The Standard Electrical Dictionary / A Popular Dictionary of Words and Terms Used in the Practice of Electrical Engineering

by T. O'Conor Sloane

Fig. 88. PENDULUM CIRCUIT BREAKER.
122 STANDARD ELECTRICAL DICTIONARY.
Circuit Breaker, Tuning Fork.
A circuit breaker in which a tuning fork makes and breaks the circuit.
Each vibration of one of the prongs in one direction makes a contact,
and the reverse vibration breaks a contact. The adjustment is
necessarily delicate, owing to the limited amplitude of the motion of
the fork. The fork is kept in vibration sometimes by an electro-magnet,
which is excited as the circuit is closed by the fork. One leg of the
fork acts as the armature of the magnet, and is attracted according to
its own natural period.
Circuit Breaker, Wheel.
A toothed wheel with a spring bearing against its teeth. One terminal of
a circuit connects with the wheel through its axle, the other connects
with the spring. When the wheel is turned the circuit is opened and
closed once for each tooth. The interstices between teeth on such a
wheel may be filled with insulating material, giving a cylindrical
surface for the contact spring to rub on.

Fig. 89--TOOTHED WHEEL CIRCUIT BREAKER.
Circuit, Closed.
A circuit whose electric continuity is complete; to make an open circuit
complete by closing a switch or otherwise is to close, complete, or make
a circuit.
Synonyms--Completed Circuit--Made Circuit.
Circuit, Compound.
A circuit characterized by compounding of generating or receiving
devices, as including several separate batteries, or several motors, or
other receiving devices. It is sometimes used to indicate a circuit
having its battery arranged in series. It should be restricted to the
first definition.
123 STANDARD ELECTRICAL DICTIONARY.
Circuit, Derived.
A partial circuit connected to two points of another circuit, so as to
be in parallel with the portion thereof between such two points; a shunt
circuit.
Synonyms--Shunt Circuit--Derivative Circuit--Parallel Circuit.
Circuit, Electric, Active.
A circuit through which a current passes. The circuit itself need only
be a conducting ring, or endless wire. Generally it includes, as part of
the circuit, a generator of electro-motive force, and through which
generator by conduction, ordinary or electrolytic, the same current goes
that passes through the rest of the circuit. One and the same current
passes through all parts of a series circuit when such current is
constant.
A current being produced by electro-motive force, and electromotive
force disappearing in its production in an active circuit, there must be
some source of energy which will maintain electromotive force against
the drain made upon it by the current.
The simplest conception of an active electric circuit is a ring or
endless conductor swept through a field of force so as to cut lines of
force. A simple ring dropped over a magnet pole represents the
simplification of this process. In such a ring a current, exceedingly
slight, of course, will be produced. In this case there is no generator
in the circuit. An earth coil (see Coil, Earth,) represents such a
circuit, with the addition, when experimented with, of a galvanometer in
the circuit.
In practice, a circuit includes a generator such as a battery or dynamo,
and by conductors is led through a continuous path. Electric lamps,
electrolytic cells, motors and the like may be included in it.
The term "circuit" is also applied to portions of a true circuit, as the
internal circuit, or external circuit. A certain amount of elasticity is
allowed in its use. It by no means necessarily indicates a complete
through circuit.
Circuit, Electrostatic.
(a) A circuit through which an electrostatic or high tension discharge
takes place. It is virtually an electric circuit.
(b) The term is applied also to the closed paths of electrostatic lines
of force.
Circuit, External.
The portion of a circuit not included within the generator.
Circuit, Grounded.
A circuit, one of whose members, the return circuit, is represented by
the earth, so that the earth completes the circuit. In telegraphy each
end of the line is grounded or connected to an earth-plate, q. v., or to
the water or gas-pipes, and the current is assumed to go through the
earth on its return. It really amounts to a discharging at one end, and
charging at the other end of the line. The resistance of the earth is
zero, but the resistance of the grounding or connection with the earth
may be considerable.
Synonyms--Ground Circuit--Earth Circuit--Single Wire Circuit.
[Transcriber's note: The resistance of the earth is high enough that
large power system return currents may produce dangerous voltage
gradients when a power line is shorted to the ground. Don't walk near
downed lines!]
124 STANDARD ELECTRICAL DICTIONARY.
Circuit Indicator.
A pocket compass, decomposition apparatus, galvanometer or other device
for indicating the condition of a wire, whether carrying a current or
not, and, if carrying one, its direction, and sometimes roughly
indicating its strength.
Circuit, Internal.
The portion of an electric circuit included within the generator.
Circuit, Line.
The portion of a circuit embracing the main line or conductor, as in a
telegraph circuit the line carried on the poles; distinguished from the
local circuit (see Circuit, Local,) in telegraphy.
Circuit, Local.
In telegraphy, a short circuit with local generator or battery included,
contained within the limits of the office or station and operated by a
relay, q. v. This was the original local circuit; the term is applicable
to any similar arrangement in other systems. Referring to the cut, the
main line circuit includes the main battery, E, Key, P, Relay, R, ground
plates, G, G1. The relay magnet opens and closes the local circuit with
its local battery, L, and sounder magnet, H, with its armature, B. The
minor parts, such as switches, are omitted.

Fig. 90. LOCAL CIRCUIT OF TELEGRAPH SYSTEM.
Circuit, Local Battery.
A local circuit worked by and including a local battery in its course.
125 STANDARD ELECTRICAL DICTIONARY.
Circuit, Loop.
A minor circuit introduced in series into another circuit by a cut-out,
or other device, so as to become a portion of the main circuit.
Circuit Loop Break.
A supporter or bracket with two arms for carrying insulators. Its use is
to enable a loop connection to be introduced into a line which is cut,
so as to enable the connection of the ends of the loop to be made, one
to each end of the through wire, which ends are attached, one to each of
the two insulators.
Circuit, Main.
The circuit including the main line and apparatus supplied by the main
battery, as distinguished from the local circuit. (See Circuit, Local.)
Circuit, Main Battery.
The main circuit, including the main or principal battery in its course.
Circuit, Metallic.
A circuit in which the current outside the generator, or similar parts,
is carried on a metallic conductor; a circuit without any ground
circuit. The including of a galvanic battery or electro plating bath
would not prevent the application of the term; its essential meaning is
the omission of the earth as the return circuit.
Circuit, Negative Side of.
The side of a circuit opposite to the positive side. (See Circuit,
Positive Side of) It is defined as the half of a circuit leading to the
positive terminal of the generator.
Circuit, Open.
A circuit with its continuity broken, as by disconnecting a wire from
the battery, or opening a switch; a broken circuit is its synonym. To
open a switch or disconnect or cut the wire is termed opening or
breaking the circuit.
Synonyms--Incomplete Circuit--Broken Circuit.
Circuit, Positive Side of.
This side is such that an observer standing girdled by the current with
his head in the positive side or region, would see the current pass
around him from his right toward his left hand. It is also defined as
the half of the circuit leading to the negative terminal of the
generator.
Circuit, Recoil.
The portion of a parallel circuit presenting an alternative path, q. v.,
for a disruptive discharge.
Circuit, Return.
(a) The part of a circuit extending from the generator to the extreme
point in general, upon which no apparatus is placed. In telegraph
systems the ground generally forms the return circuit. The distinction
of return and working circuit cannot always be made.
(b) It may also be defined as the portion of a circuit leading to the
negative terminal of the generator.
126 STANDARD ELECTRICAL DICTIONARY
Circuits, Forked.
Circuits starting in different paths or directions from one and the same
point.
Circuit, Simple.
A circuit containing a single generator, and single receiver of any
kind, such as a motor or sounder, with a single connecting conductor. It
is also used to indicate arrangement in multiple arc, but not generally,
or with approval.
Circuits, Parallel.
Two or more conductors starting from a common point and ending at
another common point are termed, parallel circuits, although really but
parts of circuits. If of equal resistance their joint resistance is
obtained by dividing the resistance of one by the number of parallel
circuits. If of unequal resistance r, r', r" , etc., the formula for
joint resistance, R, of two is
R = ( r * r' ) / ( r + r' )
This resistance may then be combined with a third one by the same
formula, and thus any number may be calculated.
Synonym--Shunt Circuit.
Circuit, Voltaic.
Properly a circuit including a conductor and voltaic couple.
It is also applied to the electric circuit, q. v., or to any circuit
considered as a bearer of current electricity.
Circular Units.
Units of area, usually applied to cross sectional area of conductors, by
whose use area is expressed in terms of circle of unit diameter,
usually a circular mil, which is the area of a circle of one-thousandth
of an inch diameter, or a circular millimeter, which is the area of a
circle of one millimeter diameter. Thus a wire one-quarter of an inch
in diameter has an area of 250 circular mils; a bar one centimeter in
diameter has an area of ten circular millimeters.
[Transcriber's Note: Area is the diameter squared. A 1/4 inch wire has
62500 circular mils of area. A one centimeter (10 millimeter) wire has
100 circular millimeters of area. Actual area = circular mils * (PI/4).]
Circumflux.
The product of the total number of conductor turns on the armature of a
dynamo or motor, into the current carried thereby. For two pole machines
it is equal to twice the armature ampere-turns; for four pole machines
to four times such quantity, and so on.
Clamp.
The appliance for grasping and retaining the end of the rod that holds a
carbon in the arc lamp.
Clark's Compound.
A cement used for the outside of the sheath of telegraph cables.
Its formula is:
Mineral Pitch, 65 parts.
Silica, 30 parts.
Tar, 5 parts.
All parts by weight.
127 STANDARD ELECTRICAL DICTIONARY.
Cleats.
A support; a short block of wood, grooved transversely, for holding
electric wires against a wall. For the three wire system three grooves
are used. The entire wiring of apartments is sometimes done by the
"cleat system," using cleats instead of battens, q. v., or mouldings.
The cleats are secured against the wall with the grooves facing it, and
the wires are introduced therein.

Fig. 91. TWO WIRE CLEAT.

Fig. 92. THREE WIRE CLEAT.
Cleat, Crossing.
A cleat with grooves or apertures to support wires which cross each
other. Two or three grooves are transverse, and on the under side, as
above; one groove is longitudinal and on the upper side.
Cleavage, Electrification by.
If a mass of mica is rapidly split in the dark a slight flash is
perceived. Becquerel found that in such separation the two pieces came
away oppositely charged with electricity. The splitting of mica is its
cleavage.
Clock, Controlled.
In a system of electric clocks, the clocks whose movements are
controlled by the current, regulated by the master or controlling clock.
Synonym--Secondary Clock.
Clock, Controlling.
In a system of electric clocks the master clock which controls the
movements of the others, by regulating the current.
Synonym--Master Clock.
Clock, Electric Annunciator.
A clock operating any form of electric annunciator, as dropping
shutters, ringing bells, and the like. It operates by the machinery
closing circuits as required at any desired hour or intervals.
128 STANDARD ELECTRICAL DICTIONARY.
Clock, Electrolytic.
A clock worked by the electrolytic deposition and resolution of a
deposit of metal upon a disc. It is the invention of Nikola Tesla. A
metallic disc is mounted on a transverse axis, so as to readily rotate.
It is immersed in a vessel of copper sulphate. A current is passed
through the bath, the terminals or electrodes being near to and facing
the opposite edges of the disc, so that the line connecting the
electrodes lies in the plane of the disc. If a current is passed through
the solution by the electrodes, copper is deposited on one side of the
disc, and as it rotates under the influence of the weight thus
accumulated on one side, the same metal as it is brought to the other
side of the disc is redissolved. Thus a continuous rotation is
maintained. The cause of the deposition and solution is the position of
the disc; one-half becomes negative and the other positive in their
mutual relations.
Clock, Self-winding Electric.
A clock which is wound periodically by an electric motor and battery.
Clockwork, Feed.
In arc-lamps the system of feeding the carbon or carbons by clockwork
whose movements are controlled by the resistance of the arc. This system
is employed in the Serrin, and in the Gramme regulators, among others.
The carbons, if they approach, move clockwork. The movement of this is
stopped or freed by an electro-magnet placed in shunt around the arc
and carbons.
Cloisons.
Partitions or divisions; applied to the winding of electro-magnets and
coils where the winding is put on to the full depth, over single
sections of the core, one section at a time, until the whole core is
filled up.
Closure.
The closing or completion of a circuit by depressing a key or moving a
switch.
Clutch.
In arc lamps a device for the feed of the upper carbons. In its simplest
form it is simply a plate or bar pierced with a hole through which the
carbon passes loosely. The action of the mechanism raises or lowers one
end of the plate or bar. As it rises it binds and clutches the carbon,
and if the action continues it lifts it a little. When the same end is
lowered the carbon and clutch descend together until the opposite end of
the clutch being prevented from further descent, the clutch approaches
the horizontal position and the rod drops bodily through the aperture.
The cut shows the clutches of the Brush double carbon lamp. In practice
the lifting and releasing as regulated by an electro-magnet are so very
slight that practically an almost absolutely steady feed is secured. A
similar clutch is used in the Weston lamp.
129 STANDARD ELECTRICAL DICTIONARY.
Clutch, Electro-magnetic.
A clutch or appliance for connecting a shaft to a source of rotary
motion while the latter is in action. In one form a disc, in whose face
a groove has been formed, which groove is filled with a coil of wire, is
attached to the loose wheel, while the shaft carries a flat plate to act
as armature. On turning on the current the flat plate is attached,
adheres, and causes its wheel to partake of the motion of the shaft.
Contact is made by brushes and collecting rings.
In the cut, A A is the attracted disc; the brushes, B B, take current to
the collecting rings, C. The magnetizing coil is embedded in the body of
the pulley, as shown.