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Depending on the nature of the elements through which it passes, electric current can have several physical effects:

Effect

Description

Application Examples

Thermal Effect

  • When a current pass through a material with electrical resistivity, electrical energy is converted into thermal (heat) energy.
  • Lighting, electric heating.


Chemical Effect

  • When a current is passed between two electrodes in an ionic solution, it causes an exchange of electrons, and thus matter, between the two electrodes. This is electrolysis: the current caused a chemical reaction.
  • The effect can be reversed: by performing electrolysis in a container, a chemical reaction can create electrical current.
  • Current creates chemical reaction: metal refining, electroplating.
  • Chemical reaction creates current: batteries, storage cells.

Magnetic Effect

  • Electric current passing through a copper rod produces a magnetic field.
  • The effect can be reversed: turning an electric motor mechanically produces current.
  • Current produces a magnetic field: electric motors, transformers, electromagnets.
  • Magnetic field produces current: electric generators, bicycle dynamos.

Photovoltaic Effect

  • When light or other radiant energy strikes two dissimilar materials in close contact produce an electrical voltage.
  • Solar cell to produce electricity.

Adapted from MSF

Electrical Installations and Circuits

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  • 50 oscillations per second in Europe (50Hz),
  • 60 oscillations per second in the US (60Hz).

AC is the type of current supplied by electric utility companies because AC voltage can be increased and decreased with a transformer. This allows the power to be transported through power lines efficiently at high voltage and transformed to a lower, safer, voltage for use into businesses and residences. Therefore, it is the form of electrical energy that consumers typically use when they plug an appliance into a wall socket.

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There are two types of AC:





Single-Phase

A single-phase current is the most common type of current, and thus is usually the configuration delivered by public networks, but also by a single-phase generator. A single-phase AC current is supplied via two lines (phase and neutral), usually with a 220 V voltage difference between them. Plugs can be inserted in both ways.

Because the voltage of a single-phase system reaches a peak value twice in each cycle, the instantaneous power is not constant and is mainly use for lighting and heating but cannot work with industrial motors.

A single-phase load may be powered from a three-phase distribution transformer allowing single-phase lighting to be connected phase-to-neutral and three-phase motors to be connected to all three phases. This eliminates the need of a separate single-phase transformer.





Three-Phase

Once Power needs are increased, in the use of large electrical motor for example, constancy and balance pay a key role. Three-phase is the common current configuration for electricity companies, and can also be produced with a three-phase generator. A three-phase current is the combination of three single phase currents.

To carry a given power with 3 separate single-phase cables, 9 wires are needed. To carry the same power in a three-phase cable, only 5 wires are required (3 phase, 1 neutral, 1 ground), which it is why there can be significant savings when properly planning a three-phase current: saving on wires, cables, and also in apparatus using or producing electricity: three phase motor or alternator will be smaller than the same power produced by three single phase equivalent units.

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