Electrical Terms

Definition of Terms – Electrical

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ACTUATOR SOLENOID – The solenoid in the actuator
housing on the back of the injection pump which moves the control rack
as commanded by the engine controller.

ALTERNATOR – A device which converts mechanical energy
into electrical energy.

ALTERNATING CURRENT (AC) – A flow of electrons which
reverses its direction of flow at regular intervals in a conductor.

AMBIENT
TEMPERATURE – The temperature of the surrounding medium, such as gas,
air or liquid, which comes into contact with a particular component.

AMMETER – An instrument for measuring the flow of electrical current in amperes.
Ammeters are always connected in series with the circuit to be tested.

AMPERE – A unit of measure for the flow of current in a
circuit. One ampere is the amount of current flow provided when one volt
of electrical pressure is applied against one ohm of resistance. The
ampere is used to measure electricity much as “gallons per minute” is
used to measure water flow.

AMPERE-HOUR – A unit of measure for battery capacity. It
is obtained by multiplying the current (in amperes) by the time (in
hours) during which current flows. For example, a battery which provides
5 amperes for 20 hours is said to deliver 100 ampere – hours.

AMPLIFIER – A device of
electronic components used to increase power, voltage, or current of
a signal.

AMPLITUDE – A term used to describe the
maximum value of a pulse or wave. It is the crest value measured from
zero.

ANALOG IC – lntegrated circuits
composed to produce, amplify, or respond to variable voltages. They
include many kinds of amplifiers that involve analog – to – digital conversions
and vice versa, timers, and inverters. They are known as Operational
Amplifier Circuits or OP – Amps.

ANALOG
GAUGE – A display device utilizing a varying current to cause a mechanical
change in the position of its needle.

ARMATURE – The movable part of a generator
or motor. It is made up of conductors which rotate through a magnetic
field to provide voltage or force by electromagnetic induction. The
pivoted points in generator regulators are also called armatures.

ARTIFICIAL MAGNETS – A magnet which has
been magnetized by artificial means. It is also called, according to
shape, a bar magnet or a horseshoe magnet.

ATOM – A particle which is the smallest unit of a chemical element.
It is made up mainly of electrons (minus charges) in orbit around protons
(positive charges).

AUXiliARY SPEED SENSOR – The engine speed sensor located
on the engine timing gear cover. It serves as a back – up to the primary
engine speed sensor.

BENDIX DRIVE – One type flywheel engaging device for
a starting motor. It is said to be mechanical because it engages by
inertia.

BREAK – See “Open.”

BRUSH – A device which
rubs against a rotating slip ring or commutator to provide a passage
for electric current to a stationary conductor.

CALIBRATION – The determination or rectification of
the graduations used on a testing instrument.

CAPACITOR – A device which stores electrical
energy. Commonly used for filtering out voltage spikes.

CHARGE – To
restore the active materials in a storage battery by the passage of
direct current through the battery cells in a direction opposite that
of the discharging current.

CURRENT – Movement of electricity along a
conductor. Current is measured in amperes.

CURRENT FLOW – The flow
or movement of electrons from atom to atom in a conductor.

CYCLE –
The change in an alternating electrical sine wave from zero to a positive
peak to zero to a negative peak and back to zero.

CYCLING – The process
by which a battery is discharged and recharged.

DIAGNOSTIC CODE – A number which represents a problem detected by the
engine controller. Diagnostic codes are transmitted for use by on –
board
displays or a diagnostic reader so the operator or technician is aware
there is a problem and in what part of the fuel injection system the
problem can be found.

DIFFERENTIATOR CIRCUIT – A circuit that consists
of resistors and capacitors designed to change a DC input to an AC
output. It is used to make narrow pulse generators and to trigger digital
logic circuits. When used in integrated circuits it is known as an inverter.

DIGITAL IC – lntegrated circuits that produce logic voltage signals
or pulses that have only two levels of output that are either ON or OFF
(yes or no). Some component output examples are: Diagnostic Codes Output,
Pulse – Width – Modulated (PWM) Throttle Output, Auxiliary Speed Output,
and Fuel FlowfThrottle Output.

DIODE – An electrical device that will
allow current to pass through itself in one direction only. Also
see “Zener diode.”

DIRECT CURRENT (DC) – A steady
flow of electrons moving steadily and continually in the same direction
along a conductor from a point of high potential to one of lower potential.
It is produced by a battery, generator, or rectifier.

DISCHARGE – To
remove electrical energy from a charged body such as a capacitor or
battery.

DISTRIBUTOR (IGNITION) – A device which directs
the high voltage of the ignition coil to the engine spark plugs.

DISTRIBUTOR LEAD CONNECTOR – A connection plug in the wires that lead from the sensor in the distributor
to the electronic control unit.

DYER
DRIVE – One type of flywheel engaging mechanism in a starting motor.

ELECTRICAL FIELD – The region around a charged body
in which the charge has an effect.

ELECTRICITY – The flow of electrons from atom to atom
in a conductor.

ELECTROCHEMICAL – The relationship of electricity to chemical changes
and with the conversions of chemical and electrical energy. A battery
is an electrochemical device.

ELECTRO-HYDRAULIC VALVE – A hydraulic
valve actuated by a solenoid through variable voltage applied to the
solenoid coil.

ELECTROLYTE –
Any substance which, in solution, is dissociated into ions and is thus
made capable of conducting an electrical current. The sulfuric acid
– water solution in a storage battery is an electrolyte.

ELECTROMAGNET – core of magnetic material, generally soft iron, surrounded by a coil
of wire through which electrical current is passed to magnetize the
core.

ELECTROMAGNETIC CLUTCH – An electromagnetic device which stops
the operation of one part of a machine while other parts of the unit
keep on operating.

ELECTROMAGNETIC FIELD – The magnetic field about a conductor created
by the flow of electrical current through it.

ELECTROMAGNETIC INDUCTION – The process by which voltage is induced in a conductor by varying
the magnetic field so that lines of force cut across the conductor.

ELECTRON – A tiny particle which rotates around
the nucleus of an atom. It has a negative charge of electricity.

ELECTRON THEORY – The theory
which explains the nature of electricity and the exchange of “free” electrons between atoms of a conductor.
It is also used as one theory to explain direction of current flow in
a circuit.

ELECTRONICS – The control of electrons (electricity) and the
study of their behavior and effects. This control is accomplished by
devices that resist, carry, select, steer, switch, store, manipulate,
and exploit the electron.

ELECTRONIC CONTROL UNIT (ECU) – General term for any electronic
controller. See “controller:’

ELECTRONIC GOVERNOR – The computer program within
the engine controller which deterines the commanded fuel delivery based
on throttle command, engine speed, and fuel temperature. It replaces
the function of a mechanical govnor.

ELECTRONIC IGNITION SYSTEM – A system in which the timing of
the ignition spark is controlled electronically. Electronic ignition
systems have no points or condenser, but instead have a reluctor, sensor,
and electronic control unit.

ELEMENT – (1) Any substance that normally cannot be separated
into different substances. (2) The completed assembly of a battery
consisting of negative plates, positive plates, and separators mounted
in a cell compartment.

ENGINE CONTROLLER – The electronic module which controls fuel delivery,
diagnostic outputs, back – up operation, and communications with other
electronic modules.

FIELD EFFECT TRANSISTOR (FET) – A transistor
which uses voltage to control the flow of current. Connections are
the source (input), drain (output) and gate (control).

FIXED RESISTOR – A resistor which has only one resistance value.

FREOUENCY – The
number of pulse or wave cycles that are completed in one second. Frequency
is measured in Hertz, as in 60Hz (hertz) per second.

FUNDAMENTAL LAW
OF MAGNETISM – The fundamental law of magnetism is that unlike poles
attract each other, and like poles repel each other.

FUSE – A replaceable
safety device for an electrical circuit. A fuse consists of a fine
wire or a thin metal strip encased in glass or some fireresistant material.
When an overload occurs in the circuit, the wire or metal strip melts,
breaking the circuit.

GATE – A logic circuit device which makes a YES or
NO (one or zero) decision (output) based on two or more inputs.

GENERATOR – A device which converts
mechanical energy into electrical energy.

GRID – A wire mesh to which the active materials of a storage
battery are attached.

GROUND – A ground occurs when any part of a wiring circuit
unintentionally touches a metallic part of the machine frame.

GROUNDED CIRCUIT – A connection
of any electrical unit to the frame, engine, or any part of the tractor
or machine, completing the electrical circuit to its source.

GROWLER – A device for testing the armature of
a generator or motor.

H
HYDROMETER – An instrument for measuring specific gravity. A hydrometer
is used to test the specific gravity of the electrolyte in a battery.

IGNITION CONTROL UN IT – The module that contains the
transistors and resistors that controls the electronic ignition.

INDUCTANCE – The property
of an electric circuit by which an electromotive force (voltage)
is induced in it by a variation of current either in the circuit itself
or in a neighboring circuit.

INDUCTOR – A coil of
wire wrapped around an iron core.

INSULATED GATE
FIELD EFFECT TRANSISTOR (IGFET) – A diffused transistor which has an
insulated gate and almost infinite gate – channel resistance.

INSULATOR – A substance or body that resists the flow of electrical
current through it. Also see “Conductor:’

INTEGRATED CIRCUIT (IC) – An electronic
circuit which utilizes resistors, capacitors, diodes, and transistors
to perform various types of operations. The two major types are Analog
and Digital Integrated Circuits. Also
see “Analog
IC” and “DigitaI
IC.”

INTEGRATOR
CIRCUIT – A circuit that consists of resistors and capacitors and functions
as a filter which can pass signals only below a certain frequency.

INVERTER – A device with only one input and one output; it
inverts or reverses any input.

ION – An atom having either a shortage or excess
of electrons.

ISOLATION
DIODE – A diode placed between the battery and the alternator. It blocks
any current flow from the battery back through the alternator regulator
when the alternator is not operating.

LIGHT EMITTING DIODE (LED) – A solid – state display
device that emits infrared light when a forward – biased current flows
through it.

LINES OF FORCE – Invisible lines which conveniently illustrate
the characteristics of a magnetic field and magnetic flux about a magnet.

LIQUID CRYSTAL DISPLAY (LCD) – A display device utilizing a special
crystal fluid to allow segmented displays.

MAGNET – A body which has the property of at. tracting
iron or other magnets. Its molecules are aligned.

MAGNETIC FIELD –
That area near a magnet in which its property of magnetism can be detected.
It is shown by magnetic lines of force.

MAGNETIC FLUX – The flow of magnetism about a magnet exhibited by magnetic lines
of force in a magnetic field.

MAGNETIC INDUCTION – The process
of introducing magnetism into a bar of iron or other magnetic material.

MAGNETIC LINES OF FORCE – Invisible
lines which conveniently illustrate the characteristics of a magnetic
field and magnetic flux about a magnet.

MAGNETIC MATERIAL – Any material to whose molecules the property of
magnetism can be imparted.

MAGNETIC NORTH – The direction sought by the
north pole end of a magnet, such as a magnetic needle, in a horizontal
position. It is near the geographic north pole of the Earth.

MAGNETIC PICKUP ASSEMBLY – The assembly
in a self – integrated electronic ignition system that contains a permanent
magnet, a pole piece with internal teeth, and a pickup coil. These
parts, when properly aligned, cause the primary circuit to switch off
and induce high voltage in the secondary windings.

MAGNETIC SOUTH – The opposite direction from magnetic
north towards which the south pole end of a magnet, such as a magnetic
needle, is attracted when in a horizontal position. It is near the
geographic south pole of the Earth.

MAGNETIC SWITCH – A solenoid which performs a simple function,
such as closing or opening switch contacts.

MAGNETISM – The property inherent
in the molecules of certain substances, such as iron, to become magnetized,
thus making the substance into a magnet

MICROPROCESSOR – An integrated circuit combing logic, amplification
and memory functions.

MILLIAMPERE – 1/1,OOO,OOO ampere.

MOLECULE – A unit of matter which is
the smallest portion of an element or compound that retains chemical
identity with the substance in mass. It is made up of one or more atoms.

MOTOR – A device which converts electric
energy into mechanical energy.

MUL TIMETER – A testing device that can be set to read ohms (resistance),
voltage (force), or amperes (current) of a circuit.

MUTUAL INDUCTION – Occurs when changing current in one coil induces voltage in a second
coil.

NATURAL MAGNET – A magnet which occurs in nature,
such as a lodestone. Its property of magnetism has been imparted by
the magnetic effects of the Earth.

NEGATIVE – Designating or pertaining to a kind of electricity.
Specifically, an atom that gains negative electrons is negatively
charged.

NEUTRON – An uncharged elementary particle. Present in all atomic nuclei except
the hydrogen nucleus.

NON-MAGNETIC MATERIAL – A material whose
molecules cannot be magnetized.

NORMALLY
OPEN and NORMALLY CLOSED – These terms refer to the position taken
by the contacts in a magnetically operated switching device, such as
a relay, when the operating magnet is de. energized.

OHM – The standard unit for measuring resistance to
flow of an electrical current. Every electrical
conductor offers resistance to the flow of current, just as a tube
through which water flows offers resistance to the current of water.
One ohm is the amount of resistance that limits current flow to one
ampere in a circuit with one volt of electrical pressure.

OHMMETER – An instrument
for measuring the resistance in ohms of an electrical circuit.

OHM’S LAW – Ohm’s Law states that when an electric current is
flowing through a conductor, such as a wire, the intensity of the current
(in amperes) equals the electromotive force (volts) driving it, divided
by the resistance of the conductor. The flow is in proportion to the
electromotive force, or voltage, as long as the resistance remains
the same.

OPEN OR
OPEN CIRCUIT – An open or open circuit occurs when a circuit is broken,
such as by a broken wire or open switch, interrupting the flow of current
through the circuit. It is analogous to a closed valve in a water system.

OPERATIONAL AMPLIFIER – A high – voltage gain, low
– power, linear amplifying circuit device used to add, subtract, average,
etc.

OVERRUNNING CLUTCH – One type of flywheelengaging member in a starting motor.

PARALLEL CIRCUIT – A circuit in which the circuit
components are arranged in branches so that there is a separate path
to each unit along which electrical current can flow.

PERMANENT MAGNET – A magnet which retains
its property of magnetism for an indefinite period.

PIEZO ELECTRIC DEVICE – A device made of crystalline
materials, such as quartz, which bend or distort when force or pressure
is exerted on them. This pressure forces the electrons to move.

PLATE – A solid substance
from which electrons flow. Batteries have positive plates and negative
plates.

POLARITY – A collective term applied to the
positive (+) and negative ( – ) ends of a magnet or electrical mechanism
such as a coil or battery.

POLE – One or two points of a magnet at which its magnetic attraction
is concentrated.

POLE SHOES – Iron blocks fastened to the inside of a
generator or motor housing around which the field or stator coils are
wound. The pole shoes may be permanent or electro – magnets.

POSITIVE – Designating or pertaining
to a kind of electricity. Specifically, an atom which loses negative
electrons and is positively charged.

POTENTIOMETER – A variable resistor used as a voltage divider.

POWER
SWITCH TRANSISTOR – The part responsible for switching off the primary
circuit that causes high voltage induction in the secondary winding
in an electronic ignition system.

PRIMARY SPEED SENSOR – An engine speed
sensor located inside the actuator housing on the back of the injection
pump.

PRINCIPLE OF TURNING FORCE – Explains how magnetic force acts on a current – carrying conductor
to create movement of an armature, such as in an electric motor.

PRINTED CIRCUIT BOARD – A device used to hold integrated
circuit components in place and provide current paths from component
to component. Copper pathways are etched into the board with acid.

PROTON – A particle which,
together with the neutron constitutes the nucleus of an atom. It exhibits
a positive charge of electricity.

PULSE – A signal that is produced by a sudden ON and OFF of direct current
(DC) within a circuit.

PULSE-WIDTH-MODULATED (PWM) – A digital electronic
signal which consists of a pulse generated at a fixed frequency. The
information transmitted by the signal is contained in the width of
the pulse. The width of the pulse is changed (modulated) to indicate
a corresponding change in the information being transmitted, such as
throttle command.

RECTIFIER – A device (such as a vacuum tube, commutator, or diode) that
converts alternating current into direct current.

REGULATOR – A device
which controls the flow of current or voltage in a circuit to a certain
desired level.

RELAY – An electrical coil switch that uses a small current
to control a much larger current.

RELUCTANCE – The resistance that a
magnetic circuit offers to lines of force in a magnetic field.

RELUCTOR – A metal cylinder, with teeth or legs, mounted on the distributor
shaft in an electronic ignition system. The reluctor rotates with the
distributor
shaft and passes through the electromagnetic field of the sensor.

RESISTANCE – The opposing or retarding force offered by a circuit or component
of a circuit to the passage of electrical current through it. Resistance
is measured in ohms.

RESISTOR – A device usually made of wire or carbon
which presents a resistance to current flow.

RHEOSTAT – A resistor used
for regulating a current by means of variable resistance; rheostats
allow only one current path.

RIGHT-HAND RULE – A method used to determine
the direction a magnetic field rotates about a conductor, or to find
the north pole of a magnetic field in a coil.

ROTOR – The rotating
part of an electrical machine such as a generator, motor, or alternator.

SELF-INDUCTION – Voltage which occurs in a coil when there is a change
of current.

SEMICONDUCTOR – An element which has four electrons in the
outer ring of its atoms. Silicon and germanium are examples. These elements
are neither good conductors nor good insulators. Semiconductors are used
to make diodes, transistors, and integrated circuits.

SENDING UNIT – A
device, usually located in some part of an engine, to transmit information
to a gauge on an instrument panel.

SENSOR – A small
coil of fine wire in the distributor on electronic ignition systems.
The sensor develops an electromagnetic field that is sensitive to the
presence of metal. In monitors and controllers, they sense operations
of machines and relay the information to a console.

SEPARATOR – Any of
several substances used to keep one substance from another. In batteries
a separator separates the positive plates from the negative plates.

SERIES CIRCUIT – A circuit in which the parts are
connected end to end, positive pole to negative pole, so that only
one path is provided for current flow.

SERIES-PARALLEL CIRCUIT – A circuit in which some of
the circuit components are connected in series and others are connected
in parallel.

SHORT (OR
SHORT CIRCUIT) – This occurs when one part of a circuit comes in contact
with another part of the same circuit, diverting the flow of current
from its desired path.

SHUNT – A conductor joining two points
in a circuit so as to form a parallel circuit through which a portion
of the current may pass.

SLIP
RING – In a generator, motor, or alternator, one of two or more continuous
conducting rings from which brushes take, or deliver to, current.

SOLENOID – A tubular coil used for producing a magnetic field. A solenoid
usually performs some type of mechanical work.

SOLID-STATE CIRCUITS – Electronic (integrated) circuits which utilize semiconductor devices
such as transistors, diodes and silicon controlled rectifiers.

SPARK PLUGS – Devices which ignite the fuel by a spark in
a spark – ignition engine.

SPECIFIC GRAVITY – The ratio of a weight of any volume of a substance
to the weight of an equal volume of some substance taken as a standard,
usually water for solids and liquids. When a battery electrolyte is
tested the result is the specific gravity of the electrolyte.

SPRAG CLUTCH DRIVE – A type of flywheel engaging device for a starting motor.

STARTER MOTOR – A device that converts electrical
energy from the battery into mechanical energy that turns an engine
over for starting.

STATOR – The stationary part of an alternator in which another part (the rotor)
revolves.

STORAGE BATTERY – A group of electrochemical cells connected
together to generate electrical energy. It stores the energy in a chemical
form.

SULFATION – The formation of hard crystals of lead sulfate on battery
plates. The battery is then “sulfated.”

SWITCH – A device which
opens or closes electrical pathways in an electrical circuit.

SYNCHROGRAPH – An all – purpose distributor tester.

TACHOMETER – An instrument for measuring rotary speed;
usually revolutions per minute.

TEMPORARY MAGNET – A magnet which loses its property of
magnetism quickly unless forces act to re – magnetize it.

THERMISTOR – A temperature –
compensated resistor. The degree of its resistance varies with the
temperature. In some regulators, it controls a Zener diode so that a
higher system voltage is produced in cold weather, when needed.

TRANSFORMER – A device made of two coil windings that transfers
voltage from one coil to the next through electromagnetic induction.
Depending upon the number of windings per coil, a transformer can be
designed to step – up or step – down its output voltage from its input
voltage. Transformers can only function with alternating current (AC).

TRANSIENT VOLTAGE PROTECTION
MODULE (TVP) – A device which protects the engine controller electronics
against high energy voltage transients such as alternator load dumps.

TRANSISTOR – A device constructed of semi
– conductors that is used in circuits to control a larger current by
using a smaller current for operation. Its function is the same as
a relay.

TRIMMER RESISTOR – A resistor used
in applications where only a small resistance change is needed.

VACUUM FLORESCENT DISPLAY (VDC) – An anode – controlled
display which emits its own light. It works like a television tube,
directing streams of electrons to strike phosphorescent segments.

VARIABLE RESISTOR –
A resistor that can beadjusted to different ranges of value.

VISCOSITY – The internal resistance of a fluid, caused by molecular
attraction, which makes it resist a tendency to flow.

VOLT – A unit of electrical
pressure (or electromotive force) which causes current to flow in a
circuit. One volt is the amount of pressure required to cause one ampere
of current to flow against one ohm of resistance.

VOLTAGE – That force which is generated to cause current to flow in
an electrical circuit. It is also referred to as electromotive force
or electrical potential. Voltage is measured in volts.

VOLTAGE REGULATOR – A device that controls the strength of a magnetic field produced
by a generator or alternator. It prevents the battery from being overor
undercharged during high – or low – speed operation of the generator
or alternator.

VOLTMETER – An instrument for measuring
the force in volts of an electrical current. This is the difference
of potential (voltage) between different points in an electrical circuit.
Voltmeters are connected across (parallel to) the points where voltage
is to be measured.

WATT – A unit of measure for indicating the electrical
power applied in a circuit. It is obtained by multiplying the current
(in amperes) by the electrical pressure (in volts) which cause it to
flow. That is: watts = amperes x volts.

WATT-HOUR – A unit of electrical energy.
It indicates the amount of work done in an hour by a circuit at a
steady rate of one watt. That is, watthours = ampere – hours x volts.

WAVE – A signal that is produced
by varying a continuous flow of current within a circuit. Waveforms
can be created by either AC or DC current.

WAVEFORM – A graphical representation ofelectrical cycles which shows
the amount of variation in amplitude over some period of time.

WINDING – The coiling of a wire about itself or about some object. Often identified
as a series winding, a shunt winding, etc.

WIRING HARNESS – Thf3 trunk and branches which feed an electrical circuit. Wires from
one part of the circuit enter the trunk, joining other wires, and then
emerge at another point in the circuit.

ZENER DIODE (Reverse Bias Direction Diode) – A semiconductor
device that will conduct current in the reverse direction when the
voltage becomes higher than a predetermined voltage.