1ELECTRIC SYMBOLS

By: Sanchit Kanwar

Class: X-C

Roll No: 26

2What Are Electric Symbols?

• 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.

3Standards 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

5Wire

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

6GROUND

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.

 

SIGNAL GROUND

Chess ground

7Power 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.

(2). Variable power source: An AC power supply typically takes the voltage from mains supply and lowers it to the desired voltage

FIXED

Variable

8AC 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.

9DC CURRENT SOURCE:

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.

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Cell

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

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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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Switches1. 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

Fixed Resistor: This type of resistor resists the flow of current.

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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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 flow when exposed to light.

A photodiode is capable

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 semi-conductor 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 mode!!! TRY!!

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