© SOCOTEC 2012 - D82101 - E12 - Diaporama S01 T01 -D1/D26

ELECTRIC UNITSELECTRIC UNITS

© SOCOTEC 2012 - D82101 - E12 - Diaporama S01 T01 -D2/D26

The electric principles

What are the different electric source you kwnow ?

© SOCOTEC 2012 - D82101 - E12 - Diaporama S01 T01 -D3/D26

There is two sources :

Direct current Alternative current

The electric principles

+ -

ACCU FLASH

12 V

Dynamo

Alternateur

© SOCOTEC 2012 - D82101 - E12 - Diaporama S01 T01 -D4/D26

Direct current sources are polarized with positive and negative poles

Direct current

Direct current could be produced by an electrochemical generator like a battery or by a swinging device like a dtnamo or by cells.

+ -

ACCU FLASH

12 V

Dynamo

© SOCOTEC 2012 - D82101 - E12 - Diaporama S01 T01 -D5/D26

Uses of direct current

The direct current is used to supply electric devices like portable electric drills or electric vehicles…

© SOCOTEC 2012 - D82101 - E12 - Diaporama S01 T01 -D6/D26

Direct current representation

The direction of electrons is always the same

© SOCOTEC 2012 - D82101 - E12 - Diaporama S01 T01 -D7/D26

Alternative current sources

Un Alternateur produit l’électricité

il transforme une énergie mécanique en énergie électrique

En général, on utilise la force de l’eau ( centrale hydraulique ) ou de la vapeur ( centrale thermique ou nucléaire ) pour faire tourner une turbineMais, on peut utiliser la force du vent ( les éoliennes )

We can also use mechanical energy produced by thermical engine, that what we calle a generator.

© SOCOTEC 2012 - D82101 - E12 - Diaporama S01 T01 -D8/D26

Alternative current sources

The alternative current is generally used for houses and company electrical installations.

© SOCOTEC 2012 - D82101 - E12 - Diaporama S01 T01 -D9/D26

Alternative current representation

Le Courant Alternatif change de sens périodiquement Une Période se divise en deux Alternances

The frequency of alternative current match with the number of period per seconds.

The frequency is express in Hertz.

© SOCOTEC 2012 - D82101 - E12 - Diaporama S01 T01 -D10/D26

Parallel of water : the Voltage

The Voltage is an electric potential difference

Is similar to a level difference

The Voltage (U) is express in VOLT (V)

© SOCOTEC 2012 - D82101 - E12 - Diaporama S01 T01 -D11/D26

Parallel of water : the current intensity (amperage)

The Amperage is similar to a throughput

The current intensity ( I ) is express in Amp ( A )

© SOCOTEC 2012 - D82101 - E12 - Diaporama S01 T01 -D12/D26

Parallel of water : electric resistance

The electric resistance is similar to pipes sections

The electric resistance ( R ) is express in OHM ( Ω )

© SOCOTEC 2012 - D82101 - E12 - Diaporama S01 T01 -D13/D26

Ohm’s law

Volatge ( U ), electric resistance( R ) and intensity ( I )

are linked by the Ohm’s law:

U = R x I

Exercice : What will be the intensity value of a current passing through a 100 Ω device supplied by a 12 V source?

© SOCOTEC 2012 - D82101 - E12 - Diaporama S01 T01 -D14/D26

The unitsThe units

© SOCOTEC 2012 - D82101 - E12 - Diaporama S01 T01 -D15/D26

Units

What units are in this light bulb ?

Volt

watt

© SOCOTEC 2012 - D82101 - E12 - Diaporama S01 T01 -D16/D26

Units

What units are in this fuse ?

Intensity - Amp

© SOCOTEC 2012 - D82101 - E12 - Diaporama S01 T01 -D17/D26

Units

What units are in this speaker ?

8 Ω resistance - Ohms