[Footnote 1: Read before the electric light convention, New York,
August, 1888.]
The theoretical side of the electric motor question has been very ably
presented to and discussed by this association, but thus far the
practical side has been somewhat neglected.
It will be my purpose in this paper, if possible, to show that there
is a general average controlling the use of machinery which it will be
safe for electric light and power companies to follow in making their
charges for motor service, rather than adopt an arbitrary price per
horse power regardless of the character of service required of the
motor.
I have arranged what might be called a power curve, representing the
approximate average actual service in electric motors in connection
with the several classes of work represented in the list accompanying
the diagram.
This curve is calculated on motors which are only of sufficient
capacity in each case to carry the full load. If the motor should be
larger than is necessary to drive the machinery, the percentage of
actual service will, of course, drop below that shown in the diagram.
By adopting a basis of averages which shall be general among members
of this association, the charges for a constant horse power of current
may vary with the circumstances of its first cost in each case, but
the general classification of motor service may be a comparatively
fixed rule. I am not prepared to say that this is the best plan to
follow, but respectfully submit the following as a possible solution
of the frequently asked question, "How shall we charge for electric
motor service?"
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