NIAGARA FALLS POWER--APPLIANCES.
Some years ago a company was formed for the purpose of utilizing, to
some extent, this greatest of all water-powers. A tunnel of large
capacity was run from a point a short distance below the falls on a
level a little above the river at that point. The general direction of
this tunnel is up the river; it is about a mile and one-half in length,
terminating at a point near the bank of the river a mile or more above
the falls. Above the end of this tunnel an upright pit comes to the
surface, where a power-house of large dimensions has been constructed of
solid masonry. It is long enough at present to contain ten dynamos of
mammoth size. Along the side of this power-house a deep broad canal is
cut, which communicates with the river at that point, and through which
flows the water that is to furnish the power. Of course the water level
of this canal is the same as that of the river.
The foundations of the power-house extend to the bottom of the tunnel,
which at that point is 180 feet below the surface of the ground. To put
it in other words, the cellar or pit under the power-house is 180 feet
deep and communicates with the great tunnel, which has its outlet below
the falls.
Each of the ten dynamos is driven by a turbine water-wheel situated near
the bottom of the pit heretofore described. The turbine-wheel is on the
lower end of a continuous shaft, which reaches from a point near the
bottom of the tunnel to a point ten or fifteen feet above the floor of
the power-house (which is about on a level with the surface of the
ground).
This shaft is incased in a water-tight cylinder of such diameter as will
admit a sufficient amount of water, and connects with the turbine wheel
at the bottom in the ordinary way. The water is admitted into the top of
this cylinder from the canal, so that the wheel is under the pressure of
a falling column of water over 140 feet high. The water, forcing its way
out at the bottom through the turbine, revolves it and its long,
upward-reaching shaft with great power, and enables it to work the
dynamos in the power-house above, as will be described. The water
discharges through the wheel in such a manner as to lift the whole
shaft, thus taking away the tremendous end-thrust downward that would
otherwise interfere greatly with the running of the machine through
friction. After the water has done its work it flows off through the
tunnel into the river below the falls.
To the upper end of the power-shaft is attached a great revolving
umbrella-shaped hood; to the periphery (circumference) of this hood is
attached a forged steel ring, 5 inches in thickness, about 12 feet in
diameter and from 4 to 5 feet in width. The whole of the revolving
portion--including the ring upon which are mounted the field-magnets,
the hood, and the shaft running to the bottom of the pit, where the
turbine wheel is attached--weighs about thirty-five tons.
The dynamos belong to the alternating type, and are comparatively simple
in construction. In a previous chapter upon the dynamo it was stated
that the fundamental feature was the relation that the field-magnet and
the armature sustained to each other, and that in some cases the
field-magnet revolves while the part that is technically called the
armature remains stationary. In other cases the armature revolves and
the field-magnets are stationary. In the latter case brushes and
commutators are used, to catch and transfer the generated electricity,
while in the former these are not needed, which simplifies the
construction of the machine.
As we have stated, the dynamos used at Niagara are constructed with
revolving field-magnets that are bolted on to the inner surface of the
steel ring that is carried by the hood, so that there are no brushes
connected with the machine except the small ones used to carry the
current to the field-magnets.
The current for power purposes is generated in a large stationary
armature about ten feet in diameter and of the same depth as the
revolving ring. The revolutions of the ring send out currents of
alternating polarity, and each of the ten machines will furnish
electrical energy equal to 5000 horse-power, so that when the work that
is now under way is completed 50,000 horse-power can be furnished in the
form of electricity. About 35,000 horse-power is now actually delivered
to the various industrial enterprises. The dynamos are set horizontally,
since the shaft which connects them with the turbine wheel stands in a
perpendicular position.
Not all of the energy that is developed by the water-wheel is converted
into electricity, but some of it appears as heat. In order to prevent
the heat from becoming so great as to be dangerous to the machine it
must be constructed in such a way as to admit of sufficient ventilation
for cooling purposes. The armature is so constructed that there are
air-passages running all through it, and on top of the revolving hood
are two bonnet-shaped air-tubes set in such a way as to force the air
down through the armature, which carries off the heat and warms the
power-house, on the principle of a hot-air furnace. This great
machine--which, in a way, is so simple in its construction--when in
action conveys to the mind of the beholder a sense of wonderful power.
It is only when we stand in the presence of such exhibitions as may be
seen in this power-house, devised and executed by the genius of man, and
in that greater presence, the mighty Falls of Niagara, that we get
something of a conception of the power of the silent yet potent energy
of the great king of daylight, the sun.
There are very many interesting details that work in connection with
this great power-plant, some of which we will describe, in a general
way.
Standing within a few feet of each one of the great dynamos is a very
beautifully constructed piece of machinery called the governor. The
governor regulates the speed of the dynamos by partially opening and
closing the water-gates that regulate the flow of water into the
turbines. The question may be asked, why is there any regulation needed,
if there is always an even head of water? There are two reasons--one
because the load on the dynamo is constantly changing, and another that
the head of water changes, although this latter fluctuation is in long
periods. If the circuit leading out from the dynamo is broken, the
rotating part of the dynamo will move with great ease and little power,
as compared with what is required when the circuit is closed, and the
current is going out and doing work. The increased amount of energy that
will be required to keep the dynamo moving at a certain rate of speed
when the load is on--in other words, when the circuit is closed--will
depend upon the amount of current that is going out from the dynamo to
perform work at other points. As the amount of current used outside for
the various purposes is constantly changing, it follows that the load on
the dynamo is constantly changing also. As the load changes, the speed
will change, unless the amount of water that is flowing into the turbine
is changed in a like proportion; hence the necessity for a governor that
will perform this work. You can easily imagine that it will require a
great amount of power to move the gate up or down with such a pressure
of water behind it. It is not possible here to explain the operation of
the governor in detail, as that could not be done without elaborate
drawings; suffice it to say that the whole thing is controlled by a
small ball governor such as we see used in ordinary steam-engines for
regulating steam-pressure.
The rising or falling of the balls of this governor to only a very
slight extent will bring into action a power that is driven by the
turbine itself, which is able to move the water-gate in either direction
according as the balls rise or fall. For instance, if the balls rise
beyond their normal position, it shows that the dynamo is increasing in
speed, and immediately machinery is brought into action that shuts the
water off in a small degree, just enough to bring the speed back to
normal. If the balls drop to any extent, it shows that the load is too
great for the amount of water, and that the dynamo is decreasing in
speed; immediately the power is brought into action, now in the opposite
direction, and the water-gate is opened wider. These slight variations
of speed are constantly going on, and the constant opening and closing
of the gate follows with them. It is a beautiful piece of machinery, and
is beautifully adapted to the work it has to perform. It is continually
standing guard over this greater piece of machinery that is exerting an
energy of 5000 horse-power and prevents it from going wrong, both in
doing "that which it should not do and leaving undone that which it
should do." It is a machine that, when in action, points a moral to
every thinking person who beholds it. Every man has such a governor if
he only has the inclination to use it.
I have said further back that the water-head varies, but usually at long
periods. This variation is chiefly caused by changes of wind, and it is
very much greater than one would suppose without studying the causes.
Lake Erie lies in an easterly and westerly direction, and when the wind
blows constantly for a time from the west, with considerable force, the
water piles up at the eastern end of the lake, which causes the level of
the Niagara River to rise to a very sensible extent. It is not so
noticeable above the falls as below, because of the great difference in
the width of the river at these two points. Sometimes the river below
the falls, as it flows through the narrow gorge, will vary in height
from twenty to forty feet. When the wind stops blowing from the west and
suddenly changes and blows from the east, it carries the water of the
lake away from the east toward the west end, which will produce a
corresponding depression in the Niagara River. No doubt there is an
effect produced by the difference of annual rainfall, but the effect
from this cause is not so marked as that from the changing winds.
Another appliance used in the power-house, chiefly for handling heavy
loads and transferring them from one point to another, is called the
electric crane. It is mounted upon tracks located on each side of the
power-house. The crane spans the whole distance, and runs on this track
by means of trucks from one end of the power-house to the other. Running
across this crane is another track which carries the lifting-machinery,
consisting of block and tackle, able to sustain a weight of fifty tons.
Situated at one end of the crane are one or more electric motors, which
are able, under the control of the engineer, to produce a motion in any
direction, which is the resultant of a compound motion of the two cars
acting crosswise to each other together with the perpendicular motion of
the lifting-rope connected with the block and tackle. It seems like a
thing endowed with human reason, when we see it move off to a distant
part of the building, reach down and pick up a piece of metal weighing
several tons, carry it to some other portion of the building and lower
it into place, to the fraction of an inch. While the machine itself does
not reason, there is a reasoning being at the helm, who controls it and
makes it subservient to his will. The machine is to the engineer who
manipulates it what a man's brain is to the man himself. The brain is
the instrument through which the unseen man expresses his will and
impresses his work upon men and things in the visible world.