEngineering: Measuring Instruments for Commercial and

Laboratory Use, It has already been pointed out that the great trouble in the generality of motor

meters is the friction of the moving parts, which, if not minimized and compensated for, causes

irregularities in the direct proportion between speed and the thing measured. Shallenbergers design

uses the induced magnetic field from the current to measure the amount of current used which

consumes little to no power. The textbook goes on to say, Consequently it is an advantage that there

should be no rubbing contacts in the meter, other than, of course, in the bearing, which can be

minimized, but not entirely eliminated. Shallenberger also did this by using gears, turned by the disc

and rod, which had very little friction. A meter madethat fulfills the above requirements in a highlysatisfactory degree is that introduced by Mr. Shallenberger some years ago, and which may be said to be

one of the most satisfactory coulomb-motor meters in existence at the present day. (Meters intended

to measure electric quantity are called coulomb meters) These statements still hold true just as they did

over a hundred years ago.

Once electric companies had an effective way to monitor the power consumption of individual

households and businesses, the Second Industrial Revolution ensued as rural areas received electricity.

Since then, electricity has become an absolute necessity for modern day living. Every appliance and

luxury electronic in a typical household runs on electricity provided by the local power company, and

will continue to do so for quite some time.

Through the development of other technologies like computers and highly sophisticated communication

systems, electric meters have begun to evolve into more technologically advanced systems as well.

Concepts such as Smart Grids and AMRs (automatic meter readings) have become integrated with the

electromechanical electricity meters that are based on Shallenbergers original design. These newer

technologies eliminate the need for the meter man to get the reading from the meter itself.

Essentially the registering system in the original design has gone from analog to digital and can now

send readings to huge databases for billing, analysis, and troubleshooting. Smart Grids even take it a

step further and can actually give real-time readings from anywhere as well as statistically determine

how much power individual households will use allowing for more efficient power consumption.

They say the greatest ideas are those that stand the test of time. O.B Shallenbergers design of an

induction motor-based electricity meter is still used in most meters today. The simple yet effective

design has been able to monitor and register power consumption of individual households and

businesses for over a century. Despite our shared dislike of paying the electric bill, if no one has

complained enough to make it change, we must be getting a fair deal after all.


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Works Cited

Brown, C.N. "Charging for electricity in the early years of electricity supply." IEEEProceedings. 132.8

(1985): 513-24.

Dahle, David. "Dave." Westinghouse Electric (& Mfg.) Co. (1886-1990). 02 November 2009.

(16 February 2010). .

Dahle, David.A brief history of meter companies and meter evolution. 02 November 2009.

(16 February 2010). .

Parr, G. D. Aspinall. ElectricalEngineering Measuring Instruments for Commercial and Laboratory

Purposes. Blackie & Son: London, 1903. p. 284-8.

Shallenberger, Oliver B. "Armature for Electric Meters." Patent 426,335. 22 April 1890.

Shallenberger, Oliver B. "Meter for Alternating Electric Currents." Patent 388,003. 14 August 1888.

Shallenberger, Oliver B. "Method of Measuring Alternating Electric Currents." Patent 388,004.

14 August 1888.

Shallenberger's Electric Meter. 7. New York, NY: Electrical Engineer, 1888. p. 382-4.


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Modern day electric meter

with a digital read out.

http://www.flickr.com/photos/cjfinley/512263975/

Inside a modern day electromechanical electric

meter:

1. Voltage coil - many turns of fine wireencased in plastic, connected in parallel with load.

2. Current coil - three turns of thick wire,connected in series with load.

3. Stator - concentrates and confinesmagnetic field.

4. Aluminum rotor disc.5. Rotor brake magnets.6. Spindle with worm gear.

7. Display dials - note that the 1/10, 10 and 1000 dials rotate clockwise while the 1, 100 and 10000dials rotate counter-clockwise.

http://en.wikipedia.org/wiki/Image:ElectricityMeterMechanism.jpg


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Modern day Westinghouse

electric meter based on

Shallenbergers original design.

http://www.flickr.com/photos/mrbeck/2718357659/

Oliver B. Shallenberger the inventor of the modern day

electricity meter.

http://upload.wikimedia.org/wikipedia/de/0/0c/Oliver_B_Shallenberger.jpg


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Shallenbergers original design used in his

first electric meter. Actual image used in his

first patent.

Shallenberger, Oliver B. "Meter for Alternating Electric Currents." Patent 388,003. 14 August 1888.

An improved design of

Shallenbergers electric meter, made

by Shallenberger himself.

http://upload.wikimedia.org/wikipedia/de/2/2f/Shallenberger-meter.jpg


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Nikola Tesla, along with George Westinghouse helped to

commercialize AC power in the United States.

http://www.flickr.com/photos/30417084@N05/2959725647/

George Westinghouse bought the rights to many of

Nikola Teslas designs to help his company be the

first to commercial supply AC electric power.

http://www.flickr.com/photos/schenectady2009/3170493817/


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Visual representation of the difference between

DC and AC forms of electricity.

http://www.physics4kids.com/files/elec_current.html

article for the pa center for the book--electric meter invention

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