ELECTRIC SYMBOLS
By: Sanchit Kanwar
Class: X-C
Roll No: 26
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What Are Electric Symbols?
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• An electronic symbol is a pictogram used to
represent various electrical and electronic
devices (such as wires, batteries, resistors,
and transistors) in a schematic diagram of an
electrical or electronic circuit.
Standards For Symbols
There are several national and international standards
for graphical symbols in circuit diagrams, in particular:
• IEC 60617 (also known as British Standard BS 3939)
• IEEE Std 91/91a
• ANSI standard Y32 (also known as IEEE Std 315)
• Australian Standard AS 1102
Different symbols may be used depending on the
discipline using the drawing. For example, lighting and
power symbols used as part of architectural drawings
may be different from symbols for devices used in
electronics. National and local variations to
international standards also exist.
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“ Soon now, the faint tinkling of a
broken filament will become
another sound of another
century.
Jane Brox, Brilliant: The Evolution of Artificial Light
Various Electric symbols
”
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Wire
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A
wire is a single flexible
strand or rod of metal. Wires
are used to pass current very
easily from one part of the
circuit to another.
Wire Junction
Wire Not connected
GROUND

Ground or earth can refer to the
reference point in an electrical
circuit from which voltages are
measure. A common return path
for electric current or a direct
physical connection to the Earth.
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Chess ground
SIGNAL
GROUND
Power source


(1). Fixed power source: The free DC
output is fixed to a constant voltage level
by using a voltage controller. If it is used
to produce DC, a rectifier is used to
convert alternating voltage to direct
voltage.
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FIXE
D
(2). Variable power source: An AC
power supply typically takes the voltage
from mains supply and lowers it to the
desired voltage
Variable
AC CURRENT SOURCE:
 AC is the form in
which electric power is
delivered to businesses and
residences. In alternating
current the flow of electric
charge continually changes
the direction.
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DC CURRENT SOURCE:
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Direct current (DC) is the unidirectional flow of electric
charge. Direct current is produced by sources such as
batteries, thermocouples, solar cells.
Direct current is used to charge batteries, and in nearly
all electronic systems, as the power supply.
Cell
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 It
supplies electrical energy.
The larger terminal (on the
left) is positive (+) while the
smaller (on the right) is
negative (-). A single cell is
often called a battery, but
strictly the battery is two or
more cell joined together.
Battery
Solar Cell

It converts light
energy into
electrical energy.
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Battery
A
battery
supplies
electrical energy to the
circuit. It is like cell but
the difference is that cell
is considered as one but
the battery is considered
more than one cell.
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Switches
1. Push switch: A push switch allows
current to flow only when the
button is pressed like switch in
door bell.
2. Push to break switch: This type
of switch is normally closed i.e. on.
It is open only when button is
pressed.
3. SPST: Single Pole, single Throw:
An on—off switch allows current
to flow only when it is closed.
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Switches
4.
SPDT: Single Pole, Double
Throw: They are described as on
off on switch.
5. DPST: Double Pole, single
Throw: A dual on off switch often
used to switch main electricity.
6. DPDT: Double Pole, Double
Throw: They are used in motors.
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Bulb
 It
provides the light when
electric current passes
through it. A light bulb
produces light with a
filament wire heated to a
high temperature by an
electric current passing
through it until it glows.
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Lamp

(a).It is the lighting lamp transducer
which converts electrical energy to
light. This symbol is used for a lamp
providing illumination.
e.g. A car head lamp or torch bulb.

b. It is the indicating transducer that
converts electrical energy to light. This
symbol is used for a lamp which is an
indicator.
e.g. A warning light on cars dashboard
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Fuse
A fuse is a special kind of
resistor that acts as short
circuit (0 resistances) unless
the current exceeds the rated
value. If the current exceeds
a rated value the fuse blows
and acts as an open circuit
(an infinite resistance).
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Circuit Breaker

The circuit breaker is a The circuit
breaker is a mechanical switching
device capable of protecting the
circuit wiring, capable of making,
carrying and breaking currents under
normal circuit conditions and also
making, carrying for a specified time
and
breaking
currents
under
specified abnormal circuit conditions
such as short circuit.
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Resistor
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 Fixed Resistor: This type of resistor
resists the flow of current.
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Variable Resistor: This type of resistor
is used to control the current known as
rheostat.
Variable Resistor Potentiometer: This
type of resistor consist of 3 contacts. It is
used to control the voltage.
Variable resistor Preset: Preset
resistors are used in circuits when it is
necessary to alter the resistance.
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3
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Diodes

A device which is
only allows current to
flow in one direction.

It has low (ideally
zero) resistance to
current flow in one
direction, and high
(ideally
infinite)
resistance
in
the
opposite direction.
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Photo diode

It is a light sensitive diode.

Photodiode
allows current
when exposed to light.

A photodiode is capable
flow
of converting light into either current or
voltage, depending upon the mode of
operation
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LED
LED stands for (light
emitting diode). It is a semiconductor
light
source.
LED’s are used in general
lightning, traffic signals and
are
used
in
advance
communication technology.
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LDR

LDR stands for (light dependent
resistor) made up of semi conductor,
they are useful in light/dark sensor
circuits. Normally the resistance of an
LDR is very high, sometimes as high
as

1000000 ohms, but when they are
illuminated with light resistance drops
dramatically.
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RCD
A residual - current device
(RCD) is an electrical wiring
device that disconnects a circuit
whenever it detects that the
electric current is not balanced
between
the
energized
conductor and the return neutral
conductor.
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HEATER

An electric heater is an
electrical appliance that
convert electrical energy
into heat .The heating
element inside every
electric heater is simply
an electrical resistor, and
works on the principle of
Joule heating.
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GENERATOR

An electric generator is a
device that
converts
mechanical
energy to electrical energy.
A generator forces electric
current to flow through an
external circuit. The source
of mechanical energy may
be
a
reciprocating
or turbine steam engine,
water falling through
a turbine.
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MOTOR

An electric motor is an electric
machine that converts electrical
energy into mechanical energy.

In normal motoring mode, most
electric motors operate through the
interaction between an electric
motor's magnetic field and winding
currents to generate force within
the motor.
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Transformer

A transformer is a static electrical device that
transfers energy by inductive coupling
between its winding circuits. A varying
current in the primary coil creates a varying
magnetic flux in the transformer's core and
thus a varying magnetic flux through the
secondary coil.

This varying magnetic flux induces a varying
electromotive force (emf) in the secondary
coil. Transformers can be used to vary the
relative voltage of circuits or isolate them, or
both.
Better if OPTIONS ARE SELECTED in slide show
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