Honolulu star-bulletin. [volume] (Honolulu [Oahu, Hawaii]) 1912-2010, 1917-03-03
IL 49, ~ABOUT ANTOMOBI is >Gl96Slz4Slz
PURPOSE AND OPERATION OF CUTOUTS


ways used In combination with O
storage battery. The generator is used
10 charge the battery and TO produce
81 current In the various electrical de
vices on the car while the generatoD
Is In operation. The battery serves q:
sort OF reservoir. In which electrica
energy may be stored and then Mset
when the generator itself Is not oper
ating. A battery and generator ART
shown connected In series In Fig.
The positive terminal Of the generator
is connected TO the positive termina
OF the batteries and their negative ter
minals are connected. The effective
pressure acting in such a circuit 1
equal 10 the difference in the pressur
produced by the generator and tn
pressure produced within the battery
n these two pressures are equal tn
value OF the effective pressure VIII
be zero and there win be no current II
the circuit II the pressure produce
10y the generator exceeds in value thu
pressure produced by the battery there
will be an effective pressure acting II
the circuit and ifs direction will cor
respond TO that of the larger pres
sure. or the pressure OF the gener
ator. The current produced by this
effective pressure will charge the bat
terry and the value Of the current viii
be equal to the effective pressure
divided by the total resistance of thu
current. including the internal resist
ance of the battery. the resistance OF
the connecting wires and the resist
anee OF the armature winding OF the
generator.
II the pressure generated In the
armatnre winding OF the generator 10
less than the pressure of the battery
then the direction Of the battery pres
sure and the battery will discharge
instead Of being charged. The calue
OF the current viii, as In the previous
case be equal to the effective pres
sure divided by the total resistance
OF the circuit.
Since the pressure generated in the
armature winding Of the generator
may vary Id value from zero on up,
depen0Ing upon its speed and field
control. II Is apparent that some
means must be provided for control
ling the connection between the gen
orator and the battery in order that
the battery viii not be allowed to dis
charge through the generator when
the pressure OF the generator becomes
lower than the pressure Of the hat
terry. The object OF the cutout may
be understood by use OF the simple
diagram given IN Fig. 2. An electro.
magnet. NJ. has q winding OF q large
number OF turns. and this winding Is
connected directly to the terminals OF
the generator. The resistance OF the
winding OF this eiectro-magnet is usu-
ally such that very small current
passes through Il in comparison to the
total current output of the generator.
An armature, A, carried on a spring
pivoted at its left, hand end and carry
ing q contact point on its right hand
end is mounted near the core Of the
electro-magnet.
Action o. Device
This armature Is usually held away
from the core OF the eiectro-magnet by
means Of the springs, and the movable
contact point G is not In contact with
the stationary contact point. The con.
necti0ns Of the generator and battery
are clearly indicated In the figure.
Now. as the pressure generated In the
armature OF the generator increases
there VIII be an increase IN the cur
rent In the winding OF the electro
magnet NJ. and the tension of the
spring s may be so adjusted that the
armature A pulls up the desired value.
The tension In the spring S Is usually
so adjusted that the generator pres
sure is q little higher than the battery
pressure when the circuit Is com
pleted. and the battery viii always
start TO charge. When the pressure
OF the generator decreases, due to any
cause. there Is a decrease in the cur
rent in the winding OF the electro
magnet AZ and the magnet pull II pro-
duces on the armatnre A decreases In
value. II the pull of the spring s
exceeds the magnet pull the armature
viii move away from the core OF the
electromagnet and the circuit be.
tween the battery and generator will
be broken at the contact c.
The cutout whose connections and
arrangement are shown in Fig would
be satisfactory for closing the electri-
cal circuit connecting the generator
( e--eA oNNeStJg u0t NOut0 uOl OHCu IL
properly In practise for the following
reasons: In theory the spring 8
would pulr the armature away from
the core Of the eIectro-magnet when
the electrical pressure generated in
the armature OF the generator dropped
below a value which would produce
the necessary current in the winding
TO hold the armature up. The fol.
lowing action. however takes place in
actual practise; When the electrical
pressure of the generator exceeds
the electrical pressure Of the
battery the direction of the current
in the battery. generator and winding
Of the electromagnetic win be as indi-
Gated by the three arrows In Fig. 8.
II there is decrease in the electrical
pressure Of the generator. due to any
cause. or an increase in the electrical
pressure of the battery and the two
pressures become equal in value,
there viii be no current in the circuit
composed Of the generator and the
battery.
Division Of Current
II the winding Of the cutout be con-