, 1890-07-24
ELECTRIC SYSTEMS.
iscussed by the Spokane
Electrical Society.
PAPER BY A DYNAMO ENGINEER.
Explanation Of Some of the Scien-
tifio Principles of Lighting
by Electricity.

This electrical society, which keeps
its eye on all things scientific, met
in it's rooms in the Witherspoon
building last eveng at s o'clock to
hear Mr.. II. Flcming's paper OH
ALTERNATING and Direct Systems. "
Mr.. John Mackenzie occupied the
chair and introduced Mr.. Fleming,
the lecturer of the evening. The
lecture, which was listened to with
great interest throughout, is given
below. This society Is collecting
some very interesting electrical APP
paratus in it's rooms. An electrical
cigar lighter, handsome lamp
show case, a motor and fan for ven
tilation, an electric meter for meas
uring the amount of current used,
an ammeter, large photograph of
the big Edison lamp Mt the Paris
Exposition, are few of the things
which this promising young society
already possesses to ndorn its rooms.
Scientific lectures, papers and dis
cussions are given every two weeks,
one of the objects Of tho society be-
ing to keep It's members and the
public generally posted In the latest
scientific advances of this scientific
age.
The following Is the lecture of the
evening:
THE RELATIVE MERITS OF THE
DIRECT AND ALTERNATING sYs-
TENS.
Ever since Edison proved that the
lighting of towns and cities could be
practically and prohtably done by
means of electric incandescent lamps
the number of systems of distribu-
tion for the supply of these lamps
from single central station has
been quite numerous, the principal
systems being the series, series null
tiple, multiple series, the single null
tiple arc or two wire system, the
double multiple arc or three wire
system and the different systems of
converter distribution of alternating
currents.
There have also been various mod
iiications of the different systems
put forth from time to time, but the
only systems that may be said to
have stood the test of time are the
multiple arc systems of converter
distribution and the Edison three
wire system of direct current distri-
button. And 1t Is with n practical
consideration of these systems
that | will occupy your time to-
night.
Electrically the difference be-
tween the two systems is very
great. In the converter systems,
IA current of small volume and high
II. Nj. Il. Is used, which Is reduced
down in the lamp circuit to cur
rent of large volume and low f.. NJ.
F., the lamps having no electrical
connection whatever with the dy-
namo, while In the direct current
systems Il current of comparatively
large volume Is used at low voltage,
the lamps being connected directly
across the poles of the dynamo.
The selection of system before
hand that will give the best salts
faction in the working and the best
returns for the number of dollars
and cents invested is quite n deli
cate operation, and depends en-
tirely on the local surroundings.
diee dt in N faVor sns5f of either h2 prsSa- sys.
tenn, it can he done with II
little perseverance and n knowledge
of the merits of the system. But if
we take our data from those people
who have their ''little axe to grind, ~
. and will dilate by the hour ON some
, particular advantage of their sys-
TEN, dexterously keeping all its dis
, advantages in the shade, the matter
, becomes very complicated indeed
Until very recently there was very
little or no reliable information out
side of the manufacturers concern
ing the real efficiency of the con-
verter from which one could make
his calculations. We had to take
the word of the maker for all 1t was
worth. n few months past, how
ever, several tests have been made
tests conducted by Professor II. j..
and which serve to throw consider
able light on the subject.
The tests made by those men
were of the most exhaustive and
complete character, and includes al
converter would be expected to
work in actual every day practice.
From these tests ii will be seen that
under favorable conditions the con-
verter is very efficient piece of APP
paratus, its efficiency being under
iull load from SO to 04 per cent. of
the total energy put into it, ac-
cording to the size, those of the
largest size being more efficient. IL
this high efficiency could be main
tanned under all charges of load, 1t
would certainly be the ideal sys-
tenn of distribution. But it can not.
Directly the load falls oil, the
efficiency falls of, too, very rapidly,
: till at half load II is only 65 per
cent, and at one-fourth load 1t is
as low as 40 per cent. About the
average load of most central sta
tions for the twenty-four hours is
about % per cent. of the
greatest load. According to DIR.
: Louis Duncan, the efficiency of an
alternating plant at this load is
, about 40 per cent. that is, for every
| 100 horsepower generated ut the sta
J tion, only forty Is actually available
, for useful work at the lamps.
This is certainly u very low ef.
ficiency-too low for this late dav.
, 1t should he tolerated only where il
was absolutely necessary, such ns
| locations where the current had to
be taken extremely long distances,
with customers few and scattered
and where first cost was IA primary,
and affiriencv n secOnuury tnuttor