THESIS
on
THE ECONOMICS OF THE APPLICATION
OF
ELECTRICITY
.TO
Submitted to
COUNTRY LIFE
the.
Faculty
of the
OREGON AGRICULTURAL COLLEGE
for the degree of
Electrical Engineer
by
Approved:
Department of Electrical Engineering
1909
CONTENTS
Introduction
2
Design of a Plant
5
Cost of Operation
13
A Plant Without a Battery
16
A Water Power Plant
19
A Plant for Lights only
22
An alternating Current Plant
25
Appendix
30
-nINTRODUCTION
Farmers and residents of small country towns
have long felt the need of the electric light.
They appreciate the safety, cleanliness, and convenience
of this method of illumination and would gladly adopt
it in their homes and about their farms if possible.
The farmer would like to be able to provide satisfactory
lighting for his barns without the fire hazard which is
inseparably connected with any other form of illumination.
But desirable as electric lights are, it is in
the application of electric power to the driving of
various labor saving devices that the great gain comes
in on the farm.
to
This, of course, applies more especially
the larger and more prosperous ones; but there are
few farmers who would not use the electric light if
they could get current on the same terms as their
cousins in the cities, and of those who would make
use of it practically all would employ current for other
purposes such as the electric flatiron, electric fans,
and small motors for
the grindstone.
th
laundry and dairy and to turn
Larger farms would be equipped with
many other power driven machines such as some of the
following: a cream separator, churn, butter worker, and
milking machine for the dairy; a pump to furnish the
water supply for the house and barns; a washing machine
for the laundry; electric fans for the kitchen, dining-
-3-
room and perhaps other rooms; a hay cutter, a root
cutter, and a mill to grind feed for the cattle;
a green bone cutter for the poultry department;
a forge blower, a grindstone, an emery grinder and
a post drill for the shop; a sheep shearing machine,
a fanning mill,
etc.
The list could be extended almost
indefinitely.
The farmer is surrounded with natural resources
which make him
a
producer but in order to make the most
of his advantages he must use numerous machines which
means that he must have an abundant supply of some
reliable and economical power. Many farms in the hills
along the valleys of Oregon and the other Pacific
Coast states are crossed by small streams which if
developed would furnish the desired power at an
extremely low cost and give the owner a great advantage
over his less favored neighbor. However, there are more
farms which are not so favorably situated, and for them
the only solution seems to be the internal combustion
engine. The water wheel and the gasoline engine will
develop the power but it can not be conveniently or
economically applied to the various machines except
thru the medium of electricity.
The private electric plant has until recently
been too expensive and inconvenient for most people.
Dut recent improvements in gasoline engines, electrical
generators, and storage batteries and the development
-4-
of the tungsten lamp have opened up new possibilities
in the way of private electric light and power plants.
The purpose of this paper is to estimate the
probable cost of installation and operation of a
private electric light and power plant,
estimates
for several plants will be given and an effort will
be made to indicate the general method of designing
to suit a given set of conditions.
-0-0-0-0-0-0-
DESIGN OF A PLANT
We will first carry thru the design of a private
electric light and power plant in accordiance with
conditions which we will assume to be as follows.
The house has on the first floor a living room,
a dining room, a kitchen,a pantry, a bedroom, a rear
porch, a front hall, and a large porch in front.
On the second floor there are a hall, a bath room,
a linen closet
,
and three bedrooms with closets.
There will also be either a basement or a wood house.
There will be several barns and out buildings to be
lighted. The water supply for the house and barns will
be pumped from a well fifty feet deep and be stored in
a steel tank from which it will be delivered by compressed
air under a pressure of about fifty pounds to the square
inch.
About three hundred gallons a day will be
required.
The well is so situated that the pump oan
be driven direct from the engine. In the house there
will be a small motor of say one fourth horse power
to run the
washing machine and the sewing machine,
also a flatiron and one or two electric fans so that
the kitchen and dining room may be kept comfortable
at all times. The dairy will require a small motor of
about one half horse power to run the separator and the
churn.
A portable motor of about three horse power will
-6-
be needed to run a grist mill, hay cutter, wood saw,
and other machinery. We wish to be able to operate
from the storage battery not only all of the lights
but also all of our other machinery with the exception
of the three horse power motor.
We will now design the plant to meet these
conditions. The first thing to decide upon is the
voltage to be employed.
As we wish to use an electric
flatiron and the new tungsten lamps, the voltage of
the battery is practically limited to 110 volts;
as flatirons are not made for lower voltages and
tungsten lamps are not made for higher.
We would not
wish to use a higher pressure in any case as that
would make the battery much more expensive.
We will therefore use a 110 volt battery and a dynamo
of the same pressure.
As the voltage of each cell
when nearly discharged is only 1.8 volt, we will
have to have sixty cells.
Let us now determine the capacity of the battery.
In order to do this we will assume the maximum load
which it will probably be expected to carry.
The maximum demand would be on an occasion in the
winter when the family were for some reason kept up
later than usual and when an extra large amount of
current would be used for power.
The following is
a probable schedule for such a day.
-7-
Dining Room
5.00 - 6.30 a.m.
2
)
lamps
= 6 lamp hours
5.30 - 7.00 p.m.)
Living Room
7.00 - 10.30 p.m.
ft
3 lamps
= 10*
2 lamps
= 10
n
Kitchen
5.00 - 7.30 a.m.
5.00 - 7.30 p.m.
Front Hall
8.00 - 10.30 p.m.
1
lamp
=
2-t-
n
1
lamp
=
lk
ft
Front Porch
7.30 - 9.00 p.m.
Bedrooms
5.00 - 5.30 a.m.
)
4 lamps
=4
ft
6 lamps
=6
ft
10.30 - 11.00 p.m.
Barns
5.30 - 6.00 a.m.
5.30 - 6.00 p.m.
30* lamp hours
This makes a total of thirty and one half lamp hours
but the lamps in the closets, wood house, and etc.
would probably bring the total up to thirty six lamp
hours.
If the lamps are only eight candle power carbon
-8-
and twenty candle power tungsten, each of them will
allow one fourth of an ampere to flow thru it.
Therefore the lighting load on the storage battery
will be one fourth of thirty six or nine ampere hours.
In addition to the lighting load there will be the
following motor load.
Washing Machine (1/4 H.P. motor)
Two hours
2
amperes
= 4 ampere hours
Dairy (1/2 H.P. motor)
Two hours
4 amperes
= 8 ampere hours
Electric flatiron
Two hours
5
amperes
= 10 ampere hours
This makes a total of only thirty two ampere hours but
in order that there may be no possibility of an over-
load we will adopt the forty ampere h©ur size.
The voltage required to charge a battery is
considerable in excess of the voltage given by the
battery on discharge, and as we wish to use a 110 volt
dynamo, we will arrange the battery so that,by throwing
a switch, we can divide the divide the battery into
two equal parts connected in parallel for charging.
The normal rate of charge for a battery isthe
number of amperes which must be passed thru it for
eight hours to charge it from an almost discharged
-9-
condition.
Ours, being a forty ampere hour battery,
will take five amperes thru each group of cells or
a total of ten amperes to charge it at the normal rate.
The battery should never be charged at less
than the normal rate and it may be charged at almost
twice this rate or about eighteen amperes in this
case.
A battery of this size will not require charging
oftener than once a day when there is the maximum
probable load.
There will usually be a much lighter
load so that it will not ordinarily require to be
charged oftener than once in two days even in the
winter, and in the summer when the days are long and
lights are required only for a few hours at night,
the battery will not require carping oftener than
once a week.
The dynamo will next be considered.
As we have
already specified a 110 volt machine, the capacity
alone remains to be considered.
The voltage required
to charge the battery ranges from 70 to 85 volts, so
the dynamo must be capable of delivering 85 x 18 = 1530
watts or a little over one and one half kilo -watt.
We wish to use a portable motor of about three horse
power and as a motor of this size requires two kilo -watts,
our dynamo will be of two kilo -watt capacity.
To drive
the dynamo we will have to have a three
horse power gasoline engine of the special electric
type, which is made extra heavy and fitted with a special
-10-
governor to give close speed regulation.
With this
outfit we can use the dynamo to furnish lights direct
or if an extra amount of current is required for some
purpose the dynamo may be run in parallel with the
battery making a combined output of nearly four
kilo -watts.
A switchboard and apparatus with which to
control the dynamo and storage battery will be the
next in order.
A rheostat in the field circuit of the
dynamo will be required to regulate the voltage generated.
An ammeter will be required to show the rate of charge
or the load on the battery or
dynamo.
A voltmeter
should be provided with arrangements for reading the
voltage in two different places; across the dynamo
terminals, or the terminals of the battery.
There should be two circuit- breakers.
One of these
should be so arranged as to open the battery circuit
whenever the charging current falls below the normal
rate (10 amperes).
The ether should open the circuit
when either charging or discharging current reaches
an abnormal value; in our case nineteen amperes.
It would be well to provide a third one to protect the
dynamo circuit when the large motor is being used;
this one might be set at twenty one amperes as the
dynamo is capable of carrying an overload of twenty
five per cent.
Any or all of these circuit breakers
-11-
may be
replaced by fuses, which should be of the
inclosed cartridge type to avoid the fire risk.
Fuses are, however, less satisfactory than the
circuit -breakers and altho cheaper to install, cost
considerable to maintain if they are blown often.
The storage battery when almost discharged
gives only one and eight tenths volts percell and then
all of the sixty cells are required. Whenfully charged
the cells give about two and two tenths volts and thus
only fifty cells are required to produce the desired
voltage.
An end cell switch should therefore be
provided with which to
matt
voltage falls on discharge.
in the end cells as the
As the battery is divided
into two sections which are charged in parallel, it
is imperative that the two groups of cells should be
evenly ballanoed and in order to effect this result
we will arrange five of the end cells at each end of
the battery and connect them to an end cell switch
which will alternately cut in a cell from either end
of the battery.*
Three double pole switches are
required, one of them being
used
to
a double throw switch
divide the battery for charging.
As the building in which the plant is installed
will usually not be fire proof, it will be necessary
to bury the fuel tank in the ground and have
the fuel
pumped up to the engine as required. A large tank
-12-
should be provided so that advantage may be taken of
quantity prices. The building in which the plant is
installed should also house the shop; and many tools
such as a grindstone, emery grinder, post drill, and
etc.
may be driven from the line shaft when the battery
is being charged.
The water supply pump should also
be located here, otherwise another one fourth horse
power motor will have to be provided to run it.
COST OF INSTALLATION
The wiring of the house and barns will cost
(depending on the quantity and quality of fixtures
upwards of
- - -- $75.00
A small electric fan will cost about
20.00
A flatiron can be had for $3.50 to
5.00
A 1/4 H.P. motor
30.00
A 1/2 H.P. motor
50.00
A 3 H.P. motor
115.00
$295.00
--
A self contained, 3 H.P., 2 K.W., generating
unit ( engine dynamo and belt etc.) - - - - -,- $500.00
Storage battery g $4.65 per cell
280.00
Switch board and instruments
100,00
Fuel tank and piping
25.00
Testing set for battery
25.00
Labor installing plant
20.00
Cost of plant
Total cost of installation
$750.00
1045.00
The total cost of instalation will be $1050 or
more depending on the cost of fixtures in the house
and other buildings
-13-
COST OF OPERATION
Assuming that the average load per day thruout
the year is a little over thirteen ampere hours or
aboutone and one half kilo -watt hours, the total
amount of energy subblied by the battery during the
year will be five hundred fifty kilo -watt hours.
As the efficiency of the battery is only seventy five
per cent, the dynamo will have to supply seven hundred
thirty kilo -watt hours.
If the average rate of charge
is fourteen amperes or one kilo -watt,
the generator
will have to run a total of seven hundred thirty hours
during the year to keep the battery charged. As the
engine is running at approximately half load the cost
for fuel will be 3.38 cents an hour or a total of
24.70 for the year.
In addition we will assume that
the large motor is used at eight tenths of full load
for twenty hours each week or a total of 1040 hours.
The energy consumed will be 1.6 x 1040 = 1872 kilo -watt
hours.
The engine will be running at about eight
tenths of full load and the cost for fuel will be
4.6 cents per hour or $42.25 for the year. The maintenance
of the battery will amount to about twelve and one half
per cent.
-14-
The total cost of operation will be as follows
Interest on plant, 5% on $750
Depreciation on engine, 10% on 175 - - Maintenance of battery 12*% on 280 - -Depreciation on rest of plant, 3% on $295
Fuel for charging battery
Fuel for power
Lubricating oil and incidentals
Total operating charges
--
$37.50
17.50
35.00
8.85
24.70
42.25
4.20
170.00
The amount of power developed during the year
will be 550 + 1872 = 2422 kilo -watt hours at a cost of
17000/2422 = about seven cents per kilo -watt hour.
This compares favorably with the charges made by the
companies in the cities.
Power generated by steam
generally sells for fifteen cents while water power
plants sometimes sell their power for ten cents.
The owner of the plant above described not only gets
his power for less than the usual city ,prices but he
also can run various devices such as the water supply
pump, grindstone,
etc.
at the same time that he is
charging the storage battery and there will be no extra
charge for fuel, as the engine is more efficient when
running near full load.
The owner of this plant could furnish current
to a neighbor situated at a reasonable distance, say
1,000 feet,
He could afford to sell the power at
seven cents a kilo -watt hour provided his customer
would take as much as five hundred fifty kilo -watts
hours per year, under proper restrictions regarding
-15-
maximum demand etc.
Should the demand exceed the
capacity of the battery, the generator
may be
run
in parallel with the battery and being run at full
capacity would be more efficient than the battery.
To
produce the extra 550 kilo -watt hours would
cost an extra $25 for fuel making the total yearly cost
,$195.
The total amount of power produced would be
2970 kilo -watt hours at a cost of 19500/2970 = 6.6 cents
a kilo -watt hour.
sell power without
For ten cents he could afford to
making any minimum charge.
ONO
OM
-0 --o --
-16-
A PLANT WITHOUT A BATTERY
It would be impossible to design a plant which
would suit every body.
Some people would object to
the plant just described because of the fact that it
contains a storage battery. The battery is not only
expensive to install but the cost of maintenance is
quite high amounting in our case to $35. This together
with the interest on the investment amounts to $49
a year.
Apart from the expense, there is another
objection which some people would urge against the
storage battery and that is the trouble of caring for
it.
Once a week the battery should be over charged
and each of the sixty cells should be tested for
voltage, density of electrolyte, etc.
For those who do not consider that the ability
to run electric fans and the convenience of having
current on tap.at all hours of the day and night, is
sufficient to warrant the expense and trouble of ah
battery, the following design is suggested.
House and barn wiring with carbon
lamps instead of tungsten, upwards of - - - - $60.00
!Tlectric flatiron
5.00
1/4 H.P. motor
30.00
1/2 H.P. motor
50.00
$145.00
A self contained, 2 H.P., 1 X.W. outfit
engine dynamo belt etc.
250.00
Instruments but no switchboard
50.00
Fuel tank and piping
25.00
labor installing plant
20.00
Cost of plant
$345.00
-17-
Allowing ton dollars for incidentals not
mentioned the total cost of the instalation will be
about $500 and the cost of the plant itself will
be about $350.
No electric fan is included in this outfit
as it would usually be wanted at hours when the plant
would not be running for anything else and it would
hardly pay to run a two horse power engine just to
keep a
1 /10
horse power fan going.
It is supposed
that this plant will be installed in a house which
will house all of the power driven machinery of the
farm excett such as can
be.
driven by the 1/4 or 1/2
horse power motors.
The approximate cost of operation will be as
follows.
Lights
An average of 4 hours daily = 1460 hrs A 2.25 c = $35.50
Dairy (1/2 H.P. motor)°
One hour daily, during summer = 180 hrs ßi'2.1
=
3.80
Laundry
1/4 HIP. motor 2 hrs weekly = 100 hrs $ 1.3
=
1.80
Flatiron 2 hours weekly = 100 hours A 2.25 cts =
2.25
Power
1.5 H.P., ten hrs weekly = 520 hours a 2.7 cts = 14.10
Total for fuel (distillate)
57.25
Lubricating oil and incidentals - - - 6.00
Fixed Charges
Interest on plant 5% on $350
17.50
Depreciation on engine 10% on $125
12.50
Depreciation on rest of plant 3% on $225
6.75
Total fixed charges
36.75
Total cost of aeration for ear
1.100.00
--
--
M.
r
.rrrr
MIN!
During the winter the dairy motor will be used during
the hours when the plant is running for lights and there
would be no extra charge for fuel.
°
-18-
The amount of power developed will be:
Lights; 1/2 X.W., 1460 hours
Dairy; 1/2 H.P., 180 hrs = 90 H.P. hrs Laundry; 1/4 H.P., 100 hrs = 25 H.P. hrs
Flatiron, 1/2 K.W., 100 hrs - Power; 1.5 H.P., 1040 hrs, 1560 H.P. hrs
730 K.W. hrs.
"
67
"
18
"
50
-
-1165
"
2030
A total of 2030 kilo -watt hours are produced at
a cost of 10000 /2030 = 4.93 cents per kilo -watt hour.
No allowance is made for the power to pump the
water used about the farm as it is assumed that the pump
will be run direct from the engine during the hours when
lights are on and therefore the extra power required is
much less than the variation in the lighting load.
The power required to pump 300 gallons in)four hours from
a well fifty feet deep and store it in a tank under
fifty pounds pressure (equal to an elevated tank
115 feet high) is only a little over 1 /10 horse power
assuming that one half of the energy is lost as friction
in the pump and piping.
The cost of producing electricity by this outfit,
.
or by any other in fact, depends upon the amount produced
and upon the ratio of the average load to the capacity
of the plant.
If the average load is only a small part
say 1/5 of the capacity of the plant the cost of
production may become excessive. Care should therefore
be taken to select a plant which can run at nearly full
load all of the time it is in operation.
-19A WATER POWER PLANT
Let us assume that our farm is crossed by a
small stream in which we may develop power at a point
within 1000 feet of the house.
We will assume that a
fall of twenty feet can be secured and that a storage
reservoir of some size may be constructed.
The cost of installation will be approximately
as follows:
Wiring of house and barns
Electric flatiron
Electric fans, two at $20
Motor for laundry 1/4 H.P.
Motor for dairy 1/2 H.P.
Portable motor, 7-HP;
$75.00
5.00
40.00
30.00
50.00
160.00
$360.00
Sampson turbine, 15.25 inch - - - - $110
Dam and spillway
400
Power house
100
Dynamo, 5 Iii. W.
250 volt.
160
Switchboard and instruments - - - 100
Wire, 2000 feet #8 copper
45
Pole line
20
Labor installing plant
25
Cost of plant
$1000
Total cost of instalation - - - $1360
--
,
Allowing five per cent interest and another
five per cent for depreciation, maintenance, etc
the total operating cost for the year is only $100
As the cost of operation is just the same
whether much or little power is used, the only
limitation on the amount which may be used will be
the capacity of the stream.
Let us assume the
following schedule.
-20-
Lights
K.W., an average of 5 hours daily
1825
= 1825 hours Power
Laundry motor, 2 hours weekly,
180 hrs = 25 H.P. hrs - - - - 18
Flatiron, 2 hours weekly,
50
100 hours
Dairy motor;
Milking one hour night and morning 730 hrs
Separating 1 hour night & morning 730 hrs
180 hrs
Churning 1/2 hour daily
A total of 1640 hrs = 820 H.P. hrs = - - 615
7 H.P. motor, 20 hrs weekly
1040 hours = 7440 H.P. hrs = - - 5550
1
K.W. hours
K.W. hours
K.W. hours
K.W. hours
,
K.W. hours
8058 K.W. hours
A total of 8058 kilo -watt hours are developed
at a cost of 10000/8058 = 1.24 cents per kilo -watt
hour.
It might at first glance be supposed that a
large stream would be required to furnish so much
power but such is not the case. If the minimum flow
is
.64 cubic feet per second
(
thirty eight and one
half cubic feet per minute) and there is a reservoir
capable of retaining the flow of one or two days there
would be ample power available provided the water wheel
operates at 85% efficiency.
In other words a stream
which has an average velocity of one foot per second
at low water will only need to be twelve inches wide
and eight inches deep. Just think of it; there are
numerous streames of this size or larger scattered
all up and down the Willamette Valley.
If the owner of a farm crossed by such a stream
-21-
does not wish to use so much power he malt install an
alternator instead of the direct current generator.
He can then deliver energy for lights and small motors
to his neighbors anywhere within a radius of four or
five miles.
The cost of the installation would be
much higher or account of the higher price of the
alternator and the necessity for transformers, meters,
and a transmission line. The cost of production would
be correspondingly increased and perhaps would be as
high as five cents a kilo -watt hour, but no one would
object to paying ten cents and at that rate the farmer
would receive a good return on his investment and would
at the same time be adding to the attractiveness of the
locality and hence increasing the value of real estate.
MM.
4-4-
.22-
A PLANT FOR LIGHTS ONLY
The following is a veru inexpensive plant
having the advantages of a storage battery and not
costing very much to operate.
Wiring of house and barns, including 15
tungsten lamps and an equal number of
$100.00
the carbon filament variety
70.00
Storage battery, 15 cells, 40 amp.hr. Dynamo, 1/2 K.W., 45 volt shunt wound - - 65.00
125.00
Gasoline engine, 2 H.P.,
100.00
Switchboard and instruments
Labor installing plant
50.00
$500.00
Total cost of installation
It is assumed that the maximum probable load on
time
battery for one day will not exceed forty ampere
hours or one kilo -watt hour. It is further assumed that
the average load thruout the year will be about one
third of this or
.3
kilo -watt hour. The total.amount of
energy required at the lamps will then be
.3
x 365 =
110 kilo -watt hours. As the efficiency of the battery is
onit 75 %, the generator will have to supply 110/.75=
146 kilo -watt hours.
As the average load on the
generator when charging the battery is only seven
amperes or .315 kilo -watts, the outfit will have to
run a total of 146/.315 = 465 hours.
It does not require nearly all of the capacity
of the engine to drive the dynamo. We will therefore
assume that when the battery is being charged, other
machines are driven direct from the engine making the
-23-
average load on the engine about
.8
of its capacity.
Then the following energy will be developed.
146 K.W.hrs. at dynamo = at lights - - - - 110 K.W.hrs.
As power direct, .8 K.W., 465 hrs - - - 372 K.W.hrs.
482
The cost of running the engine will be about 2.7 cents
per hour or $12.60 for the year.
The fixed charges
including interest on the investment at 5%, depreciation
of the plant, and maintenance including lubricating oil
and about
x$10
for battery renewals; amount to $44.50
a year, making the total cost for the year $57.10
For this amount the equivalent of 482 kilo -watt
hours were produced at a cost of 5710/482 = 12 cents
a kilowatt hour.
purpose
If the engine were used for no other
than to furnish current for lights, the fuel
cost would be only $9 a year, the total cost per year
would be $53.50 and the cost per kilo -watt hour would
be about forty nine cents.
The annual operating expense of this plant is
moderate but as only a small amount of power is
developed the cost per kilo -watt hour is quite high.
To offset this difficulty we use the new tungsten lamps
which are much more efficient than the old carbon
filament variety, giving about three times as much
light for the same amount of current.
-24-
This plant is adapted to the needs of those
who want only a limited amount of current, who want
all of the advantages of a storage battery and who
can not afford the expense of a larger plant.
Those who want to use current for other purposes than
lighting and running small fans, or wh wish to
transmit current farther than about 200 or 300 feet;
should adopt some other design.
00
00
NOTE
The plant descrided above is essentially the
same as one which is described in greater detail in
Bulletin No.25 of the University of Illinois
Engineering Experiment Station,
-25-
AN ALTERNATING CURRENT PLANT
There are numerous localities where five or six
families living close together could combiné and
install an alternating current plant and secure for
themselves the advantages of electric lights. It is
only lately that such plants have been made possible
by the advent on the market of small self excited
alternators in sixes of 2, 3, and 5 kilo -watts.
Let us assume the following conditions.
There are six families who want electric lights and
who are so situated that only three miles of transmission
line are required.
It is desired that power for lights
shall be on from 5.00 a.m. till sun rise and from
sunset till 11.00 p.m., making an average of five hours
a day or a total of 1825 hours for the year.
By counting up the lights which will be installed in
each house and determining the hours when they will
burn, we estimate the probable maximum load on the plant
and also the probablt average load.
We find in this
case that the probable maximum load will be about
.3
K.W. for each family of a total of 1.8 K.W.
The average load during these hours figures out about
150 watts per family or .96 kilo -watts for the plant.
A 2 kilo -watt alternator will therefore be sufficient
-26-
in this case and a three horse power, special electric
gasoline engine will be required to drive it.
Perhaps the most satisfactory plan would be for
one of the farmers to put in the plant and sell current
to
his neighbors.
Each family should pay for its
individual transformer, meter, and service leads which
would cost about forty dollars for each family.
(House wiring will cost about $2 per lamp, not including
fixtures)
Under these conditions the cost of installing
the plant would be as follows.
Gasoline engine, 3 H.P., special electric - - - $175.00
Alternator, 2 K.W., 110 volt, single phase - 200.00
Power -house
100.00
Fuel tank and piping
25.00
Switchboard instruments
16.00
Voltmeter
16.00
Ammeter
Circuit- breaker
20.00
3.00
Switches, fuses, etc.
Rheostat (furnished with generator)
Transformer, step -up, 2 K.W., 110 -2300 volt - 40.00
Wire, 6 miles, #12 bare copper,
630 pounds at 25 cents - 160.00
- - Pole line; poles with cross -arms, insulators,
etc. in place, 3 miles at $75
225.00
Labor stringing wire at $4 a mile
25.00
Labor installing machinery in power -house - - 25.00
Incidentals
20.00
$1050.00
-
.Cost of Operation
Interest, 5% on 1050
Depreciation on engine, 10% on $175
Maintenance and depreciation on rest of
plant, 3% on $875
FIXED CHARGES
$52.50
17.50
26.25
$96.25
-27-
Fuel Cost
$61.20
For lights, 1825 hours at 3.36 cents
Flatirons etc., 4 hrs weekly, 208 hrs at 3.36c - - 7.00
5.55
Lubricating oil and incidentals
$73.75
This makes the total annual expense $170.
For this amount there will be developed .96(1825 +208)
= 1920 kilo -watt hours at a cost of 17000/1920 = 8.85
cents per kilo -watt hour. If the engine were used only
for driving the generator the price charged would have
to be about ten cents a kilo -watt hour
and the average
cost to each family would be about $2.40 a month.
Usually, however, the owner of the plant would
use the engine to drive various machines about the farm
pumping his water, sawing his fire -wood, grinding his
cow -feed, etc.
If he uses the engine at half load for
eight hours a week or a total of 416 hours, the additional
expense will be about $15,making the total operating
expense for the year $185..The extra amount of power
developed will be 1.5 x 416 = 624 horse -power hours or
the equivalent of 465 kilo -watt hours. The total amount
of power developed will then be 1920 + 465 = 2385 K.W. hrs
at a cost of 18500/2385 = 7.8 cents per kilo -watt hour.
Under these circumstances the power could be sold for
eight or nine cents, which is'very reasonable.
If the lighting load were equally distributed,the cost
-28-
to
each family would be about $23.60 or an average of
i2.00 a month. Of- course to secure an economical load
on the generator, a minimum charge will have to be
made and experience alone can determine what that
charge should be.
In the cities it is usually fixed
at from 75 cents to $1.50 a month, but in our case
might have to be made higher.
If the plant were used to supply current for
lights only, a flat rate might be mede and flat =rate
controllers be installed instead of the meters.
This would enable the plant to be run at full capacity
all of the time. The cost for distillate would then be
4.5 cents an hour or a total of 4.5 x 1825 = $82.50
The fixed charges would be $85.85 as before and the
total cost for the year would be $170. Thirty two
16 c.p. carbon filament lamps could be burned at a
cost of $170/32 = $5.32 per lamp per year. Or if some
wanted
to
use the more efficient tungsten lamps,
sixty four 20 candle power lamps could be operated'at
a cost per lamp of only 170/64 = $2.85 a year.
A sufficient number of patrons could be connected up
to take the total capacity of the plant and the yearly
cost per family could be made quite low. Under these
conditions carrent could be sold for 90 cents to $1.00
per ampere per month which means that the average cost
of burning an ordinary 16 c.p. lamp one month would
be only fifty cents or for a 20 c.p. tungsten only 25c.
-29-
For lighting only, this arrangement would be
very good; but as some people would want to use current
for other purposes and all might want to do so at some
future time, it would probably be the best plan to put
in the meters.
If each family is required to make its maximum
demand but little higher than its average load, the
plant may be operated at nearly lull capacity and
hterefore at high efficiency. This ratio of the average
load to the maximum or the "load -factor" as it is
called is one of the most important factors in the
design of
a
plant; especially if an internal combustion
engine is used as the source of rower. The higher the
load factor the higher the efficiency of the plant,
other things being equal, and the lower the consequent
cost of production.
waaoiffiaga
-30-
APPENDI
X
The following table gives the cost per hour of
operation of gasoline engines at various loads, figured
on the basis of gasoline at 20 cents a gallon and
distillate at ten cents. These results are computed
from a table given by Carpenter & Diedrichs on page
554 of their treatise on the "Internal Combustion
Engines ".
2
Horse Power Engine
Fuel
Max
load
Gasoline
Distillate
3
1/10
.0
.8
.7
.6
.5
.4
.3
.2
Max
4:754.4.2514.03.7513.3.3532.51
5 ots12.
3
85j2.
70J2.5512.4012.2512.10j1.95J2J1.5
Horse Power Engine
Gasoline
Distillate
1
7.517.1316.766.3816.013.35.254.874.53.7
1
1
1
51
4.514.2814.06113.8313.613.368 3.25 2.93 2.7 2.25
The above table is for the special electric
engine which governs by throttling.
This is the kind
of engine required to drive a dynamo for lighting.
For ordinary power requirements the hit -and -miss
engine is eaten ivel$ used,
It will do to drive a
dynamo to charge a storage battery or to furnish
current for power but will not do for lights as it
does not give sufficiently close speed regulation.
It is slightly more efficient at part load but has no
-31-
advantage at full load.
Energy Consumption and Cost of Domestic
Electrical Devices°
Average
watt -hour
consumption
Article
lame
Chafing -dish
Stove, 6 inch
Stove, 8 inch
Curling iron
heater
Flatiron, 3* lb
Flatiron, 6 lb.
Frying pan, 7"
Tea kettle
Glue pofl 1 qt.
Soldering iron
,
two lb.
400
500
S00
Period
of
operation
20 minutes
15
15
Cost during
that period
at 10 cents
per K.W. hour
$0.0134
.0125
.02
250
500
500
300
300
15
30
30
30
20
20
.0015
.0125
.025
.025
200
30
.01
60
.01
.01
A one fourth horse -power motor takes nearly
two amperes at 110 volts and costs only two cents an
hour with energy at ten cents per kilo -watt hour.
The cost of pumping water a vertical distance
of 150 feet or against a pressure of sixty five pounds
to
the square inch,
is only a little less than two and
one half cents per thousand gallons if electrical
power costs ten cents per K.W. hour; assuming that one
half of the energy is wasted as friction in the pump
and piping
°
.
Electrical World Vol. XLVIII, p. 848.
-33-
FUEL
The estimated cost of operation of the various
plants was made on the basis of distillate at ten cents
a
Distillate is a petroleum product slightly
gallon.
heavier than gasoline and having about the same fuel
value.
It can be had in Portland Oregon at the present
time (1909) for nine cents a gallon in fifty gallon
lots.
Gasoline is scarcely any better and will cost
about twenty cents if bought in large quantities.
PRICES
The prices quoted are only approximate and are
for new apparatus of standard make f.o.b. Portland
Prices vary with changes in market conditions
Oregon.
and some companies make lower quotations than others.
The services of an expert should be secured to order
supplies and install the plant. He will select the
most suitable apparatus and see that it is properly
installed.
The efficiency and reliability of the plant
will usually be better and the first cost
probably
no more.
WHERE TO ORDER
For the benefit of those who wish to select
and order their own supplies direct we will mention
s
^venal prominent firms who deal in electrical
supplies.
-33-
The two largest manufacturers of electrical
machinery are the "General Electric Company" and the
"Westinghouse Electric and Manufacturing Company ".
There are numerous smaller firms whose advertisements
may be found in the technical periodicals.
The "Central Laboratory Supply Company "of Lafayette
Indiana,
make small alternators as well as other
supplies.
The "Fairbanks Morse Company" make a special
electric gasoline engine in various sizes from two
horse power up.
They are also able to supply any kind
of electrical machinery and will make same to order
if other than standard sizes are wanted.
James Leffel & Company are one of the firms who
manufacture turbine water -wheels for low and medium
heads.
The "Pelton Water -Wheel Company" make the
Pelton Wheel which is especially adapted to high heads.